A lactone (C8H6O2) obtained as a white crystalline substance by reduction of phthalyl chloride and other processes; hence, by extension, any one of the series of which phthalide proper is the type. (Written also phthalid)
2.
Specifically: A fungicide (C8H2Cl4O2) which is a tetrachloro derivative of phthalide (1) proper; in this sense, the spelling fthalide is also used. It has CAS Registry Number 27355-22-2.
