Chemical modification of poly(vinyl chloride) by nucleophilic substitution

The reaction of poly(vinyl chloride) (PVC) in nucleophile (Nu)/ethylene glycol (EG) or Nu/N,N-dimethylformamide (DMF) solution was found to result in the substitution of Cl in PVC with Nu from solution, in addition to the straight elimination of HCl, both of which led to the dechlorination of PVC. Examined Nu⁻ were I⁻, SCN⁻, OH⁻, N₃⁻, and the phthalimide anion. For the Nu/EG solution, elimination was favoured over substitution for all Nu⁻. The ratio of substitution to dechlorination was notable, descending in the order OH⁻ > SCN⁻ = N₃⁻ > phthalimide anion > I⁻. For the Nu/DMF solution, the ratio of substitution to dechlorination was high, in the order SCN⁻ > N₃⁻ > I⁻ > phthalimide anion. In both cases, the orders of the ratios were similar to those of the nucleophilic reactivity constant, I⁻ > SCN⁻ > N₃⁻ > phthalimide anion, except for I⁻. The low ratio for I⁻ was attributable to the elimination of HI after the substitution of Cl in PVC with I in solution, because I⁻ is a strong nucleophile, as well as an excellent leaving group. Comparing the effect of EG and DMF on the substitution of Cl in PVC with Nu in solution, the ratio of substitution to dechlorination was higher for I⁻, SCN⁻, N₃⁻, and the phthalimide anion in DMF than in EG. The substitution of Cl in PVC with Nu in solution was found to occur preferentially in DMF versus EG.