Sciencemadness Discussion Board

toluene --> benzaldehyde

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len1 - 9-4-2008 at 16:51

Quote:
Originally posted by solo
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....


Somehow I find that hard to believe given the Cannizzaro reaction - which is well known and normally proceeds under much milder conditions.

MagicJigPipe - 9-4-2008 at 16:53

I agree. Also, if it were that easy wouldn't that be the method of choice and be more wide spread?

I think the best method (other than oxidation of BnOH) is hydrolysis of benzal chloride.

[Edited on 4-9-2008 by MagicJigPipe]

The benzyl cyanide reference

Fleaker - 10-4-2008 at 16:54

Here is one taken from the literature. Apparently I was wrong about the yield; it is 77% rather than 75% of BzCN from phenyl alanine.

While this isn't related to benzaldehyde, I did offer the paper and several members have asked me for it so I will provide it here for their convenience.

Attachment: Hiegel.pdf (95kB)
This file has been downloaded 5174 times


Shingoshi - 21-4-2008 at 00:00

I just couldn't resist joining you guys. Although, that's not meant to be sexist :o in the presence of women. Found this site looking information on azeotropic solutions of Trichloroisocyanuric-acid (TCCA).

Glad I found you!
Shingoshi

Yes, precisely

Shingoshi - 21-4-2008 at 03:15

Quote:
Originally posted by Sauron
Welcome

TCCA is a solid. So I am not sure what you mean by an azeotropic solution of TCCA.

Do you mean an azeotropic mixture (of two or more solvents) in which TCCA is soluble?


Acetone and chlorine will make chloroform. I want to try mixing tcca with various solvents to produce special refrigerants. Using Ethanol, produces another refrigerant as well. IRC, it's R-130.

Shingoshi

not_important - 21-4-2008 at 03:37

R-130 is 1,1,2,2-tetrachloroethane, moderately nasty stuff. Ethanol + chlorine source generally gives di- or tri- chloro-acetaldehyde, or chloroform, depending on reaction conditions.

I admit, I don't have the skill most of you have...

Shingoshi - 21-4-2008 at 04:37

Quote:
Originally posted by not_important
R-130 is 1,1,2,2-tetrachloroethane, moderately nasty stuff. Ethanol + chlorine source generally gives di- or tri- chloro-acetaldehyde, or chloroform, depending on reaction conditions.


My assumptions are often incorrect. ;) But I am only concerned with having a mixture with a very low freezing point.

Question: Should I start another topic, so as not to pollute this one? That's fine by me, and would likely feel better about that also.

Shingoshi

Ok, here's the new thread. http://www.sciencemadness.org/talk/viewthread.php?tid=10387&...

EDIT by Nicodem: Yes, please open a new thread rather than continuing this off topic discussion.

[Edited on 21/4/2008 by Nicodem]

[Edited on 2008.4.21 by Shingoshi]

Accidental omission

Panache - 1-5-2008 at 14:31

Quote:
Originally posted by Panache
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.


I just re-read this post of mine and realised i omitted the oxidant (ammonium persulphate), 200g were used and added to the sulphuric acid solution. Apologies.

Klute - 1-5-2008 at 15:30

It appears that the two articles Trilobite posted in Polverone's thread are not available anymore. Considering how complete the first is on the persulfate/Fe2+/Cu2+ oxidation is, and that the other one does shed some light on the H2O2/Cu+ oxydation, I am attaching them.

Thanks alot to Trilobite for finding and sharing these articles.

Paper 1:
Electron transfert process: Selective syntheses of aromatic aldehydes of industrial interest by catalyzed-peroxydisulfate oxidation
P. Maggioni, F. Minisci
Chimica & Indus. (2), 61, 101-105 (1979)

[Edited on 2-5-2008 by Klute]

Attachment: Paper1.pdf (1.1MB)
This file has been downloaded 1030 times


Klute - 1-5-2008 at 16:06

Paper 2:

pH dependence in the Cu+ mediated oxidation of toluene by oxygen or hydrogen peroxide
Okunowski et al.
Rec. Trav. Chim., 109, 103-106 (1990)

(Sorry: forgot to attach file! :) )

[Edited on 2-5-2008 by Klute]

Attachment: pH_dep.pdf (1.4MB)
This file has been downloaded 1137 times


LSD25 - 13-5-2008 at 02:22

I just finished reading the attached article about extracting BnO from aqueous solution and thought it would probably be of interest.

Of rather more interest to myself is whether or not strongly basic exchange resins (generally tertiary amines) could be used in place of hexamine in a modified Sommelet reaction with Benzyl halide (Chloride/Bromide).

I was thinking this would remove the problems associated with phase-transfer one encounters with 2-phase reactions, the n-benzyl amine resin would then be extracted rather simply by filtration. It would be interesting to see whether the benzaldehyde could be regenerated easily or not...

Any ideas?

Attachment: Recovery.BnO.fromAqSoln.with.ExchangeResin.pdf (425kB)
This file has been downloaded 2201 times


manimal - 14-5-2008 at 02:55

Incidently, I wonder if manganese persulfate would oxidize ethylbenzene to phenylacetaldehyde/phenylacetic acid.

not_important - 14-5-2008 at 04:00

Quote:
Originally posted by manimal
Incidently, I wonder if manganese persulfate would oxidize ethylbenzene to phenylacetaldehyde/phenylacetic acid.


No, the benzylic carbon is attacked first, giving the aromatic ketone like acetophenone, or benzoic acid.

Siddy - 17-5-2008 at 23:25

Quote:
Originally posted by not_important
Quote:
Originally posted by manimal
Incidently, I wonder if manganese persulfate would oxidize ethylbenzene to phenylacetaldehyde/phenylacetic acid.


No, the benzylic carbon is attacked first, giving the aromatic ketone like acetophenone, or benzoic acid.


Which is why you use Cr6+ instead.
Na2Cr2O7 + H2SO4 > Phenylacetic Acid

not_important - 18-5-2008 at 00:11

Quote:
Originally posted by Siddy
Which is why you use Cr6+ instead.
Na2Cr2O7 + H2SO4 > Phenylacetic Acid



I suspect that is not so, from

Oxidation of ethylbenzene with aqueous sodium dichromate
Donald G. Lee and Udo A. Spitzer
pp 1493 - 1495; DOI: 10.1021/jo01257a078

Quote:
Several attempts were made to find the proper conditions for the conversion of ethylbenzene to phenylacetic acid. In some twenty-four different experiments the temperature was varied from 126 to 282", the time of reaction was varied from 0.5 to 12 hr, the ratio of oxidant to reductant was varied from 2: 1 to 1 : 2, and the pH was varied from 5 to 11. However, in every experiment the only isolable products obtained were acetophenone and benzoic acid. In general, long reaction times, high temperatures, low pH, and an excess of oxidant tended to favor the production of benzoic acid, while less vigorous conditions decreased the amount of reaction and tended to make acetophenone the main product. Some typical results are presented in Table I, no. 1-10. (Friedman and coworkers5 have also been unable to reproduce the results reported by Reitsema and Allphin.z)

Siddy - 19-5-2008 at 23:59

Quote:
Originally posted by not_important

I suspect that is not so, from



The method for the oxidation is very important -as with all oxidations. Just chucking the precursors in a flask and mixing probably wont get you PAA. What your reference obtained is probably accurate. Commonly oxidations dont stop at the desired compound, you have to remove them as they form and make a complex reaction vessel.


You will find a practical method at anyone of your drug site:
http://designer-drug.com/pte/12.162.180.114/dcd/chemistry/ph...

Note, the acetophenone obtained from a more simple approach can give PAA easily

Siddy - 27-5-2008 at 23:10

Has anyone had any luck with:

Toluene + Na(OCl)2 > Benzyl Chloride + Benzal Chloride

Benzal Chloride + H2O > Benzaldehyde


n.b. Na(OCl)2 could be any hypochloride salt
H20 could need -OH from salt, eg NaOH.
benzyl chloirde + H2O > Benzyl alcohol
benzyl alcohol [O] > Benzaldehyde
[O] = ammonium persulphate and conc. sulphuric acid.

not_important - 27-5-2008 at 23:36

Do you mean Sodium hypochlorite - NaOCl?

The relatively dilute aqueous solutions NaOCl comes in work against it in this case.

Earlier in the thread are discussions on using TCT, the current equavalent of hypochlorites in swimming pool applications. It can also do the oxidation to benzaldehyde. Ring chlorination is a potential problem with chlorine based routes.

General purpose oxidation, electrochemistry

kalacrow - 9-6-2008 at 20:54

I've found this thread fascinating, but most especially the bits given by Cycloknight early on. His excellent treatment of an electrocell is really fantastic, and I was wondering if anyone could answer a question I had.

He states late in his posts that you could use the cell to simply generate MAA, remove it from the cell, put in more MAS and continue on. The MAA could be reacted with your starting material outside the cell with "no heating".

