α-Methylstyrene (AMS) is an organic compound with the formula C6H5C(CH3)=CH2. It is a colorless oil.[4]

α-Methylstyrene
Skeletal formula
Skeletal formula
Ball-and-stick model
Ball-and-stick model
Names
Preferred IUPAC name
(Prop-1-en-2-yl)benzene
Other names
2-Phenylpropene; 2-Phenylpropylene; 1-Methyl-1-phenylethylene; 1-Methyl-1-phenylethene; 1-Phenyl-1-methylethylene; 1-Phenyl-1-methylethene; (1-Methylethenyl)benzene; β-Phenylpropene; β-Phenylpropylene; α-Methylstyrol; α-Methylvinylbenzene; Isopropenylbenzene
Identifiers
3D model (JSmol)
Abbreviations AMS
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.459 Edit this at Wikidata
EC Number
  • 202-705-0
KEGG
RTECS number
  • WL5075300
UNII
UN number 2303
  • InChI=1S/C9H10/c1-8(2)9-6-4-3-5-7-9/h3-7H,1H2,2H3 checkY
    Key: XYLMUPLGERFSHI-UHFFFAOYSA-N checkY
  • InChI=1/C9H10/c1-8(2)9-6-4-3-5-7-9/h3-7H,1H2,2H3
    Key: XYLMUPLGERFSHI-UHFFFAOYAS
  • C=C(c1ccccc1)C
  • CC(=C)c1ccccc1
Properties
C9H10
Molar mass 118.179 g·mol−1
Appearance Colorless liquid
Density 0.91 g/cm3
Melting point −24 °C (−11 °F; 249 K)
Boiling point 165 to 169 °C (329 to 336 °F; 438 to 442 K)
Insoluble
Vapor pressure 2 mmHg (20 °C)[1]
-80.1·10−6 cm3/mol
Hazards
GHS labelling:[3]
GHS02: FlammableGHS07: Exclamation markGHS09: Environmental hazard
Warning
H226, H319, H335, H411
P210, P233, P240, P241, P242, P243, P261, P264+P265, P271, P273, P280, P303+P361+P353, P304+P340, P305+P351+P338, P319, P337+P317, P370+P378, P391, P403+P233, P403+P235, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
0
0
Flash point 45 °C (113 °F; 318 K)
Explosive limits 1.9–6.1%[1]
Lethal dose or concentration (LD, LC):
4900 mg/kg (oral, rat)[2]
NIOSH (US health exposure limits):
PEL (Permissible)
C 100 ppm (480 mg/m3)[1]
REL (Recommended)
TWA 50 ppm (240 mg/m3) ST 100 ppm (485 mg/m3)[1]
IDLH (Immediate danger)
700 ppm[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Synthesis and reactions

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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.

 

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

 

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.[5][6]

Side Effects in Humans

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The American Conference of Governmental Industrial Hygienists (2009) defined occupational exposure limits of 10 ppm for airborne concentrations of a-methylstyrene.[7] based on allergic reactions, and effects on the central nervous system.[7][8]

References

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  1. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0429". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ "alpha-Methyl styrene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. ^ "alpha-Methylstyrene". pubchem.ncbi.nlm.nih.gov.
  4. ^ James, Denis H.; Castor, William M. (2007). "Styrene". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_329.pub2. ISBN 978-3527306732.
  5. ^ Stevens, Malcolm P. (1999). "6". Polymer Chemistry an Introduction (3rd ed.). New York: Oxford University Press. pp. 193–194. ISBN 978-0-19-512444-6.
  6. ^ Jones, G. R.; Wang, H. S.; Parkatzidis, K.; Whitfield, R.; Truong, N. P.; Anastasaki, A. (2023). "Reversed Controlled Polymerization (RCP): Depolymerization from Well-Defined Polymers to Monomers". Journal of the American Chemical Society. 145 (18): 9898–9915. doi:10.1021/jacs.3c00589. PMC 10176471. PMID 37127289.
  7. ^ a b Morgan, D. L.; Mahler, J. F.; Kirkpatrick, D. T.; Price, H. C.; O'Connor, R. W.; Wilson, R. E.; Moorman, M. P. (February 1999). "Characterization of inhaled alpha-methylstyrene vapor toxicity for B6C3F1 mice and F344 rats". Toxicological Sciences. 47 (2): 187–194. doi:10.1093/toxsci/47.2.187. ISSN 1096-6080. PMID 10220856.
  8. ^ "α-METHYL STYRENE†". OSHA.