3-Tolylboronic acid

121-43-7

591-17-3

17933-03-8

The general procedure for the synthesis of 3-methylphenylboronic acid from trimethyl borate and 3-bromomethylbenzene is as follows: 0.10 mol (0.1 eq.) of 3-bromomethylbenzene, 1.1 mol (1.1 eq.) of magnesium scraps, a few iodine crystals, and 800 mL of tetrahydrofuran (THF) were added to a reaction flask, stirred and heated to reflux. When the Grignard reaction was initiated, 0.90 mol (0.9 eq.) of 3-bromomethylbenzene was slowly added dropwise under reflux conditions, and the reaction was continued at reflux after completion of the dropwise addition. After completion of the reaction, the reaction system was cooled down to -50.0 °C. Subsequently, 2.2 mol (2.2 eq.) of trimethyl borate was slowly added dropwise and the reaction was kept at a low temperature until the feedstock was completely consumed. Upon completion of the reaction, the temperature was gradually increased and water was added to quench the reaction. Then, hydrochloric acid was added dropwise to adjust the pH to 1-2 and the reaction was continued with stirring. After completion of the reaction, the solvent was removed by rotary evaporation and the product was dried by filtration to give 0.90 mol of 3-methylphenylboronic acid as a white solid with 0.03% water content, 98.86% purity and 90.0% yield.