Assuming you've worked out the molar amounts, would this simply be a process of:

1) measuring out starting material (let's assume we want vanillin from eugenol, so eugenol to start)

2) Combining it with the MAA

3) With stirring react over time until completion

4) Extract with low boiling point solvent

5) Heat the now depleted MAA (now it should be MAS) to drive off the remaining solvent

6) Save it to turn it back into MAA in the cell

Or.. do you need H2SO4 in there as a promoter? I'm guessing not. Also, in the particular case of eugenol -> vanillin, the classic case has you isomerizing it before oxidizing.. would this be accomplished in situ here?

With a solid (at RT) starting product, would you simply dissolve it in an appropriate solvent to react? I'm assuming you'd need to be careful about that solvent as you'd want one that was relatively impervious to oxidation by this material. Im also aware that this is a complicated question.. so a general answer with one theoretically working example would be great.. not looking for case by case.. just the general theory!

Thanks very much in advance! Im fascinated by electrochem.. I've done all the basic stuff.. cl2, H + O2, and so on. Love the mechanism of it :)

[Edited on 9-6-2008 by kalacrow]

Siddy - 16-6-2008 at 22:07

kalacrow, PM Cycloknight he will answer.

AFAIK, no one was successful in converting Benzyl Chloride to Benzaldehyde in 1 step (without going though Benzyl alcohol).
Here is something i read, NOT ATTEMPTED though.


Quote:
Strike
In a flask with stirring is added 126g benzyl chloride, 140g hexamine and either, 500mL 50% aqueous acetic acid or 500mL 60% aqueous ethanol. The solution is refluxed for 2 hours, then 200mL 3N HCL is added and refluxing is continued for 15 minutes more. When cool, the solution is extracted with ether, the ether washed 4 times with water, dried through NaSO4 and vacuum distilled to afford benzaldehyde (yield=70%). The two products are quite fragrant which will give the chemist an idea of the success of the procedure. Did you know that a lot of methylamine is produced as a side product of this reaction? How it can be salvaged Strike has no idea.


So Benzyl Chloride (easily made from toluene) can either be hydrolyzed to benzyl alcohol, then oxidized to benzaldehyde with Persulfate, or directly from chloride to aldehyde with hexamine. Both are not particularly high yields, but as long as you benzyl chloride was easy enough to make who cares.
Alternatively, Len1's write up, advising Benzal Chloride from Cl2+Light radical chlorination of toluene, + HCl > Benzaldehyde.
NB: Benzyl chloride can be made from heating Toluene and Hypochlorite to 105oC, but not Benzal Chloride, it needs Cl2 (TCCA + HCl).

Ephoton - 27-6-2008 at 18:11

http://en.wikipedia.org/wiki/Sommelet_reaction

yes it has

methylamine im not so sure on as I think it goes through
benzylamine so I can not see how methyl amine can be produced.

it is truly an easy reaction just add water hexamine and reflux
for 2 too 4 hours. steam distill out aldehyde.

alcohol and acetic acid make clean up harder.

[Edited on 28-6-2008 by Ephoton]

brew - 17-7-2008 at 01:17

I know this thread is to do with the conversion of toluene to benzaldehyde, but I found the following that produced this target compound along with some other things that could be quite useful. I have purchased 250g of almond meal and due to not having a stirring device will not reflux it in ethanol. Instead I will let it sit for some time and add heat and stir occasionally.

Amygdalin is extracted from almond or apricot kernel cake by boiling ethanol; on evaporation of the solution and the addition of diethyl ether, amygdalin is precipitated as white minute crystals. Liebig and Wöhler were already able to find three decomposition products of the newly discovered amygdalin: sugar, benzaldehyde, and prussic acid.[2] Later research showed that sulfuric acid decomposes it into d-glucose, benzaldehyde, and prussic acid (hydrogen cyanide); while hydrochloric acid gives mandelic acid, d-glucose, and ammonia.[3]

The decomposition induced by enzymes may occur in two ways. Maltase partially decomposes it, giving d-glucose and mandelic nitrile glucoside, C6H5CH(CN)O·C6H11O5; this compound is isomeric with sambunigrin, a glucoside found by E.E. Bourquelot and Danjou in the berries of the common elder, Sambucus nigra. Emulsin, on the other hand, decomposes it into benzaldehyde, cyanide, and two molecules of glucose; this enzyme occurs in the bitter almond, and consequently the seeds invariably contain free cyanide and benzaldehyde. An "amorphous amygdalin" is said to occur in the cherry-laurel. Closely related to these glucosides is dhurrin, C14H17O7N, isolated by W. Dunstan and T. A. Henry from the common sorghum or "great millet," Sorghum vulgare; this substance is decomposed by emulsin or hydrochloric acid into d-glucose, cyanide, and 4-hydroxybenzaldehyde.[

I will also be careful if indeed I attempt the decomposition with the potential hydrogen cyanide being produced. Perhaps this is a known method and been already discussed. Perhaps not.

manimal - 21-7-2008 at 16:19

I tried to make benzaldehyde using the method from US780404 which uses a divided cell to oxidize manganese sulfate to manganese persulfate.

For the cell I used a gallon glass jar into which I placed ~1165 ml of 93% H2SO4 from drain cleaner and ~1478 ml of water, which should equal ~55% acid if my calculations were correct. For the cathode compartment I used a small flower pot which I filled with the same acid mix and suspended in the glass jar. I put into the jar approx. 450 grams of mn sulfate fertilizer, which I assume is the monohydrate (the bag says 31% Mn content, and Mn makes up 32% by weight of the monohydrate).

I used a battery charger set to 6 V with no current control, which passed about 6-8 amps of current. I electrolysed the mixture for around 28 hours or so, until it turned dark purplish black. There was a lot of undissolved sulfate at the bottom which would just resettle when stirred, but with continued electrolysis it too turned brownish purple with white flecks.

When it didn't seem to be doing much else, I removed the electrodes and put ~250 ml of toluene into the jar. I used an electric eggbeater to stir it around, and put it outside overnight to react. In the morning, nothing much had happened except that it had formed an emulsion. This was probably because it had gotten quite cold outside (9 C) which had retarded the reaction. I then placed the jar on a hotplate set to low and commenced mixing. I could smell the benzaldehyde within about half an hour. But after a long time (18+ hours) nothing much more seemed to be happening.

As you can see, it looks almost exactly like the first photo from Hilski's experiment (http://www.sciencemadness.org/talk/viewthread.php?tid=6882&page=3) with this method except that mine only has two layers. If the benzaldehyde is in there, it's trapped in a wicked emulsion. The inside of the jar has the sweet smell of cherries and I can't detect any toluene, but maybe that's because the benzaldehyde is masking the odor. Incidentally, the metal mixers from the eggbeater, which were unaffected after mixing overnight, became badly corroded within an hour after I started warming the mixture. I coated them with epoxy, but after many hours even that started to dissolve. I'll have to find some better mixers if I continue experimenting with this.

According to Hilski, his reaction was done in just 12 hours, but mine is still black, even though I used the same proportions of ingredients. Maybe he used 450 g of the tetrahydrate, and if mine was the monohydrate I would have ended up with a greater mass of oxidant. I don't think significant toluene would have evaporated. I'll probably try adding 100ml more of toluene and continue oxidizing till the mix turns sand colored. Does anyone else have experience with this particular reaction?

Please excuse the shitty quality of my cellphone pic, k thnx.

benzaldehyde.jpg - 65kB

electrochemical benzaldehyde

Dr.3vil - 30-7-2008 at 14:31

I mentioned this in a prior post (kolbe) but figured it needed to be here since the scope of the article is more about the production of benzaldehyde.

Attachment: reduction of aromatic carboxylic acids.pdf (438kB)
This file has been downloaded 3449 times


HeilHamas - 25-8-2008 at 11:50

Is vacuum distillation or distillation through a column necessary for the toluene/benzaldehyde mix? I tried simple distillation at atmospheric pressure, and got clear toluene and toluene/water azeotrope, and distillate all the way from 85C to about 145C, however after that smoke and orange liquid came through, that looked not unlike the pre-distillation liquid. Is that caused by high temperatures degrading the benz?

Alternative synth of benzaldehyde

tapira1 - 27-8-2008 at 14:52

You may use the oxidation of styrene with oxygen under TiO2 catalysis. TiO2 is a paint pigment that can be mixed with SiO2 (sand) to make it more manageable.

Siddy - 28-8-2008 at 19:01

Quote:
Originally posted by tapira1
You may use the oxidation of styrene with oxygen under TiO2 catalysis. TiO2 is a paint pigment that can be mixed with SiO2 (sand) to make it more manageable.


And what about styrene, how does one manage to get that?

not_important - 28-8-2008 at 21:10

Quote:
Originally posted by Siddy
Quote:
Originally posted by tapira1
You may use the oxidation of styrene with oxygen under TiO2 catalysis. TiO2 is a paint pigment that can be mixed with SiO2 (sand) to make it more manageable.


Pigment TiO2 doesn't work very well as a catalyst, it's designed for pigmentation purposes and these days likely to have a crystal struction selected for low catalytic activity to keep it from chewing up the paint body.
Quote:

And what about styrene, how does one manage to get that?


