Abstract
A recently discovered method for the synthesis of N,N‐dialkyl‐1,3‐benzenediamines with two different alkyl groups is shown to be general. This is demonstrated by the synthesis of N‐butyl‐N‐phenethyl‐1,3‐benzenediamine by the condensation of 3‐nitroaniline with phenyl‐acetaldehyde and benzotriazole, reduction of the adduct with sodium borohydride, acylation of the resulting N‐phenethyl‐3‐nitroaniline with butyryl chloride, catalytic reduction of the nitro group by formic acid in the presence of triethylamine and palladium and finally reduction of the butyramide carbonyl group to the butyl substituent by lithium aluminum hydride. Several other routes were less efficient or failed completely.
Classical methods for the synthesis of N,N‐diethyl‐1,3‐benzenediamine were reexamined and improved. The recommended procedure involves alkylation of 3‐nitroaniline with diethyl sulfate, trapping of N‐ethyl‐3‐nitroaniline (by‐product) by benzoylation, distillation of N,N‐diethyl‐3‐nitro‐aniline under reduced pressure and reduction of the nitro group by formic acid catalyzed by palladium.