Hydrochloric Acid → 2-[2-(4'-Chloro-biphenyl-4-YL)-2-oxo-ethyl]acrylic acid

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212 g (1.59 mol) of anhydrous aluminum chloride are introduced into 1800 g of o-dichlorobenzene and the mixture is brought to 45° C. with stirring. A solid mixture of 78.5 g (0.7 mol) of itaconic anhydride and 132 g (0.7 mol) of 4-chlorobiphenyl is added in the course of one hour. The reaction mixture is stirred at 45° C. for two hours and then added to an ice-cold mixture of 900 g of water and 100 g of hydrochloric acid (37%). The aqueous phase is separated off. The organic phase is washed three times with a mixture of 1000 g of water and 25 g of hydrochloric acid (37%) in each case. After washing three times, it is allowed to cool to approximately 20° C. and the colorless product is then filtered off with suction. This is then washed twice with 150 g of ethanol/water 90:10 in each case. The product is dried at 80° C. and about 110 mbar until free of solvent and water. 148 g (0.49 mol) of 4-(4′-chlorobiphenyl-4-yl)-4-keto-2-methylenebutyric acid (70%) are obtained as a colorless, finely crystalline powder. By working up the mother liquor, as described in Example 1, the yield is increased to 87%. (HPLC purity 99.3-99.5%).

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