Effect of Light on the Formation of Grignard Reagents

Abstract

The effect of reflected sunlight on the formation of Grignard reagents has been reported¹. In the present work irradiation of mixtures of magnesium turnings and organic halides in dry diethyl ether by the method of Evans et al.² gave elevated yields of Grignard reagents as compared to those achieved in control experiments carried out in the absence of light. Four organic halides: 2-bromofluorene, 2-bromothiophene, chlorobenzene and chlorodiphenylmethane were selected for study in the light of their reputed poor performance in the Grignard reaction³. A quantitative estimate of the amount of Grignard reagent formed in each reaction was carried out by the method of Gorog and Szepesi⁴. The experimental results are shown in the table.