Sciencemadness Discussion Board

toluene --> benzaldehyde

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Hilski - 31-1-2007 at 17:28

I distilled the aldehyde from the reaction with the brownish Mn alum, and the yields were actually a bit higher than normal, say 10 -12%. But, yields of the red tar were also quite a bit higher than normal, and not as much toluene was recovered during the post reaction work up. I also tried to "over regenerate" the mixture again, and I wasn't very successful as getting the brownish colored solution. There were some brown 'swirls' mixed in with the red solution, but not nearly as pronounced as before. I don't know what the difference is now. There may be too much organic material left in the cell, which is reducing any of the brown IV valence oxidizer as soon as it is formed.
I think I'm going to focus on making a functional setup to produce the brown persulfate oxidizer for the time being. I would like to see how much the yields improve in proportion to any extra effort needed to use this oxidizer as opposed to the red alum.

jimmyboy - 31-1-2007 at 22:10

has anyone actually tried the dry distillation of calcium formate + calcium benzoate - seems it would be cheaper and easier to go this direction - formic acid is easy to get as well as benzoic acid... i wonder what the yields are..

womble - 1-2-2007 at 18:40

Just mix the two (both food additives aren't they?) and heat?

acetone cyanohydrin

chemrox - 7-2-2007 at 18:30

did anyone mention acetone cyanohydrin ala Vogels?

not_important - 7-2-2007 at 21:07

Quote:
Originally posted by jimmyboy
has anyone actually tried the dry distillation of calcium formate + calcium benzoate - seems it would be cheaper and easier to go this direction - formic acid is easy to get as well as benzoic acid... i wonder what the yields are..


Usually not that good, the aldehyde group gets trashed too easily; better when making aromatic ketones. The method was used before the reduction of the acid chloride and the various ways using oxidation of a methyl group came into use.

Organikum - 8-2-2007 at 01:20

Well I made benzene and propiophenone this way, benzene with very good and propiophenone with good (>50%) yields.

But not from the calcium salts (for benzene it was tried but gave unsatisfactory yields). Sodium salts for benzene and ferric salts for propiophenone IIRC.

The trick in these dry distillations is the heat transfer, a problem I solved by adding coarse steelwool to the mixture.

I liked these experiments very much, last not least for the dry distillations actually worked for me.

Didnt think about making b-dehyde this way as I had no source of formic acid at this time, but hey! I have seen it for sale cheap & OTC lately in this wonderful Drogerie & Chemie shop I discovered by accident, next to the ether and stuff.

Thanks for bringing this up!

/ORG

not_important - 8-2-2007 at 01:35

Benzene from benzoic acid is an aromatic decarboxylation, while the aromatic and other ketones usually are a condensation to a beta-keto acid, followed by decarboxylation of that. Different reactions going on. For the ketones calcium, barium, manganese, and occasionally iron, salts were the choices to go with. The alternative is to pass the free acids over a heated oxide, thorium being the most common but manganese and calcium being used as well.

The aldehydes are yet another reaction, and as the resulting aldehyde is fairly reactive the yields tend to be lower than for the ketones. From some reading I did years ago, you can tune the conditions to optimise yields, in some cases becoming respectable, but a rather tedious process to get there. But when the acids are cheap and easy to get, it's worth trying.

S.C. Wack - 8-2-2007 at 02:24

The older literature does say that the yields for benzaldehyde are bad from formate/benzoate. Inert gas flow or at least flushing out oxygen, and experiments with different cations would be a good idea if one wanted to try it.

Organikum - 8-2-2007 at 02:40

I referred to the benzene synthesis mainly for the similarity of the technique as I posted this in the benzene thread. Solvent can and coarse steelwool and this.

The synthesis of P2P from phenylacetic acid and acetic acid via the lead salts by dry distillation is a classic, yields are told to be >70% when mild vacuum is applied and the reaction is done on a decent scale.
Propiophenone from benzoic acid and propionic acid via the iron salts (black magnetic iron powder as used as concrete pigment works, no reduced iron needed) works well too, >50% yield without vacuum and on a comparable small scale (800ml solvent can as reactor).
I have little doubt that b-dehyde can be made this way in good yields. I dont think that oxygen is a big issue, but if one thinks so then adding some sodium bicarb at the bottom of the reactor should take nicely care of this, the CO2 evolved upon heating should drive out the oxygen.
Oxydation in the condensor is probably a bigger issue - I would recommend to use a short copper condensor and to prevent air circulation in the condensor.

nightflight - 15-2-2007 at 12:55

Quote:
Originally posted by technologist
May be an Stupid Question?
Can I make it using Benzene & some aldehyde or ....May be any other route leaving Toluene.

_________________________________
Visit my Blog - http://profmaster.blogspot.com


Yes there´re, also not very common yet, making use of the DMSO and protonating it to a kation which will form a substitutionproduct with an 1° or 2° alcohol in a swern like oxidation.

Starting compund for benzaldehyde would be benzylalcohol, DMSO can be activated by acetic anhydrid, oxalchlorid (swern-oxidation) or dicyclohexylcarbodiimid by -20°C at least and addition of a water-scavenger.

Anyone wants to try?:cool:


The mosdt simple way may be Benzylacohol ->MnO2 +CH2Cl/Me(OH) to benzaldehyde and Mn(OH)
[Edited on 15-2-2007 by nightflight]

[Edited on 15-2-2007 by nightflight]

nightflight - 11-3-2007 at 09:40

Experimental: Betonite (catlitter) and KMnO4 were ground in equal amounts until purple turned to light violet and all was ground to dust and a mol ratio of 0.1 Toulene and 0,4 KMnO2 was measured out.

It was then put into a pyrex beaker and irradiated for 25min. on 1/2 power, until a gleaming of the mixture was noticed after 7min. and heating was stopped.

It was all dried out and all the tolly evapped.

[Edited on 12-3-2007 by nightflight]

Coldfinger - 11-3-2007 at 12:40

any references?

roamingnome - 11-3-2007 at 20:41

the references could bare your name... if aldehyde is what you think happened and wanted...
permanganate at an oxidation state of 7+
the clay would be absorbing water and microwaves....

did you smell any cherries...? at any time.... it may have flown out as it was made...

benzoic acid..?
shoot, you could mix anything.and something will happen.
the problem is finding out what happened.

nightflight - 13-3-2007 at 05:58

Quote:
Originally posted by Kinetic
A quick search for toluene to benzaldehyde gave me - unsurprisingly - a lot of hits. The extract from the article below is a solvent-free oxidation with potassium permanganate supported on montmorillonite, but does not suffer from the particularly large amounts of oxidant often required for such transformations. Still, it isn't a procedure you'd use on a large scale. The following is exemplified for indane -> indanone, with the same procedure giving benzaldehyde in 60% yield in 18h when applied to toluene. Taken from Tetrahedron Letters, 43, 5165-5167 (2002):


2.1. Oxidation of indan under classical conditions
Potassium permanganate (3.16 g, 20 mmol) and montmorillonite K10 (6 g) were ground together in a mortar until a fine homogeneous powder was obtained. Indan (0.24 g, 2 mmol) was added to this KMnO4/K10 mixture (4.5 g, 9.9 mmol) in a 25 mL round bottomed flask and mixed magnetically at room temperature until TLC (eluent: hexane–ethyl acetate) analysis indicated a completed reaction (20 h). The residue was then washed with CH2Cl2 (2×20 mL). After filtration and removal of the solvent, the crude product was chromatographed on silica gel (eluent: hexane–ethyl acetate) to give purified product (0.22 g, 1.7 mmol, 85%)


Using microwave irradiation, as below, gave benzaldehyde in 54% yield in 12 minutes:

2.3. Oxidation of tetralin under microwave irradiation
In a 25 mL Teflon beaker, tetralin (0.26 g, 2 mmol) was added to KMnO4/K10 (4.5 g, 9.9 mmol). After 3 min of mechanical stirring, the mixture was irradiated at medium power for 25 min. At the end of exposure to microwave irradiation, the mixture was cooled to room temperature and eluted with CH2Cl2 (2×20 mL). After filtration and solvent removal the crude product was chromatographed on silica gel (eluent: hexane–ethyl acetate) to give purified product (0.24 g, 1.7 mmol, 82%).


Some other references for the oxidation of toluene to benzaldehyde are:

Synthetic Communications, 29(7), 1177-1182 (1999), using sodium bromate and cerium dioxide;

Tetrahedron Letters, 28(10), 1067-1068 (1987), using ceric methanesulfonate (91% yield);

DE168291, in which 'air and water' is used;

DE127388, using nickel oxide (edit: duh, of course this is the same as posted by S. C. Wack above);

DE101221 (which appears to be the one cited by Orgy as DE102221), DE107722 and Journal of the Chemical Society, 91, 263 (1907), using manganese dioxide and sulfuric acid;

DE158609, using cerium dioxide and sulfuric acid;

and DE175295, using 'manganese dioxide sulfate'.

That's pretty much it for the easy to get reagents. I haven't read any of the papers (partly as I don't speak German) so I'll keep my fingers crossed that they are of use.

[Edited on 17-1-2005 by Kinetic]

this reference.:(
No, no smell of benzaldehyd or benzoic, just tolly and cat-litter smell.

I did a search on converting phenylalanine to benzaldehyd, which I heard of anywhere, but didn´t find anything, could sopmeone please help out? It´s so sad if I had to buy it instead of generating it myself.

