Hydrogenation of Isophthalonitrile with 1-Methylimidazole as an Effective Solvent for m-Xylenediamine Production

Abstract

meta-Xylenediamine (MXDA) is useful as chemical intermediates in the plastic and polymer fields. This compound can be prepared from the hydrogenation of isophthalonitrile (IPN) in the presence of ammonia using nickel catalyst or other metallic catalysts under high temperature and pressure. However, optimum reaction conditions are crucial to produce a high grade of MXDA because of the formation of undesirable products resulting from a partial hydrogenation, a polymerization or cleavage of the product. In order to prevent the side reactions, IPN were hydrogenated in the presence of ammonia with organic solvents. Especially, the correct choice of a solvent is a critical factor to govern the catalytic activity with desirable hydrogenation. Conventionally, organic materials such as aromatic hydrocarbons, aliphatic alcohols, aliphatic hydrocarbons, dimethylformamide and dioxane were employed in this reaction. Several MXDA producing processes with the organic solvent including m-xylene, pseudocumene, mesitylene, ethylbenzene, methylpyridine, benzonitrile, m-tolunitrile, MXDA and cyanopyridine were disclosed. However, the solvents and ammonia were vaporized under the operation conditions leading to amine cleavage with the resulting formation of methylbenzyl amines or the consumption of ammonia was still significant. Recently, some researchers reported that a high yield of MXDA was achieved using isopropanol under relatively low pressure condition; however, the consumption of ammonia was very significant. In this study, we used 1-methylimidazole for the hydrogenation of IPN to produce MXDA. Imidazole is a heterocyclic compound of five-membered diunsaturated ring structure composed of three carbon atoms and two nitrogen atoms at nonadjacent positions. Imidazoles are barely soluble in water normally, but are dissolved in organic solvents. Here we report the successful preparation of MXDA by hydrogenation of IPN in the presence of low ammonia concentration using 1-methylimidazole as an