Collect polystyrene. Thermally crack it to a mixture of styrene and other compounds, Fractionate that for reasonably pure styrene. Do a forum search for styrene and you'll find both posting on getting styrene and on several oxidation methods to use on it.

Baphomet - 30-9-2008 at 19:29

Tapira1 is right. Why do you guys want to do everything the hard way?

Reference is here:
"Benzaldehyde synthesis via styrene oxidation by O2 over TiO2 and TiO2/SiO2"
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi...

TiO2 from a pottery store would more than suffice. It is not a catalyst per-se, but a polymerisation inhibitor. SiO2 can be had easily from waterglass.

Styrene can be purchased by the gallon from hardware stores ;)

not_important - 30-9-2008 at 20:40

Quote:
Originally posted by Baphomet
Tapira1 is right. Why do you guys want to do everything the hard way?

Reference is here:
"Benzaldehyde synthesis via styrene oxidation by O2 over TiO2 and TiO2/SiO2"
...
TiO2 from a pottery store would more than suffice. It is not a catalyst per-se, but a polymerisation inhibitor. SiO2 can be had easily from waterglass.

Styrene can be purchased by the gallon from hardware stores ;)


Well, first wrong on the TiO2, it is a catalyst and a well known one for oxidation at that. The process is a competition between polymerisation and oxidation, the more active the oxidation catalyst the lest polymerisation byproduct. From that report:

Quote:
Styrene was oxidized by molecular oxygen over TiO2/SiO2 for the formation of benzaldehyde. At 70°C and 30 atm air with a styrene flow of 9.0 ml/h and air flow of 120 ml/min over 10.00 g catalyst, styrene conversion of more than 40% with benzaldehyde selectivity of more than 97% was obtained. Formaldehyde, phenylacetaldehyde, acetophenone, styrene oxide, benzoic acid, and minor polymer were found to be the by-products. The polymerization of styrene was initiated by the radicals formed in the oxidative reaction. The addition of radical inhibitor nitrobenzene and/or the employment of a catalyst of high specific surface area can promote the termination of the radicals, and hence improve the selectivity of benzaldehyde.


Note that there's a bit of work-up needed, and a good condenser with 9 ml of styrene in 7.2 l of air per hour and 40% conversion.

Styrene has never been in any hardware store I've been in, even back when I could buy benzene, lead arsenate, and nitric acid in them.

If you have full access, you might have attached the article.

Panache - 30-9-2008 at 20:46

So easy!
Just blast your styrene away through your continuous 10atm, 100C reactor for your 7%yield, recycling all the shit that's unreacted, if everyone stays online i'll quickly knock-up one of these babies and be back in a couple of hours to report.

NI you're a bastard! You got in to responding to this before me! i had to modify my sarcasm as you'd already used some of the material i was going to!! Damm. Ha!

Baphomet - 30-9-2008 at 20:55

Bzzt negative. What do you think the bold part means? TiO2 does not catalyse the oxidation. It soaks up the free radicals to prevent formation of polymer.

How can it be a 'competition between polymerisation and oxidation'?? The polymerisation is a direct consequence of the oxidation, indeed it cannot occur unless the styrene is oxidised first.

The reaction conditions and workup mentioned are facile and would not provide much challenge for a chemist of average ability :P

1L cans of styrene are still on sale in a famous hardware retail chain in my country as of, about one month ago..

Baphomet - 30-9-2008 at 21:01

7%.. where did you get that from? About 40% of the feedstock is reacted on each pass with almost total conversion to benzaldehyde.

Pressure is no issue. As long as you take care to construct your equipment properly.

Panache - 1-10-2008 at 01:17

Quote:
Originally posted by Baphomet
7%.. where did you get that from? About 40% of the feedstock is reacted on each pass with almost total conversion to benzaldehyde.

Pressure is no issue. As long as you take care to construct your equipment properly.


I must admit i got into the whole thing a little too much. It been a hectic day and the weather is finally warming after months of cold and i've been a little silly today!!

You are quite right about being enthusiastic in relation to this method. I always forget that toluene is not freely available everywhere as it is here in australia.

Also whenever i hear the phrase 'solid supported catalyst' i immediately think it not going to work as i spent two years once trying to replicate a variety of these indian claims regarding solid supported catalysts and got absolutely nowhere. I swear the indians think that regardless of the synthesis they will be able to improve on it using solid supported catalysts and a microwave.
An example
'.....Pb(10g) was moistened with water and ground into the previously prepared solid catalysts compound A, the slurry was subjected to microwave radiation for 2x7min bursts, obtaining internal temperatures above 240C. After the seventh pulse the Pb turned to Au, the solid supported catalyst was conveniently recovered after simply plucking out the gold nugget 'and used in 146274632758 subsequent equally successful trials'

The 7% thing was a mistake, the pressure, you are right its very acheivable, and steel is cheap, just make everything thick.
A copy of the paper would be good!! Its funny that benzaldehyde can be purchased pure in every supermarket, its just that the 2% solution only comes in 20mL bottles.

Baphomet - 1-10-2008 at 02:20

I don't have the paper. But if you like the sound of it why not spring for the $31.50 and try it out?

Fluidised bed reactions are a little more complicated than using homogenous catalysts, I agree on that. But it's still possible to take most continuous processes like this and turn them into batch runs. I mean, how much benzo do you need?? :P

Note that if you end up using a batch 'pipe' method or similar, SiO2 is not required. So you don't need to worry about supporting the TiO2 because it will settle out before workup. :cool: Whereas in a continuous process it would be advantageous to keep it in the bed.

madcease - 1-10-2008 at 03:47

What is best way to extract the benz from Almond Essence. Do you think just distill layers till reach b or should one add dcm to the mix as im scared the b will steam over with the water if there is any in the essence

??????? Maybe its just alc

kclo4 - 1-10-2008 at 05:18

Quote:
Originally posted by madcease
What is best way to extract the benz from Almond Essence. Do you think just distill layers till reach b or should one add dcm to the mix as im scared the b will steam over with the water if there is any in the essence

??????? Maybe its just alc


Hey you, make sense!

Probably could extract it by distillation or with bisulfite. http://en.wikipedia.org/wiki/Sodium_bisulfite

Panache - 5-10-2008 at 23:25

Quote:
Originally posted by madcease
What is best way to extract the benz from Almond Essence. Do you think just distill layers till reach b or should one add dcm to the mix as im scared the b will steam over with the water if there is any in the essence

??????? Maybe its just alc


Flood the essence with water, the benzaldehyde will slowly seperate and form a small globule at the bottle of the sep funnel, conversely you can extract with dcm if you are impatient.
The residual solution will always smell powerfully of benzaldehyde as benzaldehyde has a funny affect on the olfactory sense, being most potent around 0.1% in a water soltion/emulsion. Don't waste your time attempting to get it out as its pointless, unless of course the point of the excercise was to to clear a waste stream of all benzaldehyde, then you should do it.

madcease - 8-10-2008 at 01:54

Have tried flooding with water but cannot see any seperation. Smells high of b so i know its in there.
Also tried distilling and it contains what i think is ethanol and then something else in which a really bitter taste comes over at about 80-90. After that fraction added water to try steam distill with no luck of any oil in the water.
S*** is buggered and doesnt know if it steam distills with solvent as well as water so problem might be the b is going over before the water graction.
Is this possible?

Edit by Nicodem: No "swiming" or any other form of pretending illegal activity is allowed on this forum! Next time the whole post will be removed.

[Edited on 8/10/2008 by Nicodem]

Panache - 8-10-2008 at 04:31

Quote:
Originally posted by madcease
Have tried flooding with water but cannot see any seperation. Smells high of b so i know its in there.
Also tried distilling and it contains what i think is ethanol and then something else in which a really bitter taste comes over at about 80-90. After that fraction added water to try steam distill with no luck of any oil in the water.
SWIM is buggered and doesnt know if it steam distills with solvent as well as water so problem might be the b is going over before the water graction.
Is this possible?


Apologies i could have been clearer, the essence needs to be flooded with water until the polarity of the mix renders the benzaldehyde insoluble. This will be evidenced byt he solution turning turbid and white. if this does not happen then the benzaldehyde concentration in your essence is very low and what is there is soluble in water, a polar extraction will still remove it largely. In this instance steam distilling it should concentrate it nicely, some will steam distill with the ethanol (remember ethanol distills over with water) but if you examine the partial pressures you will see it steam distills poorly until the ethanol is completely removed. Once removed however it will steam distill over more quickly.

benzaldehye should burn your tongue but not really be bitter, it could be mistaken however as bitter

Perhaps a bisulfite is best however as i understand it len1 found the benzaldehyde adduct tricky, i have no experience with it.

madcease - 8-10-2008 at 08:39

Thanks Pananche but what ratieos do you consider flooding with water. Do you think i can just add DCM to the essence to extract or will that absorb the ethanol contained.
Im pretty sure it distilled over with the ethanol as when tasted it burnt and tasted like b. But had no success when added water.
Can i just add DCM to the essence then extract or will it pull to ethanol with it?

