Chlorosulfonic acid → 1,3-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-sulfonyl chloride

Participants

Reaction Steps

1,3-Dimethyluracil (411 g, 2.93M) was added portionwise over 30 minutes to chlorosulfonic acid (5480 g, 47.0M) with stirring at room temperature. The exotherm was allowed to proceed to 50° C. without cooling. Upon completion of addition, the reaction was heated gradually to reflux (~154° C.) for 2 hours. Upon cooling the reaction was cautiously poured onto ice. The resultant solid was filtered off, washed thoroughly with water and dried in vacuo at 40° C. for 16 hours. An off-white solid (554 g, 79.2%), m.p. 225°-230° C. (dec.) was obtained.

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