This synthetic method uses citric acid as a raw material, which is dehydrated to produce aconitic acid, and then oxidized to produce hydroxycitric acid. The optimized processes for aconitic acid and hydroxycitric acid were studied separately. The optimized process conditions for aconitic acid were: 1 mol of hydroxycitric acid reacted with 270 mol of 56% sulfuric acid at 140℃ for 7 h to obtain refined aconitic acid with a melting point of 186℃. Waste acid and undecomposed citric acid were recycled, achieving a citric acid recovery rate of 28% and a concentrated sulfuric acid recovery rate of 65%. The optimized process conditions for hydroxycitric acid were: a ratio of n-oxidant to n-aconitic acid of 2:1, a reaction time of 16 h, and a reaction temperature of 50℃ to obtain hydroxycitric acid with a product yield of approximately 80%.
Figure 2: Process diagram for the synthesis of hydroxycitric acid
