Acetone Cyanohydrin from Acetone and Hydrogen Cyanide

Acetone cyanohydrin is the starting material for methyl methacrylate, the monomer of acrylic glass. This is how ICI made it in Crawford's patent (US 2,042,458, 1936): acetone and a little more than its equivalent of hydrogen cyanide, with caustic potash as catalyst, then made safe with a slight excess of sulphuric acid and distilled under vacuum. The patent gives no temperature, time or amount of potash: none are given here. The picture: drawn by Youblob.