To the reaction flask was added 4-(carboxymethyl)benzoic acid (5 g, 27.78 mmol), 75 ml of methanol was added to dissolve the raw material and continued with 0.5 ml of N,N-dimethylformamide and thionyl chloride (6 ml, 83.33 mmol). The reaction was carried out at 50°C for 4 hours. After completion of the reaction, most of the thionyl chloride and methanol were removed by rotary evaporation. The residue was dissolved in 200 ml of ethyl acetate and washed sequentially with saturated sodium carbonate solution (50 ml x 3) and saturated brine (50 ml x 3). The organic phase was dried with anhydrous sodium sulfate, filtered and concentrated by rotary evaporation to give 5.5 g of a colorless transparent liquid product, methyl 4-formate phenylacetate, in 95.2% yield.
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