Hydrogen Bromide → 4,5-Dihydroxy-2-nitrobenzaldehyde

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5-Chloromethoxy-4-hydroxy-2-nitrobenzaldehyde (10) (3 g; 0.013 mol) is stirred at 23° C. with 15 ml 48% HBr for two days. The precipitate is removed by filtration, and washed well with H2O, giving 2.2 g (93%) of 4,5-dihydroxy-2-nitrobenzaldehyde (1). The remainder of the product is isolated by ether extraction of the filtrate. Drying the combined ether extracts over Na2SO4, filtering, and removing the ether at reduced pressure, gives the remaining 0.17 g (7%) of (1): mp 201°-203° C.; mass spectrum, m/e 183 (M+); 1HNMR (d6 -Me2CO) δ10.59 (br s,2H), δ10.2(s,1H), δ7.6(s,1H), δ7.3(s,1H).

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