Styrene

Source: Wikipedia, the free encyclopedia.

Styrene
Styrene
Names
IUPAC name
Styrene[2]
Systematic IUPAC name
Ethenylbenzene[1]
Other names
Styrene[1]
Vinylbenzene
Phenylethene
Phenylethylene
Cinnamene
Styrol
Diarex HF 77
Styrolene
Styropol
Identifiers
3D model (
JSmol
)
1071236
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.002.592 Edit this at Wikidata
EC Number
  • 202-851-5
2991
KEGG
RTECS number
  • WL3675000
UNII
UN number 2055
  • InChI=1S/C8H8/c1-2-8-6-4-3-5-7-8/h2-7H,1H2 checkY
    Key: PPBRXRYQALVLMV-UHFFFAOYSA-N checkY
  • c1ccccc1C=C
Properties
C8H8
Molar mass 104.15 g/mol
Appearance colorless oily liquid
Odor sweet, floral[3]
Density 0.909 g/cm3
Melting point −30 °C (−22 °F; 243 K)
Boiling point 145 °C (293 °F; 418 K)
0.03% (20 °C)[3]
log P 2.70[4]
Vapor pressure 5 mmHg (20 °C)[3]
−6.82×10−5 cm3/mol
1.5469
Viscosity 0.762 cP at 20 °C
Structure
0.13 D
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 flammable, toxic,
probably carcinogenic
GHS labelling:
GHS02: FlammableGHS07: Exclamation markGHS08: Health hazard
Danger
H226, H315, H319, H332, H361, H372
P201, P202, P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P280, P281, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P308+P313, P312, P314, P321, P332+P313, P337+P313, P362, P370+P378, P403+P235, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
2
3
2
Flash point 31 °C (88 °F; 304 K)
Explosive limits
 0.9–6.8%[3]
Lethal dose or concentration (LD, LC):
2194 ppm (mouse, 4 h)
5543 ppm (rat, 4 h)[5]
10,000 ppm (human, 30 min)
2771 ppm (rat, 4 h)[5]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 100 ppm C 200 ppm 600 ppm (5-minute maximum peak in any 3 hours)[3]
REL (Recommended)
 TWA 50 ppm (215 mg/m3)
ST 100 ppm (425 mg/m3)[3]
IDLH
(Immediate danger)
 700 ppm[3]
Safety data sheet (SDS) MSDS
Related compounds
Related styrenes;
related
aromatic
compounds
 polystyrene, stilbene;
ethylbenzene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Styrene is an organic compound with the chemical formula C6H5CH=CH2. Its structure consists of a vinyl group as substituent on benzene. Styrene is a colorless, oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concentrations have a less pleasant odor.[vague] Styrene is the precursor to polystyrene and several copolymers, and is typically made from benzene for this purpose. Approximately 25 million tonnes of styrene were produced in 2010,[6] increasing to around 35 million tonnes by 2018.

Natural occurrence

Styrene is named after

coffee beans, balsam trees and peanuts)[7] and is also found in coal tar
.

History

In 1839, the German apothecary Eduard Simon isolated a volatile liquid from the resin (called storax or styrax (Latin)) of the American sweetgum tree (Liquidambar styraciflua). He called the liquid "styrol" (now called styrene).[8][9] He also noticed that when styrol was exposed to air, light, or heat, it gradually transformed into a hard, rubber-like substance, which he called "styrol oxide".[10]

By 1845, the German chemist August Wilhelm von Hofmann and his student John Buddle Blyth had determined styrene's empirical formula: C8H8.[11] They had also determined that Simon's "styrol oxide" – which they renamed "metastyrol" – had the same empirical formula as styrene.[12] Furthermore, they could obtain styrene by dry-distilling "metastyrol".[13]

In 1865, the German chemist

decarboxylated
to form "cinnamene" (or "cinnamol"), which appeared to be styrene.

