A Simple Straightforward Synthesis of Phenylphosphane and the Photoinitiator Bis(mesitoyl)phenylphosphane Oxide (IRGACURE819)

摘要

A straightforward high-yield synthesis for the photoinitiator bis(2,4,6-trimethylbenzoyl)phenylphosphane oxide (16, IRGACURE 819) involves: ⅰ) the reaction of phenyldichlorophosphane, PhPCI_2, with sodium to give [Na_2(P_2Ph_2)(tmeda)]_6 (5); ⅱ) protonation of 5 with fert-butanol to give 1,2-diphenyldiphosphane, PhHP-PHPh (12); ⅲ) reduction of 12 by sodium to yield [Na(PHPh)]_x (13); ⅳ) protonation of 13 with fert-butanol to give phenylphosphane PhPH_2 (14) in excellent yields; ⅴ) reaction of 14 with 2,4,6-trimethylbenzoylchloride (MesCOCI) in presence of the NaOf-Bu formed in steps ii and iv to give bis(2,4,6-trimethylbenzoyl)phenylphosphane 7; ⅵ) oxygenation of 7 with 30% aqueous hydrogen peroxide to give the final product 16. This reaction can be performed in toluene with about 4 vol-% of tmeda as an activator in a one-pot synthesis without changing the solvent. The structures determined by X-ray diffraction of the unique hexameric aggregate 5 and 16 are reported.