applying a positive nitrogen pressure to the reaction flask. The resulting acid mixture was stirred at -70°for 1 hr, poured into a mixture of 200 ml of concentrated HC1 and 1 1. of ice water, and extracted with three 500-ml portions of dichloromethane. The extracts were washed once with water, dried, and evaporated in vacuo below 40°.38 The residue, obtained as an oil (ca. 7.2 g) consisting of a major amount of the cyanohydrin 91 and a small amount of the unchanged 89, was transferred to a 10-ml Claisen flask.Powdered potassium bisulfate (0.20 g) was added, and the flask was heated at 130°(5 mm) for 30 min. The pressure was then reduced to 0.2 mm and the temperature was raised to about 160°t o collect all the distillate boiling usually at 130-145°( 2 mm). Crystallization of the distillate (ca. 6.2 g) from ether-petroleum ether gave about 4 g of 6-methoxy-3,4-dihydronaphthalene-lcarbonitrile (92), mp 50-52°. The residue from the mother liquor was chromatographed. Elution with petroleum ether gave an additional crop of the nitrile 92, and elution with benzene afforded the unchanged 89. The conditions and results are shown in Table V.(38) It was found later that addition of a small amount (20 mg) of ptoluenesulfonic acid monohydrate was preferable to prevent reconversion of the unstable cyanohydrin into the starting ketone. Cf. ref 28.
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