A ^(15)N NMR Study of the Ring-Opening of Methylsydnonimine Hydrochloride

Abstract

Nitrogen-15 NMR spectroscopy has been used to study the irreversible ring-cleavage or 3-methylsydnonimine hydrochloride samples separately labeled with ^(15)N at each or the three possible nitrogens. This reaction, which occurs in hydroxylic solvents on addition of base, initially yields principally the E and Z isomers or N-methyl-N-cyanomethylnitrosamine. While 3-methylsydnonimine itselr is surely a transient intermediate in the ring-opening, no measurable concentration of the free base could be detected by ^(15)N NMR. Hydrolysis or the cyano group of N-methyl-N-cyanomethylnitrosamine to give E and Z isomers of N-methyl-N-nitrosoglycine amide and N-methyl-N-nitrosoglycine could also be followed by ^(15)N NMR and is reasonably facile in that it occurs significantly at below room temperature.