Triphenylacetic Acid

About This Product

Triphenylacetic acid, 2,2,2-triphenylacetic acid, has the formula C20H16O2, molecular weight 288.3 and CAS number 595-91-5. It is a white to off-white solid, freely soluble in dimethylformamide: an acetic acid in which all three alpha hydrogens are replaced by phenyl rings. Those three phenyl rings make it one of the bulkiest simple carboxylic acids, and its main specialist use exploits that bulk. As the carboxylate ligand in dirhodium(II) tetrakis(triphenylacetate), the rings form a crowded pocket around the catalytic rhodium centre, steering the selectivity of carbene reactions such as C–H insertion and cyclopropanation, and the acid is also used to prepare other metal carboxylate complexes and as a building block for trityl-substituted compounds. Crowding has a cost: the acid decarboxylates on strong heating to triphenylmethane, which is therefore the named impurity in this specification, limited to 0.30 percent with any other individual impurity at 0.30 and total impurities at 1.0 percent, alongside identification by infrared spectrum and an assay of 98.0 to 102.0 percent. It is used in preparing dirhodium and other metal carboxylate catalysts, as a building block in organic and pharmaceutical synthesis, and in coordination chemistry research. Bio Green Chem supplies triphenylacetic acid to specification on appearance, solubility, identification, loss on drying, residue on ignition, related substances and assay, packed in fibre drums or bags.