Sulfuric Acid → 2-Chloro-3-(p-methoxyphenyl)-2-cyclobuten-1-one

Participants

Reaction Steps

2Chloro-1,1-difluoro-3-(p-methoxyphenyl)-2-cyclobutene (215 g., 0.93 mole) is poured gradually into 272 ml. of concentrated H2SO4 with stirring. The rate of addition is adjusted to maintain the reaction temperature below 40° C. When the reaction subsides, the cooling bath is removed, but stirring is continued for 20 min. The mixture is poured into 3 l. of water. A precipitate forms, and is collected on a filter, washed with water, and air-dried. recrystallization of this material twice from i-PrOH yields 128.8 g. (66%) of the desired intermediate, m.p. 96°-98° C. An analytical sample was prepared by chromatography an alumina (benzene) and recrystallized from heptane, m.p. 98-100° C.

Provenance & Evidence