Organometallic reaction mechanisms. VIII. Detailed description of the mechanism of methylmagnesium bromide addition to 2-methylbenzophenone

Impact of reaction products on the Grignard reaction with silanes and ketones

“…Assuming a complete complexation of the reagents according to [4,11], (Eq. (3)) the rate constant can be calculated as…”

“…Although addressed in numerous works [1][2][3][4][5][6][7][8][9], the way how the product magnesiumalkoxydes interfere in the reaction was not entirely clear, not to mention the controversial influence of the products on the reaction rates and addition to reduction ratios.…”

“…In contrast to this, some alkoxymagnesium bromides, e.g., the reaction products, suppressed the rate of the Grignard reaction with ketones [2][3][4]. In parallel to the kinetic results, it has been signaled in numerous works [2,3,[5][6][7][8][9] that with ketones the relative amount of reduction increases readily as the reaction proceeds.…”

“…Based on their kinetic investigations Ashby et al [4,10,11] have shown that the product, alkoxymagnesium halide complexes with the Grignard reagent tightly and the equilibrium lies far toward the complex. The same proved to be valid for alkylmagnesium alkoxides.…”

“…The same proved to be valid for alkylmagnesium alkoxides. The branched alkoxide ligands derived from the Grignard addition to ketones caused a considerable decrease in the reaction rate [4,10].…”