The products of the condensation of 5-methoxy-3-methylbenzoic acid with aqueous formaldehyde and hydrochloric acid in the presence of glacial acetic acid are dependent on the length of the heating period. A very short period of heating (2 minutes) yields 6-methoxy-4-methylphthalide and the two chloromethylphthalides of m.p. 135° and 154 °C, related to the unisolated 4-methoxy-6-methylphthalide. If the period of heating is 20 minutes or longer, the above chloromethylphthalide melting at 135° is formed and in addition some of the 6-methoxy-4-methylphthalide is chloromethylated to 6-methoxy-7-chloromethyl-4-methylphthalide, melting at 179°. The orientation of all three chloromethylphthalides has been established.
在冰乙酸存在下,5-甲氧基-3-甲基苯甲酸与水甲醛和盐酸缩合的产物取决于加热时间的长短。极短的加热时间(2分钟)产生6-甲氧基-4-甲基邻苯二甲酸酐和两种氯甲基邻苯二甲酸酐(熔点分别为135℃和154℃),与未分离的4-甲氧基-6-甲基邻苯二甲酸酐有关。如果加热时间为20分钟或更长时间,则会形成上述熔点为135℃的氯甲基邻苯二甲酸酐,此外还会将一些6-甲氧基-4-甲基邻苯二甲酸酐氯甲基化为熔点为179℃的6-甲氧基-7-氯甲基-4-甲基邻苯二甲酸酐。所有三种氯甲基邻苯二甲酸酐的定向已经确定。