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 15.2 g (0.082 mol) of isobutyltrimethoxysilane (=2-methyl-1-propyltrimethoxysilane, available commercially from abcr GmbH & Co. KG), 34.4 g (0.247 mol) of methyltrimethoxysilane (available commercially from Wacker Chemie AG), and 65.9 g of Isopar (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 250 rpm, a solution of 18.5 g (0.28 mol) of potassium hydroxide (85% form, available commercially from AppliChem) in 11.9 g of demineralized water is metered in over 10 minutes. During this addition, the reaction mixture warms up to 46° C. By subsequent heating it is brought to boiling temperature. The distillate separates out as the lower phase in the water separator. It is removed from time to time and replaced each time by Isopar E. Up to a boiling temperature of 118° C., 37.1 g of clear colorless distillate are collected, which according to analysis by gas chromatography contains 85.6% methanol, 10.8% water, and 2.8% Isopar E. The hydrolysis of the methoxy radicals, accordingly, is quantitative. During the distillation, a suspension is formed in the reaction mixture. The suspension is filtered over a Beco KD3 filter plate in a suction filter, and the filter cake is subsequently dried at 110° C./4 hPa. This gives 37.8 g of fine, white powder, with a solids content of 99.8% (determined using the HR73 Halogen Moisture Analyzer solids content balance from Mettler Toledo at 160° C.)

Provenance & Evidence