Synthesis and reduction of 2-nitroalkyl polysaccharide ethers

Abstract

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. ᭧

Synthesis, analysis and reduction of 2-nitropropyl starch

“…2) at l 80, l 90 and l 92 ppm. Comparing these results to values obtained for model systems and NMR simulations 28 it can be concluded that the high field resonance originates from the CHNO 2 carbon atom, one of the resonances at about l 90 ppm originates from the quaternary C(Me)NO 2 carbon atom, formed after grafting of 2-nitropropene onto the starch backbone. The other resonance at about 90 ppm most likely signifies the pres- ence of the nitronic acid tautomer (C NO 2 H) of the 2-nitropropyl functionality.…”

“…2-Nitropropyl acetate, 1-methoxy-2-nitropropane (a), 1-methoxy-2-methyl-2,4-dini-tropentane (b) and 3-O-(2-nitropropyl)-a,b-Dglucopyranoside (c) were prepared according to literature procedures. 28 1 H and 13 C NMR spectra were recorded on a 500 Varian MHz spectrometer. FTIR spectra were recorded on a Biorad FTS 135 spectrometer.…”

“…The chemical shift is in reasonable agreement with the methine carbon of 1-methoxy-2-aminopropane, the corresponding hydroxylamine or the sulfamate. 28 In order to distinguish between these compounds we performed the reaction on a preparative scale. Unfortunately, the compound formed could not be isolated from the water layer by extraction with organic solvents and therefore we could not determine the exact nature of it.…”

Critical assessment of the efficiency of chitosan biohydrogel beads as recyclable and heterogeneous organocatalyst for C–C bond formation

“…6, a-b). To a lesser extent, nitroalkanes could be also partially associated with this process since they can interact with the free amine groups by formation of molecular (or charge-transfer) complexes, or with the hydroxyl groups of polysaccharides forming nitroalkyl ethers, 52 which would be in tautomeric equilibrium with the corresponding nitronic acid species (aci-form, R 1 R 2 C NOOH). Moreover, the formation of the aci-form is also known to be catalyzed by water 53 or amines 54 through two stabilizing hydrogen bonds, which could also support the faster catalyst deactivation observed in pure water.…”

Effect of carboxymethyl groups on degradation of modified pullulan by pullulanase from Klebsiella pneumoniae

“…To search for new properties of pullulan, many studies have been reported on the chemical modification of pullulan such as: chloroalkylation (Mocanu, Vizitiu, Mihai, & Carpov, 1999), nitroalkylation (Heeres et al, 2000), alkyl etherification (HenniSilhadi et al, 2007;Shibata, Nozawa, Teramoto, & Yosomiya, 2002). Carboxymethylation of pullulan, with the aim to obtain polyelectrolytes, may occur on the three hydroxyl functions of the two different sugars of maltotriose unit but the substitution of C-2 is predominant and decreases according to the order C-2 > C-3 > C-6 > C-4, an order of relative reactivity of hydroxyl groups as follows: (OH) 2 > (OH) 4 > (OH) 6 > (OH) 3 (Glinel, Sauvage, Oulyadi, & Huguet, 2000).…”