Methyltrimethoxysilane → Methyltrimethoxysilane Isobutyltrimethoxysilane KOH

Participants

Reaction Steps

A 500 ml 5-neck round-bottom flask rendered inert with nitrogen and equipped with paddle stirrer, dropping funnel, thermometer, and water separator with reflux condenser is charged—in an oil bath at 40° C.—with 28 g (0.157 mol) of isobutyltrimethoxysilane (=2-methyl-1-propyltrimethoxysilane, available commercially from abcr GmbH & Co. KG), 21.8 g (0.157 mol) of methyltrimethoxysilane (available commercially from Wacker Chemie AG), and 66 g of Isopar E (isoparaffinic hydrocarbon mixture with a boiling range of 113-143° C., available commercially from ExxonMobil). The water separator is filled to the brim with Isopar E. While stirring at 350 rpm, a solution of 20.7 g (0.314 mol) of potassium hydroxide (85% strength, available commercially from AppliChem) in 16.7 g of demineralized water is metered in over 10 minutes. During this addition, the reaction mixture warms up to 48° C. By subsequent heating it is bought to boiling temperature. The distillate separates out as the lower phase in the water separator. Up to a boiling temperature of 118° C., 34.3 g of clear colorless distillate are collected, which according to analysis by gas chromatography contains 87.4% methanol, 8.6% water, and 3% Isopar E. The hydrolysis of the methoxy radicals, accordingly, is quantitative. During the distillation, a pasty white solid separates out in the reaction mixture. The volatile constituents are removed by distillation at 70° C./4 hPa. The residue left is a white, coarse powder whose solids content is 97.5% (determined using the HR73 Halogen Moisture Analyzer solids content balance from Mettler Toledo at 160° C.).

Provenance & Evidence