Synthesis, separation into diastereoisomers, and resolution of o-phenylenebis(methylphenylarsine) and related studies of the o-phenylenediarsine moiety

Abstract

The nucleophilic substitution of o-dichlorobenzene by sodium methylphenylarsenide is described. The principal products of the reaction are meso- and racemic-o-phenylenebis(methylphenylarsine), although small quantities of the following compounds are formed as side-products: dimethylphenylarsine; ethoxymethylphenylarsine; methyldiphenylarsine; 1-chloro-2-methylphenylarsinobenzene; methylphenylarsinic acid; 1,2-dimethyl-1,2-diphenyldiarsane; 1,3-dimethyl-1,2,3-triphenyltriarsane; and 5,10-dihydro-5,10-diphenylarsanthren. A study of the possible stereospecific synthesis of racemic-o-phenylenebis(methylphenylarsine) from certain o-phenylenediarsine derivatives is described. The solid-state elimination of bromomethane from o-phenylenebis(dibromodimethylarsine) is stereospecific. The two diastereoisomers of o-phenylenebis(methylphenylarsine) have been separated and identified by means of their fac-[PtMe₃(I)(diarsine)] complexes using ¹H n.m.r. spectroscopy and the racemic-diarsine subsequently resolved via its D(–)-dibenzoylhydrogentartrate salt.