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

Abstract

In this work, the thermal Alder-ene functionalization of highly reactive, vinylidene-terminated, polyisobutene (PIB) with\ud stoichiometric amounts of maleic anhydride at 200 ◦C was investigated by NMR spectroscopy. The thorough interpretation of\ud the complex NMR spectra of PIB derivatives collected at different reaction times (from 4 to 21 h) was based on the combined\ud use of one- and two-dimensional techniques which allowed the precise structure of all the reaction products as well as their\ud relative content to be ascertained. The analysis evidenced the formation of large amounts of derivatives generated by the\ud classic Alder-ene mechanism and involving the more reactive vinylidene ‘exo’ double bonds of PIB. More interestingly, the\ud investigation also the investigation allowed also to detect the formation of a noteworthy amount of not expected structure\ud generated by the thermalmaleination of the less reactive PIB ‘endo’ β-form provided by the isomerization of residual PIB ‘exo’ α-form during the functionalization reaction

Kinetic and Mechanistic Studies of the Polymerization of Isobutylene Catalyzed by EtAlCl2/Bis(2-chloroethyl) Ether Complex in Hexanes

“…9 Bochmann and co-workers developed a new zinc-based initiator system to produce HR PIB at room temperature. 10 Krossing and co-workers employed novel univalent gallium salts [Ga(C 6 H 5 F) 2 4 ] − (where R F = C(CF 3 ) 3 ) to achieve synthesis of HR-PIB in several solvents including CH 2 Cl 2 and toluene. 11 Voit and co-workers reported synthesis of HR PIB using M(II) complexes (M = Mn, Cu, Zn, Mo) as catalysts.…”

Catalytic chain transfer polymerization of isobutylene: The role of nucleophilic impurities

“…The cationic polymerization of isobutylene (IB) has been receiving continued interest in academia as well as in industry due to the unique properties of polyisobutylene (PIB), a chemically stable fully saturated elastomer suitable for a wide range of material applications . Low molecular weight PIBs with a terminal exo‐olefin bond are valued precursors for motor oil and fuel additives . The exo‐olefin terminated PIB is also referred to as “highly reactive” PIB (HR PIB), since it readily reacts with maleic anhydride in a thermal “ene” reaction to produce PIB succinic anhydride that can be converted to polyisobutenylsuccinimide, used as ashless dispersants.…”

“…1,2 Low molecular weight PIBs with a terminal exo-olefin bond are valued precursors for motor oil and fuel additives. 3,4 The exo-olefin terminated PIB is also referred to as "highly reactive" PIB (HR PIB), since it readily reacts with maleic anhydride in a thermal "ene" reaction to produce PIB succinic anhydride that can be converted to polyisobutenylsuccinimide, 5,6 used as ashless dispersants. In the recent years, several research groups have reported on new catalyst systems for the synthesis of HR PIB.…”

Structural Assignment of Commercial Polyisobutylene Succinic Anhydride‐based Surfactants

“…Furthermore, high thermal stability of HR-PIB and PIBSA can be affected by the duration of the exposure to the various catalysts and temperature cycles during formation of PIB-derived products [14]. Although most structural isomers of PIBSA have been well characterized, the qualitative and quantitative analyses of commercial concentrates, which also contain unreacted starting materials, decomposition products and residual solvents, remains challenging tasks [15][16][17][18][19][20]. Thus, having a better understanding of the chemical composition of the surfactant concentrates could be useful in quality control of the end products, choice of the synthetic intermediates and calculations of the concentration-dependent parameters such as the surfactant efficiency, interfacial tension and CMC.…”