Preparation of deuteriated succinic acids

Succinic [2,3‐2H2]‐ and [2,2,3,3‐2H4]‐acids were prepared from maleic anhydride and dimethyl fumarate, and acetylene dicarboxylic acid and its dimethyl ester by treatment with CuAl and Ni‐Al alloys in 10% NaOD‐D2O in 95% to 100% isotopic purity. The succinic 2H4 acid having high isotopic purity was also obtained on the hydrolysis of 1,2‐ethanedinitrile with alkaline deuterium oxide. Based on the 1H{2H} spectra analysis of N‐(o‐biphenyl)[2,3‐2H2]succinimide, it was elucidated that the Raney alloy reduction with alkaline deuterium oxide proceeds stepwise.