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Author: Subject: The short questions thread (2)
Formula409
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[*] posted on 19-6-2009 at 17:14


Imines form water-soluble hydrochlorides, don't they?

Formula409.
Edit: Yes they can : http://www.journalarchive.jst.go.jp/english/jnlabstract_en.p...


[Edited on 20-6-2009 by Formula409]
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[*] posted on 21-6-2009 at 18:09


Organic Hypochlorites like EtOCl are effective chlorinating agents for the conversion of toluene to Benzyl Chloride.

They are synthesised in a cold dim enviroment to prevent explosion risk from R-OH + NaOH + Cl2 = R-OCl + NaCl + H2O

My question is could this possibly be used insitu to chlorinate Toluene or is purification a must? My logic is the faster it is used for chlorination and turned back into EtOH the less one risk the explosion from it. The main problem I see here is the water formed interfering with the conversion of BnCl by Hydrolysis to HCl + BnOH. Drying with MgSO4 I guess would be possible but would also take a large amount of drying agent I would think.

Even if BnOH was the main product this still would not pose a problem since BnO is the final target compound to begin with. I know of all the other ways to get there so lets not make it a discussion on that please. Just curious about this reaction in general.





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UnintentionalChaos
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[*] posted on 21-6-2009 at 19:49


Quote: Originally posted by Sedit  
Organic Hypochlorites like EtOCl are effective chlorinating agents for the conversion of toluene to Benzyl Chloride.

They are synthesised in a cold dim enviroment to prevent explosion risk from R-OH + NaOH + Cl2 = R-OCl + NaCl + H2O

My question is could this possibly be used insitu to chlorinate Toluene or is purification a must? My logic is the faster it is used for chlorination and turned back into EtOH the less one risk the explosion from it. The main problem I see here is the water formed interfering with the conversion of BnCl by Hydrolysis to HCl + BnOH. Drying with MgSO4 I guess would be possible but would also take a large amount of drying agent I would think.

Even if BnOH was the main product this still would not pose a problem since BnO is the final target compound to begin with. I know of all the other ways to get there so lets not make it a discussion on that please. Just curious about this reaction in general.


consider perhaps tert-butyl hypochlorite which is more stable and somewhat less suicidal to work with.

do you have a reference for the conversion of toluene to benzyl chloride?




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[*] posted on 21-6-2009 at 20:38


Yes, It was posted by SC Wack some time back in the organic hypochlorite threed. Its the first post on the second page.

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

Link to the file: http://www.sciencemadness.org/talk/files.php?pid=47308&a...

Suicidal don't even appear to be the word for these compounds and its mostly just for academia at the moment.

Im curious of BnCl or more then likely BnOH could be formed directly after the EtOCl or which ever organic hypochlorite thats used does. Excess NaOH could be used to neutralize the formed HCl I would think and more then lead to Benzyl Alcohol. But since BnOH in concentrated acid is suppose to give BnCl also im a little lost as to the product of performing this in one pot if its at all possible.

[Edited on 22-6-2009 by Sedit]





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[*] posted on 21-6-2009 at 20:39


I looked for a hypochlorite chlorination of toluene (only google) and my cursory results only turned up ring chlorination (attachment)
EDIT: Ah, excellent I knew I had seen the sidechain chlorination reaction somewhere before.

However ethyl hypochlorite is not too bad, at least Axt and myself have made it without incident. Smells horrible though, perhaps tBu would stink less with its lower vapour pressure. Of course, tBu also offsets the explosion risk ;)



Attachment: ref1 chloro.pdf (599kB)
This file has been downloaded 649 times

[Edited on 22-6-09 by The_Davster]




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[*] posted on 21-6-2009 at 20:42


Quote from the paper

Quote:
Results and Discussion
Reaction with Toluene.

-Toluene was chosen as
an initial substrate for our study since the occurrence
of side chain or ring substitution of halogen
is in general diagnostic for radical or polar processes.
Preliminary experiments at 40' using excew
(3: 1) toluene and azobisisobutyronitrile (AIBN)
or light as initiator showed a rapid reaction after a
variable induction period, complete consumption
of hypochlorite, and the formation of benzyl chloride
and t-butyl alcohol as major products. A more
detailed study of the effect of reaction variables on
rate gave the results appearing in Table I, while





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[*] posted on 22-6-2009 at 06:07


I may just not be looking hard enough, but are there any sites like SDBS that have two-dimensional spectra (e.g. COSY, NOESY, HSQC, HMBC)?

sparky (~_~)




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[*] posted on 22-6-2009 at 12:58


Dear sparky,

I don't know such a kind of database, but I do know there is a 2D NMR predictor from ACDLabs, it also have the capability of being tuned to improve the predictions.