Panache - 9-10-2008 at 16:11

Quote:
Originally posted by madcease
Thanks Pananche but what ratieos do you consider flooding with water. Do you think i can just add DCM to the essence to extract or will that absorb the ethanol contained.
Im pretty sure it distilled over with the ethanol as when tasted it burnt and tasted like b. But had no success when added water.
Can i just add DCM to the essence then extract or will it pull to ethanol with it?


yes, the dcm mind you will distill with an azetrope of water also(and hence benzaldehyde), but its minor, ~ 2% water/98%dcm, i have often actually wondered if this could be used to dry 96% ethanol.....2L dmc would theoretically dry 1L alcohol.

brew - 7-12-2008 at 05:26

Quote:
Originally posted by Organikum
Some stuff from the-hive and an old patent:

Quote:

Toluene to Benzaldehyde by Manganesepersulfate

by: neograviton
(edited by me)


Here is a easy way to do it with Mn(V)sulfate. A way I used many time!

First get some MnO2. You can buy it as "Manganese-Black" a pigment for cement and concrete. Thats about 70% MnO2. Then put it in an equimolar amount of H2SO4 (100%) and heat it up. Make it really hot. (>200°C). Let it be there for about half an hour. When I do this, I let The acid become so hot, that white steam comes out. After that, let it cool down. You just have made Mn(V)SO4. It is soluble in 37% H2SO4 (battery acid) with a deep, chocolate like brown color.
After that put it 1:1 with the toluene in about 60% H2SO4 (enough H2SO4, so that nearly everything dissolves). Heat (or cool) it to about 50-60°C and stirr it well. After 3-4 hours you will have mostly Benzaldehyd (in my cases about 70%)
Distill the Benzaldehyd/Toluene out by a simple steam distillation. (Just boil water out, until there is no oily layer any more)
When you start boiling that stuff, the color of the liquid becomes sand-like. Thats because the rest of the Mn(V)SO4 breaks down to Mn(II)SO4.

And now the best: just put the liquid in a electrolytic cell (in the anode-part) and put some electricity through it, while stirring. The color will chance to chocolate brown once again, and you can use it again!!! About 6 times!



Hi, I am trying to work out the ratios for this reaction. Perhaps I am confused with the term equimolar. Disregarding the 70% for now. Mn02 is 86.9gmol-1 The acid at 98% with a specific gravity of 1.84gml-1 making it 1840gL-1 therefore 1840/98 = 18.7molL-1. So if I was to use 10g of the Mn02 which is 0.11 moles, (10/86.9 = 0.11 then how much acid should I add for this amount, surely it is not the same amount of moles, for if it was it would come to a dismal aprox 6ml. This cannot be right, and I am obviously missing something very important. I was reading this, and am not ready to do this reaction, but it didn't make sence and I thought I would queerie the instructions. Perhaps this is a beginners question and belongs in that area, It obviously isn't a begginers procedure. I am wondering also if others have indeed followed this route for the production of this compound.

brew - 9-12-2008 at 02:47

Well I tried this reaction and used an excess amount of acid, 15g MnO2 with 80ml 98% acid.and it only turned into a grey sludge, I kept the temp over 200 deg for over 30 minutes and let it cool, and then added the 38% acid and no brown compound in sight, only the grey sludge as described. I used the same cement black 70% Mn02 as described. I maintained a uniformed heat with constant stirring. Ive just ordered some other MnO2 with some other material from a pottery supply place, so perhaps it is the quality of the manganese that is stuffing this up.Ill keep on experimenting, but if anyone has done this, and can see the errors of my ways, it would be good to get some feed back.

ItalianXKem - 10-12-2008 at 08:23

need a aqueous solution of strong oxydizers
dichromates and permanganates

step one , make benzyl alcohol C6H5-CH2-OH

step two , oxydize carbinol , alcohol to aldehyde

1) reaction toluene and a oxygen donator (H2O2 , NaClO or other)
2) reaction benzol with strong oxydizing solution
H2O + X2Cr2O7 or H2O + XMnO4
X = Na , K , NH4

and benzaldehyde is maked !

DJF90 - 10-12-2008 at 09:44

It really isnt this simple. If you cared enough to look through the whole thread you would see that a strong oxidiser on benzyl alcohol will yeild mostly benzoic acid. An oxidising agent that is will only oxidise to aldehyde is needed, IIRC something like PCC (pyridinium chlorochromate), but this is difficult to obtain for the amatuer chemist.

Paddywhacker - 28-2-2009 at 04:46

Quote:
[quote by: neograviton]
Toluene to Benzaldehyde by Manganesepersulfate

Here is a easy way to do it with Mn(V)sulfate. A way I used many time!

First get some MnO2. You can buy it as "Manganese-Black" a pigment for cement and concrete. Thats about 70% MnO2. Then put it in an equimolar amount of H2SO4 (100%) and heat it up. Make it really hot. (>200°C). Let it be there for about half an hour. When I do this, I let The acid become so hot, that white steam comes out. After that, let it cool down. You just have made Mn(V)SO4. It is soluble in 37% H2SO4 (battery acid) with a deep, chocolate like brown color.
After that put it 1:1 with the toluene in about 60% H2SO4 (enough H2SO4, so that nearly everything dissolves). Heat (or cool) it to about 50-60°C and stirr it well. After 3-4 hours you will have mostly Benzaldehyd (in my cases about 70%)
Distill the Benzaldehyd/Toluene out by a simple steam distillation. (Just boil water out, until there is no oily layer any more)
When you start boiling that stuff, the color of the liquid becomes sand-like. Thats because the rest of the Mn(V)SO4 breaks down to Mn(II)SO4.

And now the best: just put the liquid in a electrolytic cell (in the anode-part) and put some electricity through it, while stirring. The color will chance to chocolate brown once again, and you can use it again!!! About 6 times!


I'd be worried about forming toluene sulphonic acid with all that acid, but maybe it is too dilute, but benzaldehyde is getting old, and anyway is a reasonably available chemical.... not like some that are notorious precursors.

Has anybody used this oxidation technique on Xylene to give methylbenzaldehydes or even benzene with two aldehyde groups?

Or used it to oxidize anything else? Benzophenone from ethyl benzene sounds interesting, but what else can it do.

brew - 28-2-2009 at 13:05

Quote:
Has anybody used this oxidation technique on Xylene to give methylbenzaldehydes or even benzene with two aldehyde groups?

Or used it to oxidize anything else? Benzophenone from ethyl benzene sounds interesting, but what else can it do.


Yes, I was interested in this chemistry for other things such as formic acid rather than list 1 chem. I used the electro manganese, ammonium sulfate route, I did it very small scale, and used a small amount of formaldehyde, I obtained from a friend. Once it reacts, it obviously stays in solution, and one has to distill it, which resulted in a solution distilling over, at a bp, I cannot at the moment recall, and I reacted this with a base, and obtained I believe sodium formate. Next time I do it, I will not be so slap dash with amounts etc and will determine yields. I also need to test the mp of the salt formed.

[Edited on 28-2-2009 by brew]

benzylchloride1 - 14-3-2009 at 21:30

I am currently working on producing benzaldehyde from toluene via the benzal chloride method. I started with 100g of toluene and 400g TCCA for the chlorine source. I passed chlorine into the mixture for 7.5 hours. The mixture turned red and the final temperature of the reaction mixture was 181 degrees Celsius. The laboratory where this experiment was conducted was at an elevation above 8000ft. The refluxing mixture would boil at a much higher temperature at sea level. I have distilled ethylene glycol with the same thermometer and the glycol boiled at 180 Celsius; its boiling point at standard conditions is around 200 celsius. I distilled the mixture, much of the mixture distilled between 170-180 Celsius. I have prepared benzyl chloride before and it distilled between 150-165 Celsius. There is a liquid residue in the 500mL reaction flask that I will transfer to a smaller flask to obtain more of the product from it by distillation. The distillate smelled similar to benzyl chloride with more of a biting odor. Toluene in my lab distills at 100 celsius. I plan to use the benzaldehyde in my synthesis of hexaphenyl benzene from toluene as the only organic molecule that is incorporated into the final product. I am planning on running a thiamine catalysed benzoin condensation; I have conducted this with Loranne almond oil and the reaction proceded with a yield of around 80%. Currently, I cannot obtain Loranne almond oil, it was a useful source of benzaldehyde.

benzylchloride1 - 15-3-2009 at 22:19

I measured the density of my benzyl chloride, benzal chloride mixture. The density was around 1.18 which indicates that the chlorination is not complete. I will set the chlorine generator up again in a few days to finish the chlorination. The benzyl chloride was not a problem until I cleaned up the glassware. No chlorine smell was noticed in the laboratory due to the efficient hood and also because of the ground glass equipment. In the meanwhile, I am trying the manganic sulfate oxidation of toluene using 1/4 of the amount of oxidizer that Cycloknight used. I am currently generating the oxidizer using a 7.5 amp battery charger, the reaction that forms the oxidizer procedes very quickly due to the high current. What is the best way to use this manganese compound for producing benzaldehyde?

benzylchloride1 - 18-3-2009 at 19:57

I did not have very good success with the electrolytic preparation of benzaldehyde. I was able to produce several mililiters of benzaldehyde using this method. I think I will have better luch with the chlorination of the toluene. I put my benzal chloride-benzyl chloride mixture back into the chlorination apparatus and chlornated the product for another 4.5 hours. After distilling, the product had a density of 1.23 and did not have the benzyl chloride odor. The product distilled between 180 to 190 Celsius at a pressure of around 580mm.