[Edited on 13-3-2007 by nightflight]

guy - 18-3-2007 at 15:13

Just a question. How do the Cu and Fe catalysts work? What is the mechanism?

Filemon - 4-4-2007 at 16:59

Quote:
Originally posted by S.C. Wack
There are of course a jillion ways to do things...they all have some disadvantage or other...even in the dark


Does it mean that the benzal bromide forms peroxides with the H2O? Is the benzal bromide been accustomed to room temperature?

Sauron - 4-4-2007 at 20:29

In the Oxidation of ethanol thread, the use of nickel peroxide (aka nickel oxide hydroxide) arose, which can be catalytic or used stochiometrically or in excess. The reagent is in either case generated in situ from nickel salt and common 5% Na hypochlorite bleach, and is a black insoiluble solid.

A review I dug up mentions early on the use of nickel peroxide to oxidize toluene to benzaldehyde so I thought I would call this to you attention. Apologies all around if this has been brought up in this thread before.

If not, anyone want the review?

Polverone - 4-4-2007 at 21:03

It appears that S.C. posted an old German patent early in this thread that mentions the use of this nickel compound or a closely related one, but I don't read German. I would appreciate having the review that you have.

Sauron - 4-4-2007 at 21:11

Your wish is my commend.

The review cites German Patent 127,388 of 1900, which may be same as @S.C. posted. This appears to be first use of this reagent. Toluene is oxidized to benzaldehyde and benzoic acid.

Reference 11 from this review concerns among other things the use of nichel peroxide to selectively oxidize benzyl alcohol to benzaldehyde under mild conditions.

I have already obtained this in full text as I finally mastered the trick of getting ACS journals to give up their pdf's. Want this one as well?



[Edited on 5-4-2007 by Sauron]

Attachment: cr60296a004[1].pdf (1.6MB)
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S.C. Wack - 5-4-2007 at 04:07

The patent says little, as far as I can tell. NiO(OH) is made from a nickel salt + hypochlorite or alkali/halogen; and 300 kg toluene + 150 kg "dry" NiO(OH) are heated to 100C for 5-6 hours, the reduced nickel cpd. is filtered, and the mystery yield of benzaldehyde isolated by bisulfite or steam distillation. CoO(OH) also works.

There would be little surprise if the isolated yields are in the single digits.

I suspect that the other review mentioned is an older Chem Rev from vol. 38 (1946). BTW it and the above Ni oxide review are part of my 65 selected Chemical Reviews available via ftp.

Sauron - 5-4-2007 at 05:05

True enough, that 1900 German patent failed to mention yield.

Not so however the J.Org.Chem. article cited in the CR review as Ref. 11 and hereby attached.

Benzyl alcohol is smoothly and very selectively oxidized by only a slight excess (1.1-1.2 eq based on available oxygen) in 3 hours at 50 C in a yield of >90% and with only a slight recovery of unreacted benzyl alcohol or benzoic acid. This reaction is carried out in benzene as solvent. Other solvents such as ether or pet.ether as possible.

Unfortunately for the acetaldehyde thread, oxidation of ethanol in organic solvent gives very poor results, while oxidation in aq. alkaline soln gives high yields of acetic acid.

I would like to also call your attention to another J.Org.Chem article concerning the use of same reagent on a catalytic basis (2.5 mol%) rather than in stoichiometric amounts. This is instructive by comparison and might perhaps be extended to the topical problem of this thread. Such application at this time is purely speculative.

J.M.Grill, J.W.Ogle, S.A. Miller, J.Org.Chem. 71, 9291 (2006)

which I will be happy to post if anyone wants to see it.

[Edited on 5-4-2007 by Sauron]

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tupence_hapeny - 20-4-2007 at 13:28

Here is one which I have yet to see here, it uses trichloroisocyanuric acid to chlorinate toluene (using catalytic quantities of benzoyl peroxide) in 44% yield, but without photo/etc.

http://pubs.acs.org/cgi-bin/abstract.cgi/joceah/1970/35/i03/...

The resultant benzyl chloride apparently is mixed only with unreacted toluene (as unlike other experiments there are no mention of side-products). This appeals, as it would appear that most people can get hold of goodly amounts of tri/dichloroisocyanuric acid (or its sodium salt). Benzoyl peroxide is available (try the catalyst/hardener for automotive putty/bog - generally ~50%wv).

Of rather more importance, here is a relatively recent article on the two-phase chlorination of toluene, using (sorry my bad, I originally wrote trichloroethylene, thinking of something else entirely;)) chloroform/water and salt - which proceeds in ~90% conversion and almost total selectivity. The beauty of this procedure is that there is no need for hydrochloric acid (or exotic chlorinating agents) the Chlorine is generated in situ from the electrolysis of the upper aqueous layer, and apparently passes through the interface between the layers quite well.



[Edited on 21-4-2007 by tupence_hapeny]

[Edited on 21-4-2007 by tupence_hapeny]

Attachment: Electrochemical Chlorination Toluene (2-Phase), Electrochemica Acta (2005).pdf (108kB)
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Sauron - 20-4-2007 at 17:02

Both look interesting.

44% yield is not so impressive, but might be useful for the chemically challenged who cannot obtain TCT.

TCCA does seem to be ubiquitous.

TCT/DMF and benzyl alcohol ->benzyl chloride 100%.

Anyone making BzCl is going to need a good hood.

Hmmm. You forgot to mention a wee detail. Your 44% chlorination of toluene w/TCCA ONLY RUNS IN CCl4. In absence of carbon tetrachloride, TCCA with either of the two catalysts (FeCl2 or H2SO4) produced ONLY mixed o- and p-chlorotoluenes in modest yields 45-66% and no benzyl chloride.

That takes it right out of the OTC category and dumps it in the UNOBTAINIUM file. CCl4 is no longer available in most countried OTC and is restricted (by special license only) for academic or industrial users, just like chloroform and Tric, Perc, ethylene dichloride etc. Is this not the case where you are? It's the bloody environmentalist assholes at work.

Waste of time!

Some nice references in there, re TCCA iand THF -> GBL. Well maybe not so nice. 19% yld, ugh.




[Edited on 21-4-2007 by Sauron]

tupence_hapeny - 20-4-2007 at 23:54

Quote:
Hmmm. You forgot to mention a wee detail. Your 44% chlorination of toluene w/TCCA ONLY RUNS IN CCl4. In absence of carbon tetrachloride, TCCA with either of the two catalysts (FeCl2 or H2SO4) produced ONLY mixed o- and p-chlorotoluenes in modest yields 45-66% and no benzyl chloride.

That takes it right out of the OTC category and dumps it in the UNOBTAINIUM file. CCl4 is no longer available in most countried OTC and is restricted (by special license only) for academic or industrial users, just like chloroform and Tric, Perc, ethylene dichloride etc. Is this not the case where you are? It's the bloody environmentalist assholes at work.


I noticed that only after you pointed it out, however, I assume another solvent could be utilised to make this work? For instance, how does chloroform cope with benzoyl peroxide? Alternatively, wouldn't trichloroethylene be just as effective? Particularly if, as would appear likely, it was converted to the tetrachlor in situ? (I ask this last question as I have access to gallons of trichlor for stuff all (electrical cleaning solvent) and would really like to know if it would be able to be used instead of chloroform in the electrolytic chlorination procedure).

Personally, I would probably convert the benzyl chloride directly to benzyl alcohol (rxn with water), and then oxidize that to benzaldehyde. The two step approach would appear preferable, given the consistent low yields experienced by all trying to establish 1 step approaches. Anyhow, this is my opinion, if someone wants to direct me to a 80+% conversion & yield, 1 step approach, I would obviously prefer that - then again, so would industry:)

PS the catalyst for the reaction is Benzoyl peroxide, I do not suggest using the H2SO4 or FeCL2, however - we have a problem with the solvent only.

BTW, this would appear to, at least, partially validate your proposal that TCCA could be useful for the preparation of acyl chlorides, especially given that this route is essentially the same as another which uses the same system, albeit with sulfuryl chloride (but still toluene & benzoyl peroxide) to prepare benzyl chloride. This would suggest that TCCA is a fairly useful chlorinating agent, of the same category as sulfuryl chloride, thionyl chloride, etc.

I have attached an article, detailing the uses of 2,4,6-Trichloro-1,3,5-triazine (aka 2,4,6-trichloroisocyanuric acid, cyanuric chloride is the cyclic version of cyanuric acid (altered as there was ambiguity - not a good thing on this board:))).

ENJOY:P

[Edited on 21-4-2007 by tupence_hapeny]

[Edited on 21-4-2007 by tupence_hapeny]

Attachment: Recent Applications of TCICA in Organic Synthesis (2006) 62 Tetrahedron 9507–9522.pdf (418kB)
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Sauron - 21-4-2007 at 00:05

Both chloroform and trichloroethane are just as verboten as carbon tet here and I fgather in most places in the world.

DCM has a much lower bp and cannot achieve the required reaction temps

In short maybe obe can find a replacement solvent, and maybe not. At the minimum, this turns a literature prep into a research project.

Nicodem - 21-4-2007 at 00:23

Quote:
Originally posted by tupence_hapeny
For instance, how does chloroform cope with benzoyl peroxide? Alternatively, wouldn't trichloroethylene be just as effective? Particularly if, as would appear likely, it was converted to the tetrachlor in situ?

