A Grignard reaction-solution prepared from 220 grams ( 1.15 mol ) of p-chlorobromobenzene and 29 grams of magnesium turnings ( 1.2 mol ) in 1500 milliliters of dry ether was added dropwise in the course of one hour to a suspension of 213 grams of 5-bromphthalide ( 1 mol ) in 1500 milliliters of dry tetrahydrofuran.
