反应详情

Various processes are known for preparing substituted phthalic anhydrides. In two such processes 4-methyl-1,2,3,6-tetrahydrophthalic anhydride is dehydrogenated either by sulfur or by bromine in acetic acid. Yields of 4-methylphthalic anhydride of 59 percent to 87 percent are claimed for the former method, while the latter gives only a 16 percent yield [see Izv. Akad. Nauk. SSSR, Ser. Khim., 6, 1315 (1973) English translation, page 1271 and D. Craig, Journal of American Chemical Society, Vol. 72, page 3732, (1950)].