In chemistry, isomerization or isomerisation is the process in which a molecule, polyatomic ion or molecular fragment is transformed into an isomer with a different chemical structure. Enolization is an example of isomerization, as is tautomerization. When the isomerization occurs intramolecularly it may be called a rearrangement reaction.
When the activation energy for the isomerization reaction is sufficiently small, both isomers will exist in a temperature-dependent equilibrium with each other. Many values of the standard free energy difference, , have been calculated, with good agreement between observed and calculated data.
Skeletal isomerization occurs in the cracking process, used in the petrochemical industry. As well as reducing the average chain length, straight-chain hydrocarbons are converted to branched isomers in the process, as illustrated the following reaction of n-butane to i-butane.
\overset{n-butane}{CH3CH2CH2CH3} -> \overset{i-butane}{CH3CH(CH3)CH3}
Fuels containing branched hydrocarbons are favored for internal combustion engines for their higher octane rating.
Terminal alkenes isomerize to internal alkenes in the presence of metal catalysts. This process is employed in the Shell higher olefin process to convert alpha-olefins to internal olefins, which are subjected to olefin metathesis. In certain kinds of alkene polymerization reactions, chain walking is an isomerization process that introduces branches into growing polymers.
The trans isomer of resveratrol can be converted to the cis isomer in a photochemical reaction.
Thermal rearrangement of azulene to naphthalene has been observed.
Aldose-ketose isomerism, also known as Lobry de Bruyn–van Ekenstein transformation, provides an example in saccharide chemistry.
An example of an organometallic isomerization is the production of decaphenylferrocene, from its linkage isomer.
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The isomerization of iridium(III) complexes with metalated N-heterocyclic carbene (NHC) ligands was studied. The fac isomers of complexes with 1-phenyl-3-methylbenzimidazolin-2-ylidene or 1-phenyl-3-benzylbenzimidazolin-2-ylidene ligands are transformed cl ...
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Olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds. Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions. For their elucidation of the reaction mechanism and their discovery of a variety of highly active catalysts, Yves Chauvin, Robert H. Grubbs, and Richard R.
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism refers to the existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural or constitutional isomerism, in which bonds between the atoms differ; and stereoisomerism or spatial isomerism, in which the bonds are the same but the relative positions of the atoms differ.
Stoichiometry (ˌstɔɪkiˈɒmᵻtri) is the relationship between the quantities of reactants and products before, during, and following chemical reactions. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the total mass of the products, leading to the insight that the relations among quantities of reactants and products typically form a ratio of positive integers. This means that ,if the amounts of the separate reactants are known, then the amount of the product can be calculated.
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