Sedit - 15-5-2009 at 22:52

Neograviton method seems to work for me and after about 6 hours at about 55 degrees the smell of BnO was strong. Sadly the flask broke when I attempted to steam it out so I will not be able to get an idea of yeild although I did manage to save quite abit but can not attempt a steam distilling until I get all the left over toluene and mess cleared up.

Are the yeilds as Neograviton states at 70%?

Im a little confused on the first step where he stated the need for Mn(IV) IIRC would it not need a 2x molar excess of H2SO4 to form the desired salt instead of the 1:1 he mentions.

Org posted a synthesis from Osmium that stated FeSO4/cupric acetate and sodium persulfate. Im getting ready to run this and was woundering if its really 95% such as stated. Has anyone had experiance with this method. It seems to be largly ignored when it was posted.

Klute - 18-5-2009 at 04:18

I tried it sevral times without getting any definitate results. There was benzoic acid produced, and unreacted benzyl alcohol, depending on the reaction time. But it's worth a try IMHO, I did produce a fair amount at the end. Be carefull to heat above 70°C before adding the persulfate, as there a run-out reaction if you heat to that temp after adding a large amount of persulfate.

Sedit - 18-5-2009 at 08:32

I did manage to get the mess cleaned up and steam some out. What came out from the steam distilling smelled of toluene yet it seems the benzaldahyde got let behind judging from the smell. It is quite possible that I didnt let it steam long enough but after the accident its not worth my time to attempt to salvage it.

Hinski posted another means using just Mn(IV) in a electrochemical cell. I think I will proceed in this direction for the time being and keep the persulfate route just for academics. I have heard of the runaway but did not realise that it was caused by preloading the persulfate so thats good to know.

benzylchloride1 - 20-5-2009 at 20:49

Alkyl hypochlorites as reagents for the side chain halogenation of toluene.

Tert butyl hypochlorite is an interesting chlorinating/oxidizing agent. A safe synthesis of this reagent is given in Organic Synthesis Collective volume 5. Isopropyl hypochlorite can be prepared in a similar method. A US patent describes the chlorination of theyl benzene to a,a-dichloro-1-phenylethane in high yields. This could be applicable to toluene for the synthesis of benzal chloride and other side chain halogenated products. This would be significantly better then passing dry chlorine through refluxing toluene for 12 hours for a 1 mole experiment. Here is an excript from US Patent 5064518 - Method for the selective alpha halogenation of alkylaromatic compounds. Hopefully this is patnet is not totally BS. Tert butyl hypochlorite is the preferred reagent because of its ability to form radicals, an experiment will be conducted with the more easily prepared isopropyl hypochlorite. This may considerably simplify the synthesis of benzal chloride for the home chemist.

Preparation of 1,1-dichloroethylbenzene Using t-butyl hypochlorite.

Into a 5-neck 2-liter flask, equipped with thermometer, mechanical stirrer and a pH probe, is placed 1000 mL of an aqueous bleach solution (~5.25% NaOCl). The flask is placed in an ice bath and cooled to 8° C. and t-butyl alcohol (56.5 mL, 0.59 mole) and glacial acetic acid (34.35 mL) are added with stirring. The temperature rises to about 15° C. and the pH drops from about 11.3 to about 6.5. Stirring is continued for about five minutes and then allowed to phase-separate, during which time a yellow oil floats to the surface. Ethylbenzene (36.9 mL, 0.30 mole) is added, stirring resumed and a 275-watt sun lamp is placed over the flask. The mixture is stirred with illumination for one hour while the temperature is maintained within the range of 8°-18° C., after which stirring is stopped and the mixture is allowed to phase-separate.

The aqueous phase is extracted with two×100 mL portions of methylene chloride and combined with the organic phase. The combined solvent and organic phase is then dried over MgSO4 and the solvent is removed by distillation, leaving 52.01 g of oil. G.C. analysis shows that the product is 73.6% 1,1-dichloroethylbenzene, 10.34% 1-chloroethylbenzene and 10.48% acetophenone and some minor impurities.

The following three experiments (Examples 4, 5 and 6) show the use of other solvents in the reaction using t-butyl hypochlorite as the chlorinating agent.

EXAMPLE 4

Use of Carbon tetrachloride as Solvent

A quantity of t-butyl hypochlorite (7.0 mols, 759.99 g, 775 mL) is chilled to -5° C. in a brine jacketed reaction flask equipped with mechanical stirrer, light well, thermometer and nitrogen supply. Ethylbenzene (2.0 mole, 213.4 g, 246 mL) in CCl4 (10.4 moles, 1594 g, 1000 mL) is added to the reactor and the reaction is started by turning on the lamp (incandescent, 25 watt lamp, General Electric model FG648-X). The reaction temperature is allowed to rise to 10° C. and samples are taken periodically for G.C. analysis. After 4 hours the reaction is complete and the mixture is drained from the reactor and the t-butanol is stripped using a rotary evaporator which leaves 322.62 g of a colorless oil which is 89.4% 1,1-dichloroethylbenzene by G.C. analysis (82.3% yield).

EXAMPLE 5

Use of Benzene as Solvent

The reaction of Example 4 is repeated except that benzene (11.18 moles, 874 g, 1000 mL) is used in place of carbon tetrachloride. The t-butanol is removed on a rotary evaporator and there remains 341 g of a colorless oil which is 91.7% 1,1-dichloroethylbenzene by G.C. analysis (89.3% yield).

EXAMPLE 6

Use of t-butyl hypochlorite as Solvent

Ethylbenzene (4.0 mole, 424.68 g, 492 mL) is charged to a brine jacketed reaction flask equipped with a subsurface N2 sparge, light well, thermometer and condenser. The t-butyl hypochlorite (14.0 mole, 1520 g, 1670 mL) is added to the reactor and the mixture is chilled to -5° C. while sparging with N2. The same lamp employed in Example 4 is switched on to initiate the reaction which is conveniently held at 0° C. by controlling the lamps' output with a temperature controller. Samples are taken periodically and analyzed by G.C. analysis. When the reaction is complete (3 hours) the mixture is drained from the reactor and the t-butanol and excess t-butylhypochlorite is removed on a rotary evaporator, leaving 709.0 g of a clear oil which is 93.2% 1,1-dichloroethylbenzene by G.C. (93% yield).



[Edited on 21-5-2009 by benzylchloride1]

Eclectic - 21-5-2009 at 01:11

Regarding isopropyl hypochlorite:

http://www.sciencemadness.org/talk/viewthread.php?tid=1896&a...

"DANGER, Will Robinson!"

S.C. Wack - 21-5-2009 at 03:08

Regarding t-butyl hypochlorite:

http://www.sciencemadness.org/talk/viewthread.php?tid=1896&a...

benzylchloride1 - 28-5-2009 at 15:45

The isopropyl hypochlorite chlorination of toluene works fairly well, not explosions or violent reactions, keep mixture below 25C at all times with ice bath, the reaction is very mildly exothermic, the end product had the density of benzyl chloride. A 60W light was used to catalyze the reaction.

