Preparation And Study Of The Different Structures Of Chitosan Sulfate

There is intimate relationship between biological activity and structure of sulfated chitosan.The sites of sulfation , sulfate content , molecular weight and raw chitosan are key factors.In this paper we study homogeneous-phase preparation of sulfated chitosan in detail and the optimum preparative conditions of a water soluble sulfated chitosan with high sulfate content and high molecular weight by two kinds chitosan . The sulfate content and molecular weight are examed The structure of sulfated chitosan are charged by means of IR spectroscopy and 13C NMR. The sulfate content are over 30% and The molecular weight are over 10 104.Chitosan sulfate by shrimp shell is composed of chitosan units 6-O-monosulfate,but chitosan sulfate by crab shell is composed of chitosan units 6-O-monosulfate and 3,6-O-disulfate .On the other hand there is not oxidation groups of units chitosan and no wreck units chitosan .On the base of experience of above experiment ,sulfated chitosan with low molecular weight and high sulfate content by two kinds of chitosan are prepared and the better preparative conditions are determined . The sulfate content is about 30% and molecular weight examed by terminal group method is under 5000 .Two kinds of sulfated chitosan with low molecular weight and high sulfate content are considered as copolymers ofchitosan 6-O-monosulfate and 3-0-monosulfate by IR and there is neither oxidation groups of units chitosan nor wreck units chitosan under strong sulfation conditionsThough a lot of exiperment,we prepare sulfated chitosan with low sufate content and high molecular weight by two kinds of chitosan and determine the suitable synthesisconditions. Results indicate that the molecular weight are correspond to parent polymers and sulfate content are under 15% and they are considered as copolymers of chitosan 6-O-monosulfate by same analysis.The former three kinds of sulfate chitosan are considered as copolymers composed of chitosan mono,di and tri-substituted units of chitosan .We regioselective synthesize 3-0-sulfated chitosan by protected 2-amino groups and 6-hydroxyl groups. The sulfate percent are about 5% from two kinds of parent polymer and molecular weight are about 2 X 104by same analysis. Reaction process is testified by IR spectroscopy and the suitable synthesis conditions are described.This series suitable synthesis conditions are high-yield, simple-operating, time-saving ,raw material-saving, energy-saving,pollution-relieving compared with documents.