(2-Carboxyethyl)triphenylphosphonium tribromide, is a fine chemical and pharmaceutical intermediate. It is a bromine transfer agent for selective α-bromination of ketones and ketone acetals in the presence of double bonds, activated aromatic rings, esters or another free enolic position.
Synthesis of (2-CARBOXYETHYL)TRIPHENYLPHOSPHONIUM TRIBROMIDE: Ph3P (26.2 g, 0.1 mol), acrylic acid (7.2 g, 0.1 mol) and 49% HBr (50 mL) were stirred at rt until a homogeneous solution was obtained, then heated at 95-100 °C for 10 min, whereupon the mixture was cooled and glacial HOAc (240 mL) was added; bromine (9.8 mL) was added slowly with stirring to this mixture at 0 °C; after 0.5 h, the product was filtered and recrystallized from MeCN to give the perbromide (52.5 g, 91%);1 a two step procedure involving bromination of the isolated intermediate monobromide can also be used.
1. Armstrong, V. W.; Chishti, N. H.; Ramage, R. TL 1975, 373
(2-CARBOXYETHYL)TRIPHENYLPHOSPHONIUM TRIBROMIDE is irritant and moisture sensitive solid; store in a dry place. It should be handled in a fume hood.
