methylenimine

Methylenimine, also known as methanimine, is the simplest imine derived from formaldehyde. Its formula is CH2NH and it features a carbon–nitrogen double bond with one hydrogen attached to carbon and one hydrogen attached to nitrogen (H2C=NH). It is a colorless, highly volatile gas at room temperature and is markedly reactive. In the absence of stabilizers it tends to oligomerize to higher imines, and it hydrolyzes in water to formaldehyde and ammonia.

Preparation and handling of methylenimine is typically by dehydration of formamide over acid catalysts, producing methylenimine and water. It can also be generated in situ by dehydration of formamide or via other dehydrogenation routes, allowing it to be used directly in reactions without isolation.

As a one-carbon imine, methylenimine is a useful reactive intermediate in organic synthesis. It can be hydrogenated to give methylamine (CH3NH2) and can react with various nucleophiles to form amines after hydrolysis or trapping of the methyleneimino group. It serves as a precursor to certain polymers and heterocycles in specialized syntheses and is used in laboratory-scale routes to amino compounds.

Safety and handling: methylenimine is toxic and irritating; exposures should be avoided. It is flammable and can form explosive mixtures with air. Handling should be conducted in a well-ventilated fume hood, with appropriate gas monitoring and containment. Due to its reactivity and instability, it is often generated in situ for use in chemical reactions rather than stored long term.