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The Radical and Ion-Radical Mechanism of Polymerization of 2,6-Xylenol. IV. Reaction Catalyzed by Copper(II)-amine Complexes

A. Tkáč and J. Kresta

Institute of Chemical Physics, Department of Physical Chemistry, Slovak Technical University, Bratislava 1

 

Abstract: The reaction scheme of the radical and ion-radical mechanism of the oxidative polymerization of 2,6-xylenol conditioned by the type of the actually used catalyst (Ag20; CuCl2 • 2 eyelohexylamině) is described. An equilibrium state between complexes of copper(II) coordinated in various degrees with cyclohexylamine as a function of the molar ratio of Cu(II) : amine was ascertained. The catalytic activity passes through a maximum, indicating that only the copper(II) complex uncompletely coordinated with amine is effective for polymerization. In inert atmosphere during the polymerization the concentration of the Cu(II) ions decreases, the reaction approaches the equilibrium state, while in the presence of oxygen the catalyst is regenerated. If the momentary surplus of monomer in the beginning of the polymerization is very high, the concentration of Cu(II) ions will decrease in such a degree that the consecutive reaction of phenoxy radicals with the Cu(II) complexes cannot effectively take place. Due to this circumstance the recombination of the primary radicals takes place with precedence forming bisphenol and finally undesirable diphenoquinone. After reaching a steady state concentration of the Cu(II) ions diphenoquinone is not formed any more because the reaction of phenoxy radicals with Cu(II) ions is preferred. This state observed only later in the stationary region of polymerization can be established already in the beginning of the polymerization suppressing the local monomer surplus with respect to the catalyst to the lowest degree.

Full paper in Portable Document Format: 252a104.pdf

 

Chemical Papers 25 (2) 104–113 (1971)

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