No, trichloethylene would be a bad choice. Besides nobody sane of mind would use CCl4 or any other solvent for a preparative benzylic chlorination of toluene with TCCA when the reaction proceeds just as well with excess toluene as solvent. Why would you want to add something as nasty as CCl4 or just any other things that would just complicate the fractionation in the reaction workup?
Quote:
Anyhow, this is my opinion, if someone wants to direct me to a 80+% conversion & yield, 1 step approach, I would obviously prefer that - then again, so would industry:)

Benzyl chloride can be consistently oxidized to benzaldehyde with >80% yield. Where did you see claims to otherwise?
Quote:
PS the catalyst for the reaction is Benzoyl peroxide, I do not suggest using the H2SO4 or FeCL2, however - we have a problem with the solvent only.

Benzoyl peroxide is not a catalyst in the above mentioned chlorination. It is only a radical initiator required to induce a change in the chlorination mechanism. You can use sun light or a mercury lamp instead. H2SO4 and FeCl3 have no place in this preparation since they would cause the consumption of TCCA by ring chlorination of toluene before any benzyl chloride would form. It would also be a bitch to separate o- and p-chlorotoluene from benzyl chloride, so make sure there are no such acids present in the reaction mixture.
Quote:
BTW, this would appear to, at least, partially validate your proposal that TCCA could be useful for the preparation of acyl chlorides, especially given that this route is essentially the same as another which uses the same system, albeit with sulfuryl chloride (but still toluene & benzoyl peroxide) to prepare benzyl chloride. This would suggest that TCCA is a fairly useful chlorinating agent, of the same category as sulfuryl chloride, thionyl chloride, etc.

What are you talking about? You can not use TCCA per se for chlorination of carboxylic acids to acyl chlorides. It can only do so in the presence of triphenyl phosphine and similar "aprotic" reducents, but why would anybody want to use TCCA/Ph3P for that when POCl3, SOCl2, oxalyl chloride and such would be way more practical (not to mention cyanuric chloride that Sauron keeps promoting so annoyingly at any opportunity he gets). You can use TCCA instead other chlorinating oxidants like sulfuryl chloride or Cl2 in many cases, but certainly not instead thionyl chloride or POCl3. Have you confused something again?

Sauron - 21-4-2007 at 00:54

I think tup does not know the difference between TCCA and TCT (CC), that's all. Also he does not know the difference between a "proposal" for a carboxylic acid chlorination method and a solidly documented literature method for the last 30 years.

@Nicodem, why do you find my "promotion" of TCT annoying? I find it versatile and useful, it is inexpensive and easily handled, and readily available except in EU. It can be used to prepare valuable reagents otherwise difficult to access by purchase. Like oxalyl chloride and acetyl chloride, and acetic anhydride by extension; propionyl chloride, etc. By comparison many of the reagents you propose above are simply outlawed in many places without a special government dispensation. Thionyl chloride, phosphoryl chloride both CWC listed. In this country I'd have to kiss the ass of the MOD for a permit to import those. And that would be unlikely to be granted. A large corporation or a government university MIGHT get such a permit. No permit reqd for TCT. TCT can do many of the dehydration and condensation reactions of POCl3. It can be used to prepare alkyl chlorides, bromides and iodides as well as acyl chlorides. It converts ketoximes to amides and aldoximes to nitriles (Beckmann) under very mild conditions.

So I think as long as I keep finding new uses for TCT/CC not yet discussed on this forum or underdiscussed, I will just go on "annoying" you. You act as if you think I get a royalty or commission on every Kg TCT sold, instead of just trying to post useful and practical information for the members.

---------

For a change of pace here are not one but two preparations of benzaldehyde using TCCA (sorry, @Nicodem, not TCT) in moderate yield

1. slight excess benzyl ethyl ether + TCCA -> benzaldehyde 53% + ethyl benzoate <5%

Stirred 15 hrs @ 3 C and in presence of an excess of water.

2. Benzyl alcohol + TCCA -> benzaldehyde 53%

3 C, stir, time not given. Excess of water present.

Thanks for the correction @Nicodem - misreading on my part.

The benzyl alcohol route is the more interesting as the benzyl ethyl ether would be less common/more expensive and would be prepared from the alcohol most likely anyway.



[Edited on 21-4-2007 by Sauron]

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Nicodem - 21-4-2007 at 01:43

Quote:
Originally posted by Sauron
@Nicodem, why do you find my "promotion" of TCT annoying?
...
You act as if you think I get a royalty or commission on every Kg TCT sold, instead of just trying to post useful and practical information for the members.

You said it! It does not matter if it is not true. What matters is that you persistently try to make it look this way. Obviously, cyanuric chloride is a very useful reagent, not just for making herbicides, but especially for members here who want to make acid chlorides and have no access to SOCl2 or POCl3. I certainly do not mind reading as much literature about it as possible. But do you just have to exaggerate so much in its promotion? Do I have to note that lately you have been promoting it, for example, even for things like preparation of benzyl chloride from benzyl alcohol when something as OTC as hydrochloric acid suffices? If that can not be considered an annoying exaggeration, then I just don't know what it is. I can understand Tupence's propositions in making simple preparations as complex as they can get since he obviously knows practically nothing about organic chemistry and even less so about practical chemistry, but you often like to do the same.

Quote:
For a change of pace here are not one but two preparations of benzaldehyde using TCCA (sorry, @Nicodem, not TCT) in moderate yield

1. slight excess Phenetole (phenyl ethyl ether) + TCCA -> benzaldehyde 53% + ethyl formate <5%

It is benzyl ethyl ether (PhCH2OEt) and not phenethole. And the side product is ethyl benzoate and not ethyl formate.

tupence_hapeny - 21-4-2007 at 01:47

@Nicodem,

Benzyl Chloride most assuredly can be oxidised to benzaldehyde in over 80% yield, I agree, that was not my point. My point was that Toluene can not be oxidised directly to benzaldehyde in anything like that yield, thus the suggested two-step process.

http://pubs.acs.org/cgi-bin/abstract.cgi/iecred/1990/29/i07/...

@Sauron,

I have not been able, until I carried out my own research (which has taken more time than I really have to give) to find all that many references to what you state is a known process? This is fine, however, as the simple fact is, mild reactions with available reagents appeal to me (and to many others) and I don't mind doing my own research. I became interested in the idea, basically because of your continued references to the same, do you have any further details or references?

However, given that I have only just managed to access some recent literature, which details the resurgent interest in this reagent (also 1,3-dihalo-5,5-dimethylhydantoin) - I have only just managed to find the references which were lacking in your previous posts regarding this procedure. I feel sure that others here, beside myself, would be interested in such procedures - especially if specific details were forthcoming?

That said (also note that I edited my previous post regarding the differences between cyanuric chloride and trichloroisocyanuric acid), I have begun to encounter a number of papers, detailing the uses of this reagent. Nicodem is partially correct, quite a few proceed only in the presence of triphenyl phosphite(?), although it appears that others do not require the same.

I am not here to piss in anyones pocket (please DO trust me on that - I have NO reason to be overly fond of either Sauron or Nicodem), quite frankly, I started researching the topic because it appeared somewhat farfetched and improbable. I am however, only interested in the application of the same and the chemistry, if it works it will be a fucking great day for me and others - who quite frankly, haven't a snowballs chance in hell of being allowed to buy PCl3/PCl5/POCl3 either now or at any time before hell freezes over.

Lets keep to the science, I ain't interested in your egos

PS Nicodem, I thought you would have read the Electrochemica Acta article? Are you suggesting that the author really utilized a solvent when excess toluene would have done just as well? I find that hard to believe, which is unusual, as you are normally very informative and honest, albeit somewhat spiteful at times?

Nicodem - 21-4-2007 at 01:58

Quote:
Originally posted by tupence_hapeny
PS Nicodem, I thought you would have read the Electrochemica Acta article? Are you suggesting that the author really utilized a solvent when excess toluene would have done just as well? I find that hard to believe, which is unusual, as you are normally very informative and honest, albeit somewhat spiteful at times?

What are you talking again? I was replying to your discussion about CCl4 as a solvent in the benzylic chlorination of toluene by Juenge et al.

PS: Try to UTFSE about TCCA. You will find many papers and relevant threads.

Sauron - 21-4-2007 at 02:04

@tup, I have POSTED quite a few articles here on TCT/CC so UTFSE!

I have not posted any that require triphenylphosphine, which reagent is a pain in the ass to use. It requires scrupulous drying and air-free handling or it either fails, or oxidizes to triphenyl phosphate in a New York minute.

As the search engine sucks, if you can't find them I will assemble the links and PM the list to you.

Google will reveal a lot of activity with TCT/CC.

TCCA is also quite interesting, but not as stategically so IMO as TCT. TCCA is much more OTC.

Nothing to do with egos. I liked your posted articles in this thread, and was sorry to have had to poke a hole in that one, but there it was to be poked. So maybe you should read your chosen articles before putting them up, eh? I know the temptation is great to post first and study later when something looks promising. But that can come back to bite you.

