Sciencemadness Discussion Board

Aniline

Bean - 7-4-2016 at 09:45

Could aniline be synthesised successfully through this route:

1. Ammonylsis of ethyl benzoate with ammonia solution
2.Hofmann rearangement of the amide

I would be pleased to hear from somebody who has tried this or a similar procedure to find out is yields are decent and how long each stage takes and what conditions are advised.
Many thanks in advance.

DFliyerz - 7-4-2016 at 11:53

Here's some stuff on aniline via benzamide:
http://www.sciencemadness.org/talk/viewthread.php?tid=4201

Bean - 7-4-2016 at 13:25

Thanks.

gatosgr - 4-6-2016 at 04:32

Why has aniline suddendly become hard to find?

[Edited on 4-6-2016 by gatosgr]

Orenousername - 4-6-2016 at 05:04

Isn't aniline usually prepared from nitrobenzene though? The process is pretty straight forward I believe, the only real downside being the toxicity of nitrobenzene. Is there a reason you want to prepare aniline in a different way?

CRUSTY - 5-6-2016 at 19:29

Quote: Originally posted by Orenousername  
Isn't aniline usually prepared from nitrobenzene though? ... Is there a reason you want to prepare aniline in a different way?


I recall reading somewhere that in Japan somewhere, they commercially produce aniline via the ammonolysis of phenol. The reaction occurs between ammonia and phenol at 300-ish degrees Celsius with a zinc chloride catalyst (or another Lewis acid if preferred) under pressure. I honestly agree with you though, reduction of nitrobenzene under acidic conditions with tin seems far easier than the aforementioned phenol-based process. Maybe somebody somewhere just has a thing against nitro groups ;).

[Edited on 6-6-2016 by CRUSTY]

Orenousername - 5-6-2016 at 21:24

Quote: Originally posted by CRUSTY  
Quote: Originally posted by Orenousername  
Isn't aniline usually prepared from nitrobenzene though? ... Is there a reason you want to prepare aniline in a different way?


I recall reading somewhere that in Japan somewhere, they commercially produce aniline via the ammonolysis of phenol. The reaction occurs between ammonia and phenol at 300-ish degrees Celsius with a zinc chloride catalyst (or another Lewis acid if preferred) under pressure. I honestly agree with you though, reduction of nitrobenzene under acidic conditions with tin seems far easier than the aforementioned phenol-based process. Maybe somebody somewhere just has a thing against nitro groups ;).

[Edited on 6-6-2016 by CRUSTY]


That's interesting. Phenol is much more pleasant than nitrobenzene and can be obtained very easily. If someone can get this reaction to work it would probably be a good source of aniline.

https://www.youtube.com/watch?v=I_DD2_7QkRk
https://www.youtube.com/watch?v=A0e0BDEE4Ic

CuReUS - 6-6-2016 at 05:16

Quote: Originally posted by CRUSTY  

I recall reading somewhere that in Japan somewhere, they commercially produce aniline via the ammonolysis of phenol. The reaction occurs between ammonia and phenol at 300-ish degrees Celsius with a zinc chloride catalyst (or another Lewis acid if preferred) under pressure.

I remember reading long back about bayer's method to make aniline from phenol where they used Al2O3 as the dehydrating agent.After a quick search I found the patent
http://www.google.co.in/patents/US1935209
this method was improved by halcon and is now used commercially
Quote: Originally posted by Orenousername  

That's interesting. Phenol is much more pleasant than nitrobenzene and can be obtained very easily. If someone can get this reaction to work it would probably be a good source of aniline.

from the patent :
Quote:
We have now found that in the said reaction much better yields and more uniform products can be obtained by carrying out the conversion at increased pressures preferably between 100 and 300 atmospheres....It is preferable to work'at temperatures of about 450 C. and with a large excess of ammonia

Orenousername - 6-6-2016 at 05:58

Quote: Originally posted by CuReUS  

We have now found that in the said reaction much better yields and more uniform products can be obtained by carrying out the conversion at increased pressures preferably between 100 and 300 atmospheres....It is preferable to work'at temperatures of about 450 C. and with a large excess of ammonia


100-300 atm at 450C :o :o :o

Nevermind :P it's never happening

PHILOU Zrealone - 6-6-2016 at 11:56

Aniline could be obtained by pyrolysis of anthranilic acid (o-amino-benzoic acid) via decarboxylation...

zed - 6-6-2016 at 18:52

"Isn't aniline usually prepared from nitrobenzene though? The process is pretty straight forward I believe, the only real downside being the toxicity of nitrobenzene. Is there a reason you want to prepare aniline in a different way?"

Seems to me, Aniline itself is pretty toxic. Is Nitrobenzene worse?

Orenousername - 6-6-2016 at 21:14

Quote: Originally posted by zed  
"Isn't aniline usually prepared from nitrobenzene though? The process is pretty straight forward I believe, the only real downside being the toxicity of nitrobenzene. Is there a reason you want to prepare aniline in a different way?"

Seems to me, Aniline itself is pretty toxic. Is Nitrobenzene worse?


Aniline:
The approximate minimum lethal dose for a 150 lb human is 10 g.
Pohanish, R.P. (ed). Sittig's Handbook of Toxic and Hazardous Chemical Carcinogens 5th Edition Volume 1: A-H,Volume 2: I-Z. William Andrew, Norwich, NY 2008, p. 215-6

Nitrobenzene:
Mean lethal dose by mouth probably lies between 1 and 5 g.
Gosselin, R.E., R.P. Smith, H.C. Hodge. Clinical Toxicology of Commercial Products. 5th ed. Baltimore: Williams and Wilkins, 1984., p. II-214

5-10 mL of nitrobenzene (near 200 mg/kg bw) could be fatal in the absence of medical intervention.
WHO; Environmental Health Criteria 230: Nitrobenzene (2003) http://www.inchem.org/pages/ehc.html

Sourced these values from pubchem. Don't take my word for it.

gatosgr - 5-7-2016 at 09:33

Well the problem with aniline is that it passes through the skin (as well as nitro benzene does), I read a paper from basf claiming that if you get a 10 cm by 10 cm aniline spill on your clothing you should get intensive treatment meaning that things won't work out very well for you. The antidote is methylene blue or toluidine blue. I read someone from here saying that if you get blue lips e.t.c. you should take care but if you do get blue lips you already have overexposure and should take the antidote! The safety limit of vapors is like 10 ppm and dangerous at 100 ppm I wonder how are these guys in India making all those aniline dyes with their low standards of safety?


[Edited on 5-7-2016 by gatosgr]