Ternary Molecular Complex Research Articles

Polymerization of coordinated monomers VII. A kinetic study on the alternating copolymerization of methyl methacrylate with styrene using stannic chloride

AbstractThe alternating copolymerization of methyl methacrylate with styrene in the presence of stannic chloride at −50°C in toluene was kinetically investigated both under photoirradiation and with the tri‐n‐butylboron‐benzoyl peroxide initiator. The concentrations of the binary and ternary molecular complexes in the copolymerization solution were estimated by use of the equilibrium constants. The rates are found to be proportional to the 1.5th and 1.0th orders of the concentration of the ternary molecular complex composed of stannic chloride, methyl methacrylate, and styrene, under photoirradiation and with initiator, respectively. The conversion increases proportionally with the polymerization time, while the degree of polymerization is constant irrespective of the time. The rates depend linearly upon the square root of the intensity of the incident light and upon the concentration of tri‐n‐butylboron, respectively. The alternating copolymerization is confirmed experimentally to precede the homopolymerization of the monomer charged in large excess both under photoirradiation and with initiator. The kinetic results indicate consistently that the alternating copolymerization proceeds through the homopolymerization of the ternary molecular complex in the steady state with a bimolecular termination. Both the conventional radical mechanism and the double complex mechanism are unsuitable for the present alternating copolymerization.

Ternary Molecular Complex in the Alternating Copolymerization of Methyl Methacrylate with Styrene Using Stannic Chloride

Abstract The equimolar alternating copolymerization of methyl methacrylate (MMA) with styrene (St) in the presence of stannic chloride in toluene (Tl) is investigated kinetically. The concentrations of the ternary molecular complexes, [SnCl4-MMA … St] and [SnCl4-MMA … T1], are calculated by use of the formation constants of the ternary molecular complexes. The rates of copolymerization under photo-irradiation and with tri-n-butyl boron-benzoyl peroxide as an initiator are proportional to the 1.5th order and 1. Oth order, respectively, of the concentration of the ternary molecular complex [SnCl4 · MMA … St]. The alternating copolymerization precedes the homopolymerization of the methyl methacrylate charged in excess. The alternating regulation of the copolymerization is ascribed to the homopolymerization of the ternary molecular complex from the kinetic results. The magnitudes of the shifts for

Polymerization of coordinated monomers. VI. Molecular complex formation of methyl methacrylate coordinated to stannic chloride with styrene or toluene

AbstractThe equilibrium constants for the complex formation between stannic chloride and methyl methacrylate were determined in n‐hexane–toluene solution at 0, −20, and −30°C by using the absorption band at 350 nm. Continuous variation plots at −20°C in n‐hexane based on the 1H‐chemical shifts definitely show a 1:1 interaction between the coordinated methyl methacrylate and styrene or toluene. The magnitudes of the shifts for the four groups of protons in methyl methacrylate are found to be in a specific ratio in common with the 1:2 complex–styrene or ‐toluene system. The equilibrium constants for the ternary molecular complex formation between the 1:2 complex and styrene or toluene were determined in n‐hexane in the temperature range −50 to +20°C by use of the chemical shifts. The concentrations of the complex species in the alternating copolymerization solutions were estimated by use of the equilibrium constants. There is a linear relationship between the enthalpy and the entropy changes for the ternary molecular complex formation, which is governed by the enthalpy factor. The specificity of the interactions indicates a specific time‐averaged orientation of benzene ring to the coordinated methyl methacrylate. The effects of the coordination of methyl methacrylate to stannic chloride were discussed on the basis of results of 13C‐NMR spectroscopy.

Charge-transfer and Proton-transfer in the Formation of Molecular Complexes. II. Kofler’s Ternary Molecular Complex

Charge-transfer and Proton-transfer in the Formation of Molecular Complexes. II. Kofler’s Ternary Molecular Complex