Lots of people are confused by distinction between TCT and TCCA so that is nothing to be concerned about. They are quite similar and both derive from cyanuric acid. But they have very different chemistries, one being a N-chloro compound and the other being essentially an acid chloride.

tupence_hapeny - 21-4-2007 at 02:07

Nicodem,

Quote:
What are you talking again? I was replying to your discussion about CCl4 as a solvent in the benzylic chlorination of toluene by Juenge et al.


I presume that this statement attempts to answer the question that I asked on the previous page, for your benefit therefore, I will provide a direct quote of the same, where the question was asked:

Quote:
I ask this last question as I have access to gallons of trichlor for stuff all (electrical cleaning solvent) and would really like to know if it would be able to be used instead of chloroform in the electrolytic chlorination procedure


For those that have not read the article that was cited, it refered to a 2-phase electrolytic chlorination of toluene, which was in chloroform (and stirred at 40rpm) while the top (aqueous phase) contained deionised water and NaCl and two (platinum) electrodes and was not stirred.

I realise that I may have confused you, for which I apologise, however, as this is (for mine) the simplest, high yielding method of converting toluene to benzyl chloride (I don't care how OTC HCl is, NaCl is even more so). Now I reiterate the original question, is it possible to use trichloroethylene instead of chloroform?

However, and just so that I do not appear to utterly spiteful and horrid, here is an article which supports your statement re.PPh3 being necessary for some such reactions with acids to acyl chlorides.

[Edited on 21-4-2007 by tupence_hapeny]

Attachment: Mild One-Pot conversion of Acid to Acid Chloride PPh3 & TCCA (2005) 46 Tet Let 5945.pdf (103kB)
This file has been downloaded 10277 times


Organikum - 21-4-2007 at 02:12

Quote:
Originally posted by Sauron
Both look interesting.

44% yield is not so impressive, but might be useful for the chemically challenged who cannot obtain TCT.

TCCA does seem to be ubiquitous.

TCT/DMF and benzyl alcohol ->benzyl chloride 100%.

Anyone making BzCl is going to need a good hood.

Hmmm. You forgot to mention a wee detail. Your 44% chlorination of toluene w/TCCA ONLY RUNS IN CCl4. In absence of carbon tetrachloride, TCCA with either of the two catalysts (FeCl2 or H2SO4) produced ONLY mixed o- and p-chlorotoluenes in modest yields 45-66% and no benzyl chloride.

That takes it right out of the OTC category and dumps it in the UNOBTAINIUM file. CCl4 is no longer available in most countried OTC and is restricted (by special license only) for academic or industrial users, just like chloroform and Tric, Perc, ethylene dichloride etc. Is this not the case where you are? It's the bloody environmentalist assholes at work.

Waste of time!

Some nice references in there, re TCCA iand THF -> GBL. Well maybe not so nice. 19% yld, ugh.




[Edited on 21-4-2007 by Sauron]


Adding TCCA in small chunks to 5-fold excess of almost boiling toluene with a small amount of HCl added under irridation of a 150W halogen lamp without UV protection produces Benzylchloride in decent yields. The main problem was the separation of the product/toluene from the cyanuric acid which is IMHO very hard to filter.
Upon addition of alcohol/water + hexamine benzaldehyde is formed in good yields. I think I posted this already.

The HCl is necesssary to initiate the reaction. Without it one can add a lot of TCCA without much going to happen and suddenly when the reaction kicks in one is confonted with a very unpleasant runaway.
When the reaction does not kick in after the first chunk is added, add more HCl (30% is ok, alternativly one can mix conc. HCl with toluene let this sit for some hours and separate. Some HCl will be go into in the toluene and use this) DONT ADD MORE TCCA!
The addition of chunks of TCCA to almost boiling toluene with a halogen lamp next is NOT trivial. Using a longer glasstube on the sideneck is strictly advised. A good condensor is also necessary, a Liebig does not suffice, a spiral does.

The reaction goes quick and smooth, the workup was unpleasant. If somebody has a good method for filtration of precipitated cyanuric acid - tell. Gravity filtration methods are preferred.

For the used subtrates are cheap and abundant yields are actually not so very important, the procedure is not without dangers though - be careful.

The large excess of toluene prevents most of polychlorination.


Been there done that.
Works.

/ORG

Nicodem - 21-4-2007 at 02:20

Organikum, I think your method produces a lot of ring chlorinated toluene as well. Did you perform any kind of analysis of the product?

Edit: Tupence, my answer about solvents was equally valid for that Indian method. When adapting an experimental procedure to a preparative one you don't want to make it more complex, dangerous and expensive, you want the opposite. I thought that needed not to be emphasized.

[Edited on by Nicodem]

tupence_hapeny - 21-4-2007 at 02:23

Thanks organikum,

I honestly looked and did not find that in the search engine, shit, I thought I had 'DISCOVERED' something:(

Honestly though, I was mainly looking to drum up interest in the electrochemical process, I mean now I have limited access to decent journals, I may be able to contribute something? Anyhow, please have a look at the electrochem article, it appears promising, although I would obviously prefer to use an OTC solvent.

Sauron - 21-4-2007 at 03:27

@Nicodem, I think it is you who is stretching a point. While I have no doubt that conc HCl can chlorinate benzyl alcohol, I'd like to hear representative time, temperature and yield details.

Whereas I can tell you that for TCT/DMF those are

15 minutes
ambient temp (stirring only)
100% purified yield (quantitative.)

So if I needed a Kg BzCl I'd choose TCT/DMF

And If I wa a clandustrialist I might favor an economical method to make some much larger quantity.

I have studies the comparative costs of other chlorinating reagents for the conversion of acetic acid to acetyl chloride and TCT always comes out as cheapest. It is easy to figure why.

TCT three active chlorines Low price
Benzoyl chloride one active chlorine, low price
Phthaloyl chloride two active chlorines high price

The last two are used in 50-100% excess, TCT is used in stoichiometric fashion on basis of active chlorines (2 or 3)

It is possible with effort to make one's own phthaloyl chloride (as I posted) and this levels out cost to about same as benzoyl chloride if certain assumptions are made and labor cost is ignored.

But TCT still comes out cheaper EVERY time. Also it is applicable to less volatile acid chlorides whose bp's are too close to benzoyl or phthaloyl chloride to make those possible.

In the end the choice of reagent is a personal/professional one and no one can force anyone to use this or that. I am not selling TCT. I am merely enthusiastic about it. Allow me my enthusiasms.

Nicodem - 21-4-2007 at 03:35

Quote:
Originally posted by Nicodem
Organikum, I think your method produces a lot of ring chlorinated toluene as well. Did you perform any kind of analysis of the product?


Organikum, nevermind, I reconsidered. The small amount of water introduced with hydrochloric acid is able to catalyze the ring chlorination to some extent, but on second thought I realized that the vapors of toluene would carry most moisture with the azeotrope out of the reaction mixture before it would do much harm. And I also only now noticed that you actually found a way to avoid this problem by partitioning toluene with conc. HCl as an alternative to adding conc. HCl directly to the reaction mixture.

PS: Cyanuric acid filters just nice using vacuum filtration. Maybe you use too fine filter paper? Alternatively you could try adding just enough water in ethanol (1.5ml H2O per 10g of TCCA used) to form the more crystalline cyanuric acid dihydrate which is even much easier to filter.

Sauron - 21-4-2007 at 03:38

Yep. benzal diacetate helped in Org.Syn as well.

But thanks for the comment.

Hilski - 21-4-2007 at 20:20

Quote:
My point was that Toluene can not be oxidised directly to benzaldehyde in anything like that yield

Um, yes.....it can.

Nicodem - 22-4-2007 at 03:37

Quote:
Originally posted by tupence_hapeny
PS Nicodem, I thought you would have read the Electrochemica Acta article? Are you suggesting that the author really utilized a solvent when excess toluene would have done just as well? I find that hard to believe, which is unusual, as you are normally very informative and honest, albeit somewhat spiteful at times?

You still need to learn the difference between an experimental and a preparative procedure. In a preparative procedure one would not use CHCl3 as solvent, but just an excess of toluene while in an experimental one it is not advisable to do so.
You do not even need a particularly efficient distillation column for separating benzyl chloride from the unreacted toluene – the boiling points are well apart.
Anyway, though it is an Indian paper, it is surprisingly well written and might actually be genuine and reproducible. Try it out and report back if you got any tears from benzyl chloride. :D

Organikum - 23-4-2007 at 01:57

Quote:
Originally posted by Nicodem
Quote:
Originally posted by tupence_hapeny
PS Nicodem, I thought you would have read the Electrochemica Acta article? Are you suggesting that the author really utilized a solvent when excess toluene would have done just as well? I find that hard to believe, which is unusual, as you are normally very informative and honest, albeit somewhat spiteful at times?

You still need to learn the difference between an experimental and a preparative procedure. In a preparative procedure one would not use CHCl3 as solvent, but just an excess of toluene while in an experimental one it is not advisable to do so.
You do not even need a particularly efficient distillation column for separating benzyl chloride from the unreacted toluene – the boiling points are well apart.
Anyway, though it is an Indian paper, it is surprisingly well written and might actually be genuine and reproducible. Try it out and report back if you got any tears from benzyl chloride. :D
I am not so sure about this. Besides the the funny way they create chlorine in situ this article says that wet toluene can be monochlorinated at the sidechain at rather low temperatures with only small amounts of ringchlorinated inpurities and that in excellent yields. Either this is facilated by the cosolvent - chloroform - or it is utter bullshit for being in contradiction to the most basic literature of organic chemistry, Vogel, Gattermann and who not else, who say that HIGH temperatures facilate sidechainchlorination, low temperature ringchlorination.
Also I thought that further chlorination of the sidechain is only to prevent by a large excess of toluene, how comes that this stops at the BzCl here. It´s either the chloroform or it is just another indian bullshit.

