Hydrochloric Acid → 2-Hydroxy-4-(trifluoromethyl)pyrimidine

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Reaction Conditions

Reaction Steps

To a solution of 8.74 moles of urea in 2.2 L of methanol in a 3-necked flask, equipped with a mechanical stirrer, a reflux condenser and a dropping funnel was added dropwise over about 3 hours under N2 atmosphere an equimolar amount of 4-ethoxy-1,1,1-trifluoro-3-buten-2-one (ETFBO) which had been manufactured by addition of trifluoroacetyl chloride to ethyl vinyl ether. The temperature of the reaction mixture was kept below 15° C. After 15 min, 1.35 L of a concentrated HCl solution (32%) was added to the cooled suspension obtained and a clear solution was obtained. The solution was slowly heated to 60° C. and after 2 hours stirring, a suspension was formed. After overnight stirring at 60° C. and subsequently 1 h stirring at 0 to 5° C., the precipitate was filtered off. The residue was washed with water until neutral pH and subsequently with hexane (ca. 500 ml). After overnight drying on a rotary evaporator under reduced pressure in a 2 L flask, 6-(trifluoromethyl)pyrimidin-2(1H)-on was obtained as colorless crystals. The yield was 1.2 kg, (85% of the theoretical yield).

Provenance & Evidence