Kinetics of the reaction of methyl iodide with poly(p-N,N-dimethylaminostyrene) and related studies.

p-N,N-Dimethylaminostyrene has been synthesised, by a known method, from p-N,N-dimethylaminobenzaldehyde. This monomer has been homopolymerised and copolymerised with styrene by initiation with alpha,alpha'- azoisobutyronitrile. The polymeric amines have been characterised by intrinsic viscosity determinations in toluene. A homopolymer of poly(4-vinylpyridine) was prepared, with alpha,alpha'-azoisobutyronitrile as the initiator, and characterised by intrinsic viscosity measurements in 96% ethanol. The rate constants for the reaction between the poly (p-N,N-dimethyl aminostyrene)s and methyl iodide in dimethylformamide at 0° have been compared with those of dimethylaniline and p-isopropyldimethylaniline and methyl iodide at the same temperature and in the same solvent. Similar kinetic measurements were made oh the reaction of n-butyl bromide at 75° with poly(4-vinylpyridine) and pyridine in dimethylformamide and sulpholane and on poly(4-vinylpyridine) in dimethylformamide-sulpholane mixtures. The initial second-order rate constant for the reaction of poly(p-N, N-dimethylaminostyrene)s with methyl iodide in dimethylformamide at 0°, is almost unaltered by change in molecular weight and by the spacing-out of amino groups by inert styrene units. Under the conditions above, the constants for dimethylaniline and p-isopropyldimethylaniline were determined. The values imply electron release from the main chain to the side-groups in the polymers. The development of a charged envelope about the macromolecule leads to a fall in the rate of quaternisation after 20-25% reaction. A similar fall in quaternisation rate was found for the reaction between n-butyl bromide and poly(4-vinylpyridine) in sulpholane but no deceleration was observed for the same reaction in dimethylformamide as the solvent. In solvent mixtures, progressively richer in dimethylfomamide, deceleration became progressively less than that found in sulpholane. The kinetic results are discussed in relation to the size, structure and coiling of the macromolecules