Not to speak of the nice task to stir one layer without disturbing the boundaries of the two layers + running a electrolysis in the other layer. Now thats not trivial one might believe.

Or did I get something wrong again?

Sauron - 23-4-2007 at 02:25

Maybe they added some curry as a PTC.

tupence_hapeny - 23-4-2007 at 17:57

Tally ho,

ummmm, I have to go elsewhere for the next month or so (family issues), I will attempt this procedure whilst at the alternative venue (using trichloroethylene and another run with excess toluene). The bitch is going to be the anode/cathode materials (not having a surplus of Pt foil:o - I will try with stainless steel and carbon/graphite).

It is going to be a BITCH to build a mag-stirrer which is controllable to the point of doing just 40rpm - but, providing I can do so - I intend to give this a shot, as it is quite possibly the easiest route I have seen (providing the fucking thing is reproducible).

BTW, I did not notice where the bloody thing was written - are they really that dodgy?

tup

PS I hope my password will work when I get back;)

PPS @ Sauron, what curry would you recommend? IMHO a korma or rogan josh would be preferable - seems that they would be easier to stir - although a good spicy curry would be a valuable adjunct in hiding the fumes of the benzyl chloride:D

@ Nicodem, thank you for your assistance and words of wisdom

& @ Organikum, what can I say - one just has to trust refereed journals sometimes - I know it looks odd, but so does my recent find where H2 is generated in situ (in reductive amination via Al powder with Pt/C).

At everyone, as I am somewhat amateurish at the hands on aspect of this stuff, could someone else try this shit? I mean, if I fail (and that is only too likely) that is hardly representative of whether or not the reaction works in the hands of someone who knows what they are doing, is it?

Nicodem - 24-4-2007 at 03:14

Quote:
Originally posted by Organikum
I am not so sure about this. Besides the the funny way they create chlorine in situ this article says that wet toluene can be monochlorinated at the sidechain at rather low temperatures with only small amounts of ringchlorinated inpurities and that in excellent yields. Either this is facilated by the cosolvent - chloroform - or it is utter bullshit for being in contradiction to the most basic literature of organic chemistry, Vogel, Gattermann and who not else, who say that HIGH temperatures facilate sidechainchlorination, low temperature ringchlorination.
Also I thought that further chlorination of the sidechain is only to prevent by a large excess of toluene, how comes that this stops at the BzCl here. It´s either the chloroform or it is just another indian bullshit.

Not to speak of the nice task to stir one layer without disturbing the boundaries of the two layers + running a electrolysis in the other layer. Now thats not trivial one might believe.

Or did I get something wrong again?

Your doubts are reasonable. There are indeed a couple of suspicious things in that paper. The one that you mention is not even the strangest one since benzylic positions can be chlorinated at room temperature, just not with chlorine. In the system they use (NaCl/H2SO4) there forms not only chlorine, but also appreciable amounts of Cl2O which is able to chlorinate toluene to benzyl chloride even at room temperature in the slightest presence of a radical initiation (light) or heat. However, where there is Cl2O and water together there are also present highly electrophilic species that chlorinate toluene by electrophilic substitution so their >90% benzylic selectivity is extremely suspicious.
I don't think chloroform has any role in the mechanism. If that would be the case the authors would not miss the opportunity to describe its importance for the outcome as that would make their paper look better. It is just a standard inert solvent used only so that their method could appear as having prospects for generality in benzylic chlorination. Besides this way they can claim 85% conversion even though the current efficiency is lower. If describing an experiment with excess toluene as solvent they could not note the conversion which is very important for the experimental of the paper.
Their mechanistic proposition sucks in that it smells of the ancient "nascent gas" theory that was debunked already several decades ago.
Stirring without getting the organic phase over the electrodes is in my opinion not that important in a preparative approach where the current density on the electrode surface needs not to be constant. I think one can just stir normaly provided that the electrode surfaces are high enough to compensate for the drops of the non-conducting organic phase that sticks to the surface (provided also that the electrodes are made of an inert material).
Quote:
Originally posted by tupence_hapeny
I will attempt this procedure whilst at the alternative venue (using trichloroethylene and another run with excess toluene). The bitch is going to be the anode/cathode materials (not having a surplus of Pt foil - I will try with stainless steel and carbon/graphite).

Didn't I already told you that trichloroethylene is a bad idea? Though it is quite an inert alkene due to the inductive effects of the chlorines, it is nevertheless an alkene. Benzylic chlorinations proceed by a radical mechanism so you certainly don't want to add anything into the reaction mixture that quenches radicals.
In this case stainless steel does not work for the anode.
Quote:
At everyone, as I am somewhat amateurish at the hands on aspect of this stuff, could someone else try this shit?

There are other simpler and full proof methods to obtain benzyl chloride so I'm afraid it is up to you to check the validity of this one.

IPN - 26-4-2007 at 09:54

Finally got some TCCA to do some chlorinations with and as I inspected the product it had some blue specs in it (came as 200g pucks). Checking the MSDS revealed that it contains only 92% TCCA, rest being 4% CuSO4 and 4% Al2(SO4)3. :(
Any ideas on how to purify it? Recrystallization perhaps? Or do I even need to bother trying to purify it?

Rosco Bodine - 26-4-2007 at 11:00

Sounds like an algaecide there for the copper and
a flocculent for the aluminum sulfates , which will
precipitate as hydroxide when water pH is cycled basic , dragging any particulates from the water with it
by " sliming them " and then getting filtered out . Under acid pH reaction conditions , both should be pretty inert .

Hilski - 26-4-2007 at 16:00

Man, oxidation with Mn salts is so much easier and reproducible that I can't think of any reasons to go the BzCl route.

Sauron - 26-4-2007 at 19:19

I'd try finding the TCCA without the inorganic additives.

Otherwise, just find a solvent that dissolves the TCCA readily and does not touch the ionic solids, filter them off, and recover the TCCA.

It's a nuisance, though.

Nicodem - 26-4-2007 at 21:27

Quote:
Originally posted by IPN
Finally got some TCCA to do some chlorinations with and as I inspected the product it had some blue specs in it (came as 200g pucks). Checking the MSDS revealed that it contains only 92% TCCA, rest being 4% CuSO4 and 4% Al2(SO4)3. :(
Any ideas on how to purify it? Recrystallization perhaps? Or do I even need to bother trying to purify it?

You could dissolve it in ethyl acetate, filter and evaporate. Do not use acetone since CuSO4 and Al2(SO4)3 might catalyze its oxidation with TCCA to chloroacetone due to their acidity!
Alternatively you could ground it very finely and wash the inorganics with water and let it dry. This will never completely remove them, but will remove most of it. Besides this, much of TCCA will decompose to dichloroisocyanuric acid by hydrolysis to HClO unless you somehow manage to dry it very quick.

PS1: But why don't you just buy TCCA without additives? Surely it must be available. I never saw it being sold with additives anyway.

PS2: Hilski is right about it. Going trough benzyl chloride is one of the least sensible routes from toluene to benzaldehyde. But if benzyl chloride is what you need, then chlorination of toluene with TCCA is one of the most sensible routes. Not as sensible as benzyl alcohol with HCl, but toluene at least is as cheap and available as it can get and the same is true about TCCA.

IPN - 27-4-2007 at 04:56

Thanks for the input. :)
Unfortunately the company which sold me the TCCA said that because of lack of sales with the non-additive version it was discontinued. I could get it from sigma-aldrich in pure form but the price is quite high.

I'll try purifying with ethyl acetate to get some purer product. I do need some benzyl chloride but as Hilski said it's much easier to use Mn salts to oxidize toluene if one needs benzaldehyde.
Main reason to get the TCCA was to make chlorobenzene in large amounts to experiment with the derivatives of 2,4-dinitrochlorobenzene.

garage chemist - 27-4-2007 at 05:00

You can always use the impure TCCA to make chlorine, which would be the best use for it.
From that you can make chlorobenzene very easily.

Nicodem - 27-4-2007 at 08:04

Quote:
Originally posted by IPN
Main reason to get the TCCA was to make chlorobenzene in large amounts to experiment with the derivatives of 2,4-dinitrochlorobenzene.

You do not need to remove the Cu/Al sulfate additives for the electrophilic chlorination of benzene. These additives will do no harm. However, for the benzylic chlorination of toluene you better make your self some clean TCCA. You might try another shop or another supplier before cleaning it by yourself.

Filemon - 30-4-2007 at 16:02

Quote:
Originally posted by garage chemist
An advantage of bromine is that benzotribromide cannot be formed. So you get nearly quantitative yields of benzal bromide when using a stochiometric amount of bromine (don't forget that half of the bromine is evolved as HBr!).
C6H5-CH3 + 2 Br2 -----> C6H5-CHBr2 + 2 HBr
No special initiators are needed, just slowly add the bromine to refluxing toluene irradiated with bright light.

