Salicylic Acid → 3-Nitrosalicylic acid

Participants

Reaction Steps

To a stirred suspension of salicylic acid (0.69 g, 5 mmol) in dichloromethane (10 mL) at room temperature was added tetrabutylammoniumhydrogen sulphate (0.085 g, 5 mol %) followed by isopropyl nitrate (1.31 g, 12.5 mmol). Sulphuric acid (96%, 0.69 mL) was then added dropwise to the mixture which was allowed to stir at room temperature for thirty minutes (became a yellow solution, followed by formation of a yellow precipitate) and then poured onto water (50 mL). The yellow precipitate was filtered off and then triturated with water (10 mL). The insoluble material was filtered off and dried to afford yellow crystals, (0.42 g, 46%) of m.p. 121–122° C. identified by NMR as the title compound (lit. m.p. 123° C., Merck Index No. 6553). The mother liqours were concentrated on a rotary evaporator (60° C., water aspirator pressure) and recrystallised from a dichloromethane/petroleum ether mixture to give yellow/orange crystals (0.35 g, 39%) of m.p. 226–228° C., identified by NMR as 2-hydroxy-5-nitrobenzoic acid (5-nitrosalicylic acid) (lit. m.p. 228–230° C., Merck Index No. 6554). (85% combined yield, Ortho:Para selectivity, 1.2:1)

Provenance & Evidence