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cis-but-2-ene
trans-but-2-ene

Cis/trans isomerism (geometric isomerism, configurational isomerism) is a term used in organic chemistry to refer to the stereoisomerism engendered in the relative orientation of functional groups within a molecule. It is not to be confused with E/Z isomerism, which is an absolute stereochemical description, and only to be used with alkenes. In general, such isomers contain double bonds that cannot rotate, or they may contain ring structures, where the rotation of bonds is restricted or eliminated.<ref name=Reusch10>William Reusch, 2010, "Stereoisomers Part I," In Virtual Textbook of Organic Chemistry, Michigan State University, see [1], accessed 7 April 2015.</ref> Cis and trans isomers occur both in organic molecules and in inorganic coordination complexes. Cis and trans descriptors are not used for cases of conformational isomerism where the two geometric forms easily interconvert, such as most open-chain single-bonded structures; instead, the terms “syn” and “anti” would be used.

The terms “cis” and “trans” are from Latin, in which cis means "on this side"<ref>Charlton T. Lewis, Charles Short, A Latin Dictionary (Clarendon Press, 1879) Entry for cis</ref> and trans means "on the other side" or "across". The term "geometric isomerism" is considered an obsolete synonym of "cis/trans isomerism" by IUPAC.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>


Cis–trans isomerism sections
Intro   Organic chemistry    Inorganic chemistry    See also    References    External links   

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cis-but-2-ene
trans-but-2-ene

Cis/trans isomerism (geometric isomerism, configurational isomerism) is a term used in organic chemistry to refer to the stereoisomerism engendered in the relative orientation of functional groups within a molecule. It is not to be confused with E/Z isomerism, which is an absolute stereochemical description, and only to be used with alkenes. In general, such isomers contain double bonds that cannot rotate, or they may contain ring structures, where the rotation of bonds is restricted or eliminated.<ref name=Reusch10>William Reusch, 2010, "Stereoisomers Part I," In Virtual Textbook of Organic Chemistry, Michigan State University, see [1], accessed 7 April 2015.</ref> Cis and trans isomers occur both in organic molecules and in inorganic coordination complexes. Cis and trans descriptors are not used for cases of conformational isomerism where the two geometric forms easily interconvert, such as most open-chain single-bonded structures; instead, the terms “syn” and “anti” would be used.

The terms “cis” and “trans” are from Latin, in which cis means "on this side"<ref>Charlton T. Lewis, Charles Short, A Latin Dictionary (Clarendon Press, 1879) Entry for cis</ref> and trans means "on the other side" or "across". The term "geometric isomerism" is considered an obsolete synonym of "cis/trans isomerism" by IUPAC.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>


Cis–trans isomerism sections
Intro   Organic chemistry    Inorganic chemistry    See also    References    External links   

PREVIOUS: IntroNEXT: Organic chemistry
<<>>