Studies on Anthranilic Acid Derivatives (I) -Reactions of Anthranilamide with Carboxylic Acid in Polyphosphoric Acid-

The treatment in polyphosphoric acid (PPA) of anthranilamide with carboxylic acid (acetic acid and propionic acid) has been shown to yield three kinds of reaction products, N-acyl-anthranilic acid, 2-alkyl-3, 4-dihydro-4-oxo-quinazo-line and 2-alkyl-3, 4-dihydro-3-(o-carbamoyl-phenyl)-4-oxo-quinazoline. The relative yields of a set of reaction products were determined at various reaction temperatures. The variation of the relative amounts of reaction products with temperature did not depend on the use of either acetic acid or propionic acid. Amount of 2-alkyl-3, 4-dihydro-4-oxo-quinazoline was much more than 2-alkyl-3, 4-dihydro-3-(o-carbamoyl-phenyl)-4-oxo-quinazoline at a lower temperature. But at an elevated temperature amount of the latter was found to increase as compared with that of the former. In order to examine the mechanism of the reaction, some experiments were undertaken