Water → Acetic acid, 2-(triphenylphosphoranylidene)-, ethyl ester

Participants

Reaction Conditions

Reaction Steps

A 4.5 L reactor equipped with a mechanical stirrer, a Pt-100 thermometer, a dropping funnel and a nitrogen inlet was charged with 450 g (1.03 mol) ethoxycarbonylmethyl-triphenyl phosphonium bromide, 1.0 L dichloromethane and 1.5 L water. The two-phase mixture was cooled to 5° C. and 565 ml (1.13 mol) 2N sodium hydroxide solution was added during 30 min, maintaining the temperature between 3 and 7° C. After completed addition the mixture was stirred for 75 min at that temperature, then the phases were separated, the aqueous layer extracted with 500 ml dichloromethane and the combined organic layers were concentrated on a rotatory evaporator at 50° C./10 mbar to give 363 g crude product as slightly brownish crystals. These were dissolved in 450 ml dichloromethane under reflux. Ca. 1.35 L heptane were added during 30 min to the refluxing mixture until a slight turbidity persisted. After 1 h at 40-45° C. the mixture was seeded with product crystals and the suspension was allowed to cool to 30-32° C. during 3 h. At that point another 450 mL heptane were added and the mixture was stirred overnight at RT, followed by 2 h at 0-4° C. The crystals were filtered off, washed with 450 mL pre-cooled heptane and dried overnight at 45° C./10 mbar, to give 310 g carbethoxymethylene triphenylphosphorane (98% yield; assay: 98.4%) as white crystals.

Provenance & Evidence