Carbon tetrabromide → 3,5-Bis(4-vinylbenzyloxy)benzyl bromide

Participants

Reaction Steps

A 1 L flask is charged with 10.0 g (268.6 mmol, 2.3 eq) of LiAlH4 in THF (250 ml) under an argon atmosphere. The resultant solution is cooled with an ice bath and 46.9 g (116.9 mmol) of ester (2A) in THF (250 ml) is added dropwise with stirring and the mixture, stirred over a 2 hour period. Thereafter water (10 ml) and 15% NaOH (10 ml) and finally water (24 ml) is added to the mixture. The grey precipitate is filtered and the filtrate is washed with diethylether. Thereafter water (500 ml) is added and the organic phase is collected. The remaining aqueous phase is further extracted with diethylether (3×500 ml) and the organic phases are collected and combined, dried over MgSO4 and evaporated to dryness. A colourless oil is obtained (38.7 g, 88.5%). Addition of a little hexane effects precipitation of white crystals of 3,5-di(4-vinylbenzyloxy)benzylalcohol (2B). A 1 L flask is charged with 64.5 g (173 mmol) of (2B) in THF (250 ml) under an argon atmosphere. Thereafter, 68.1 g (260 mmol, 1.5 eq) of PPh3 and then 86.2 g (260 mmol, 1.5 eq) of CBr4 are added and the resultant mixture stirred gently for 1 hour in an ice bath whereupon a milky suspension is obtained. To this suspension is added water (600 ml) and diethylether (400 ml). The organic phase is collected and the aqueous phase is further extracted with diethylether (2×500 ml). The organic phases are collected and combined, dried over MgS04 and evaporated to dryness. A yellow oil is obtained which is dissolved in hexane/acetone 9:1 and filtered over Kieselgel. The resultant solution is left to recrystallise to yield fine white crystals of 3,5-di(4-vinylbenzyloxy)benzylbromide (2).

Provenance & Evidence