METHOD FOR DETERMINING WATER-FREE OR MOSTLY WATER-FREE FORMIC ACID

摘要

Anhydrous or substantially anhydrous formic acid is obtained by hydrolysis of methyl formate, in a process wherein (a) methyl formate is hydrolyzed, (b) the methanol and excess methyl formate are distilled from the hydrolysis mixture obtained, (c) the bottom product of distillation (b), consisting of formic acid and water, is extracted, in a liquid-liquid extraction, with an extractant which in the main takes up the formic acid, (d) the resulting extract phase, consisting of formic acid, the extractant and a part of the water, is subjected to distillation, (e) the top product obtained from this distillation and consisting of all or part of the water introduced into the distillation, and part of the formic acid, is recycled, as vapor, into the lower part of the distillation column of stage (b), (f) the bottom product of distillation stage (d), consisting of the extractant, with or without part of the water, and the greater part of the formic acid, is separated by distillation into anhydrous or substantially anhydrous formic acid and the extractant, and (g) the extractant leaving stage (f) is recycled to the process.