Abstract Carboxymethyl chitosan (CM-chitosan) was prepared by chemical reaction with monochloroacetic acid under various conditions, and the chemical structure was analyzed by IR and NMR. The water solubility of the CM-chitosans had close relationships to the modifying conditions and the degree of carboxymethylation. The CM-chitosans, prepared at temperatures of 0–10 °C were soluble in water. But the CM-chitosan prepared between 20 and 60 °C were insoluble in the water at near-neutral pH. The water insolubility of CM-chitosans at various pHs varied with the degree of carboxymethylation. The increase in reaction temperature increased the fraction of carboxymethylation and increased the insolubility at lower pHs; the increase of the ratio of water/isopropanol in the reaction solvent decreased the fraction of carboxymethylation and increased the insolubility at higher pHs.

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O-羧甲基壳聚糖的化学特性与制备条件有关

摘要 以一氯乙酸在不同条件下进行化学反应制备羧甲基壳聚糖（CM-壳聚糖），并通过IR和NMR对其化学结构进行了分析。CM-壳聚糖的水溶性与改性条件和羧甲基化程度密切相关。在 0-10 °C 温度下制备的 CM-壳聚糖可溶于水。但在 20 至 60 °C 之间制备的 CM-壳聚糖在接近中性 pH 值时不溶于水。CM-壳聚糖在不同 pH 值下的水不溶性随羧甲基化程度的不同而变化。反应温度的升高增加了羧甲基化的比例并增加了在较低 pH 值下的不溶性；