Potassium Hydroxide → 3-Methyl-4-phenylbut-3-enoic acid

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Reaction Conditions

Reaction Steps

To mixture of the above hydroxy-ester (3.06 g, 13.76 mmole) and pyridine (10 ml), cooled to 0° C., is slowly added phosphorus oxychloride (3.59 g, 23.39 mmole). The reaction mixture is stirred for about 2 hrs and then heated to 100° for 1.5 hours. The reaction is worked up by pouring into ice and extracting with water-hexane. The aqueous layer is back-extracted with hexane. The organic phases are combined, washed with 2 N hydrochloric acid, water and brine, dried over sodium sulfate and rotoevaporated to yield a mixture of esters--ethyl 3-methyl-4-phenyl-3- butenoate and ethyl 3-methyl-4-phenyl-2-butenoate. The mixture of esters is hydrolyzed using potassium hydroxide, water/methanol at 40° for about 20 hrs to yield the acids, 3-methyl-4-phenyl-3-butenoic acid and some 3-methyl-4-phenyl-2-butenoic acid.

Provenance & Evidence