Color Reaction of Benzaldehyde with 1-Naphthol in Concentrated Sulfuric Acid

Abstract

The color reaction of benzaldehyde with 1-naphthol in concentrated sulfuric acid was investigated to clarify the reaction mechanism. Two reaction products, bis(4-hydroxy-1-naphthyl)phenylmethane and (4-hydroxy-1-naphthyl) (1-hydroxy-2-naphthyl)phenylmethane were isolated from the colored reaction mixture. These compounds were found to be the key intermediates to the colored species, since their colored solutions in concentrated sulfuric acid showed the same absorption maxima as the colored solution obtained from the reaction of benzaldehyde with 1-naphthol in the acid. The compounds were considered to be transformed into the cation radicals, which were responsible for the colorations. © 1982, The Pharmaceutical Society of Japan. All rights reserved.