The disadvantage of bromine is that formation of ringbrominated derivatives is promoted, because the reaction will take longer and cannot be made as hot as the reaction with chlorine (think about the boiling point of bromine).
So the produced benzaldehyde would have to be fractionated thoroughly in order to seperate bromobenzaldehyde.
It is also crucial that the toluene be distilled before use! Any iron contamination will totally screw up the reaction.

For industry, bromine is too expensive, so only methods using chlorine have been used.

But in the laboratory, bromine has the very important advantage of convenience.
All the reagents are liquid, and can be mixed in every desired proportions.
The ringbrominated byproducts can be seperated by fractional distillation, this step would be needed with chlorine too because of the formation of benzotrichloride.

In the lab, bromine is the better choice.

[Edited on 15-11-2005 by garage chemist]


Which the best way is of making that reaction? I had planned to use benzene like solvent for the generated HBr. Is a good idea?

Filemon - 3-6-2007 at 17:06

Quote:
Originally posted by S.C. Wack

benzyl bromide and sodium nitrate: US1272522


Are there it has proven this method?

jackson2004 - 3-7-2007 at 19:27

benzaldehyde is not really worth synthesising,
it is so easily available, no watched, at least no in the UK and quite cheap

benzyl bromide and sodium nitrate theory looks promising,
but benzyl bromide cost same as benzaldehyde anyway.
If fact i pay slightly more for benzyl bromide

ewok_poacher - 8-9-2007 at 00:46

Quote:
Originally posted by solo
Recently Wizard X found this little pearl and made it available over at WD..........solo

Quote:

Phenylalanine when heated in 5N sodium hydroxide at 110~115° for 5
hours, it decomposes forming benzaldehyde.


...........as reported at,

http://www.ajinomoto.co.jp/amino/e_aminoscience/bc/amino_13....

[Edited on 27-7-2005 by solo]



Has anyone tried this ??

Siddy - 9-10-2007 at 20:50

has anyone tried some thing like:

ALL IN SITU`

Toluene -1mole
Ca(OCl)2 -1mole (or just under)
MnO2 - 2-5moles
H2SO4 - 2moles (just enough to MnO2 > MnSO4)

Into a RB flask, refluxed with UV light for 10hrs.

Im thinking, the small amount of Benzyl Chloride will easily be oxidized to Benzaldehyde by the MnSO4 and as it is used the Benzyl Chloride equilibrium will shift to produce more. Giving a higher yeilding methold for benzyl chloride. Remaining benyl chloride that isnt oxidised could later be added to anther mix.

Any ideas?

p.s. im trying the benyl bromide + sodium nitrate first.

p.p.s. with the cost of phenylalanine whats the point of the about method? even if it did work.

Antwain - 11-10-2007 at 12:48

I can't see how that would work. And MnSO4 is NOT an oxidising agent.

Also, for chlorination, the equilibrium sits far to the right, I believe, and only the rate of reaction may be slow.

roamingnome - 11-10-2007 at 13:03

"Into a RB flask, refluxed with UV light for 10hrs"

in regards to UV lite which is always appealing, there is a paper that deals with the use of zeolites, toulene, and molecular oxygen under irradation to form the aldehyde
since the reactant is traped in a cage it only takes one allowable pathway....

http://pubs.acs.org/hotartcl/chemtech/96/jun/jun.html

without the cage a mixture of products resulting from radical pathways results in alcohols and such. probabilty is played out in a distribution of products.

Siddy - 11-10-2007 at 15:49

Ive read that, and similar zeolite based patents. Problem is, where can you get zeolite?

My, ALL IN SITU post was based on the original idea's of this thread, which i think are dead because of bad yeilds. Anyway, that reaction mix didnt work (as you predicted).

How about this:

Benzyl Bromine + Nitromethane anion > Benzaldehyde + ?

n.b. nitromethane anion is prepared from nitromethane and base, NaOH.
Ive searched high and low and i think this is the first time its been written on the internet but it seams a documented method in books. McMurry Organic and others.
There is no yield in McMurry, but ill do some testing and find out what happens. Thought id throw it up here before i start so someone else could have a try.

Im going to use Br2 to make Benzyl Bromide with a equal molar weight added to toluene with presence of UV. No other catalyst. Also, HBr (b.p. -66C) pipes (to release pressure) into dry EtOH. To make EtBr. (trying to kill 1 and a half birds with a liquid Br2 stone.

p.s. i dont know what the "?" is, i only just found this reaction and havent even written it down on paper.

Ephoton - 18-12-2007 at 22:54

your going to use nitoalkanes for what a simple somellet type reaction you have to be joking me

Ephoton - 18-12-2007 at 23:00

so much about uv and manganese how many have done it. some I know of me included. give it up unless you get the electro route down in my opinion manganese is truly a shitty reagent to work with dirty on your hands.
dirty on your work surfaces dirty for forensics. they will love ya for eva. I must say that I am a bit attracted to the idea of persulfate oxidations they sound rather neat and clean though I have yet to have on work for me.
ive always had the halide formation then sommelet work for me every time. its just the halegenation thats the problem. its smelly and its very very irratating to the lungs nose and eyes. but im look at iodine these days.
honestly its fully recylable and thats got to be a plus even if its dear to get. got to love the fact that my horses are dumb asses and cant help running into barb wire fences all the time.

Siddy - 24-12-2007 at 04:37

If there is a better method for Benzaldehyde, it would be used over nitroalkanes. Nitromethane is cheap (for me), so is NaOH, yes its using a lot of precursers but the only other method is cinnamaldehyde, which is $200/L (for me).

A note on MnO2 reactions, just because you go to your hardware store and buy black cement dye, does not mean its MnO2, it could be a lot of other oxides. I think very early on in this thread people where getting 0% benz. they probably had CuO2.

Ammonium Persulphate/Silver Something Toluene, 65C, 30mins

Panache - 1-3-2008 at 23:25

I remember reading somewhere in this thread or elsewhere about a method utilising ammoniumpersulphate (around 360g), toluene(around 60g), some 0.1M silver something solution and stirring at 65C for 30mins.
I have all these chemicals at hand, and a desire for almond cordial, if someone can find the exact details (yes i have UTFSE but it sucks big cocks) i will bash out a couple of trials tomorrow to satiate all those interested. Otherwise I won't. 8)

LSD25 - 2-3-2008 at 06:27

This I got from a google result - Synthetikal:

Quote:
Elbs Persulfate Oxidation Patent (IndoleAmine)
I think I have what you're looking for - the thing is called "Elbs persulfate oxidation" and uses ferrous, cupric and/or silver salt catalysts together with sodium persulfate in the oxidation of toluene or (benzyl alcohol) to benzaldehyde....

Patent US4146582 "Process for preparing aromatic aldehydes and ketones", P.Maggioni filed Jan. 31, 1977:

page 4, example 9:

"p-Anisaldehyde

Ferrous-copper catalyst: Anisic alcohol (50g), ferrous sulfate heptahydrate (0.3892g), copper acetate (0.7783g), demineralized water (100ml) and methanol (40ml) are placed in a reactor.
The temperature of the rection mixture is raised to 80°C and a flow of nitrogen is fed to the reactor under fierce agitation while drip feeding a solution of sodium persulfate (103.4g of Na2S2O8 in 335ml of H2O). The reaction is complete within two hours. The products are extracted with diethyl ether and, after evaporation of the solvent, 0.8g of anisic alcohol and 43.86g of p-anisaldehyde are obtained by distillation at 100mm Hg.
The yield of p-anisaldehyde with respect to the reaczted anisic alcohol is 90.5%."

...some time ago, a friend told me he had had this strange dream involving BzOH, some lab glassware, some turquoise and green salts and much of a white, stinging oxidizing agent - and a buttload of BzCHO after the dream was finished - in retrospect I think his dream is just what is claimed in the above patent...

The trick is that with toluene, a 2x molar excess of oxidizing agent is required, whereas with benzyl alcohol, only one molar equivalent is needed. This makes me think the toluene would be oxidized to BzOH anyway before being oxidized further to the aldehyde, and that therefore Elbs persulfate oxidations of hydrocarbons to aldehydes/ketones always proceed via an alcohol intermediate. But that's just my 2 cents.

http://l2.espacenet.com/espacenet/bnsviewer?CY=de&LG=de&...

This is from: http://www.synthetikal.org/hiveboard/arch/forum/topic/topic_...



I also found the following on page 2 of this very thread:

Quote:
Originally posted by S.C. Wack

... Looked up Kinetic's JCS ref. There were other oxidants in that article as well. Looked in CA and found some things. Found Beilstein (all versions except online, stingy Uni), the sometimes helpful Richter's Organic Chemistry, and the Fiesers' Reagents... of no use. Looked strictly for toluene->benzaldehyde without high temps and in English.

First in the JCS was PbO2. 280 g of it and 300 ml of H2SO4 (sp. gr. 1.52) were mixed in a lead vessel with ice bath cooling. CO2 was blown in to the reactor. With stirring, 50 g toluene was added. This was steam distilled after 3 hrs and a 24% yield of benzaldehyde was isolated with bisulfite. They got an 18% yield without the ice bath and with slow addition of the toluene. The temp got up to 40C either way.

Also in lead, 100 g MnO2, 300 ml of the 1.52 H2SO4, and 50 g toluene were stirred for 5 hrs. Less than 1% yield. Repeating with "freshly precipitated" MnO2 and 6.5 hrs, a 5% yield.

