Water → (S)-styrene oxide

Participants

Reaction Steps

A 500-mL flask, equipped with a temperature probe, a mechanical stirrer, a vacuum adapter, and a dip tube, was charged with (S,S)—Co(salen) (5.51 g, 0.0083 mol, 0.500 mol %), styrene oxide (200.0 g, 1.66 mol, 100 mol %), and water (59.8 g, 3.32 mol, 200 mol %). A slight vacuum was applied to the flask to draw air into the reaction mixture through the dip tube (subsurface), and agitation was initiated. The flask was placed in a water bath and p-nitrobenzoic acid (2.83 g, 0.0166 mol, 1.00 mol %) was added in one portion. After stirring overnight at room temperature, the reaction was deemed complete by HPLC. The reaction mixture was a brown solution with suspended orange solids. Ammonium hydroxide (4.15 g, 4.63 mL, 28% NH3, 0.0332 mol, 2.00 mol %) was added and the reaction mixture was stirred at room temperature with continued air flow for 1 h. A dark brown solution was obtained. Air flow through the reaction mixture was stopped, and the reaction mixture was washed with water (2×200 mL). The organic layer was fractionally distilled to give (S)-styrene oxide (67.86 g, 67.9% yield, 99.6% e.e.). The aqueous layer was treated with activated carbon and warmed to a gentle boil. After cooling and filtration, the aqueous layer was concentrated to give (R)-styrene glycol (95.25 g, 95.3% yield, 93.9% e.e.).

Provenance & Evidence