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A mixture of 27.5 g (0.25 mol) of hydroquinone, 11.2 g (0.2 mol) of potassium hydroxide in 600 ml of dimethylsulfoxide is stirred at room temperature under a nitrogen atmosphere until everything is dissolved. A solution of 30 g (0.2 mol) of 5-chloro-2,3-difluoropyridine in 200 ml of dimethylsulfoxide is added dropwise thereto. The reaction mixture is then heated to 70° and stirred at that temperature for 4 hours. Then it is poured into ice/water and the mixture is acidified with hydrochloric acid, extracted with ethyl acetate, dried over magnesium sulfate, filtered and evaporated to dryness. The residue is taken up in a hexane/ethyl acetate 2:1 solvent and passed over a silicagel column for purification. After concentrating the eluate, the residue crystallizes to yield 33 g of white crystals, melting at 97°-98°.

1. dissolutionis dissolved
2. temperatureThe reaction mixture is then heated to 70°
3. stirringstirred at that temperature for 4 hours
4. extractionextracted with ethyl acetate
5. dry with materialdried over magnesium sulfate
6. filtrationfiltered
7. customevaporated to dryness
8. custompassed over a silicagel column for purification
9. concentrationAfter concentrating the eluate, the residue
10. customcrystallizes