Process for preparing glyoxylic esters and their hydrates

摘要

Process for preparing glyoxylic esters or their hydrates in which a water-soluble salt of a maleic or fumaric monoester or a mixture thereof is reacted with ozone in aqueous solution at temperatures of from 0 to 50 DEG C., and the corresponding glyoxylic ester or its hydrate is isolated from the resulting reaction mixture.