Alder-ene addition of maleic anhydride to polyisobutene: nuclear magnetic resonance evidence for an unconventional mechanism
Alder-ene addition of maleic anhydride to polyisobutene: nuclear magnetic resonance evidence for an unconventional mechanism
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DOI：
10.1002/pi.4228
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发表时间：
2012-08-01
影响因子：
3.2
通讯作者：
Uccello-Barretta, Gloria
中科院分区：
文献类型：
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作者：
Balzano, Federica;Pucci, Andrea;Uccello-Barretta, Gloria
在这项工作中，用核磁共振波谱研究了在200℃下，高活性、亚乙烯封端的聚异丁烯(PIB)与化学计量的马来酸酐(MAH)的热Alder-ene官能化。对不同反应时间(从4~21h)收集的PIB衍生物的复杂核磁共振谱进行了全面的解释，这是基于一维和二维技术的结合使用，从而可以确定所有反应产物的精确结构及其相对含量。分析证明，由经典的Alder-Ene机理产生的大量衍生物的形成涉及PIB的更具活性的亚乙烯基外双键。更有趣的是，调查还允许检测到由于在官能化反应期间残留的PIB外α-异构化所提供的活性较低的PIB内切β-形式的热马来化而产生的显著数量的非预期结构的形成。版权所有(C)2012年美国化学工业学会
In this work, the thermal Alder-ene functionalization of highly reactive, vinylidene-terminated, polyisobutene (PIB) with stoichiometric amounts of maleic anhydride at 200 degrees C was investigated by NMR spectroscopy. The thorough interpretation of the complex NMR spectra of PIB derivatives collected at different reaction times (from 4 to 21 h) was based on the combined use of one- and two-dimensional techniques which allowed the precise structure of all the reaction products as well as their relative content to be ascertained. The analysis evidenced the formation of large amounts of derivatives generated by the classic Alder-ene mechanism and involving the more reactive vinylidene exo double bonds of PIB. More interestingly, the investigation also the investigation allowed also to detect the formation of a noteworthy amount of not expected structure generated by the thermal maleination of the less reactive PIB endo beta-form provided by the isomerization of residual PIB exo a-form during the functionalization reaction. Copyright (c) 2012 Society of Chemical Industry