Ethenol, also calle vinyl alcohol, hydroxyethene or hydroxyethylene, is an alcohol with chemical formula C2H3OH (H2C=CHOH) and CAS number 557-75-5. Under normal conditions, it tautomerizes to acetaldehyde. For this reason the thermoplastic polyvinyl alcohol (PVA or PVOH), which would be derived from this monomer, is made indirectly by polymerization of vinyl acetate followed by hydrolysis of the ester bonds.