α-methylstyrene
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α-Methylstyrene (AMS) is an
organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
with the formula C6H5C(CH3)=CH2. It is a colorless oil.


Synthesis and reactions

AMS is formed as a by-product of the
cumene process The cumene process (cumene-phenol process, Hock process) is an industrial process for synthesizing phenol and acetone from benzene and propylene. The term stems from cumene (isopropyl benzene), the intermediate material during the process. It ...
. In this procedure,
cumene Cumene (isopropylbenzene) is an organic compound that contains a benzene ring with an isopropyl substituent. It is a constituent of crude oil and refined fuels. It is a flammable colorless liquid that has a boiling point of 152 Â°C. Near ...
is converted to its
radical Radical (from Latin: ', root) may refer to: Politics and ideology Politics *Classical radicalism, the Radical Movement that began in late 18th century Britain and spread to continental Europe and Latin America in the 19th century *Radical politics ...
, through a reaction with oxygen. : Normally these cumene radicals are converted to
cumene hydroperoxide Cumene hydroperoxide is the organic compound with the formula C6H5C(CH3)2OOH; this oily liquid is classified as an organic hydroperoxide. Products of decomposition of cumene hydroperoxide are methylstyrene, acetophenone, and 2-phenylpropan-2- ...
, however they can also undergo
radical disproportionation Radical (from Latin: ', root) may refer to: Politics and ideology Politics *Classical radicalism, the Radical Movement that began in late 18th century Britain and spread to continental Europe and Latin America in the 19th century *Radical politics ...
to form AMS. : Although this is only a minor
side reaction A side reaction is a chemical reaction that occurs at the same time as the actual main reaction, but to a lesser extent. It leads to the formation of by-product, so that the Yield (chemistry), yield of main product is reduced: : + B ->[] P1 : + C ...
, the cumene process is run at such a large scale that the recovery of AMS is commercially viable and satisfies much of the global demand. AMS can also be produced by dehydrogenation of cumene. The homopolymer obtained from this
monomer A monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called polymerization. Classification Chemis ...
, poly(α-methylstyrene), is unstable, being characterized by a low ceiling temperature of 65°C.


Side effects in humans

The
American Conference of Governmental Industrial Hygienists The American Conference of Governmental Industrial Hygienists (ACGIH) is a professional association of industrial hygienists and practitioners of related professions, with headquarters in Cincinnati, Ohio. One of its goals is to advance worker pr ...
(2009) defined occupational exposure limits of 10 ppm for airborne concentrations of α-methylstyrene based on allergic reactions and effects on the central nervous system.


References

{{DEFAULTSORT:Methylstyrene, alpha- Isopropenyl compounds Benzene derivatives Monomers IARC Group 2B carcinogens