Α-Methylstyrene

α-Methylstyrene (AMS) is an organic compound 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. In this procedure, cumene is converted to its radical, through a reaction with oxygen.


 * [[Image:Cumene-radical-formation-2D-skeletal.png|200px]]

Normally these cumene radicals are converted to cumene hydroperoxide, however they can also undergo radical disproportionation to form AMS.


 * [[Image:Cumolhydroperoxid-Verfahren Kettenabbruch V1.2.svg|300px]]

Although this is only a minor side reaction, 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, 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 (2009) defined occupational exposure limits of 10 ppm for airborne concentrations of a-methylstyrene. based on allergic reactions, and effects on the central nervous system.