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Yushan, China

Gong P.,University of Sichuan | Peng S.,Jingkun Chemical Company | He J.,Jingkun Chemical Company | Deng M.,Jingkun Chemical Company | And 2 more authors.
Carbohydrate Research | Year: 2011

The synthesis of branched polysaccharides using naturally occurring materials has been reported since 1975, but applications of branched polysaccharides are relatively limited because of the long and complex modification processes. In this work, a practical and efficient procedure is presented that in one step levoglucosan can be grafted to galactomannan (at 115 °C for 15 h) with monochloroacetic acid as catalyst. The structural characteristics of the resulting substances were investigated by NMR spectroscopy. The MS (molar degree of substitution) of glucose was shown to gradually increase with the increase of the ratio of levoglucosan to galactomannan, and the maximal MS is 0.6. Levoglucosan units are mostly grafted to the C6-OH of the galactosyl residues in galactomannan, and the maximal percentage of the substituted C6-OH of galactosyl residues is 42.2%. The resulting levoglucosan tended to graft to the branching glucosyl residues of copolymers with an increase in MS, and the average length of the branching glucose is 3.6 when MS is 0.6. © 2011 Elsevier Ltd. All rights reserved. Source

Chen Q.,Sichuan University | Han X.,Sichuan University | Peng S.,Jingkun Chemical Company | He J.,Jingkun Chemical Company | And 3 more authors.
Journal of Applied Polymer Science | Year: 2014

A novel N,O-carboxymethyl hydroxypropyl chitosan (HPCMS) derivative was prepared by a two-step reaction. Water-soluble hydroxypropyl chitosan (HPCS) with a degree of substitution of hydroxypropyl higher than 0.8 was first synthesized by the reaction of chitosan (CS) with propylene oxide (PO) with alkali as a catalyst. Then, amphoteric chitosan derivatives (HPCMS) with a degree of substitution of carboxymethyl ranging from 0.42 to 1.38 were prepared by the reaction of HPCS with chloroacetic acid in an aqueous solution with alkali as a catalyst. The structures of the polymers were characterized by Fourier transform infrared spectroscopy and NMR; this showed that the hydroxypropylation mainly occurred on the -OH groups at the C-6 of CS in the reaction of CS with PO. In the reaction of HPCS with chloroacetic acid, both the -OH and -NH2 groups of HPCS were susceptible to the carboxymethylation. Copyright © 2014 Wiley Periodicals, Inc. Source

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