Hydrochloric Acid → (2E)-4-(3,4-Dimethoxyphenyl)-4-oxo-2-butenoic acid

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Reaction Conditions

Reaction Steps

Into a 500 ml four-neck flask were charged 66.9 g (0.682 mol) of maleic anhydride and 150 ml of chlorobenzene under a nitrogen atmosphere. Then, the whole was cooled to 10° C. or lower and 67.6 g (0.507 mol) of aluminum chloride was added thereto. While temperature was maintained at 10 to 15° C., 25 ml (0.195 mol) of 1,2-dimethoxybenzene was added dropwise, followed by 48 hours of reaction at 20 to 30° C. After termination of the reaction was confirmed by HPLC analysis, the reaction solution was added dropwise to 200 ml of a 1N hydrochloric acid aqueous solution cooled to 0° C. to decompose excess aluminum chloride. The resulting mixture was extracted with 400 ml of ethyl acetate and washing was conducted twice with 200 ml of a 1N hydrochloric acid aqueous solution. The organic layer was washed three times with 200 ml of a saturated sodium hydrogen carbonate aqueous solution to extract (E)-4-(3,4-dimethoxyphenyl)-4-oxo-2-butenoic acid into the aqueous layer, followed by adjusting the aqueous layer to pH 2.0. After 24 h of stirring at 5° C., filtration was carried out to obtain 28.6 g (yield 62.1%) of the aimed compound as light yellow crystals. As a result of HPLC analysis, the purity was found to be 96.5%.

Provenance & Evidence