Institute of Plant and Wood Chemistry, Dresden University of Technology, Tharandt, Germany.
J Phys Chem B. 2012 Apr 19;116(15):4584-92. doi: 10.1021/jp210469x. Epub 2012 Apr 5.
Synthesis and spectroscopic characterization of α-chitins exhibiting degrees of acetylation (DA) between 0.5 and 1 were reported. Crab shell α-chitin consisting of microfibrils with a width of less than 1 μm was regenerated from or alkaline deacetylated in 30% aqueous NaOH solution. After the deacetylation in homogeneous solution, the DA of α-chitins decreased steadily with prolonged deacetylation times from 1 to 0.54. The native microfibrils of starting α-chitin were destroyed, while aggregates or sheets were formed depending on the DA of chitins. According to WAXD measurements, deacetylated chitins with DA lower than 0.76 have different crystalline structures than starting α-chitin. Furthermore, FT Raman spectroscopy demonstrated a novel rapid method to determine the DA of chitin with correlation coefficients greater than 0.99. On the basis of the FT Raman signals ascribed to the amide groups, the amount of hydrogen bonds linked to C═O groups decreased strongly with lower DA and the relationship between them was presented.
报道了具有 0.5 至 1 的乙酰化度（DA）的 α-壳聚糖的合成和光谱特性。由宽度小于 1μm 的微纤维组成的蟹壳α-壳聚糖是从 30%的水溶液中再生或在碱性条件下去乙酰化得到的。在均相溶液中脱乙酰化后，α-壳聚糖的 DA 随着脱乙酰化时间的延长从 1 持续稳定地降低至 0.54。起始α-壳聚糖的天然微纤维被破坏，而取决于壳聚糖的 DA，形成了聚集体或薄片。根据 WAXD 测量，DA 低于 0.76 的脱乙酰壳聚糖具有与起始α-壳聚糖不同的结晶结构。此外，FT 拉曼光谱证明了一种快速测定壳聚糖 DA 的新方法，其相关系数大于 0.99。基于归因于酰胺基团的 FT 拉曼信号，与 C═O 基团相连的氢键数量随着较低的 DA 而强烈减少，并且呈现了它们之间的关系。
