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But-2-ene is an acyclic alkene with four carbon atoms. It is the simplest alkene exhibiting cis/trans-isomerism (also known as (E/Z)-isomerism); that is, it exists as two geometric isomers cis-but-2-ene ((Z)-but-2-ene) and trans-but-2-ene ((E)-but-2-ene). It is a petrochemical, produced by the catalytic cracking of crude oil or the dimerization ...
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" are used. According to IUPAC, "geometric isomerism" is an obsolete synonym of "cis–trans isomerism". [2]
For monoalkenes, the configuration is often indicated by the prefixes cis- (from Latin "on this side of") or trans- ("across", "on the other side of") before the name, respectively; as in cis-2-pentene or trans-2-butene. The difference between cis-and trans-isomers. More generally, cis–trans isomerism will exist if each of the two carbons of ...
Trans-alkenes are about 1 kcal/mol more stable than cis-alkenes. An example of this effect is cis- vs trans-2-butene. The difference is attributed to unfavorable non-bonded interactions in the cis isomer. Terminal alkenes isomerize to internal alkenes in the presence of metal catalysts.
[5] [6] Examples of the latter are the enantiomers, whose molecules are mirror images of each other, and the cis and trans versions of 2-butene. Among the structural isomers, one can distinguish several classes including skeletal isomers, positional isomers (or regioisomers), functional isomers, tautomers, [7] and structural isotopomers. [8]
In greater carbon number cycloalkenes, the addition of CH 2 substituents decreases strain. [2] trans-Cycloalkenes with 7 or fewer carbons in the ring will not occur under normal conditions because of the large amount of ring strain needed. In larger rings (8 or more atoms), cis–trans isomerism of the double bond may occur.
For example, 2-butene exists in two isomeric forms: cis-2-butene and trans-2-butene. [2] The sub-categories of isomerases containing racemases, epimerases and cis-trans isomers are examples of enzymes catalyzing the interconversion of stereoisomers.
Butene, also known as butylene, is an alkene with the formula C 4 H 8.The word butene may refer to any of the individual compounds. They are colourless gases that are present in crude oil as a minor constituent in quantities that are too small for viable extraction.