Potassium Hydroxide → 1,1-Dimethylethyl 4-ethenylphenyl carbonate

Participants

Reaction Conditions

Reaction Steps

A solution of 751 g (4.6 moles) of 4-acetoxystyrene in 3767 g of ethyl acetate was charged to a 12-liter three-necked flask equipped with a mechanical stirrer, condenser, and ice-bath. A solution of 634 g (0.8 moles) of potassium hydroxide in 1197 g of methanol, and 1685 g (7.6 moles) of molten di-tert-butyl dicarbonate was added in small poritons to the stirred reaction mixture, over a period of 1 hour 20 minutes. The reaction temperature was maintained at 25° C. throughout the addition. The contents of the vessel were stirred an additional 1.4 hours at 25° C. The reaction slurry was washed twice with 4-liter portions of deionized water. The organic layer was vacuum stripped at 35° C. and 50 mm Hg until most of the solvent had been removed. The residue was further stripped at 75° C. and 1.5 mm Hg. The residual oil, 1015 g (99.5% conversion and 82% yield, based on 4-acetoxystyrene) was vacuum distilled to yield pure t-botoxycarbonyloxystyrene (TBSM). Yields observed in multiple experiments, employing the above procedure are shown below. The method is not yet optimized in terms of all of the variables, which variables may have differed slightly from batch to batch, accounting for the range in yield.

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