In 1845, French chemist Emil Kopp suggested that the two compounds were identical,[16] and in 1866, Erlenmeyer suggested that both "cinnamol" and styrene might be vinylbenzene.[17] However, the styrene that was obtained from cinnamic acid seemed different from the styrene that was obtained by distilling storax resin: the latter was optically active.[18] Eventually, in 1876, the Dutch chemist van 't Hoff resolved the ambiguity: the optical activity of the styrene that was obtained by distilling storax resin was due to a contaminant.[19]

Industrial production

From ethylbenzene

The vast majority of styrene is produced from

catalyst, but in modern production this has been replaced by zeolites
.

By dehydrogenation

Around 80% of styrene is produced by the

endothermic
and reversible, with a typical yield of 88–94%.

The crude ethylbenzene/styrene product is then purified by distillation. As the difference in boiling points between the two compounds is only 9 °C at ambient pressure this necessitates the use of a series of distillation columns. This is energy intensive and is further complicated by the tendency of styrene to undergo thermally induced polymerisation into polystyrene,

polymerization inhibitor
to the system.

Via ethylbenzene hydroperoxide

Styrene is also co-produced commercially in a process known as POSM (

Shell) for styrene monomer / propylene oxide. In this process, ethylbenzene is treated with oxygen to form the ethylbenzene hydroperoxide. This hydroperoxide is then used to oxidize propylene
to propylene oxide, which is also recovered as a co-product. The remaining 1-phenylethanol is dehydrated to give styrene:

Synthesis of styrene

Other industrial routes

Pyrolysis gasoline extraction

Extraction from pyrolysis gasoline is performed on a limited scale.[20]

From toluene and methanol

Styrene can be produced from

zeolitic catalyst. It is reported[24] that an approximately 9:1 mixture of styrene and ethylbenzene is obtained, with a total styrene yield of over 60%.[25]

From benzene and ethane

Another route to styrene involves the reaction of benzene and ethane. This process is being developed by Snamprogetti and Dow. Ethane, along with ethylbenzene, is fed to a dehydrogenation reactor with a catalyst capable of simultaneously producing styrene and ethylene. The dehydrogenation effluent is cooled and separated and the ethylene stream is recycled to the alkylation unit. The process attempts to overcome previous shortcomings in earlier attempts to develop production of styrene from ethane and benzene, such as inefficient recovery of aromatics, production of high levels of heavies and tars, and inefficient separation of hydrogen and ethane. Development of the process is ongoing.[26]

Laboratory synthesis

A laboratory synthesis of styrene entails the decarboxylation of cinnamic acid:[27]

C6H5CH=CHCO2H → C6H5CH=CH2 + CO2

Styrene was first prepared by this method.[28]

Polymerization

The presence of the vinyl group allows styrene to

automobile
and boat parts, food containers, and carpet backing.

Hazards

Autopolymerisation

As a liquid or a gas, pure styrene will polymerise spontaneously to polystyrene, without the need of external

1999 and 2000 and overheating styrene tanks leading to the 2020 Visakhapatnam gas leak, which killed several people.[31][32] The autopolymerisation reaction can only be kept in check by the continuous addition of polymerisation inhibitors
.

Health effects

Styrene is regarded as a "known

US Environmental Protection Agency (EPA) has described styrene to be "a suspected toxin to the gastrointestinal tract, kidney, and respiratory system, among others".[37][38]

On 10 June 2011, the US National Toxicology Program has described styrene as "reasonably anticipated to be a human carcinogen".[39][40] However, a STATS author describes[41] a review that was done on scientific literature and concluded that "The available epidemiologic evidence does not support a causal relationship between styrene exposure and any type of human cancer".[42] Despite this claim, work has been done by Danish researchers to investigate the relationship between occupational exposure to styrene and cancer. They concluded, "The findings have to be interpreted with caution, due to the company based exposure assessment, but the possible association between exposures in the reinforced plastics industry, mainly styrene, and degenerative disorders of the nervous system and pancreatic cancer, deserves attention".[43] In 2012, the Danish EPA concluded that the styrene data do not support a cancer concern for styrene.[44] The US EPA does not have a cancer classification for styrene,[45] but it has been the subject of their Integrated Risk Information System (IRIS) program.[46]

