Preparation of 3,4-dinitroaniline from 3,4-dinitrobenzoic acid with the Schmidt reaction. The Schmidt reaction is something what sounds like a horrible idea when you learnt basic organic chemistry. For this transformation you’ll need: a carboxylic acid, oleum (fuming sulfuric acid), sodium azide and some luck.

The reaction mechanism looks like this (from Wikipedia):





Oleum (sulfuric acid with free SO3) is needed for the protonation of the carboxylic acid, what will give an acylium ion (1) what reacts with hydrazoic acid to form a protonated azido ketone (2), which goes through a rearrangement with the 3,4-dinirtrophenyl group ®, migrating over the C-N bond with expulsion of nitrogen gas. During the workup, the protonated isocyanate is attacked by water forming carbamate (4), which after deprotonation loses carbon dioxide to the amine (5).



On the picture the reaction mixture was just before pouring it on water, accoring to the scheme it was at intermediate (3).

9:30 pm • 7 February 2015 • 352 notes • View comments