Formation of phenylmagnesium halides in toluene

Formation reactions of phenylmagnesium chloride and bromide in toluene in the presence of one or two equivalents of diethyl ether or THF were investigated kinetically. Also, the reaction in diethyl ether and in chlorobenzene was addressed. Kinetic features of the reactions are similar to those found previously for the formation of alkylmagnesium halides in toluene and consist of rapid formation of a disolvated Grignard reagent followed by a slower formation of a monosolvated reagent. The latter is able of catalyzing the conversion of different halides into Grignard reagents. However, the contribution of Wurtz-type side reactions is considerable except when THF is used in toluene. Involving the kinetic data and the activation parameters some details of the reaction mechanism were discussed.

Graphical abstractFormation kinetics of phenylmagnesium chloride and bromide was investigated in diethyl ether and in toluene with minor additions of diethyl ether or THF. In toluene, a rapid formation of a disolvated Grignard reagent proceeds followed by a slow formation of a monosolvated reagent, able to catalyze the conversion of different halides into Grignard reagents.Figure optionsDownload full-size imageDownload as PowerPoint slide