Preparation of 1-Halo-2,3-propanediol and glyceryl monoester from glycerol waste

Abstract

Glycerol waste from biodiesel production of Bangchak oil refinery plant was separated and utilized to prepare value-added products as mono- and diglycerides. The purification of glycerol waste was successfully carried out by acid-base extraction. The most appropriate acid was H2SO4 and the glycerol could be recovered in the range of 40-45%. 1,2-O-isopropylideneglycerol was next synthesized from the purified glycerol. The mild and efficient approach for (2,2-dimethyl-1,3-dioxolan-4-yl)methyl ester synthesis by esterification of various fatty acids with 1,2-O-isopropylideneglycerol is developed employing Cl3CCONH2 and PPh3 under mild conditions providing the desired esters in high yield. The novel method for deprotecting isopropylidene group of (2,2-dimethyl-1,3-dioxolan-4-yl)methyl ester into the corresponding glyceryl monoester in excellent yield by Br3CCOCBr3–UV irradiation in methanol is also successfully performed. The chlorination of 1,2-O-isopropylidene glycerol to the corresponding alkyl chlorides in moderate yield can also be achieved by the combination of Cl3CCONH2 and PPh3. The advantages of these methods were mild reaction conditions, operational simplicity and good compatibility to alkyl chlorides from cyclic ether of 1,2-O-isopropylidene glycerol.