Phosphoric Acid → HCID 12756957, compound

Participants

Reaction Steps

[4-Fluoro-2-(4-nitrophenylthio)phenyl]acetic acid (17.6 g) was added at 150° C. to polyphosphoric acid, prepared from 60 ml 85% phosphoric acid and 100 g phosphorus pentoxide, and the mixture stirred at 150°-155° C. for two hours. After cooling, it was decomposed by pouring into a mixture of ice and water. The precipitated crude product was filtered and boiled for a short time under stirring with a mixture of a 10% sodium carbonate solution and benzene. It was filtered again, the benzene layer separated and benzene evaporated. The residue was dissolved in a small volume of benzene and the solution chromatographed on a column of 420 g alumina (act. II) Benzene eluted first a small amount of a less polar and high-melting by-product. The elution was continued with benzene and finally with a mixture of benzene and chloroform; 7.25 g of the desired crystalline 3-fluoro-8-nitrodibenzo(b,f)thiepin-10(11H)-one were obtained, m.p. 161°-163° C. (benzene-petroleum ether).

Provenance & Evidence