Preparation of glycolic acid

Glycolic acid

[Structural formula]

[Physical and chemical properties] Glycolic acid, molecular formula is C ₂ H ₄ O ₃ , relative molecular mass is 76.

[Preparation]

(1) Industrially, it is mainly produced by hydrolysis of monochloroacetic acid under alkaline conditions

(2) US Patent 3867440 discloses a method for preparing glycolic acid

(3) US Patent 4,054,601 proposes a method for recovering pure glycolic acid from an aqueous solution containing impurities

(4) Chinese patent 92104616.

Take the raffinate after the above extraction operation, first adjust the pH to neutral with a saturated aqueous ammonia solution, then evaporate under reduced pressure, cool, crystallize and filter to obtain white solid crystals of ammonium sulfate.

(5) Chinese patent 200510041168.

Compared with the prior art, it has many advantages, such as wide sources of hydroxyacetonitrile aqueous solution, low price, simple production equipment and strong versatility, mild and easy-to-control reaction conditions, high purity of the produced glycolic acid, and the residue can be made by ammonia Ammonium sulfate is obtained, and methanol and distilled water can be recycled and reused, and so on

The specific implementation method is: in a glass reactor with a stirrer, a thermometer, a reflux tube, a distillation tube and a dripping feed tube, first add 16 kg of water and 40 kg of 98% concentrated sulfuric acid, heat with steam, and gradually add hydroxyacetonitrile The 50% solution is 45.

Related links: physicochemical properties and preparation methods of hydroxysuccinic acid