Catalytic reduction (5% platinum or 5% palladium placed on carbon and under 1 atm of H2) of o-nitroanisole [1 ] with hydrogen was carried out in sulfuric acid-methanol solution at a room temperature. The reaction products were o-anisidine , 2,4-dimethoxyaniline , and 2,6-dimethoxyaniline . The products  and  were considered to form in terms of the Bamberger-type rearrangement of o-methoxyphenylhydroxylamine, formed in the course of catalytic reduction of  to . The yield of amines (, , ) was significantly dependent upon the amount of sulfuric acid. Pt-C catalyst is more effective than Pd-C to obtain significant amount of  and . When catalytic reduction of  (4.0g) over Pt-C (120mg) was carried out in 40ml of methanol, the maximum yield of  achieved when 20.0 g of sulfuric acid was added (the yield of , or  being 56%, 12%, or 27%, respectively) and that of  was achieved when 40.0g of sulfuric acid was added (the yield of , , or  being 33%, 26% or 2%, respectively). It was also found that addition of dimethyl sulfoxide, a catalyst poison, enhances significantly the yield of rearrangement products: for example, while the yield of , , or  being 81%, 18%, or 1%, respectively, in the case of 2.8 g of sulfuric acid and in the absence of dimethyl sulfoxide, the yeild of , , or  being 55%, 28%, 9%, respectively, in the presence of dimethyl sulfoxide (0.05 ml).
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)