Efficient Preparation of Nitrosoarenes for the Synthesis of Azobenzenes

摘要

Reaction conditions are described for the oxidation of anilines furnishing nitrosoarenes and the synthesis of un-symmetrically substituted azobenzenes.In a comparative study,the catalytic oxidation of methyl 4-aminobenzoate by-hydrogen peroxide was investigated,and SeO_2 proved to be superior or equal to methyl trioxorhenium (MTO) and Na_2WO_4,respectively.Nevertheless,the application of the inexpensive,environmentally friendly.Oxone in a biphasic system proved to be more efficient,and a variety of useful nitrosoarenes for the synthesis of azo compounds were prepared in high yield and purity on a large scale.