Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Triphenylphosphine oxide (often abbreviated TPPO) is the chemical compound with the formula OP(C6H5)3. Often chemists abbreviate the formula by writing Ph3PO or PPh3O (Ph = C6H5). This white crystalline compound is a common side product in reactions involving triphenylphosphine. It is a popular reagent to induce the crystallizing of chemical compounds. An alternative IUPAC name is (diphenylphosphoryl)benzene.