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The main kinetic behavior of the slurry polymerization of propene with a MgC1,-supported TiC14/C,H,COOC,H, catalyst, activated by Al(C,H,), , was studied. Examination of the dependence of the polymerization rate on temperature and concentrations of A1(C2H5), and of propene resulted in a Langmuir-Hinshelwood rate law with the number of polymerization centers dependent on time. The polymerization rate as function of the polymerization temperature shows a maximum, which is compatible with the rate law. The analysis of the phenomenon of an optimum temperature gave 15 kJ . mol-' and 36 kJ . mol-' for the activation energy of the rate determining step and the adsorption energy of Al(C,H,), , respectively. Examination of the rapid decay of the polymerization rate showed that the main part of the decay is represented by a second order decay independent of the amount of polymer produced, which can be understood by a second order decay of surface sites by A1 (C,H5),. The number of active centers of the catalyst in gas phase polymerization was estimated applying the inhibition method with carbon monoxide. The results show a constant value for the propagation rate constant, kp, during the second order rate decay. The observed polymerization kinetics strongly suggest the existence of two kinds of polymerization centers (isotactic and atactic).

The electronic spectrum of p-benzosemiquinone anion in aqueous solution formed through the oxidation of hydroquinone with manganese dioxide was measured at room temperature. The absorption maxima were found at 430, 404, and 316 mμ with shoulders at 371 and 310 mμ. It was confirmed that these absorption maxima are due to the same species p-benzosemiquinone anion, on the ground that their kinetic behaviors are the same. The molar extinction coefficients of the absorption maxima and the oscillator strengths of the absorption bands were estimated.

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