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Alder-ene addition of maleic anhydride to polyisobutene: nuclear magnetic resonance evidence for an unconventional mechanism

Authors

  • Federica Balzano,

    1. Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa, Italy
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  • Andrea Pucci,

    Corresponding author
    1. Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa, Italy
    2. CNR NANO, Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127 Pisa, Italy
    • Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, I-56126 Pisa, Italy.
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  • Riccardo Rausa,

    1. ENI S.p.A. Div. Refining and Marketing, Centro Ricerche di S. Donato M.se, Via Felice Maritano 26, 20097 S. Donato Milanese, Italy
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  • Gloria Uccello-Barretta

    1. Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa, Italy
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Abstract

In this work, the thermal Alder-ene functionalization of highly reactive, vinylidene-terminated, polyisobutene (PIB) with stoichiometric amounts of maleic anhydride at 200 °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’ β-form provided by the isomerization of residual PIB ‘exo’ α-form during the functionalization reaction. Copyright © 2012 Society of Chemical Industry

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