Simplified method for the synthesis of triacetin – food additive E1518

Abstract

Aim. Development of a simplified technology for the production of triacetin – a food additive (E1518) and a water-retaining agent. Materials and Methods. The following main raw materials were used: distilled glycerol 99.5% (LLC «Ukrkhimresursy», Ukraine), glacial acetic acid (LLC «Chemical Alliance», Russia). It is proposed to control the content of unreacted products – glycerol – spectrophotometrically with copper (II), and acetic acid – by acid-base titration. Results. The conditions for the synthesis of triacetin are as follows: the molar ratio of glycerol and acetic acid is 1:6, temperature – 120-125оC, duration – 90 minutes. The distillation of excess acetic acid was carried out at a temperature of 130-140оC for 3 hours, which ensured the receipt of 100% of the product – triacetin, which contains trace amounts of acetic acid. The residual content of acetic acid in the final product is not more than 0.01% of the mass. After distillation, acetic acid is obtained with a concentration of 79-80% (azeotropic mixture). The use of a catalyst – sulfuric acid – negatively affects the color of the final product (from yellow to light brown) and pH (about an 0). The use of a hydrobromic acid catalyst does not lead to a 100% product, but it negatively affects the pH of the finished product (near zero), which requires additional purification of the final product (vacuum distillation) and neutralization, which in turn contaminates the product with inorganic salts. Conclusion. A simplified method for the synthesis of triacetin from glycerol and acetic acid has been developed, which excludes the use of catalysts, vacuum, and sorption purification.