B. Matyska

Donor-Acceptor Complexes in Copolymerization. VIII. Evidence of Participation of Complexes in Copolymerization of Styrene and Methyl Methacrylate… Al(C2H5))1.5Cl1.5

Abstract The copolymerization of styrene and methyl methacrylate in the presence of ethylaluminum sesquichloride in toluene yields alternating copoly-mers, independent of initial monomer ratio. The rate of polymerization is not influenced by the presence of an excess of either monomer, the conversion curves following a parallel course at a given total monomer concentration. When the concentration of the AlEt1.5Cl1.5 and the S/MMA ratio are kept constant and the total monomer concentration is increased, the polymerization rate increases and reaches a limiting value at a S/MMA/Al ratio of 2:2:1. A similar result is obtained when the total monomer and the AlEt1.5Cl1.5 concentrations are kept constant and the S/MMA ratio is varied. When the concentration of either monomer and the AlEt1.5Cl1.5 concentration are kept constant and the concentration of the other monomer is varied, the polymerization rate reaches a limiting value at the same mole ratio, irrespective of which monomer is varied. The rate of polymeri...

Effect of carboxylic acids on the metathesis of methyl 10-undecenoate

Abstract The metathesis of esters of unsaturated carboxylic acids catalyzed by the WCl6/Me4Sn system is influenced by the presence of free acids. The extent of their effect depends on how they are delivered into the reaction mixture. If the acid is allowed to react with WCl6 (either free or as an ad-mixture to the ester) before dosing Me4Sn, the equivalent part of WCl6 is converted rapidly to WOCl4 and the activity of the catalyst is not affected. An excess of the acid over WCl6, however, leads to carboxylation of WOCl4 followed by the formation of WO2Cl2, and to loss of catalytic activity. Reaction of the acid with active centres already formed results in their deactivation.

Donor-Acceptor Complexes in Copolymerization. IX. Kinetic Features of Copolymerization of Styrene and Methyl Methacrylate… Al(C2H5))1.5Cl1.5

Abstract The kinetic features of the copolymerization of styrene and methyl methacrylate in the presence of ethylaluminum sesquichloride in toluene do not unequivocally distinguish between first- and second-order reactions. The reaction does not attain steady-state conditions. The course of the reaction is apparently influenced by many factors including the dissociation of the polymerizable complex into unreactive monomeric species and physical phenomena such as diffusion and dilution effects as well as matrix formation. The use of azobisisobutyronitrile as an initiator indicates apparent bimolecu-lar termination but the kinetic curves show deviation from linearity.

Cyclo- and Cyclized Diene Polymers. XXII. Kinetics of Cyclopolymerization of Isoprene with C2H5AlCl2 + TiCl4 Catalyst

Abstract The polymerization of isoprene in aromatic solvents, catalyzed by an ethylaluminum dichloride-titanium tetrachloride system, proceeds via a complex of the monomer with the catalyst, chain growth occurring when a monomer cation-radical is formed through the transfer of one electron from the monomer to the catalyst. The deactivation of the active species results from the dissociation of the complex polymer cation-radical to free ions. The over-all reaction is a nonstationary process during which the concentration of free ions increases and the concentration of the active species decreases. A reaction mechanism is proposed which leads to kinetic expressions that quantitatively describe the experimental data.

Formation of ions in metathesis catalysts

Abstract Reactions of WCl 6 with Ph 4 Sn and its chloro derivatives are accompanied by a considerable increase of the electric conductivity of the solution. Comparison of the catalytic activity in olefin metathesis with the time dependence of the electrical conductivity does not give any evidence for a direct relationship between the ionic species formed during the reaction of the starting components and the catalytically active centres.