Preparation of 6-O-(4-alkoxytrityl)celluloses and their properties.
Preparation of 6-O-(4-alkoxytrityl)celluloses and their properties.
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DOI：
10.1039/b308985a
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发表时间：
2004-01
影响因子：
3.2
通讯作者：
S. Ifuku;Hiroshi Kamitakahara;T. Takano;F. Tanaka;F. Nakatsubo
中科院分区：
文献类型：
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作者：
S. Ifuku;Hiroshi Kamitakahara;T. Takano;F. Tanaka;F. Nakatsubo
在LiCl-N，N-二甲基乙酰胺中，纤维素与一系列4-烷氧基三苯甲基氯（C（n）TCl，n：饱和烷基链上的碳原子数）在均相反应条件下反应，得到一系列6-O-（4-烷氧基三苯甲基）纤维素（C（n）TC），其取代度（DS）为0.94 ~ 0.99，在6-O位具有高的区域选择性。C（n）TC在非极性溶剂中的溶解度取决于烷基链的长度：随着烷基链的延长，纤维素衍生物变得更加疏水，并且容易溶于非极性溶剂，但不溶于极性溶剂。C（4）-C（18）TC（C（4）-C（18）TCAc）的乙酸酯在偏光显微镜下观察到在熔融温度（T（m））范围内具有各向异性结构。在各向同性温度（T（i））上，检测到C（12）-C（18）TCAc的流动双折射。T（m）和T（i）随着烷基取代基中碳原子数的增加而线性降低。广角X射线散射（WAXS）研究表明，C（n）TC的完全伸展的侧链是垂直于聚合物主链和叉指。这些具有改善的溶解度的C（n）TC可以用作进一步衍生化的起始材料，所述衍生化集中于C-2和C-3位上的仲羟基。
Cellulose was reacted with a series of 4-alkoxytrityl chlorides (C(n)TCl, n: number of carbon atoms in a saturated alkyl chain) under homogeneous reaction conditions in LiCl-N,N-dimethyl acetoamide to give a series of 6-O-(4-alkoxytrityl)celluloses (C(n)TC) with a high degree of substitution (DS), from 0.94 to 0.99, and with high regioselectivity at the 6-O position. Solubility of the C(n)TC in nonpolar solvents depended on the alkyl chain length: as the alkyl chain lengthens, cellulose derivatives become more hydrophobic and are readily soluble in nonpolar solvents, but not in polar solvents. Acetates of the C(4)-C(18)TC (C(4)-C(18)TCAc) showed anisotropic structures over melting temperatures (T(m)) examined under a polarized optical microscope (POM). Over isotropization temperatures (T(i)), flow birefringence were detected for C(12)-C(18)TCAc. The T(m) and T(i) decreased linearly with an increasing number of carbon atoms in the alkyl substituent. Wide-angle X-ray scattering (WAXS) studies of C(n)TC indicated that the fully extended side chains were perpendicular to the polymer backbone and interdigitated. These C(n)TC with the improved solubility may be used as starting materials for further derivatization focused on the secondary hydroxyl groups at the C-2 and C-3 positions.