Accession Number : AD0709798

Title :   MECHANISM OF INITIATION IN THE THERMAL POLYMERIZATION OF STYRENE. KINETIC DEUTERIUM ISOTOPE EFFECTS IN THE INITIATION STEP OF THE THERMAL POLYMERIZATION OF SOME DEUTERATED STYRENES,

Corporate Author : ALBERTA UNIV EDMONTON DEPT OF CHEMISTRY

Personal Author(s) : Kopecky,Karl R. ; Evani,Syamalarao

Report Date : 12 JUN 1969

Pagination or Media Count : 11

Abstract : A convenient synthesis of 2,6-dideuteriostyrene starts with N,N-dimethyl-(1-phenylethyl)-amine which is deuterated in the 2 and 6 positions by a series of exchanges using n-butyllithium followed by deuterium oxide. The deuterium isotope effects at 70C on the rates of the thermal polymerization, of 2,6-dideuterio-, alpha-deuterio-, and beta,beta-dideuteriostyrene are 1.29, 1.00, and 0.78, respectively. The deuterium isotope effects at 70C on the 2,2'-azobis(2-methylpropionitrile) initiated rates of polymerization, are 0.96, 0.86, and 0.81, respectively. From these values the deuterium isotope effects on the rates of initiation of the thermal polymerization, k(iH)/k(iD), are calculated to be 1.80, 1.31, and 0.92, respectively. At 147C the presence of 1.5% potassium t-butoxide decreases the rate of the thermal polymerization of neat styrene by a factor of 17, and results in the formation of 1-phenyltetralin as the greatly predominant dimer. The results support the suggestion that the thermal polymerization of styrene is initiated by hydrogen transfer from 1-phenyl-1,2,3,9-tetrahydronaphthalene, formed by a concerted dimerization of two molecules of styrene, to a third molecule of styrene. (Author)

Descriptors :   (*STYRENES, *POLYMERIZATION), DEUTERIUM COMPOUNDS, REACTION KINETICS, FREE RADICALS, CANADA

Subject Categories : Organic Chemistry
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE