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%-87% are claimed for the former method, while the latter gives only a 16% yield [see IZV. Akad Nauk SSSR, Ser Khim, 6, 1315(1973) English trans. Pg. 1271 and D. Craig, Journal of Am. Chem. Soc., Vol. 72, Pg. 3732 (1950)].