styrene enol 1-phenylethenol 1-phenylethenol VEIIEWOTAHXGKS-UHFFFAOYSA-N InChI=1S/C8H8O/c1-7(9)8-5-3-2-4-6-8/h2-6,9H,1H2 C8H8O 0 120.05751 CHEBI:38961 120.14852 OC(=C)c1ccccc1 chebi_ontology CAS:4383-15-7