Synthesis and electronic factors in thermal cyclodimerization of functionalized aromatic trifluorovinyl ethers.
Synthesis and electronic factors in thermal cyclodimerization of functionalized aromatic trifluorovinyl ethers.
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DOI：
10.1021/ja0600227
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发表时间：
2006-05
影响因子：
15
通讯作者：
Bryan K. Spraul;S. Suresh;Jianyong Jin;Dennis W. Smith
中科院分区：
文献类型：
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作者：
Bryan K. Spraul;S. Suresh;Jianyong Jin;Dennis W. Smith
以通用中间体p-Br-C(6)H(4)-O-CF=CF(2)为原料制备了一系列19种对位取代的芳香族三氟乙烯基醚化合物，并进行热自由基介导的环二聚反应，生成含有1,2-二取代全氟环丁基(PFCB)键的新型双官能化合物。合成范围证明了氟乙烯基醚的官能团转化耐受性，并且二聚体可用作传统逐步增长聚合方法的单体。 (19)F NMR谱证实p-取代影响三氟乙烯基醚基团的化学位移。首次进行了动力学研究和取代基对热环二聚反应的影响，结果表明吸电子基团减慢了环二聚反应的速率。使用哈米特方程进一步分析数据，计算出120℃时的反应常数(rho)为-0.46，130℃时的反应常数(rho)为-0.59。本研究提出了芳香族三氟乙烯基醚环二聚成 PFCB 化合物的第一个线性自由能关系。
A series of 19 p-substituted aromatic trifluorovinyl ether compounds were prepared from versatile intermediate p-Br-C(6)H(4)-O-CF=CF(2) and underwent thermal radical mediated cyclodimerization to new difunctional compounds containing the 1,2-disubstituted perfluorocyclobutyl (PFCB) linkage. The synthetic scope demonstrates the functional group transformation tolerance of the fluorovinyl ether, and the dimers are useful as monomers for traditional step-growth polymerization methods. (19)F NMR spectra confirmed that p-substitution affects the trifluorovinyl ether group chemical shifts. The first kinetic studies and substituent effects on thermal cyclodimerization were performed, and the results indicated that electron-withdrawing groups slow the rate of cyclodimerization. The data were further analyzed using the Hammett equation, and reaction constants (rho) of -0.46 at 120 degrees C and -0.59 at 130 degrees C were calculated. This study presents the first liner free energy relationship reported for the cyclodimerization of aromatic trifluorovinyl ethers to PFCB compounds.