Synthesis and reduction of 2-nitroalkyl polysaccharide ethers

Several 2-nitroalkyl polysaccharide ethers (from pullulan (1), guar (2), agarose (3), inulin (4), cellulose (5), Na-a-polyglucuronate (6) and hydroxyethyl cellulose (7)) were synthesized by reaction with 2-nitro-1-alkenes (2-nitro-1-propene and 2-nitro-1-butene) formed in situ from 2-nitroalkyl acetates.Moderate to high efficiencies are obtained in concentrated aqueous solution/suspension for addition to 1-4 and 7. Analysis of this new class of polysaccharide derivatives with the aid of labeled 2-nitropropyl-2-13 C pullulan revealed that the nitrogroup is a mixture of the nitroalkane and nitronic acid tautomers.Grafting of nitroalkenes is observed and, to a lesser extent, additional reactions of the nitro group (formation of carbonyl, oxime and allyl groups) take place.Reduction of 2-nitroalkyl polysaccharide ethers with Na 2 S 2 O 4 or Na 2 S 2 O 4 /NaBH 4 leads to complex polysaccharide ethers.The products obtained are most likely mixtures of starting material, nitroso compounds, hydroxylamines, hydroxypropyl ethers and sulfamates.