Another interesting synthesis of benzaldehyde through benzaldoxime:
Benzaldoxime in practically 100% yield based on NOCl. The nitrosyl chloride could be generated insitu by passing anhydrous HCl into a mixture of toluene and isopropyl nitrite. The oxime can be hydrolyzed with hydrochloric acid to benzaldehyde and hydroxylamine hydrochloride.
THE REACTION OF NITROSYL CHLORIDE ON TOLUENE
BY E. V. LYNN AND HELEN I,. ARKLEY
Received January 19,1923
Some time ago one of us found' that nitrosyl chloride will readily react
with normal heptane in the sunlight to produce a blue material which
easily changes to a colorless oil. The blue compound was later shown2
to be nitroso-dipropylmethane and the rearranged oil, dipropyl-ketone
oxime. It was also demonstrated that this reaction is probably general
for all of the paraffin hydrocarbons, a conclusion reached mainly because
gasoline and petroleum ether give a similar blue color with nitrosyl
chloride.
In experimenting with various substances, it was found that benzene
could not be induced to react at all with the reagent, even in sunlight;
a sample of benzene solution was kept for months without any change in
the brown color of the nitrosyl chloride. In view of this fact, paraffin
derivatives of benzene should react in such a way that only the alkyl
radical is attacked. Toluene, the simplest alkyl drivative, should give,
according to previous experience, phenylnitrosomethane rearranging to
benzaldoxime. CsH5-CHs + NOCl ---j CeHb-CH2-N0 f HC1.
CBHS-CH~---NO --3 C6Hb-cH = N-OH. Experiment has fully
demonstrated the correctness of this reasoning, as toluene reacts readily
in the sunlight with nitrosyl chloride producing benzaldoxime, which has
been converted to benzaldehyde, benzoic acid and benzanilide in the usual
way.
Experimental Part
The nitrosyl chloride was prepared as previously described2 by the reaction
of nitrosyl sulfate and sodium chloride. The toluene was first dried
over sodium hydroxide and then distilled, the portion boiling between 110 '
and 112' being used. This was saturated with the gas, giving a dark
red-brown liquid. In the dark at room temperature there was practically
no change in the appearance, but after some time a heavy, insoluble oil
and some gas were formed. In the sunlight the reaction was quite rapid,
producing large quantities of gas, mostly hydrogen chloride, and an amount
of the heavy oil equal to about 3% of the toluene used. In later experiments
the saturated solution was exposed to the sunlight at temperatures
below 10'. In these cases the reaction proceeded somewhat more slowly
and, in place of the oil, there were deposited beautiful, white, iridescent,
feathery crystals. In all experiments the color of the solution disappeared
with the formation of the precipitate. There was, however, no intermediate
production of a blue color and one can only conclude that phenylnitrosomethane
is very unstable.
In subsequent changes the oil and crystals acted alike and, since it was
just as easy to produce the latter and more convenient to work with them,
they were employed in the reactions recorded below. The crystals had an
indefinite melting point, from 35" to 70". They were dissolved in sodium
carbonate solution and extracted with ether, evaporation of the latter
leaving characteristic crystals of P-benzaldoxime, melting at 128 '. The
primary product was, therefore, undoubtedly a mixture of the hydrochlorides
of both benzaldoximes, since the above procedure transforms the
QC to the 0 form. Hydrolysis of the oxime with dil. acid gave an oil identified
by its odor as benzaldehyde. It was oxidized by nitric acid and the
resulting benzoic acid was precipitated on cooling, and melted at 118". It
was further identified by converting to its ferric salt and to benzanilide,
m. p. 158'.
The amount of benzaldoxime crystals obtained is practically that calculated
based upon the nitrosyl chloride used, about 3% by weight of the
toluene. The time required is dependent upon the temperature and upon
the intensity of the sunlight but in no case was it longer than 2 hours.
Under the right conditions the reaction could undoubtedly be made to
proceed more rapidly and probably continuously. Whether the process
can be utilized commercially under the influence of some catalyst is a
problem which is at present engaging our attention. Furthermore, we are
studying the action of nitrosyl chloride on other substances and will report
the results later.
Summary
Nitrosyl chloride readily reacts with toluene in the sunlight to produce
crystals of benzaldoxime hydrochloride, from which benzaldoxime, benzaldehyde,
benzoic acid and benzanilide can be prepared in the usual way.

497 - 28-5-2009 at 22:54

Does anyone know how well the above stated reaction would work with substituted toluenes?

For example, how does it treat alkoxy substitutions?

DyD - 28-6-2009 at 10:52

Wow. Has nobody mentioned the "Etard" reaction?
It appears that Chromyl Chloride [Cr(VI)O2Cl2] is excellent at partially oxidizing toluene to benzaldehyde.
While I haven't prepared benzaldehyde from toluene yet, I've successfully prepared chromyl chloride from Chromium(III) oxide via the below process:
--------------------
2 KMnO4 + Cr2O3 + 2 H2SO4 → H2Cr2O7 + 2 KHSO4 + 2MnO2
H2Cr2O7 + 4 KCl + 4 H2SO4 → 2 CrO2Cl2 + 4 KHSO4 + 3 H2O
Overall:
2 KMnO4 + Cr2O3 + 4 KCl + 6 H2SO4 → 2 CrO2Cl2 + 6 KHSO4 + 2 MnO2 + 3 H2O
--------------------
While gaseous hexavalent chromium sounds like a sure-fire recipie for lung cancer, the fumes are dense enough that I feel the risk to be within the realm of reason.
What do you all think? I'm going to try it in the next few weeks and I'll post back with an update. Feel free to PM me with questions or comments.

Polverone - 28-6-2009 at 12:48

There's considerable good reading material about this reaction in older publications. Main problems with Etard are hexavalent chromium health hazards, expense of the reagents, violence of the initial reaction, and needing to take careful measures to protect the liberated aldehyde from further oxidation at the end. I will look forward to the results of your experiments.

What form was your Cr2O3 initially in? Was it pottery-grade or something more reactive? Woelen reported not long ago that acid bromate solution would dissolve pottery Cr2O3, which was something of a surprise, since usually it takes high-temperature alkaline-oxidative fusion to get to Cr(VI) from such material. I am curious if the use of KMnO4 was inspired by his posts, derived from some other reference, or discovered independently by you.

DyD - 28-6-2009 at 15:53

I procured the Cr2O3 from the greenish ash left over from the ammonium dichromate volcano demo performed by an old chemistry teacher for a 101 class. I washed it with a dilute acid-peroxide solution to neutralize any residual hexavalent chromium and allowed it to dry. I then packed it into glass vials for future use. Now I'm very happy I did so. :)
The KMnO4-acid discovery was determined entirely by myself. The inspiration came after remarking to a friend that Mn2O7 could oxidize "damn near anything."
In addition, I added some of the liquid formed by:
2 KMnO4 + Cr2O3 + 2 H2SO4 → H2Cr2O7 + 2 KHSO4 + 2MnO2
to water and observed an orange solution with brown precipitate, precisely as expected.

UnintentionalChaos - 28-6-2009 at 16:05

This covers substituted toluenes, but is helpful at any rate for reaction conditions.

You're welcome :P

Attachment: Etard Reaction.pdf (221kB)
This file has been downloaded 2876 times

[Edited on 6-29-09 by UnintentionalChaos]

entropy51 - 29-6-2009 at 15:08

Thanks for the article, UnintentionalChaos. The preps in the article specify CCl4. Has anyone ever run this reaction in CH2Cl2?

[Edit] By that I meant actual experience, not theorizing. Adding chromyl chloride to neat toluene will result in a fire, if you're lucky.

[Edited on 30-6-2009 by entropy51]

DJF90 - 29-6-2009 at 15:59

CS2 and CHCl3 are also listed as alternative solvents. CHCl3 has the trouble of forming emulsions apparently, so CH2Cl2 might also suffer from this drawback. Adding chromyl chloride dropwise to excess toluene may work, but care should be exercised when trying this as the reaction may be too exothermic with neat liquid reactants.

Rattata2 - 12-9-2009 at 02:38

The way I thought to do it was to slowly add bromine to an excess of toluene, forming benzyl bromide. This would be separated from any remaining toluene and hydroxylated with NaOH to form benzyl alcohol and NaBr. The salt is separated from the alcohol and recycled, while the benzyl alcohol is then mixed with DMSO and HCl or HBr solution is added - producing benzaldehyde and dimethyl sulfate.

Bromine can of course be made by acidifying NaBr followed by simple oxidation with 3% H2O2. Since it is a liquid at feasible temperatures this would ease the halogenation of the toluene. Since adding NaOH reforms the NaBr, it can be recycled.

acid-catalyzed DMSO can oxidize benzyl alcohol (and similar compounds) to benzaldehyde with as high as 95% yield!

Nicodem - 12-9-2009 at 06:39

When someone claims such unusual things, like that slowly adding bromine to an excess of toluene, forms benzyl bromide, or that oxidation of benzyl alcohol with DMSO gives dimethyl sulfate besides benzaldehyde, it is expected that some references are provided.

Why would we believe you just for your word? It is experimentally known that bromine reacts only very slowly with toluene at room temperature, and even this via the electrophilic aromatic substitution, thus giving a mixture of o- and p-bromotoluene. Essentially no benzyl bromide is formed unless you use conditions for radical brominations (that is, radical initiators or photochemically). Also, the oxidation of benzyl alcohol with DMSO means that DMSO is getting reduced (basic rule of redox reactions is that the oxidant gets reduced and reductor oxidized). Dimethyl sulfate is in a higher oxidation state than DMSO, so how could it be the product of the reaction? The next sulfur lower oxidation state product forms, that is dimethyl sulfide, as is known experimentally.

PS: You would know all these things if you would just bother to read and cite references.

JohnWW - 12-9-2009 at 07:59

DMSO (of which I have about a 500 ml bottle) would be reduced to dimethyl sulfide, which being a mercaptan would have an intense garlic odor. Also, being highly volatile, it would probably be toxic like H2S.

Rattata2 - 13-9-2009 at 08:54

Benzyl halides are commonly made by free-radical halogenation of toluene - the same process is used to produce the chloride as is the bromide, only bromide would probably be loads easier since it is liquid at room temperature. Using 2x the molar ratio results in the benzal halides. Given that it was such common info I didn't see a reason to hunt down a reference for it.

http://www.erowid.org/archive/rhodium/chemistry/alcohol2alde... this describes the oxidation of benzyl alcohols to benzaldehydes using DMSO and HBr.

OHH I did mean sulfide - totally didn't mean to type sulfate - told myself over and over not to make that typo :) My bad haha.

