Styrene, also known asethenylbenzene, vinylbenzene, andphenylethene, is an organic compound with the chemical formula c6h5ch=ch2. This derivative of benzene is a colorless oily liquid that evaporates easily and has a sweet smell, although high concentrations have a less pleasant odor. Styrene is the precursor to polystyrene and several copolymers.Styrenenamespreferred iupac namephenyletheneother namesvinyl benzene; cinnamene; styrol; phenylethene; diarex hf 77; styrolene; styropol; vinylbenzene; phenylethyleneidentifierscas number100-42-5chebichebi:27452chemblchembl285235chemspider7220jmol interactive 3dkeggpubchem7501rtecs numberwl3675000unii44lj2u959vinchismilespropertieschemical formulac8h8molar mass104.15 g/molappearancecolorless oily liquidodorsweet, floral[1]density0.909 g/cm3melting point30 c (22 f; 243 k)boiling point145 c (293 f; 418 k)solubility in water0.03% (20c)[1]vapor pressure5 mmhg (20c)[1]refractive index(nd)1.5469viscosity0.762 cp at 20 cstructuredipole moment0.13 dhazardsmain hazardsflammable, toxicsafety data sheetr-phrasesr10 r36s-phrasess38 s20 s23nfpa 704322flash point31 c (88 f; 304 k)explosive limits0.9%-6.8%[1]lethal dose or concentration (ld, lc):lc50(median concentration)2194 ppm (mouse, 4 hr)5543 ppm (rat, 4 hr)[2]lclo(lowest published)10, 000 ppm (human, 30 min)2771 ppm (rat, 4 hr)[2]us health exposure limits (niosh):pel (permissible)twa 100 ppm c 200 ppm 600 ppm (5-minute maximum peak in any 3 hours)[1]rel (recommended)twa 50 ppm (215 mg/m3) st 100 ppm (425 mg/m3)[1]idlh (immediate danger700 ppm[1]related compoundsrelated styrenes;related aromaticcompoundspolystyrene, stilbene;ethylbenzeneexcept where otherwise noted, data are given for materials in their standard state (at 25 c [77 f], 100 kpa).