Phosphomolybdic acid immobilized chitosan/Fe3O4: an efficient catalyst for the N-alkylation of anilines

Abstract

In this work, phosphomolybdic acid immobilized on chitosan/Fe3O4 as a green catalyst was used for the Hofmann N-alkylation of aniline derivatives with alcohols. H3PMo12O40/chitosan/Fe3O4 (PMo/Chit/Fe3O4) was prepared from the phosphomolybdic acid, chitosan, and Fe3O4 MNPs. Several secondary amines were synthesized from primary arylamines with electron‐donating, electron‐withdrawing groups, and alcohols in good to excellent yields. The catalyst could be separated using an external magnet and recovered without reducing its catalytic activity. The optimization of the reaction conditions was evaluated using the response surface method (RSM), involving the Box-Behnken design matrix. The simple procedure, only one byproduct (i.e., water), good to excellent yields, easy separation of the catalyst, short reaction times, and environmentally benign conditions were some advantages of this method.