Diethyl allylmalonate → 2-Allyl-3-methylsuccinic acid

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Reaction Steps

90.5 g (0.5 moles) of 2-allylmalonic acid diethyl ester are reacted in diethylene glycol dimethyl ether with 0.5 moles of alcohol-free sodium ethoxide. 0.5 moles of 2-bromopropionic acid ethyl ester is added dropwise to this solution, with stirring. The mixture is heated for a further 2 hours under reflux and the solvent is then removed. The residue is subsequently subjected to hydrolysis in alcoholic KOH. After drying the organic layer that has separated, it is fractionated. The desired 2-allyl-1-methylethane-tricarboxylic acid 1,2,2-triethyl ester boils under 0.02 torr at 92° to 95° C. The ester is hydrolyzed in alcoholic KOH and, after working up in the customary manner, is decarboxylated at 170° C. with water being split off. The anhydride of 2-allyl-3-methylsuccinic acid (b.p. at 0.1 torr: 108° to 110° C.) is obtained in a 96% yield (based on the ester).

Provenance & Evidence