Biliuta Gabriela, Baron Raluca Ioana, Coseri Sergiu
"Petru Poni" Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania.
Materials (Basel). 2022 Sep 2;15(17):6086. doi: 10.3390/ma15176086.
The C-6 in the maltotriose unit of pullulan was oxidized in an alkaline medium (pH = 10), utilizing a green method that included hydrogen peroxide (HO) as an oxidant and -hydroxyphthalimide (NHPI) as a catalyst for various reaction times. The structure of the resulting oxidized pullulans (PO) was carefully characterized by titration, intrinsic viscosity, FTIR, C-NMR, and zeta potential. The content of carboxyl groups in PO was dependent on reaction time and varied accordingly. Furthermore, a fast reaction rate was found in the first 2-3 h of the reaction, followed by a decreased rate in the subsequent hours. FTIR and C-NMR proved that the selective oxidation of the primary alcohol groups of pullulan was achieved. The oxidation also caused the glycoside linkages in the pullulan chain to break, and the viscosity of the pullulan itself went down.
采用一种绿色方法，以过氧化氢（HO）作为氧化剂，以N-羟基邻苯二甲酰亚胺（NHPI）作为催化剂，在碱性介质（pH = 10）中，于不同反应时间对普鲁兰多糖麦芽三糖单元中的C-6进行氧化。通过滴定、特性黏度、傅里叶变换红外光谱（FTIR）、碳核磁共振（C-NMR）和ζ电位对所得氧化普鲁兰多糖（PO）的结构进行了细致表征。PO中羧基的含量取决于反应时间，并相应变化。此外，在反应的最初2 - 3小时发现反应速率较快，随后几小时速率下降。FTIR和C-NMR证明实现了对普鲁兰多糖伯醇基团的选择性氧化。氧化还导致普鲁兰多糖链中的糖苷键断裂，且普鲁兰多糖本身的黏度下降。