[Edited on 13-9-2009 by Rattata2]

Nicodem - 14-9-2009 at 01:31

Quote: Originally posted by Rattata2  
Benzyl halides are commonly made by free-radical halogenation of toluene - the same process is used to produce the chloride as is the bromide, only bromide would probably be loads easier since it is liquid at room temperature. Using 2x the molar ratio results in the benzal halides. Given that it was such common info I didn't see a reason to hunt down a reference for it.

Using this as an example, I will try to explain in just few words why it is so important to give references and cite sources. If you would have provided a reference for benzylic bromination of toluene, there would have (statistically) been more chances that you would had also read it, and if you would have read it, you would have also read the experimental conditions. This would have given you the knowledge that just adding bromine to toluene does not form benzyl bromide. Instead, you did the classical beginners mistake who seeing a reaction scheme jumps at the conclusion that you just add this to that and out comes the product. The reaction of bromine with toluene can either proceed via electrophilic aromatic bromination or via radical bromination, both requiring different conditions, but none proceeds to any usable extent by just "slowly adding bromine to toluene".

Quote:
http://www.erowid.org/archive/rhodium/chemistry/alcohol2alde... this describes the oxidation of benzyl alcohols to benzaldehydes using DMSO and HBr.

But why? What is the point of reacting benzyl bromide with a hydroxide (which, by the way, gives a mixture of benzyl alcohol and dibenzyl ether) just to then oxidise the benzyl alcohol with DMSO? It sounds completely irrational when you can oxidise benzyl bromide with DMSO directly using the Kornblum oxidation. (And this is another example of lack of reference checking. If you would have checked the references from the paper you linked to you would have read the reference number 3 and 4 as well).

DJF90 - 14-9-2009 at 03:36

Ratatta2: Listen to Nicodem - he makes very valid points.

JohnWW: I actually had the "pleasure" of smelling DMS as a solution in DCM. It was very cabbage like (not garlic as you describe) and rather strong smelling, although not as strong as I had anticipated (possibly due to it being in solution?). It was actually *quite nice* once the majority of the smell had gone, leaving a faint odour in the room.

ketel-one - 15-9-2009 at 20:43

toluene + Ca(OCl)2 @105C with no other reagents should make benzyl chloride...

Sedit - 15-9-2009 at 20:58

Prove it.
Book learning is all fine and well but unless your Ca(OCl)2 is pure you will run out of room. Not to mention the ugly runaway leading to over heating.
Oh yeh did I mention the product of all that hassle was junk? Im sorry but I toyed with that method and wasted alot of toluene to accomplish nothing useful and it caused my eyes to feel as though sand is in them. You will get a mixture of products doing it that way as well so there are other more focused ways one could go about its synthesis.

Check out Lens threed on the topic in prepublications. You can't beat that kind of excelent work that was performed in that writeup.

BTW: The worst part of the synthesis using the hypochlorite is the runaways. This could be due to my dirty Ca(OCl)2 but either way I think this sucks. I want so bad to try it once more because I hate like hell when a synthesis kicks my ass but I think I know when Im beat and wasting my time.

ketel-one - 15-9-2009 at 21:58

Ive never tried it, but the stuff on this site should be pretty accurate. http://www.erowid.org/archive/rhodium/chemistry/benzylchlori...

"Toluene and dry Calcium Hypochlorite (bleaching powder) are heated together to 105°C in the abscence of other reagents. This avoids by-product formation. If equal amtounts are used, volume-wise, there is a high conversion. If more bleaching powder is used, the conversion is more robust, but contaminants such as benzal chloride and benzotrichloride are formed [...]"

Sedit - 15-9-2009 at 22:21

"there is a high conversion"

Yup that explains the itchy eyes. But the contamination is to much of a pain when there are better means that even I am able to perform. Anyone with good gear should be able to perform other synthesis with ease instead of dicking with this. The part where is says avoids biproduct formation is a load of shit BTW and they dont mention the fact that when it hits 105-110 it runs away to extreamly high temps. You see them little [...] there? Thats the main problem with rhodiums archives is that it does not give the full details and don't mention what the original text states of SLOWLY adding the Ca(OCl)2 in portions. If you can site rhodiums articals then its better to look for the references at the bottom and take the writeup with a grain of salt. I love the fact he put this all out there but care must be taken. Its just bad form to not cross reference your sources.

[Edited on 16-9-2009 by Sedit]

ketel-one - 15-9-2009 at 22:48

Right, here's the patent referred to http://www.freepatentsonline.com/1280612.pdf I don't know if you say it's not good then perhaps it isn't, one step reaction it does seem too good to be true.

ketel-one - 19-9-2009 at 01:25

Doesn't styrene undergo alkene addition to form benzyl chloride? It would be awsome if styrene can be made from styrofoam.

Edit: Oh right Markovnikov's rule... the HCl would add the wrong way.

[Edited on 19-9-2009 by ketel-one]

UnintentionalChaos - 24-9-2009 at 22:28

Quote: Originally posted by ketel-one  
Doesn't styrene undergo alkene addition to form benzyl chloride? It would be awsome if styrene can be made from styrofoam.

Edit: Oh right Markovnikov's rule... the HCl would add the wrong way.

[Edited on 19-9-2009 by ketel-one]


Styrene has an extra carbon anyway. :p

Sedit - 25-9-2009 at 11:07

Benzaldahyde can be made thru the the ozoneolysis of styrene followed by either H2O2 or better still Dimethylsulfide or PPh3. To attempt to create benzyl chloride from it is just unreasonable.

DJF90 - 7-10-2009 at 07:10

Sedit: H2O2 gives an oxidative workup yielding the carboxylic acid. Stick to Me2S or Ph3P. Not a particularly fantastic route though, as ozonolysis equipment is needed, dimethyl sulfide is volatile and smelly, and triphenylphospine is pretty expensive... although the polystyrene precursor is cheap and easy to thermolyse to styrene.

User - 7-1-2010 at 04:34

I wonder, has anyone tried toluene oxidation through the etard process?
It was mentioned somewhere is this thread.
According to one of my old chemistry books toluene can be oxidised with chromyl chloride (CrO2Cl2)

As far as I understand the reaction that it undergoes is that: 2 chromyl chloride molecules bind with the methyl group of the toluene which then is hydrolyses by H2O to benzaldehyde.

The book states that the oxidation does stop with benzaldehyde and doesn't "over" oxidises to benzoic acid or friends.
This is confirmed by wikipedia, what ever that says :P

I have no references for this method except for the brief description of the method.
The book states no experimental procedures.

I know chromylchloride is a very nasty chemical.
Still it could be produced with acceptable safety and would not be ridiculously expensive.

Anyone?
PS dont kill me , my organics arn't what they should be.

*edit*
Fuck sorry it was mentioned on page 3 with a more detailed description.
Sorry for not properly using the fucking search engine.
Also it sucks big time.
Somehow it even seems to miss perfect matching search tags.



[Edited on 7-1-2010 by User]

S.C. Wack - 7-1-2010 at 14:23

After all those huge pictures were posted, one can hardly be blamed for skipping through. The experiment that I mentioned before, Perkin and Law [JCS 91, 258 (1907)] with chromyl chloride in chloroform (among other methods), on toluene (among other things):

http://books.google.com/books?id=Vuc4AAAAMAAJ&pg=PA258

[Edited on 7-1-2010 by S.C. Wack]

User - 8-1-2010 at 05:30

The link isnt working, at least for me.
Could you please give another url or upload.
Ive done some searching but cant find alternative.

Paddywhacker - 24-4-2010 at 00:01

For your pleasure-


Attachment: Prep of Chromyl chloride, Perkin & Law, JCS,1907, 91, p191.pdf (156kB)
This file has been downloaded 1378 times

Attachment: Oxidation of toluene etc., Perkin & Law, JCS,1907, 91, p258.pdf (391kB)
This file has been downloaded 1626 times


cyclohexane - 13-6-2010 at 23:54

this is a little more comprehensive
and covers both the prep of chromyl chloride
and its use on various substrates.

-----edit----------
its called 'the chemistry of chromyl compounds'
but i cant get it under 2 mb.....

but its uploaded here:

http://www.scribd.com/doc/33005325

or here

http://www.scribd.com/doc/33005325/The-Chemistry-of-Chromyl-...


[Edited on 14-6-2010 by cyclohexane]

Attachment: etard_and_solvents.pdf (160kB)
This file has been downloaded 916 times


Sedit - 14-6-2010 at 08:38

In this thread by Hinsky
http://www.sciencemadness.org/talk/viewthread.php?tid=6882&a...

