4-Chlorobenzhydrol

Uses4-Chlorobenzhydrol was used as internal standard to measure the N-demethyl antipyrine metabolite in urine by gas chromatography-mass spectrometry. It was also used in the identification of the antihistamine cetirizine as a relevant cross-reactant for the carbamazepine-specific enzyme-linked immunosorbent assay .

PreparationPreparation of 4-Chlorobenzhydrol(4-CB):about 5.0g(0.023 mol) of 4-chloro benzophenone was dissolved in 15 mL of isopropyl alcohol (IPA) and heated to 50°C followed by the addition of 0.265g(0.007 mol) of sodium borohydride as a lot with the temperature maintained at 65°C for 2 h. The reaction mixture was distilled to expel isopropyl alcohol up to 90 %. The resulting solution was cooled and treated with dil HCl (5 mL of conc. HCl in 20 mL of water). Finally the reaction mass was extracted with 15 mL of toluene. The toluene extract was washed withwater to pH-7. The compound obtained in this step was taken to next step without isolation but aliquot sample was concentrated, isolated and checked for melting point (m.p. = 58-60°C).