Synthesis of α-D-glucuronic acid by catalytic oxidation with TEMPO/NaBr/NaClO system

Synthesis route of α-D-glucuronic acid was investigated by oxidizing α-D-glucose.The synthesis step was as follows:in the first step,C1 of α-D-glucose was protected with methyl,then the primary alcohols hydroxyl groups was catalytically oxidized by TEMPO/NaClO/NaBr system to be carboxyl groups.In the third step,methyl α-D-glucuronide was hydrolyzed to obtain α-D-glucuronic acid in diluted hydrochloric acid.And the hydrolysis condition was optimized.Methyl α-D-glucuronide was hydrolyzed in diluted hydrochloric acid for 15h,30h,45h,58h,65h,respectively.HPLC analysis showed that methyl α-D-glucuronide was hydrolyzed completely after reaction for 58h with the highest yield of 64.90%.The fraction of α-D-glucuronic acid separated by HPLC was collected and evaporated.The melting point of purified α-D-glucuronic acid was 164.3～165.2°C(m.p.165 ℃),and the total yield on the basis of α-D-glucose was 45.2%.