Grafting of maleic anhydride to n-eicosane

Maleic anhydride was grafted to the linear hydrocarbon, n‐eicosane, at 165°C in the presence of the free radical initiator, 2,5‐dimethyl‐2,5‐di(t‐butylperoxy)‐3‐hexyne. The anhydride has a low solubility in eicosane and a multiple addition procedure was adopted. Grafted product which separated from the reaction mixture was fractionated and analyzed. The fractions contained on average 2–5.5 anhydride units/eicosane residue. 1H‐ and 13C‐NMR studies show that the grafts consist of single succinic anhydride rings. At the concentrations of maleic anhydride chosen for homogeneous reaction ( < 0.02 M) and at 165°C, poly(maleic anhydride) is above its ceiling temperature, so that succinic anhydride radicals cannot add maleic anhydride to form polymer side chains. Instead, these radicals hydrogen atoms to yield grafts consisting of single anhydride units.