What is "diazomethane"

n. (context organic compound English) the simplest diazo compound, CH₂=N⁺=N^-; a toxic, yellow, explosive gas; used in analytical chemistry to convert carboxylic acids into their methyl esters for analysis via gas-liquid chromatography

Diazomethane is the chemical compound CHN, discovered by German chemist Hans von Pechmann in 1894. It is the simplest diazo compound. In the pure form at room temperature, it is an extremely sensitive explosive yellow gas; thus, it is almost universally used as a solution in diethyl ether. The compound is a popular methylating agent in the laboratory, but it is too hazardous to be employed on an industrial scale without special precautions.