I don't rememeber if this module is included within the acdlabs 11 suite posted somewhere in the forum, but I hope so.


Your question pulled out my curiosity...I found this site:

http://www.ebi.ac.uk/nmrshiftdb/

maybe it would be helpful.

[Edited on 22-6-2009 by jokull]
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[*] posted on 23-6-2009 at 09:47


Can an enamine reduction using formic acid take place in a highly acidic enviroment of 60% H2SO4?

I see nothing stoping it but then again if I was a good chemist I wouldn't be here asking you folks:P

Attachment: Formic Reduction.pdf (331kB)
This file has been downloaded 620 times






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[*] posted on 23-6-2009 at 14:45


IIRC sulfuric acid of such concentration would decompose the formic acid to carbon monoxide.
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[*] posted on 23-6-2009 at 14:47


Ahh yes good point.




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[*] posted on 24-6-2009 at 03:40


What is the best type of UV light for radical chlroinations?
I understand these work with sunlight however is the UV from blacklights or from those water sterilising tubes better?
thanks,
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[*] posted on 24-6-2009 at 07:53


This has been covered in the threads that discuss making the alpha-chloro-tolulenes. Light in the blue to near UV is the best, for a variety of reasons. A non-coated (clear bulb) mercury vapor lamp for outdoor lighting applications gives both good wavelengths and high intensity, and is much more cost effective than the two choices you offered.

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[*] posted on 24-6-2009 at 12:13


Has anyone synthed benzonitrile from benzoic acid and sulphamic acid before? I've not seen this preparation described anywhere and am interested in learning a little more about it
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[*] posted on 25-6-2009 at 07:15


What is wrong with sciencemadness? I haven't been able to post anything lately and it takes me too the main screen.. has anyone else had that problem?

[Edited on 25-6-2009 by kclo4]




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[*] posted on 25-6-2009 at 08:06


KCLO4 - I had that problem when I tried to post a reply which included a equation in which I'd made a double headed arrow <=> (lesser than)(equals)(greater than)

I'm pretty sure the < > combination is behind the problem, I had to use the HTML code "& LT ;" "& GT ;" (without the internal spaces) to get them in this message.


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[*] posted on 25-6-2009 at 08:16


That must be something with HTML or something, I was posting a link to a google search, and a link to another sciencemadness thread.

Hope the problem can be fixed soon, but seems like it might be hard to diagnose. I noticed it late last night/early morning.




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[*] posted on 25-6-2009 at 09:39


Has anybody here attempted the monoethanolamine synthesis?
I understand it is made by reacting ethylene oxide (ethene + O2/Ag) with aqueous ammonia, producing a mix of the amines.
I have also read however monoethanolamine reacts with aqueous ammonia to produce diethylamine… Is there any way I can stop this reaction, or how long does it take?
I understand to produce mainly monoethylamine I must use an excess of ethene oxide…

As for the intended usage, I plan on making some taurine :)
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[*] posted on 25-6-2009 at 14:18


The classic monoalkylamine synthesis involves phthalimide as a protecting group. Because the two carbonyls polarize it, the N-H is fairly acidic and the H can be abstracted with potassium carbonate or hydroxide. An electrophile, like ethyl chloride, can substitute easily. The phthalimide is then hydrolyzed in acid, leaving the monoalkylamine salt.

Not sure if this will work with your particular alkyl. I would suppose the hydroxyl of 2-chloroethanol would sit still, it's less electrophilic. Not sure how you get it either, add HCl to ethylene oxide maybe? Also sounds hazardous or noxious...

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[*] posted on 25-6-2009 at 17:16


There's also the variation that replaces phthalimide in the Gabriel synthesis with saccharin; go look for the refs yourself, but I do recall that the saccharin has to be oven-dried for the reaction to work. Otherwise, there's also Delepine (which uses hexamine).

sparky (~_~)




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[*] posted on 27-6-2009 at 08:38


Sorry just figured out my post would not work
I will do a bit more research

[Edited on 27-6-2009 by Saber]
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[*] posted on 27-6-2009 at 10:39


Wikipedia says that the synthesis of taurine starts with 2-hydroxyethanesulfonic acid, obtained from the reaction of ethylene oxide with sodium bisulfite. From the intermediate compound you might try alcohol => halide (appel reaction? or Sn2 with HI or possibly HCl/ZnCl...) followed by gabriel or delepine reaction, or you could go alcohol => aldehyde (PCC, oppenauer oxidation, TEMPO, DMP etc...) and then reductive amination (leuckart, NH4+ HCO2-?) Or alcohol => acid (jones reagent) and then a schmidt reaction (H2SO4/NaN3). Personally the first idea looks most attractive (I dont think the appel reaction (Ph3P/CCl4) or gabriel synthesis will cause problems with the sulfonic acid group), although you might have trouble obtaining the reagents.
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[*] posted on 1-7-2009 at 18:17


Once again I need the wisdom of you folks here.

