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Another example of this is the relationship between oleic acid and elaidic acid; oleic acid, the cis isomer, has a melting point of 13.4 °C, making it a liquid at room temperature, while the trans isomer, elaidic acid, has the much higher melting point of 43 °C, due to the straighter trans isomer being able to pack more tightly, and is solid ...
See: cis–trans isomerism. cis (left) and trans (right) configured double bond in maleic acid and fumaric acid. cis (left) and trans (right) isomerism in a ring system. The descriptors cis (lat. on this side of) [2] and trans (lat. over, beyond) [3] are used in various contexts for the description of chemical configurations: [4] [5]
Traditionally, double bond stereochemistry was described as either cis (Latin, on this side) or trans (Latin, across), in reference to the relative position of substituents on either side of a double bond. A simple example of cis–trans isomerism is the 1,2-disubstituted ethenes, like the dichloroethene (C 2 H 2 Cl 2) isomers shown below. [7]
E–Z configuration, or the E–Z convention, is the IUPAC preferred method of describing the absolute stereochemistry of double bonds in organic chemistry.It is an extension of cis–trans isomer notation (which only describes relative stereochemistry) that can be used to describe double bonds having two, three or four substituents.
Simple cis and trans isomers may be indicated with a prefixed cis-or trans-: cis-but-2-ene, trans-but-2-ene. However, cis-and trans-are relative descriptors. It is IUPAC convention to describe all alkenes using absolute descriptors of Z-(same side) and E-(opposite) with the Cahn–Ingold–Prelog priority rules (see also E–Z notation).
Elaidic acid has 18 carbons and is a trans-9-mono-unsaturated fatty acid. It is also a trans isomer of oleic acid. C 17 H 33 CO 2 H, IUPAC organization name (E)-octadec-9-enoic acid, numerical representation 18:1 (9), n-9, molecular weight 282.46, melting point 43–45 °C. CAS Registry Number 112-79-8.
For ML a 4 L b 2, two isomers exist.These isomers of ML a 4 L b 2 are cis, if the L b ligands are mutually adjacent, and trans, if the L b groups are situated 180° to each other. It was the analysis of such complexes that led Alfred Werner to the 1913 Nobel Prize–winning postulation of octahedral complexes.
The cis isomer exclusively yields cis,trans-hexa-2,4-diene whereas the trans isomer gives the trans,trans diene: [2] This reaction course can be explained in a simple analysis through the frontier-orbital method : the sigma bond in the reactant will open in such a way that the resulting p-orbitals will have the same symmetry as the HOMO of the ...