Synthesis of glycolic acid by disproporationation reaction of glyoxal

A new synthetic technology of glycolic acid was studied.Calcium glycollate was synthesized by intramolecular disproportionation reaction from glyoxal with Ca(OH)2 as catalyst,while the mass concentration of Ca(OH)2 was 20% or so,the temperature was controlled between 10-30 ℃ and reaction time was about 1 h.Glycolic acid was then obtained through acidification with H2SO4 and the yield was above 95%.Meanwhile,Ca2+ ion was easily removed through the form of CaSO4 precipitate.The reaction has good selectivity and simple process.