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The general procedure for the synthesis of 4,6-dichloropyrimidin-5-ol from 4,6-dichloro-5-methoxypyrimidine was as follows: to a stirred solution of 4,6-dichloro-5-methoxypyrimidine (50 g, 0.27 mol) in dichloroethane (800 mL) was added anhydrous aluminum chloride (50.48 g, 0.411 mol) in one go at 0 °C. The reaction mixture was stirred vigorously at 50°C for 6 hours. Upon completion of the reaction, the mixture was cooled to 0 °C and a 1 M aqueous HCl solution (400 mL) was slowly added, followed by methanol (100 mL). The mixture was stirred vigorously at room temperature for 10 minutes, diluted with water and extracted with ethyl acetate. The organic layers were combined, washed with saturated sodium bicarbonate solution and then dried over anhydrous sodium sulfate. The dried organic layer was filtered and concentrated to give 4,6-dichloropyrimidin-5-ol (41 g, 91.11% yield).UPLC analysis: calculated value of C4H2Cl2N2O was 164.97 and measured value was 165.9.

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