Kinetic study of the quaternization of tertiary amine as functional group in the poly(vinylpyridine) series with alkyl bromide

The reactivity of tert‐amine groups was studied by quaternization of homopolymers and copolymers of 2‐vinyl‐, 2‐methyl‐5‐vinyl‐ and 4‐vinyl‐pyridine with butyl bromide. The reactivity of the corresponding model compounds was taken as a reference: in this case second order kinetics is obeyed until complete reaction of the pyridine derivatives. If the pyridylethylene repeating unit is included in a statistical styrene/vinylpyridine copolymer (with a low content of pyridylethylene units), the kinetics are of second order too, except for the styrene/2‐vinylpyridine copolymer. In this case the steric hindrance due to the position of the nitrogen atom is the preponderant factor. For homopolymers, in the case of the quaternization of poly(1‐pyrid‐4‐ylethylene) [poly(4‐vinylpyridine)] second order kinetics are observed, until the adjacent reactive groups are quaternized. In the case of poly[1‐(6‐methyl‐3‐pyridyl)ethylene] [poly(2‐methyl‐5‐vinylpyridine)] a second order law is obeyed only until one of the ajacent groups is quaternized. For poly(1‐pyrid‐2‐ylethylene) [poly(2‐vinylpyridine)] steric hindrance effects govern strictly the behaviour of the functional group. These results were interpreted by introducing three individual velocity constants which were determined graphically.