Imparting functional variety to cellulose ethers via olefin cross-metathesis
Imparting functional variety to cellulose ethers via olefin cross-metathesis
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DOI：
10.1039/c5py00369e
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发表时间：
2015-01-01
影响因子：
4.6
通讯作者：
Edgar, Kevin J.
中科院分区：
文献类型：
--
作者：
Dong, Yifan;Edgar, Kevin J.
烯烃交叉复分解是一种赋予纤维素醚功能多样性的有价值的新方法。从市售的乙基纤维素开始，通过使用氢化钠催化剂与烯丙基氯、5-溴-1-戊烯、7-溴-1-庚烯和11-溴-1-十一碳烯反应，将末端不饱和烷基作为复分解柄附加。然后使这些烯烃末端乙基纤维素衍生物与各种贫电子烯烃底物（包括丙烯酸和丙烯酸酯）在优化条件下（5-10摩尔% Hoveyda-Grubbs第二代催化剂，37 ℃，2小时）进行烯烃交叉复分解。改变ω-不饱和烷基柄的长度和所使用的溶剂系统的影响进行了评价。乙基纤维素的取代基为庚-4-烯基时，交叉复分解反应的效果最好，取代基为庚-6-烯基时，交叉复分解反应的效果也最好。具有烯丙基取代基的乙基纤维素具有低至中等的复分解转化率（
Olefin cross-metathesis is a valuable new approach for imparting functional variety to cellulose ethers. Starting from commercially available ethyl cellulose, terminally unsaturated alkyl groups were appended as metathesis handles by reaction with allyl chloride, 5-bromo-1-pentene, 7-bromo-1-heptene and 11-bromo-1-undecene, employing sodium hydride catalyst. These olefin-terminal ethyl cellulose derivatives were then subjected to olefin cross-metathesis with a variety of electron-poor olefin substrates, including acrylic acid and acrylate esters under optimized conditions (5-10 mol% Hoveyda-Grubbs' 2nd generation catalyst, 37 degrees C, 2 h). The effects of varying the length of the omega-unsaturated alkyl handle, and of the solvent systems used were evaluated. Ethyl cellulose containing a pent-4-enyl substituent performed best in cross metathesis reactions and a hept-6-enyl substituent gave similarly good results. Ethyl cellulose with allyl substituents gave low to moderate metathesis conversion (