Synthesis Of O,O'-dibenzoyl-Tartaric Acid

O,O'-dibenzoyl-tartaric acid is a relatively simple resolution regant derived from tartaric acid,and it is widely used in the resolution of organic amine compounds and other basic substances.The chiral O,O'-dibenzoyl-tartaric acid and the synthesis,separation and purification of its hydrates were studied in this paper.And the target compounds are O,O'-dibenzoyl-L-tartaric acid,O,O'-dibenzoyl-D-tartaric acid,O,O'-dibenzoyl-L-tartaric acid monohydrate and O,O'-dibenzoyl-D-tartaric acid monohydrate.In this study,the target compounds were synthesized in two routes.In the first route,excessive benzoyl chloride and tartaric acid are used to generate O,O'-dibenzoyl-tartaric acid anhydride and then O,O'-dibenzoyl-tartaric acid anhydride is hydrolyzed into the target products.In the second route,under the condition of SOCl2 existence,benzoyl chloride reacts with tartaric acid,generating O,O'-dibenzoyl-tartaric acid anhydride and by-product benzoic acid reacting with SOCl2 to create benzoyl chloride,which will continue to participate in the reaction.And then the O,O'-dibenzoyl-tartaric acid anhydride is finally hydrolyzed into the target products.All the factors such as reaction temperature,reactant ratio and hydrolysis conditions of the two different routes have been optimized and studied in this paper,coming up with the conclusion that the purity and yield coefficient of the target compounds through the first route is higher.The detailed synthesis route is using overdose benzoyl chloride slowly dropping into tartaric acid with the mole ratio 3.5:1,stirring under 135? for 3.5h,then reflowing by toluene.The time for the hydrolysis of acid anhydride is recommended for 2h and then the crude product will be re-crystallized by the toluene solvent,finally obtaining the target products.With this method,the ultimate yield of O,O'-dibenzoyl-L-tartaric acid is 85.90%and the purity of HPLC is 99.865%,and the corespongding number for O,O'-dibenzoyl-L-tartaric acid monohydrate is 88.46%and 99.86%.In addition,the recycling of solvent was also studied in this paper.The detailed solution is as followed:combining the filtrate and washing solution,heating to reflux for 2h,cooling to room temperature,dropping alkali solution to adjust pH to 12,letting stand for layered to get the toluene layer.The toluene recovery ratio is almost 90%.