RESEARCH IN THE CHEMISTRY OF CARBAZOLE DERIVATIVES

90. POLYMERIZATION OF 3-METHYL-9-VINYLCARBAZOLE

V. M. SUTYAGIN, V. P. LOPATINSKII, E. E. SIROTKINA

(Presented by the Scientific-Methodological Seminar of the Organic Departments of the Chemical-Technological Faculty)

No information on the polymerization of 3-methyl-9-vinylcarbazole is available in the literature. In the present work, the kinetics of polymerization of this monomer in benzene solution with azobisisobutyronitrile (AIBN) was investigated, and its polymerization in solution under the action of tin tetrachloride was also studied.

Experimental Part

3-Methyl-9-vinylcarbazole was obtained by the method of [1], with an unsaturated-content value of more than 99.9% (acetate method), and had a melting point of 33–34°C. Azobisisobutyronitrile, benzene, and tin tetrachloride were purified by known methods and had constants coinciding with the literature values. The polymerization kinetics were studied dilatometrically [2]. The polymerization rate was determined from the slope of the kinetic conversion–time curves.

The polymerization of the monomer in benzene solution in the presence of tin tetrachloride was studied by the method described by us previously [3].

Viscosimetric measurements were carried out in an Ubbelohde viscometer in benzene solution at 25°C [4].

Fig. 1. Kinetic curves during polymerization of 3-methyl-9-VK in benzene solution. AIBN concentration — \(9.15 \cdot 10^{-3}\) mol/liter, monomer concentration — 0.78 mol/liter. 1 — 50°; 2 — 60°; 3 — 70°; 4 — 75°.

Discussion of Results

Figure 1 presents kinetic curves expressing the dependence of the degree of polymerization of 3-methyl-9-vinylcarbazole (3-CH\(_3\)-9-VC) on temperature. As follows from Fig. 1, the overall rate of polymerization increases with increasing temperature. In this case, the Arrhenius dependence of the logarithm of the reaction rate on the reciprocal absolute temperature is obeyed (Fig. 2).

Fig. 2. Dependence of \(\lg W\) on \(1/T\) during the polymerization of 3-methyl-9-VC.

From the slope of the straight line (Fig. 2), the activation energy was calculated; it is equal to 21.0 kcal/mol.

To determine the value of the ratio \(K_p/K_0^{0.5}\) (\(K_p\) is the chain-growth rate constant, and \(K_0\) is the rate constant for termination of the polymer chain), polymerization of the monomer in benzene solution at 75°C, inhibited with benzoquinone, was studied. The kinetic curves of inhibited polymerization of 3-methyl-9-VC in benzene solution are presented in Fig. 3, from which it is seen that the value of the induction period is proportional to the concentration of inhibitor.

Fig. 3. Kinetics of polymerization of 3-methyl-9-VC in the presence of benzoquinone at 75°:
1 — without inhibitor; 2 — benzoquinone concentration \(1.47 \cdot 10^{-3}\) mol/l;
3 — benzoquinone concentration \(2.95 \cdot 10^{-3}\) mol/l.

The initiation rate (\(V_{\text{in}}\)) was calculated from the equation

\[ V_{\text{in}}=\frac{[X]}{t_{\text{ind}}}, \tag{1} \]

where

\[ [X] \text{ — concentration of benzoquinone, mol/l,} \]

\[ t_{\text{ind}} \text{ — duration of the induction period, sec.} \]

The numerical values of \(V_{\text{in}}\) for different concentrations of benzoquinone differed only slightly (average \(V_{\text{in}} = 0.98 \cdot 10^{-6}\) mol/l·sec). This fact gives grounds to assume that a quantitative interaction of the primary radicals with the inhibitor molecules takes place. The value \(K_p/K_0^{0.5}\) was calculated from the equation

\[ \frac{K_p}{K_0^{0.5}}=\frac{W}{V_{\text{in}}^{0.5}\cdot [\mathrm{M}]}, \tag{2} \]

where

\[ \begin{aligned} V_{\text{in}}&\text{ — rate of initiation, mol/l·sec;}\\ [\mathrm{M}]&\text{ — monomer concentration, mol/l;}\\ W&\text{ — overall rate of polymerization in the absence of inhibitor,}\\ &\quad \text{mol/l·sec.} \end{aligned} \]

For the present case it was found to be \(12.8\ \mathrm{l}^{0.5}\,\mathrm{mol}^{-0.5}\,\mathrm{sec}^{-0.5}\). The initiation efficiency is 0.45.

Ionic polymerization of 3-methyl-9-VC was carried out in benzene solution under the action of stannic chloride at 25°C. The course of monomer polymerization was judged from the amount of unreacted monomer and from the amount of polymer isolated. Stannic chloride was used as its solution in benzene.

The experimental data are presented in Table 1. As follows

Table 1

Polymerization of 3-methyl-9-vinylcarbazole in benzene solution in the presence of stannic chloride at 25°
(Initial monomer concentration — \(9.5 \cdot 10^{-2}\) mol/l; stannic chloride concentration — \(19.25 \cdot 10^{-6}\) mol/l)

from the tabulated data, the polymer yield increases with increasing reaction duration, and the viscometric molecular weight of poly-3-methyl-9-vinylcarbazole also increases.

Conclusions

1. The kinetics of polymerization of 3-methyl-9-vinylcarbazole in benzene solution in the presence of azobisisobutyric acid dinitrile have been investigated; the activation energy of the process and the ratio of the rate constants of growth and termination of the polymer chain have been determined.

2. It has been shown that the viscometric molecular weight of poly-3-methyl-9-vinylcarbazole is proportional to the degree of polymerization.

LITERATURE

1. Logatinskii V. P., Shekhirev Yu. P., Sutyagin V. M., Chernitsyna V. P., Izv. TPI, vol. 163, 1970.

1. Gladyshev, G. P. Polymerization of Vinyl Monomers. Alma-Ata: Publishing House of the Academy of Sciences of the Kazakh SSR, 1964.

2. Sutyagin, V. M.; Lopatinskii, V. P.; Shekhirev, Yu. P.; Sirotkina, E. E. Author’s Certificate 260172, 1969.

3. Shatenshtein, A. I., et al. Determination of the Molecular Weights of Polymers. Moscow–Leningrad: “Khimiya,” 1964.