The cationic ring-opening polymerization of 7-tetradecene oxide with methyl trifluoromethansulfonate. An investigation of the mechanism and the kinetics by means of H-1, C-13 and F-19 NMR
M. Clericuzio et al., The cationic ring-opening polymerization of 7-tetradecene oxide with methyl trifluoromethansulfonate. An investigation of the mechanism and the kinetics by means of H-1, C-13 and F-19 NMR, POLYMER, 40(7), 1999, pp. 1839-1851
The polymerization of a mixture of cis (ca. 30%) and trans (ca. 70%) isomer
s of 7-tetradecene oxide (7-TDO) with methyl trifluoromethansulfonate (meth
yl triflate) as initiator has been investigated. The main reaction products
afforded during the polymerization were a linear polyether, a cyclic dimer
[2,3,5,6 tetra(n-hexyl)dioxane], and 7-tetradecanone. The ketone is formed
both via pinacol rearrangement of the monomer and a transfer reaction when
all the monomer is consumed, and is favoured by an increase of temperature
. Kinetic studies on the ring opening polymerization of this system were pe
rformed by means of H-1 and F-19 NMR spectroscopies. Approximate rate const
ants of initiation (ki) for the cis and the trans isomers were determined a
t 298, 314 and 329 K in bulk, and at 298 K in C6D6 The reaction time of the
cia isomer is faster than that of the trans isomer, with an initial molar
reactivity ratio of about 11:1 at 298 K, and of about 7:1 at 329 K tin bulk
). The activation energies of the initiation reaction for the cis and the t
rans isomers were calculated to be 59 and 73 kJ/mol, respectively. By means
of H-1-, F-19- and C-13-NMR the structure of the propagating species is re
asonably well identified as an oxonium macroion rather than a linear trifli
c macroester. (C) 1999 Published by Elsevier Science Ltd. All rights reserv
ed.