The

US Department of Health and Human Services has determined that styrene is "reasonably anticipated to be a human carcinogen".[47] Various regulatory bodies refer to styrene, in various contexts, as a possible or potential human carcinogen. The International Agency for Research on Cancer considers styrene to be "probably carcinogenic to humans".[48][49]

The neurotoxic

synergistic interaction with noise in causing hearing difficulties.[57][58][59][60]

References

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  3. ^ a b c d e f g NIOSH Pocket Guide to Chemical Hazards. "#0571". National Institute for Occupational Safety and Health (NIOSH).
  4. ^ "Styrene". www.chemsrc.com.
  5. ^ a b "Styrene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  6. ^ "New Process for Producing Styrene Cuts Costs, Saves Energy, and Reduces Greenhouse Gas Emissions" (PDF). US Department of Energy. Archived from the original (PDF) on 21 April 2013.
  7. ISSN 0021-8561. Archived
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  8. ^ Simon, E. (1839) "Ueber den flüssigen Storax (Styrax liquidus)" (On liquid storax (Styrax liquidus), Annalen der Chemie, 31 : 265–277. From p. 268: "Das flüchtige Oel, für welches ich den Namen Styrol vorschlage, … " (The volatile oil, for which I suggest the name "styrol", … )
  9. ^ For further details of the history of styrene, see: F. W. Semmler, Die ätherischen Öle nach ihren chemischen Bestandteilen unter Berücksichtigung der geschichtlichen Entwicklung [The volatile liquids according to their chemical components with regard to historical development], vol. 4 (Leipzig, Germany, Veit & Co., 1907), § 327. Styrol, pp. 24-28. Archived 1 May 2018 at the Wayback Machine
  10. ^ (Simon, 1839), p. 268. From p. 268: "Für den festen Rückstand würde der Name Styroloxyd passen." (For the solid residue, the name "styrol oxide" would fit.)
  11. ^ See:
  12. ^ (Blyth and Hofmann, 1845a), p. 348. From p. 348: "Analysis as well as synthesis has equally proved that styrol and the vitreous mass (for which we propose the name of metastyrol) possess the same constitution per cent."
  13. ^ (Blyth and Hofmann, 1845a), p. 350
  14. ^ Erlenmeyer, Emil (1865) "Ueber Distyrol, ein neues Polymere des Styrols" (On distyrol, a new polymer of styrol), Annalen der Chemie, 135 : 122–123.
  15. ^ Berthelot, M. (1866) "Sur les caractères de la benzine et du styrolène, comparés avec ceux des autres carbures d'hydrogène" (On the characters of benzene and styrene, compared with those of other hydrocarbons), Bulletin de la Société Chimique de Paris, 2nd series, 6 : 289–298. From p. 294: "On sait que le styrolène chauffé en vase scellé à 200°, pendant quelques heures, se change en un polymère résineux (métastyrol), et que ce polymère, distillé brusquement, reproduit le styrolène." (One knows that styrene [when] heated in a sealed vessel at 200 °C, for several hours, is changed into a resinous polymer (metastyrol), and that this polymer, [when] distilled abruptly, reproduces styrene.)
  16. ^ Kopp, E. (1845), "Recherches sur l'acide cinnamique et sur le cinnamène" Archived 8 November 2016 at the Wayback Machine (Investigations of cinnamic acid and cinnamen), Comptes rendus, 21 : 1376–1380. From p. 1380: "Je pense qu'il faudra désormais remplacer le mot de styrol par celui de cinnamène, et le métastyrol par le métacinnamène." (I think that henceforth one will have to replace the word "styrol" with that of "cinnamène", and "metastyrol" with "metacinnamène".)
  17. ^ Erlenmeyer, Emil (1866) "Studien über die s.g. aromatischen Säuren" (Studies of the so-called aromatic acids), Annalen der Chemie, 137 : 327–359; see p. 353.
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  19. ^ van 't Hoff, J. H. (1876) "Die Identität von Styrol und Cinnamol, ein neuer Körper aus Styrax" (The identity of styrol and cinnamol, a new substance from styrax), Berichte der deutschen chemischen Gesellschaft, 9 : 5-6.
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External links
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