2-Phenylphenol, or o-phenylphenol, is an organic compound with the formula C6H5−C6H4OH. It is one of three isomers of monohydroxylated biphenyl. It is a white solid. It is a biocide used as a preservative with E number E231 and under the trade names Dowicide, Torsite, Fungal, Preventol, Nipacide and many others.