ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The kinetics of the reaction of “living” poly(α-methylstyrl sodium, potassium, and cesium) with t-butyl chloride have been studied spectrophotometrically in tetrahydrofuran (THF) in the temperature range 283-303 K. The reactions, when the free ions present in solution are suppressed by tetraphenylboron salt, are first order with respect to both living ends and halide concentrations. Additions of tetraphenylboron salts produce a slight retardation effect on the rate of reaction in the case of sodium, indicating only a small contribution of free ions to the overall rate; in the case of potassium, there is no apparent effect. Analysis of the data indicates that the free ion is approximately 30 times more reactive than the sodium ion pair. The Arrhenius plots for contact ion-pair termination are linear and the activation energies and preexponential factors determined are ENa+ = 38.6 kJ mole-1, log ANa+ = 4.44 liter mole-1 sec-1 and Ek+ = 46.0 kJ mole-1, log Ak+ = 5.10 liter mole-1 sec-1. The reaction mechanism is interpreted in terms of elimination plus some side reaction to produce two unexpected reaction products - isobutane and a 315-320-nm absorbing grouping in the polymer.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1981.170190402
Permalink