Then 40 g toluene in 2X its volume of CHCl3 was added slowly with stirring to 140 g CrO2Cl2 in 200 ml CHCl3 on a cold water bath. After standing overnight, H2SO3 was added with stirring, the whole was steam distilled, CHCl3 evaporated, and a 44% yield of benzaldehyde was isolated via bisulfite. Their description of this Etard looks different than others that I have seen in the journals. BTW, when I mentioned the Etard earlier, I was only asking for a ref specifically for DCM/toluene. DCM and other chlorinated solvents often work, usually not as well, on various substrates. The Etard will give phenylacetaldehyde with ethylbenzene, and phenylacetone with propylbenzene. Styrene also gives benzaldehyde.

And last, they mixed 200 g ammonium persulfate, 500 ml 4N H2SO4, 2 g Ag2SO4, and 40 g toluene with stirring. Steam distillation and bisulfite gave a 78% yield of the aldehyde...

Obviously this is from here: http://www.sciencemadness.org/talk/viewthread.php?tid=2223&a...



There is also this in another thread:

Quote:
Originally posted by Polverone

In the second oxidation, I was much less careful with measurements. I used a "dash" of toluene, a "quarter jarful" of water, and maybe a further "quarter jarful" of ammonium persulfate. I warmed the jar's contents and periodically shook/stirred them. The aqueous layer slowly turned a pale orange, while the non-aqueous layer turned a progressively deeper red. There was a marked change as the aqueous layer reached the boiling point. I decided that I really didn't want to boil the solution, but it actually boiled more vigorously after I removed it from the heat. I believe I had achieved the runaway oxidation stage. Fortunately, I was able to fetch some cold water to dump into it before it got vigorous enough to boil out upon the table. This effectively killed the reaction.

I smelled some very interesting scents coming from that mixture. There was an aromatic smell sweeter and lighter than toluene. The non-aqueous layer mostly turned into floating chunks of red goo. The goo was soft and sticky like recently chewed gum, and needed a non-polar solvent to remove it from the jar.

This is from here: https://sciencemadness.org/talk/viewthread.php?tid=410&p...



Again in a later post on the same page Polverone gives a reference which would probably be a good place to start:

Quote:

no particular target



I am interested in making benzaldehyde, benzyl alcohol, and benzoic acid. Benzoic acid is easy. Benzaldehyde is probably the greatest challenge, especially since I can't just buy it. Forbidden == interesting!

Benzaldehyde and benzyl alcohol can be made from halogenated toluene derivatives, but in practice the halogenation is messy and the product obtained contains impurities. This is why other methods interest me, although I am not entirely disinterested in halogenation.

I made another attempt at oxidizing toluene using ammonium persulfate and a procedure from US patent 4,146,582. Unfortunately, in my haste I botched the procedure. Nevertheless, the leftover reaction mixture has the smell of almond flavoring to it: there's definitely some benzaldehyde in there.

Next time I will be a good chemist and follow the directions more exactly. But I need to order some more equipment first.


Maybe you should look for the patent cited above, it seems like a logical starting point, eh?

Oh, fuck it - you wanted to be spoonfed dincha?

Quote:
EXAMPLE 5

Benzaldehyde

Ferrous-Copper Catalyst: Toluene (7.6 g.), water (35 ml.), ferrous sulphate (0.110 g.) heptahydrate, cupric acetate (0.072 g.) and methanol (8 ml.) are placed in a 250 ml. reactor.

Sodium persulphate (47.05 g.) in an aqueous-methanol solution of sodium persulphate is added slowly to the mixture which is maintained at 70° C., in an atmosphere of nitrogen and under agitation.

The organic phase is separated after two hours and the aqueous phase is extracted with ethyl ether.

The combined organic phases are distilled to afford 8.29 g. (95% yield) of very pure benzaldehyde (compared against a pure sample).

This, somewhat unsuprisingly is from: http://www.freepatentsonline.com/4146582.html


You'll still have to follow the link and register to gain access to the full patent (which has some additional information you should probably consider), but registration is free so I assume you can do that?

[Edited on 2-3-2008 by LSD25]

Panache - 2-3-2008 at 13:44

fomg i fove fou lsd25
fanks fery fuch

LSD25 - 3-3-2008 at 05:31

Was that what you wanted?

I do get the use of the f-key, why is it so?

Panache - 5-3-2008 at 22:38

lol, nothing meant withthe f treatment just sounds silly and funny.
yes that is the info i wanted, here is what happened when i used it

Using a 1L beaker H2SO4 (98%, 100g) was poured into distilled water (500mL) with heavy overhead stirring, the temperature rising from 25C to ~42C. Silver nitrate was added (2.15g) followed by toluene (40g) and heating begun. The temperature rose steadily over the next several minutes to 51C where it began rising quickly, ice blocks were added to the water bath around the beaker and the temperature rise was brought under control, after some 25 minutes the solution was at 65C and held here for a further 90minutes.
Stirring was ceased and the contents were poured over 300g of ice and the contents extracted with two portions of 100mL of dichloromethane.
The benzaldehyde/DCM solution was dried with MgSO4, the DCM and residual toluene evaporated off.
The benzaldehyde was vac distilled without a manometer. One fraction at 52-55C was collected (the flask contents bumping heavily during this process). The cloyingly almond smelling compound was found to have a bp of 177-179C and a density of ~1g/mL. Final mass was 17g or 35%yield, pretty shit really but damm easy and reasonably cheap.
1 drop (~.05mL) was placed into my coffee (short black with 1 sugar) and it tasted damm fine albeit a little dimensionless.

Personally i think the 2hr reaction time may be a little long as the distillation flask had heaps of tar remaining in it after the vac distil.
I will perform a further trial after i have had another 340 coffee's as i will need more then.

LSD25 - 7-3-2008 at 21:12

Hang on, 17g/0.5g = 34 not 340 - so theoretically you should need more a whole lot sooner than you seem to expect?

Ephoton - 9-3-2008 at 00:52

does this have to be silver nitrate that is used. I would think that the nitrate is converted to sulfate
as soon as it is in solution does the nitric acid help oxidation ?
very nice work very low on smell

Nicodem - 9-3-2008 at 01:12

It only matters that the silver salt is soluble with the anion preferably inoxidable to avoid side reactions. Silver cations are the catalyst in this reaction since the persulfate oxidizes Ag(I) to Ag(II) which is an extremely powerful one electron oxidant oxidizing toluene to the benzyl radical and H<sup>+</sup>. The benzyl radical is then immediately oxidized further to benzaldehyde by the persulfate.
Silver nitrate just happens to be the most available silver salt with the appropriate characteristics.

Ephoton - 9-3-2008 at 01:23

so no halides would be the rule here thanks nicodem
on second thoughts silver nitrate sounds like the best option


[Edited on 9-3-2008 by Ephoton]

gvgole - 12-3-2008 at 00:21

:mad:The MnO2/30%H2SO4 method for the oxidation of bezylic alcohol has worked out selectively over aromatic methyl oxidation into corresponding aldehyde in 50% yields.

len1 - 12-3-2008 at 01:03

This is hard to fathom. Toluene is hard to oxidize, benzaldehyde oxidizes by just sitting in air. Yet the S2O8/Ag+ mixtures gets the tough job done, but doesnt touch the benzaldehyde.

Panache - 12-3-2008 at 21:07

sry had house guests for awhile and have been touring them around the countryside.

the original reference used silver sulphate but i didn't have any and i knew silver nitrate into h2so4 solution would destroy the nitrate so i hoped it would be ok. the reference quotes 75% yields but its workup is steam distillation, however i can't see the work-up being such a factor in the yield, the next run i did i left for 30 minutes and the yield was the same so reaction time isn't the key it would appear.

if anyone has the actual paper could you link it as i only have that one paragraph abstract/reference lsd25 dug out.

and i thought one drop was ~0.05ml so my need for more is correct 340 coffee cups now x 2 because of the repeat, so thats like 640 cups coffee at 12 cups day around 3 months lol

LoKi - 14-3-2008 at 22:42

an interesting fantasy I had a few years ago..
styrofoam coffee cups are ground fine, heated to distill styrene
styrene is oxidized to benzoic acid and (hopefully) 30% benzaldehyde.
I find some references but I think the "benzal from coffee cups synth" is more comical than practical/ plausible

not_important - 15-3-2008 at 00:00

You want to look at this thread http://www.sciencemadness.org/talk/viewthread.php?tid=6914&a... and do some searching for 'styrene' in the posts.

chemninja - 20-3-2008 at 08:12

There was a method posted somewhere else that described a method of preparing benzaldehyde from toluene that used ammonium persulfate, toluene and an unknown (I forgot) compound but was easily acquired - I think it was a ceramic chemical that produced relatively pure and in high yield benzaldehyde. But I can't remember the third chemical or the quantities used.

I actually did a small scale (like 50ml of toluene) reaction following the instructions and the lab and surrounding area was overcome with the smell of bitter almonds.

Any ideas?

chemninja - 20-3-2008 at 08:42

Another rxn I found was to heat phenylalanine with a 5N NaOH solution for 5hrs at 110C and it decomposes yielding benzaldehyde.

