The synthesis of nicotinic acid‐7‐13C

Nicotinic acid, an intermediate in the pyridine nucleotide cycle, was labeled with 13C at the 7 position. The reaction of CuCN‐13C (prepared from NaCN‐13C) with 3‐bromopyridine, followed by hydrolysis to the acid and purification by ion exchange chromatography, gave an overall yield of 72% nicotinic acid‐7‐13C. This greater than 3‐fold increase in yield over previous methods is the result of in situ hydrolysis of the nitrile intermediate.