Uses
Trihexyl O-Butyrylcitrate is a non-toxic plasticizer, widely used in non-toxic PVC granulation, medical products, soft children's toys, ink coatings, etc.
Synthesis
Trihexyl O-Butyrylcitrate was prepared as follows: 1) To a 1 liter four-neck flask equipped with a stirrer, immersion thermometer, subsurface nitrogen sparge tube and Barrett trap with condenser 330 g n-hexanol, 180 g citric acid and 50 ml heptane. The reaction mass was heated to reflux (about 120°C) with a heating mantle and 1.5 grams of tetra-n-butyl titanate esterification catalyst was added. The reaction mass was esterified at 120-140°C until the acidity was less than 2 mgKOH/g acidity. The pressure was reduced to 20 mmHg using a vacuum pump to distill off excess n-hexanol and heptane azeotrope. The ester-containing reaction mass was then stripped with fresh steam at a temperature of 130-140° C. and full vacuum until no residual n-hexanol was detected by gas chromatography.
2) The ester-containing reaction mass was cooled to 90°C, and 0.4 g of concentrated sulfuric acid was added dropwise with stirring. n-Butyric anhydride (166 g) was added dropwise with stirring, maintaining the acylation temperature between 90-110°C. The acylation reaction mixture was stirred and allowed to proceed for 2 hours to prepare the acylated ester. response quality. By-product butyric acid was removed by vacuum distillation at 110°C.
