A parametric study of the terminal maleation of polypropylene through an Alder Ene reaction

A study of the parameters that affect the Alder Ene reaction with respect to the synthesis of a terminally anhydride‐functionalized polypropylene was carried out over a temperature range of 220–250°C using maleic anhydride concentrations of 2–12 mol equivalence with respect to the vinylidene group. As previously observed, a Lewis acid (i.e., SnCl2 · 2H2O) had a catalytic effect on the reaction at these temperatures, thereby improving anhydride content in the polymer for short reaction times. Increased temperature and maleic anhydride concentration had a positive effect on improving the incorporation of the succinyl anhydride moiety at the terminal site in polypropylene. Lower SnCl2 · 2H2O concentrations, likewise, improve the functionality of the product. The application of a second‐order kinetic model to the measured succinyl anhydride results was not valid over the entire temperature range studied due to side reactions, particularly vinylidene isomerization, and homopolymerization of maleic anhydride. Ruthenium chloride has been examined as another possible catalyst candidate in the reaction and has been found to improve the level of anhydride incorporation in polypropylene compared to stannous chloride. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2371–2380, 1998