He talks about Mn(IV) for the use in the electrochemical cell but never gave definitive yeilds. I experienced the same process a number of times looking exactly as his pictures but noticed VERY low yeilds not worth the bother till sometime after messing around with it I noticed a quote in his patent that explains why. The oxidiser is added dropwise into the toluene as its heated and stirred. I don't think anyone is going to get good results mixing the two and stirring away but has anyone tryed that method with drop wise addition into the toluene? Iv considered another run at it just never got around to it and since this thread has come to life again thought I would ask.

cyclohexane - 14-6-2010 at 15:28

IMO the etard uses cheaper reagents and has almost always 100% conversion if done properly. the final yeild should be 2 moles Benzaldhyde for every 3 moles put in as etard always follows a 2:1 ratio.

that .pdf is in the reference request section at ...dreams.ws -i tried to view it to check the link,looked like it worked,but then ffox crashed....

almost always the side-product is useful as well....say one gets 2 moles cumenealdehyde, and 1 mole acetophenone for every 3 moles in.....of the substrate. the .pdf includes a variety of preperation options including the pro's and cons, as well as a horde of substrates and solvents.

if cyclo's sources are right ( and journals seem to support it) then DCM would be a suitable replacement for carbon tet. etard seemed to like tet and carbon sulfide, but back in his day tet was acceptable to use as a fire extingisher.

of course i guess the consequences of breaking a flask here are much worse......


Sedit - 14-6-2010 at 15:38

Cheeper then the Mn(IV) route? I find that hard to believe. Once made all reagents other then nothing but toluene are cheeply and easily regenerate. I can't see the etard comming close to this as far as cheepness is concern as long as the dropwise addition of the Mn(IV) lives up to claims.

The Etard reaction also generates dangerous toxins that I would avoid at all cost to be honst. No need to work with danger if there is another means to an end.

Just my take on it.

cyclohexane - 14-6-2010 at 21:37



actually i was wrong, the yields are 90%.
the 2:1 rule dosent apply because different starting substrate.

3. Synthesis of aromatic aldehydes and ketones
(a) From toluene: The chief product is benzaldehyde (90 per cent); small
amounts of benzoic acid, benzyl chloride, and benzylidene chloride are formed.
CHEMISTRY OF CHROMYL COMPOUNDS 35
This is the prototype reaction first investigated by Etard (56). The general
procedure used has been described, and the yields indicated above are obtained
thereby. Reaction I is probably the only one occurring to any measurable extent.
If the addition compound is heated at 240-250°C., half of the chlorine is
driven off as hydrogen chloride (reaction 111), leaving a residue having a composition
corresponding to the formula CBH&H(Cr02C1)2. This product also can
be decomposed by water or alcohol to form benzaldehyde (reaction IV).



Electric Benzaldehyde

jono - 16-6-2010 at 02:44

Hey, I'm also interested in making benzaldehyde by oxidising toluene according to patent 808,095, however, I'll be doing it on a 1/50 basis.
I have just one question, can I reuse the oxidising mixture over and over again, assuming that I am unable to get all of the toluene and benzaldehye out of the mixture?
Because I'm hoping this procedure is a simple "plug in" and "reuse" method.

thanks

Lambda-Eyde - 16-6-2010 at 02:49

This is a forum for amateur science, not a place for people interested in scheduled substances to get spoonfed and asking for "plug and play"-syntheses.

If you had bothered to search you would see that this patent you are referring to has been discussed earlier in this thread.

cyclohexane - 17-6-2010 at 06:16

both the Etard process and benzaldehyde are are useful for things other then whats implied. if people choose to misuse information then
its up to them to deal with the possible consequences of there action.

if everything that could be misused was not spoken of then many important things would not be learned.

Melgar - 8-8-2010 at 12:24

Benzaldehyde can be made pretty easily by mixing styrene, acetone, and a small amount of water (like 5% of the quantity of acetone) then running ozone into the mixture, which should ideally be kept as cold as possible to prevent the evaporation of acetone. This method of ozonolysis seems to only produce good yields with terminal alkenes such as styrene though.

Methansaeuretier - 19-8-2010 at 16:24

Hello there...
Once I had a paper wich mentioned the oxidation of toluenes with ammonium persulfate and Ag2SO4. But I can't find it again, even when I UTFSE. Does someone know this paper or where to download?

[Edited on 20-8-2010 by Methansaeuretier]

sabbath06 - 1-9-2010 at 11:59

So to make formaldehyde with this cell I assume you just substitute methanol for toluene? Any other parts to this that I am missing?

behemoth - 18-9-2010 at 10:28

Quote: Originally posted by sabbath06  
So to make formaldehyde with this cell I assume you just substitute methanol for toluene? Any other parts to this that I am missing?


It is written in the patent US 808095 that methanole will be oxidized to formaldehyde or formic acid. Using an excess of methanole will convert the formaldehyde to methylal (formaldehyde dimethyl acetal).

aax - 18-10-2010 at 11:33

Quote: Originally posted by behemoth  
Quote: Originally posted by sabbath06  
So to make formaldehyde with this cell I assume you just substitute methanol for toluene? Any other parts to this that I am missing?


It is written in the patent US 808095 that methanole will be oxidized to formaldehyde or formic acid. Using an excess of methanole will convert the formaldehyde to methylal (formaldehyde dimethyl acetal).


That patent says nothing about MAA being used as the oxidizer... I have been trying to find a post by cycloknight in which he states that methanol can be oxidezed by MAA into formaldahyde. If anyone else is interested in this feel free to correct me if I'm wrong...

Keep in mind that formaldahyde boils at -21C when pure and not caught in an Azeotrope with water. If the MAA was mixed with methanol and then heated to 50C to start the oxidation formaldehyde should boil out of solution as long as the solution is dry. Just catch the formaldehyde in DH2O and boomshockalocka 37% formaldahyde solution.

Another "easy" path to formaldehyde was found at "http://www.ucc.ie/academic/chem/dolchem/html/comp/methanol.html"

Dehydrogenation of Methanol
Methanol can also be oxidised to formaldehyde by passing its vapour over copper heated to 300 degC. Two atoms of hydrogen are eliminated from each molecule to form hydrogen gas and hence this process is termed dehydrogenation

They have have a page for acetaldehyde that says it can be made exactly the same way as above except the methanol is substituted for ethyl alcohol... This makes me wonder if benzaldehyde can be made by using toluene instead of methanol. Doubt it..

aax - 18-10-2010 at 11:33

Quote: Originally posted by behemoth  
Quote: Originally posted by sabbath06  
So to make formaldehyde with this cell I assume you just substitute methanol for toluene? Any other parts to this that I am missing?


It is written in the patent US 808095 that methanole will be oxidized to formaldehyde or formic acid. Using an excess of methanole will convert the formaldehyde to methylal (formaldehyde dimethyl acetal).


That patent says nothing about MAA being used as the oxidizer... I have been trying to find a post by cycloknight in which he states that methanol can be oxidezed by MAA into formaldahyde. If anyone else is interested in this feel free to correct me if I'm wrong...

Keep in mind that formaldahyde boils at -21C when pure and not caught in an Azeotrope with water. If the MAA was mixed with methanol and then heated to 50C to start the oxidation formaldehyde should boil out of solution as long as the solution is dry. Just catch the formaldehyde in DH2O and boomshockalocka 37% formaldahyde solution.

Another "easy" path to formaldehyde was found at "http://www.ucc.ie/academic/chem/dolchem/html/comp/methanol.html"

Dehydrogenation of Methanol
Methanol can also be oxidised to formaldehyde by passing its vapour over copper heated to 300 degC. Two atoms of hydrogen are eliminated from each molecule to form hydrogen gas and hence this process is termed dehydrogenation

They have have a page for acetaldehyde that says it can be made exactly the same way as above except the methanol is substituted for ethyl alcohol... This makes me wonder if benzaldehyde can be made by using toluene instead of methanol. Doubt it..

behemoth - 18-10-2010 at 12:18

Quote:
Quote: Originally posted by aax  
That patent says nothing about MAA being used as the oxidizer...


Well, it does. Read the lines 63 to 71.

6.022x10^23 - 23-12-2010 at 17:25

I am constructing an oxidation cell ala Cycloknight/US 808095. I have a four liter solution of 12.5 M (66.5%) H2SO4 in which I have dissolved four moles of (NH4)2SO4. This dissolved completely; upon addition of the MnSO4 I was expecting a shift in color to the yellow as seen in the photos. It appears as though my MnSO4 is not dissolving, but rather being whipped up into suspension, with a “snow drift” on one side of the beaker.

The observed color is the dirty transparent yellow of the sulfuric acid solution obscured with suspended MnSO4.

The MnSO4 I added was the monohydrate. I have applied brief heat with no effect. The MnSO4 that has settled on the bottom still has its pink hue.

I have only added two moles of the MnSO4 and I am afraid to add anymore.

Should the MnSO4 have dissolved right away? It has been stirring for about two hours.

Should I have added (NH4)2SO4 until there was some that would not go into solution (it was really close)?


UPDATE (Next Morning):

Just to be methodical I added a few grams of MnSO4 to some 35% (battery) H2SO4, swirled and observed negligible dissolution.

I also added approximately the same amount to dH2O and again observed negligible dissolution.

This morning (~12 hours later) the MnSO4 has almost totally dissolve in each.

My liquid volume is approximately 100ml, though I added much less than 40g of MnSO4.

I am building a smaller cell, on the two liter scale, so that even if there is considerable undissolved particles my magnetic stirring will be able to function.

There is still considerable, undissolved MnSO4 in the initial four liter cell.

[Edited on 24-12-2010 by 6.022x10^23]

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