Yamaguchi Aritomo, Muramatsu Natsumi, Mimura Naoki, Shirai Masayuki, Sato Osamu
Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST), 4-2-1 Nigatake, Miyagino, Sendai 983-8551, Japan.
Phys Chem Chem Phys. 2017 Jan 25;19(4):2714-2722. doi: 10.1039/c6cp06831f.
The intramolecular dehydration of biomass-derived sugar alcohols d-sorbitol, d-mannitol, galactitol, xylitol, ribitol, l-arabitol, erythritol, l-threitol, and dl-threitol was investigated in high-temperature water at 523-573 K without the addition of any acid catalysts. d-Sorbitol and d-mannitol were dehydrated into isosorbide and isomannide, respectively, as dianhydrohexitol products. Galactitol was dehydrated into anhydrogalactitols; however, the anhydrogalactitols could not be dehydrated into dianhydrogalactitol products because of the orientation of the hydroxyl groups at the C-3 and C-6 positions. Pentitols such as xylitol, ribitol, and l-arabitol were dehydrated into anhydropentitols. The dehydration rates of the pentitols containing hydroxyl groups in the trans form, which remained as hydroxyl groups in the product tetrahydrofuran, were larger than those containing hydroxyl groups in the cis form because of the structural hindrance caused by the hydroxyl groups in the cis form during the dehydration process. In the case of the tetritols, the dehydration of erythritol was slower than that of threitol, which could also be explained by the structural hindrance of the hydroxyl groups. The dehydration of l-threitol was faster than that of dl-threitol, which implies that molecular clusters were formed by hydrogen bonding between the sugar alcohols in water, which could be an important factor that affects the dehydration process.
在523 - 573 K的高温水中，在不添加任何酸催化剂的情况下，研究了生物质衍生的糖醇（d-山梨醇、d-甘露糖醇、半乳糖醇、木糖醇、核糖醇、l-阿拉伯糖醇、赤藓糖醇、l-苏糖醇和dl-苏糖醇）的分子内脱水反应。d-山梨醇和d-甘露糖醇分别脱水生成异山梨醇和异甘露糖醇，作为二脱水己糖醇产物。半乳糖醇脱水生成脱水半乳糖醇；然而，由于C-3和C-6位羟基的取向，脱水半乳糖醇无法脱水生成二脱水半乳糖醇产物。木糖醇、核糖醇和l-阿拉伯糖醇等戊糖醇脱水生成脱水戊糖醇。在产物四氢呋喃中仍以羟基形式存在的反式羟基戊糖醇的脱水速率，高于含有顺式羟基的戊糖醇，这是因为顺式羟基在脱水过程中造成了结构阻碍。对于丁糖醇，赤藓糖醇的脱水比苏糖醇慢，这也可以用羟基的结构阻碍来解释。l-苏糖醇的脱水比dl-苏糖醇快，这意味着糖醇在水中通过氢键形成了分子簇，这可能是影响脱水过程的一个重要因素。
