Methylidene group

Jsd: minor addition: see also methylene group

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[[File:Propene Methylidene Structural Formulae V.1.svg|thumb|240px|The blue part of this diagram of a [[propene]] molecule is a '''methylidene''' group.]]

In [[organic chemistry]], a '''methylidene group''' is any part of a molecule that consists of two [[hydrogen]] atoms [[chemical bond|bound]] to a [[carbon]] atom, which is connected to the remainder of the molecule by a [[double bond]].<ref></ref>
<ref></ref> The group may be represented as CH₂=, where the '=' denotes the double bond.

This stands in contrast to [[methylene]], also called [[methylene bridge]], i.e. the −CH₂− group, which is connected to the rest of the molecule by two single bonds.<ref></ref><ref></ref> The distinction is often important, because the double bond is chemically different from two single bonds.

[[File:Methylenecyclopropene.svg|thumb|right|240px|[[Methylenecyclopropene|3-Methylidenecycloprop-1-ene]] is named as a cyclopropene with a methylidene substituent.]]

The same name (methylidene) is used for the radical , which is a molecule unto itself, also known as [[carbene]].<ref></ref><ref></ref> Formerly the methylene name was used for all three isomers (methylene, methylidene, and carbene).

Many organic compounds are named and classified as if they were the result of [[substituent|substituting]] a methylidene group for two [[geminal|adjacent]] hydrogen atoms of some parent molecule (even if they are not actually obtained that way). Thus, for example, [[methylenecyclopropene]] is named after [[cyclopropene]].

==See also ==
* [[Methylene (compound)]]
* [[Methylene group]]
* [[Methyl group]]
* [[Methine]]

==References==




[[Category:Alkanediyl groups]]
[[Category:Functional groups]]




[[bs:Metilen]]
[[cs:Methylen]]
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[[fr:Méthylène]]
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[[he:מתילן]]
[[hu:Metilén]]
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[[ru:Метилен]]

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