Sodium Hydroxide → 2-Chloro-5-[2,6-dioxo-4-(trifluoromethyl)-3,6-dihydro-1(2H)-pyrimidinyl]benzoic acid

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A mixture of 58.9 grams (0.156 mole) of isopropyl 2-chloro-5-[3,6-dihydro-4-trifluoromethyl-2,6-dioxo-1(2H) pyrimidinyl]benzoate and 11.2 grams (0.28 mole) of sodium hydroxide in 1200 ml. of 50% ethanol was heated at 65° C. for 30 minutes and stirred for 2 hours. Evaporation under a reduced pressure removed the solvent. The residue was treated with 2.3 ml. of concentrated hydrochloric acid in 130 ml. of water. Filtration collected 45 grams of crude solid. The solid product was further dissolved in a solution of 10 grams (0.25 (mole) of sodium hydroxide in 600 ml. of water. The solution was cooled with an ice-water bath and then acidified to pH 2 with concentrated hydrochloric acid. The colorless precipitate was collected by filtration, rinsed with water and air-dried. The sample of 2-chloro-5-[3,6-dihydro-4-trifluoromethyl-2,6-dioxo-1 (2H) pyrimidinyl]benzoic acid weighed 40.7 grams (78%); m.p. 311°-2° C. 'H NMR (300 MHzm/DMSO-d6) δ 3.36 (broad,1H); 6.37 (S,1H); 7.45 (dd, J=9.3, 2.1 Hz,1H); 7.67 (d,J=9.3 Hz,1H); 7.79 (d, J=2.1 Hz, 1H), 12.48 (broad, 1H).

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