AWLB - 31-7-2015 at 12:25
I have a question. Could aniline (C6H5NH2) be synthesized by reacting ammonia and benzoic acid, then dehydrating, and then performing a Hofmann
degradation/rearrangement. I have found little information regarding this synthesis so need some help.
Thank you in advance.
[Edited on 31-7-2015 by AWLB]
gdflp - 31-7-2015 at 12:54
The reaction of ammonia and benzoic acid is not very efficient, and produces quite a bit of tar. A more amateur friendly approach involves the
reaction of benzoic acid and urea in a melt at 180°C for two and a half hours. A catalyst, H3PO4 or
H3BO3, is necessary to achieve good ~80% yields. Read this thread, it provides details on both the catalyzed amidation and the Hofmann rearrangment. The workup of the amidation detailed on page 4 by smuv
is significantly better than that described on page 3, as it provides a better separation of the product from unreacted starting materials as well as
side products.
I am currently experimenting on adapting the Hofmann rearrangement to be more suitable for the synthesis of larger volumes of aniline, as my previous
attempts to scale up have only results in large amounts of tar and miniscule yields of aniline. I'm planning on running another test this weekend.
Note : Please post questions without references in the Beginnings sub-forum only or in the Short Questions Thread.
AWLB - 31-7-2015 at 13:09
Thanks for replying "gdflp", I will try using urea instead of ammonia. Thank you for linking a thread, it looks excellent.