Abstract Efficient cyclization procedure was developed for 2-nitro-, 2, 4-dinitro-, 2-nitro-5- chloro-, and 4, 5-dichloro-2-nitrophenylhydrazines with 2-acylbenzoic acids by heating the reagents in a mixture of of concentrated sulfuric acid and ethanol. A series of new phthalazin- 1-ones was obtained with a substituted 2-nitrophenyl group in the position 2 and various substituents in the position 4.
