Glyoxylic acid: synthesis, isolation, and crystallization

Resumo

The review summarizes approaches, known from the literature, to the synthesis, isolation, and crystallization of glyoxylic acid (GA), which is an important component in fine organic synthesis and is widely used in pharmaceutical, food, and perfume industry. The review describes the research dealing with GA synthesis from aqueous solutions of glyoxal by catalytic, electrochemical, and enzymatic methods and by ozonolysis of maleic acid in solution. Alternative methods for GA synthesis are considered, for example, from glycolic acid in the presence of glycolate oxidase, oxalic acid, ethyl alcohol, and from various halogenated acetic acid derivatives. Approaches to GA isolation from the products of synthesis depending on the starting compound are considered, including extraction with amines or alcohols, the use of cation or anion exchange resins at elevated temperatures, and precipitation as insoluble alkaline earth metal salts. Methods for GA crystallization using various experimental techniques are presented.