Methylene (IUPAC name: Methylidene, also called carbene or methene) is an organic compound with the chemical formula CH2 (also written [CH2] and not to be confused with compressed hydrogen, which is also denoted CH2).

It is a colourless gas that fluoresces in the mid-infrared range, and only persists in dilution, or as an adduct.

It was introduced as early as 1835 by French chemists Jean-Baptiste Dumas and Eugene Peligot after determining methanol's chemical structure.

Many organic compounds are named and classified as if they were the result of substituting a methylidene group for two adjacent hydrogen atoms of some parent molecule (even if they are not actually obtained that way).

Methylene can be prepared by decomposition of compounds with a methylidene or methanediyl group, such as ketene (ethenone) (CH2=CO), diazomethane (linear CH2=N2), diazirine (cyclic [-CH2-N=N-]) and diiodomethane (I-CH2-I).

[12] The reactions of methylene were also studied around 1960 by infrared spectroscopy using matrix isolation experiments.

[13][14] Many of methylene's electronic states lie relatively close to each other, giving rise to varying degrees of radical chemistry.

(The correct prediction of this angle was an early success of ab initio quantum chemistry.

[10] Neutral methylene complexes undergo different chemical reactions depending on the pi character of the coordinate bond to the carbon centre.

Upon treatment with a standard base, complexes with a weak contribution convert to a metal methoxide.

In the same spirit, the comic was eventually cited in the scientific literature by Peter Gaspar and George S.