YU22601A - Procedure for perwolframatic epoxidation of l,b- unsaturated acids - Google Patents

Abstract

New procedure has been developed for perwolframatic epoxidation of L,B-unsaturated acids. Epoxidation systrem is comprised of water, L,B-unsaturated acids, natrium hydroxide, natrium wolframate and hydroxyperoxide. Potentiometric titration establishes that the epoxidation should be conducted below pH 4.64 because then the maximum concentration of disodium tetraperoxydiwolframate Na2W2O11 which performs the transport of oxygene from hydrogene peroxyde into double bond of substrate -but not above pH 4.64 because in such a situation there is a beginning of establishing disodium tetraperoxymonowolframate Na2Wo8 that only dissolves hydrogen peroxyde and reduces its degree of utilization. Therefore, we determined that our working pH should be 4,5 +- 0.1. Because cisdicarbonic and threecarbonic acids can build bidental complexes with sodium wolframate wich reduces the degree of the cathalyst utilization, by adding 1,1 equaivalent, or 2.1 equivalent of sodium hydroxyde, they are transformed into monohydrogen salts, which as monodentate cannot build complexes, and then sodium wolframate is added with hydrogen peroxide. Because during the epoxydation we find L,B- epoxy acids that are ten times stronger than the initial L,B-unsaturated acids, pH ofreaction composition decreases and is maintained in the boundaries of 4,5 +- 0,1 by adding 5N solution of sodium hydroxide. This procedure, in time 1-2 hours at the temperature 20-80 C epoxidated eight commercial L,B unsaturated acids, and with considerable saving of cathalyst produced appropriate L,B epoxy acids with 100% of retention configuration and good yield and melting points.