A solution of 5-chlorofurfural 823 mg (6.305 mmol) in acetonitrile 25 mL was diluted with water 150mL and sulfamic acid 1.50g (15.4 mmol) was added. After complete dissolution, NaClO2 1.58g (80% tech product, Aldrich, 14mmol) solid was added in one portion and the mixture was stirred for 30 min at RT. (HPLC indicated complete a conversion within 10 min). The obtained golden-yellow reaction mixture (containing some dissolved Cl2 and ClO2) was extracted twice with ethyl acetate (2x100mL). The organic extracts were washed with water (100mL), combined, dried with magnesium sulfate and evaporated. The obtained crystalline residue was dissolved in acetonitrile (30mL, with gentle heating) and re-evaporated to dryness. Dried on highvac.
Y= 893 mg (96.5%) of a pearl-shiny white crystalline solid.
1H(d6-DMSO, 400MHz): 13,376(br s, 1H), 7.291(d, 3.6Hz, 1H), 6.702(d, 3.6Hz, 1H)
13C(d-DMSO, 100MHz): 158.26, 144.59, 139.10, 120.00, 109.63; LC-MS(-ESI): 145, 147 (M-1)
More sensitive substrates are often oxidized in presence of chlorine scavenger (isobutylene, etc). The chlorite + sulfamic acid in aqueous acetone allowed clean oxidation with unprotected phenolic aldehyde-arylacetone substrate: J. Chem. Soc. Perkin 1, (1980), 136-140