不同取代度的N,O-羧甲基壳聚糖的制备工艺研究

Preparation of N,O-carboxymethyl chitosan with difference degrees of substitution

N,O-羧甲基壳聚糖是在壳聚糖的氨基和羟基分别引入羧甲基而成的一类衍生物,具有良好的成膜、增稠、保湿、螯合等特性,在日化、食品、医药、水处理等领域中具有良好的应用前景。采用两步加碱法制备了不同取代度的N,O-羧甲基壳聚糖,并考察了氢氧化钠用量、氯乙酸用量、异丙醇用量、反应温度及反应时间对产物取代度的影响。结果表明,当氢氧化钠:壳聚糖为4.8:1(w:w)、氯乙酸:壳聚糖为4.8:1(w:w)、异丙醇:壳聚糖为12:1(v:w)、在50℃下反应2 h制得的N,O-羧甲基壳聚糖的取代度最高,达到了1.42。利用红外光谱法分析发现取代部位发生在羟基和氨基上,表明所制备的产物为N,O-羧甲基壳聚糖。

N,O-carboxymethyl chitosan （NOCC） is the carboxymethylated derivative of chitosan. NOCC possesses good film-forming, moisture-retention and heavy metal chelating abilities and thus has great potential applications in cosmetics, foods, medicines and water treatment. In this paper, NOCC with different degrees of substitution （DS） was prepared by a two-step alkalization method and the effects of the dosages of NaOH, chloroactic acid, isopropanol, reaction temperature and reaction time on the DS of NOCC were investigated. The results showed that, NOCC with the highest DS of 1.4235 could be prepared under the following conditions： chitosan to sodium hydroxide ratio 1：4.8 （w/w）, chitosan to chloroactic acid ratio 1：4.8 （w/w）, chitosan to isopropanol ratio 1：12 （w/w）, reaction temperature 50 ℃ and reaction duration 2 h. IR spectra revealed that the carboxymethylation occurred on both the oxygen and amidogen positions of chitosan.