Polymer Research Institute, Sichuan University, Chengdu 610065, China.
Carbohydr Polym. 2013 Apr 2;93(2):686-90. doi: 10.1016/j.carbpol.2012.12.005. Epub 2012 Dec 12.
With potassium hydroxide (KOH) as catalyst, hydroxypropyl guar gum (HPG) was successfully prepared under homogenous conditions in an ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl). The value of degree of molar substitution (MS) of HPG, which was determined by means of (1)H NMR, was easily controlled by varying the mass ratio of propylene oxide (PO) to guar gum (GG). The distribution of hydroxypropyl moieties among the seven hydroxy groups in HPGs was investigated by NMR and the results indicated that the homogeneous reaction preferentially substituted at the C3−OH of the mannosyl residues in guar gum which was quite different from the heterogeneous reaction where substitution mostly occurred at C6−OH. The average number of hydroxypropyl units per OH substitution of HPGs with MS value of 0.20, 0.37 and 0.60 was 1.82, 1.42 and 1.76, respectively.
在均相条件下，以氢氧化钾（KOH）为催化剂，在离子液体 1-丁基-3-甲基咪唑氯（BmimCl）中成功制备了羟丙基瓜尔胶（HPG）。通过 1H NMR 确定 HPG 的摩尔取代度（MS）值，通过改变环氧丙烷（PO）与瓜尔胶（GG）的质量比，很容易控制 HPG 的 MS 值。通过 NMR 研究了 HPG 中羟丙基在七羟基中的分布，结果表明，均相反应优先取代瓜尔胶中甘露糖残基的 C3-OH，这与主要发生在 C6-OH 的多相反应完全不同。MS 值分别为 0.20、0.37 和 0.60 的 HPG 的每个 OH 取代的羟丙基单元的平均数量分别为 1.82、1.42 和 1.76。