Magpie - 26-3-2008 at 19:35

I am trying the synthesis for benzal chloride in Vogel's 3rd which uses toluene at reflux and chlorine. I am using TCCA to generate Cl2 and then drying it with CaCl2 and Rooto sulfuric acid (~93%). It is then sparged into the toluene through a sintered glass diffuser tube. I am also using a Hg vapor light (100w). When I ran out of Cl2 the boiling point had risen as far as 136C. Running out of Cl2 was expected and I plan to recharge the generator and continue the chlorination tommorrow.

Everything is going smoothly but there is significant charring as indicated by the brown/black color of the product. Materials used are: glass vessels & tubes, Tygon (PVC) tubing, and rubber stoppers. All ground glass joints were sealed with Dow Corning silicone grease. I can't see any deterioration of the rubber, Tygon, or grease.

Edit: I just measured the pH of the product: it is 1. I assume this is due to the HCl byproduct from the following reacton:

C6H5CH3 +Cl2 ---> C6H5CH2Cl + HCl

Is charring normal for this method? What might be causing it? Is there something I should change?



[Edited on 26-3-2008 by Magpie]

len1 - 27-3-2008 at 07:42

The only time I got (insignificant) charring with this reaction was when I used the light source too close to the reaction vessel - which created a hot-spot on the glass. This source of charring however is obvious from a round black ring at the point of the hot spot. Other than that the reaction mixture should yellow but not char.

I also think you wont get an accurate measurement of HCl concentration with a standard pH meter in toluene, as its not an aqueous solvent. Len

Magpie - 27-3-2008 at 09:41

Although I can not visually detect this I'm wondering if a very fine aerosol of H2SO4 might be carrying over in the Cl2 stream from the H2SO4 water absorber. Could the presence of H2SO4 char the toluene/benzyl chloride at 136C?

My lamp is ~9cm from the reaction flask as shown in the picture below. When in operation I place a large sheet of aluminum foil loosely around the lamp/flask with the top and back sides open. The system is in standby waiting for a recharge of the Cl2 generator.

Len1, do you think I can continue chlorination and salvage this batch? Or do I need to solve the charring problem first?

Picture notes: The back bottle is a CaCl2 dryer, then the H2SO4 dryer bottle, then a safety bottle (Erlenmeyer flask) filled with Cl2 from yesterday. The sparge tube is being soaked in toluene in a a test tube.

[Edited on 27-3-2008 by Magpie]

benzal chloride.jpg - 61kB

garage chemist - 27-3-2008 at 09:53

Magpie, I don't think the charring is too much cause for concern.
Did you distill the toluene beforehand to clean in from heavy metal traces? If yes, there should be no problems despite the darkening.

What is mor cause for concern with this synthesis is the fact that you will have to fractionally distill very carefully in order to get a pure compound.
I have made benzyl chloride from toluene this way and even with this lower chlorination stage, there was a lot of black high-boiling oil in the distilling flask. Not to mention the work it was to isolate reasonably pure benzyl chloride. With a 30cm vigreux column, I had to do three distillations in order to get a "benzyl chloride" material that distilled over a range of 10°C.
A lot of undefined intermediate-boiling byproducts seemed to form here, and the distillation is very time-intensive and the yields low.

I will certainly never again attempt to chlorinate toluene, whenever I need benzyl chloride I make it from benzyl alcohol and HCl.
Benzaldehyde is easily available here, but if I needed to make it, I would look for an oxidation method for benzyl alcohol, of which there are plenty that have been discussed here.

Magpie - 27-3-2008 at 10:08

Yes, the toluene was distilled and then placed over 3A mole sieves.

I had a feeling that this was not a preferred route as it is not discussed much on this forum. I will continue, however, just out of curiosity and because I have already made a significant investment in time and effort. Thanks for giving me the benefit of your experience, GC.

You say you were making benzyl chloride. Did you attempt to add the 2nd chlorine to get benzal chloride?

garage chemist - 27-3-2008 at 10:16

My target product was benzyl chloride, and I stopped the chlorination at the temperature the Organikum gave if benzyl chloride is to be the main product.

len1 - 27-3-2008 at 14:09

Magpie, I thought about the aerosol possibility - generally toluene does not char with H2SO4 it is after all nitrated at 100C with oleum in the TNT reaction, but at 136C and benzyl chloride is another matter.

The chlorine generator I use has the great advantage that no H2SO4 is needed! I just use a single CaCl2/CaSO4 drying tube and it works great. When I had charring due to formation of hot-spots I continued the reaction, it had almost no effect on the yield - so I think you can continue - mind you standard texts are full of errors on this reaction - Ill post on thi shortly.

Stefan - did the benzyl chloride have any physiological effect on you? I find that I get a horrible taste in my mouth even when I can detect none of its smell?

PS Why do people call each other by these nick names? It feels artificial to me anyway. Do you prefer to be called by your first name?

[Edited on 27-3-2008 by len1]

Magpie - 27-3-2008 at 20:11

Sorry but I was not able to get to the lab today so as yet do not have anything to report on the continuation of this experiment.

I was perusing Vogel's 3rd when I found a procedure for the introduction of a large stream of Cl2 from a cylinder, dried with H2SO4. It said to use a bottle full of glass wool to prevent entrained H2SO4 from entering the reaction vessel.

Len, I used your method for the generation of Cl2. I dripped 15wt% HCl onto ground up swimming pool TCCA, no heat, no agitation. It gave a nice steady stream of Cl2. I controlled it between 1-4 bubbles/sec.

I have considered filling my Erlenmeyer flask safety bottle with glass wool. However, even though my wool is nice and white, it is from a house insulation batt. This might just introduce another impurity.

[Edited on 27-3-2008 by Magpie]

len1 - 28-3-2008 at 06:12

I think you can dispense with the H2SO4 and wash bottles altogether, I got good results with just the U-tube. I also love the TCCA Cl2 generator (using TCCA was originally Organikums idea) its almost like having a bottle of Chlorine

[Edited on 28-3-2008 by len1]

Fleaker - 28-3-2008 at 09:15

Quote:
Originally posted by chemninja
Another rxn I found was to heat phenylalanine with a 5N NaOH solution for 5hrs at 110C and it decomposes yielding benzaldehyde.


Do you have any references for this, or anyone for that matter? Phenylalanine is cheap and so is NaOH, but I worry about the OH attacking the carbonyl; I think yields would not be great. Off topic but I have a paper on taking phenylalanine to benzyl cyanide with TCCA and pyridine in 75% yields if anyone is interested? BzCN has interesting chemistry itself.


@Len, that chlorine generator is indeed very nice! Thanks to you and Organikum on that one.

Nicodem - 28-3-2008 at 09:33

I suspect benzaldehyde is not the product of such NaOH treatment of phenylalanine, but rather one of the products. Besides, this annoying claim was reposted already several times and none ever provided the reference, so it pretty much looks like some self reproducing misinformation.

I don’t know if Organikum got the idea of using the oxidation of HCl with TCCA as a handy chlorine generator independently or not, however that method is surprisingly even patented: GB1401120 (surprisingly because chlorine is used in the production of TCCA)

Ephoton - 30-3-2008 at 16:26

fleaker I would love that reference. could I please get it off you :)

jimwig - 31-3-2008 at 09:42

came across this


Conversion of Phenylalanine to Benzaldehyde Initiated by an Aminotransferase in Lactobacillus plantarum

http://aem.asm.org/cgi/reprint

but trying to go back ------this url would not past in.

so go to primary aem site and search

jimwig - 31-3-2008 at 09:44

Lactobacillus plantarum -- wouldn't that be a bacteria derived from milk? so maybe accesible?

jimwig - 31-3-2008 at 09:49

then this came forth so maybe this bacteria is available ala sour dough break conjourers !!!

Purification and Characterization of Novel Antifungal Compounds from the Sourdough Lactobacillus plantarum Strain 21B

jimwig - 31-3-2008 at 10:42

here's how (i think) to isolate and culture

http://www.google.com/patents?id=VC8YAAAAEBAJ&printsec=d...


i know kind of extreme but it should work right? i mean if one has the motivation and --- ???

[Edited on 31-3-2008 by jimwig]

benzaldehyde from phenylalanine

azo - 9-4-2008 at 02:13

I have read about the production of benzaldehyde from phenylalanine initiated by amino transferase in lactobacillus plantarum. If this is a viable method it could be an alternative way of producing benzaldehyde or at least looked at.

Klute - 9-4-2008 at 08:21

That would be a pretty expensive way of obtaining benzaldehyde!
I would rather look towards toluene oxydation, benzyl alcohol oxidation, or even almond flavourings.

Sauron - 9-4-2008 at 10:37

Rosenmund reduction of benzoyl chloride.

Probably too expensive.

TCCA gives benzaldehyde from benzyl alcohol. Yield about 52%. Now that's cheap.

Klute - 9-4-2008 at 12:17

I'm sure yields can be increased to the litterature-claimed >90% with TEMPO derivative catalysis. Using Ca hypochlorite/BnOH/DCM proved to be more efficient with plain benzyl alcohol IIRC.
The semi-electrolytic Mn alum oxidation seems pretty interesting for >50-100g quantities..

solo - 9-4-2008 at 13:44

Synthesis of benzaldehyde, heat phenylalanine with 5N NaOH solution for 5 hours, at 110 C, it then decomposes, yielding benzaldehyde........solo


..............source of information,


http://www.ajinomoto.co.jp/amino/e_aminoscience/bc/amino_13....

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