Ethyl 3-phenylpropionate → 2-Oxo-4-phenylbutyric acid

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Reaction Steps

A mixture of 143 g of ethyl 3-phenylpropionate, 234 g of ethyl oxalate and 154 ml of 28% sodium ethoxide solution in ethanol is heated on a water bath at a bath temperature of 60°-70° C. for 1.5 hours, while distilling off the ethanol under reduced pressure. To the resulting red syrupy residue is added 1.3 liters of 15 v/v % sulfuric acid. The mixture is boiled under reflux with stirring for 15 hours, and the oil layer is separated, neutralized with 10% sodium hydroxide and extracted with ethyl acetate. The aqueous layer is made acidic with diluted sulfuric acid. The resulting oil is extracted with ethyl acetate, washed with water and dried. Removal of the ethyl acetate by distillation under reduced pressure gives 130 g of 2-oxo-4-phenylbutyric acid as an oil.

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