I was distilling a small amount of bromoethane maybe about 25-35ml and I allowed it to distill to dryness at which point there was a pop and went over to find the bottom of the flask went out.

I smelled no smell but within couple seconds (10 tops)I could taste a funny taste in my mouth simular to when a funky perfume or something gets sprayed to close possibly bug spray. It is semi indoors without a fume hood but its well ventilated(few feet from a big wide open garadge door) so I turned it off and am letting it air out and got the hell out of there.

I know Bromoethane is no good for you...

How concerened should I be long term...short term.... over a small exposure.

I expected this to have a smell of some kind and yet there was nothing but the taste is obvious and not placebo effect.





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[*] posted on 1-7-2009 at 18:29


"8.1 Single exposure
8.1.1 Inhalation

In a single exposure study, groups of five mice and five rats of each sex were exposed to bromoethane at concentrations of 0, 2800, 5700, 11 000, 23 000, or 45 000 mg/m3 (0, 625, 1250, 2500, 5000, or 10 000 ppm) for 4 h (Roycroft, 1989). Mortalities were observed at 5700 mg/m3 (1250 ppm) or more in mice and only at 45 000 mg/m3 (10 000 ppm) in rats. At 45 000 mg/m3 (10 000 ppm), clinical signs of toxicity prior to death included dyspnoea, hyperactivity, and incoordination. No further information was available. LC50 values determined from these data were 21 200 mg/m3 (4681 ppm) for rats and 12 300 mg/m3 (2723 ppm) for mice.

As a comparison, 1-h LC50 values were calculated as 122 000 mg/m3 (26 986 ppm) for rats and 73 500 mg/m3 (16 230 ppm) for mice (MacEwen & Vernot, 1972). The primary response seen in both rats and mice was central nervous system (CNS) depression, although no further details were given. The authors reported seeing diarrhoea in rats exposed to the highest concentration, 180 000 mg/m3 (40 000 ppm), and in mice exposed to concentrations ranging from the highest of 90 000 mg/m3 (20 000 ppm) down to 57 000 mg/m3 (12 600 ppm). (The lowest concentrations used were 90 000 mg/m3 [20 000 ppm] for rats and 45 000 mg/m3 [10 000 ppm] for mice.)

Other LC50 values quoted are 53 000 mg/m3 (11 700 ppm) for rats and 36 000 mg/m3 (7950 ppm) for mice following 2-h exposures, with "general damage to the nervous system" occurring (Izmerov et al., 1977).

Early, generally poorly reported, studies in mice, guinea-pigs, and cats confirm the toxicity of bromoethane by inhalation (Müller, 1925; Bachem, 1927; Glaser & Frisch, 1929; Sayers & Yant, 1929). In guinea-pigs, for example, toxic signs were observed within 1 min of exposure to 45 000 mg/m3 (10 000 ppm) (Leuze, 1922; Sayers & Yant, 1929; Abreu & Emerson, 1940).
8.1.2 Oral

An oral LD50 of 1350 mg/kg body weight in rats has been listed with no further details (Izmerov et al., 1977), although in another study, Miller & Haggard (1943) observed "no serious ill effects" in rats from an oral dose of 1200 mg/kg body weight in olive oil.
8.1.3 Dermal

Schwander (1936) reported no signs of toxicity following a study in which an unspecified quantity of liquid bromoethane was placed in direct contact with the skin of one rabbit for 6 h. "




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[*] posted on 2-7-2009 at 14:39


Since concentrated ammonia solution is so useful but rather scarce, I was thinking that a promising way to prepare it would be to heat intimately mixed ammonium sulfate and calcium hydroxide in a metal can and pipe the fumes into water.

Any thoughts on this?

Apparently it is possible, but as for yields, I haven't an idea. An interesting Popular Science article recommends it for experimental preparation. http://books.google.com/books?id=mCYDAAAAMBAJ&pg=RA1-PA1...

Reading that, I can see that Popular Science has gone downhill since 1944.

[Edited on 3-7-2009 by manimal]

[Edited on 3-7-2009 by manimal]
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