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Carbohydr Polym. 2016 Jul 10;145:78-85. doi: 10.1016/j.carbpol.2016.03.022. Epub 2016 Mar 15.

Synthesis and characterization of chitosan alkyl urea.

Author information

1
School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430073, PR China.
2
Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.
3
School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430073, PR China. Electronic address: zwbai@wit.edu.cn.

Abstract

Chitosan is a versatile material employed for various purposes in many fields including the development of chiral stationary phases for enantioseparation. Chitosan alkyl urea is a kind of intermediate used to prepare enantioseparation materials. In order to synthesize the intermediates, in the present work, a new way to prepare chitosan alkyl urea has been established: chitosan was first reacted with methyl chloroformate yielding N-methoxyformylated chitosan, which was then converted to chitosan alkyl urea through amine-ester exchange reaction. With a large excess of methyl chloroformate and primary amine of low stereohindrance, the amino group in chitosan could be almost completely converted to ureido group. The as-prepared chitosan alkyl urea derivatives were characterized by IR, (1)H NMR, (13)C NMR,(1)H-(1)H COSY and (1)H-(13)C HSQC NMR spectra. The chemical shifts of hydrogen and carbon atoms of glucose unit were assigned. It was found that the degree of substitution was obviously lower if cyclopropyl amine, aniline, tert-butyl amine and diethyl amine were used as reactants for the amine-ester exchange reaction. The reason was explained with the aid of theoretical calculations.

KEYWORDS:

Amine-ester exchange; Chitosan; Chitosan alkyl urea; N-methoxyformylation; Theoretical calculation

PMID:
27106154
DOI:
10.1016/j.carbpol.2016.03.022
[Indexed for MEDLINE]

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