微波促进高相对分子质量N-丁烷基壳聚糖的合成

Synthesis of the N-butyl chitosan under microwave irradiation

在微波促进下首先对高相对分子质量壳聚糖碱化,再使之与溴代正丁烷进行烷基化反应,合成出了高取代度的N-丁烷基化壳聚糖。在n(氢氧化钠)∶n(壳聚糖)=4∶1,(壳聚糖粘均相对分子质量为1.49×106)、60℃下微波碱化处理1h、n(溴代正丁烷)∶n(碱化壳聚糖)=1.4∶1、80℃烷基化反应4h的较佳反应条件下,所得产物N-丁烷基壳聚糖的相对分子质量为1.48×106,烷基取代度达到78.5%;用扫描电镜对碱化后的壳聚糖进行表征,结果表明经微波加热碱化后壳聚糖的立体规整性及分子内的氢键得到充分的破坏,结构变得松散。采用XRD、FT-IR对N-丁烷基化壳聚糖结构进行了确证。

High molecular weight chitosan was alkalized under microwave first and then the alkalized chitosan reacted with butyl bromide to synthesize N-butyl chitosan with high molecular weight and high degree of substitution（DS）.The effects of alkalization method,alkalization and alkylation reaction temperature,reaction time of alkylation,and the ratio of reactant on the DS of N-butyl chitosan were investigated in detail,and the suitable reaction conditions were obtained as follows：n（sodium hydroxide）∶n（chitosan）=4∶1,viscosity-average molecular weight of chitosanis 1.49×106,microwave reaction alkalization temperature 60 ℃,reaction time 1 h,n（butyl bromide）∶n（alkalized chitosan）=1.4∶1,alkylation reaction temperature 80 ℃,alkalization reaction time 4 h.Under the above conditions,the molecular weight of N-butyl chitosan was 1.48×106 and the DS was up to 78.5%.The structure of alkalized chitosan was confirmed by SEM,the results indicated that the stereoregularity and the inter hydrogen bonds were destroyed.The structure of N-butyl chitosan was characterized by XRD and FT-IR.