Study of the Reaction Between Vinyl Acetate and Acetic Acid
Abstract Generated abstract
This study examines the possible side reaction between vinyl acetate and acetic acid under conditions used for synthesizing oligomers of 9-vinylcarbazole from carbazole and vinyl acetate. Experiments were carried out in acetone without carbazole, using mercury acetate and sulfuric acid catalysts, and the reaction course was followed by titration of medium acidity. The results indicate that appreciable binding of acetic acid by vinyl acetate occurs only at acetic acid concentrations above about 1.0 mol/L and that the process is reversible, with decomposition of the presumed ethylidene diacetate favored by increased catalyst concentration and temperature. These findings were used to refine conditions for the target oligomer synthesis.
Full Text
acid, the reaction rate increases in both regions. The second kinetic region, starting from a concentration of 98%, is absent. In the concentration interval 96–100%, a stepwise change in the rate constant occurs (Table 3). In the first kinetic region the sulfonating agent is the monomer \(SO_3\), which has a higher reactivity /5/; in the second, it is the bisulfone ion. The stepwise change in the rate constant is due to the sharp increase in the concentration of unbound monomer in the acid /6/. In concentrated acids the sulfonating agent is the monomer.
Conclusions
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It has been established that, with an increase in the size and volume of the pores of the copolymers, the rate of sulfonation increases. With the maximally accessible structure, despite the heterogeneity of the system, the reaction proceeds as a homogeneous one and is controlled only by the parameters of chemical kinetics.
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It has been shown that, at an acid concentration below 96%, the conversion curve contains two kinetic regions corresponding to two sulfonating agents—the monomer \(SO_3\) and the bisulfone ion. In concentrated acids the sulfonating agent is the monomer.
Literature
- D. F. Hazzington, Ind. Eng. Chem., 42, 137, 1959.
- A. K. Svetlov, S. M. Rakhovskaya, L. I. Khomutov, V. S. Borinskaya, T. N. Demenkova. Colloid Journal, 33, 264, 1971.
- Ya. I. Leitman, V. I. Diarov, ZhPKh, 34, 376, 1961.
- O. W. Kandorp, A. Cerfontain, F. L. J. Sixman. Rec. Trav. Chim., 82, 113, 1963.
- J. Betsher, J. Chem. Soc., 12, 136, 1968.
- V. A. Amelin. Production of Sulfuric Acid, Goskhimizdat, 1967.
STUDY OF THE REACTION BETWEEN VINYL ACETATE AND ACETIC ACID
V. D. Pirogov, E. E. Sirotkina
In the synthesis of oligomers of 9-vinylcarbazole /P-9-VK-O/ by the interaction of carbazole with vinyl acetate, in the course of the reaction there is released
is acetic acid /1/. The property of vinyl acetate to add acetic acid with formation of ethylidene diacetate is known /2/. In order to clarify the possible superposition of this reaction on the main process, we studied the interaction of vinyl acetate with acetic acid under the conditions of synthesis of P-9-VK-O.
The reaction was studied in the absence of carbazole in an acetone medium and in the presence of the catalysts for the synthesis of P-9-VK-O—mercury acetate and sulfuric acid. The course of the reaction was monitored by the acidity of the medium by titrating samples from the reaction medium with a caustic potash solution.
Observations of the behavior of the acetone–vinyl acetate–acetic acid systems in the presence of one of the components of the catalytic pair—sulfuric acid or mercury acetate—showed that, within the range of their concentrations \((1 \pm 10)\,10^{-5}\) mol/l, a rapid decrease in the acidity of the medium occurs, indicating binding of acetic acid. In the presence of the catalytic pair, an additional release of acetic acid is observed, probably due to saponification of vinyl acetate by water contained in the solvent, acetone.
Table I presents data on the effect of the initial concentration of acetic acid on the acidity of the system under consideration.
Table I
Effect of the initial concentration of acetic acid on the total acidity of the medium
| Initial acetic acid concentration, mol/l | Medium concentration after introduction of the catalyst, mol/l: after 1 minute | Medium concentration after introduction of the catalyst, mol/l: after 3 minutes | Medium concentration after introduction of the catalyst, mol/l: after 6 minutes | Medium concentration after introduction of the catalyst, mol/l: after 20 minutes |
|---|---|---|---|---|
| 0.48 | 0.53 | 0.58 | 0.60 | 0.60 |
| 0.80 | 0.81 | 0.83 | 0.86 | 0.86 |
| 1.25 | 1.20 | 1.22 | 1.24 | 1.24 |
| 1.80 | 1.71 | 1.76 | 1.79 | 1.79 |
Experimental conditions: acetone—50 ml (0.68 N); vinyl acetate—7.0 ml (0.075 M); sulfuric acid—0.006 ml of 96% \((1.1 \cdot 10^{-5}\text{ M})\); mercury acetate—0.06 g \((1.9 \cdot 10^{-5})\); temperature—50°C.
From the data presented it is evident that, at acetic acid concentrations up to 0.8 mol/L, its decrease due to possible binding by vinyl acetate does not occur. On the contrary, in this case an increase in the acidity of the medium is observed, probably as a result of the conversion of vinyl acetate. At acetic acid concentrations above 1.0 mol/L, at first there is a sharp decrease in the acidity in the system, but then it is restored practically to the initial state. This fact indicates the reversibility of the reaction of interaction of vinyl acetate with acetic acid under these conditions. The decrease in acidity at the initial moment may be explained by the non-simultaneous charging of the catalyst: after mercury acetate is introduced into the acetone–vinyl acetate–acetic acid system, a rapid reaction occurs in which acetic acid is bound by vinyl acetate, the total acidity falls, and the addition of sulfuric acid after 30 sec leads to cleavage of the ethylidene diacetate formed into the starting products.
Thus, in the system under consideration, if binding of acetic acid by vinyl acetate is observed, it occurs only at concentrations of the former above 1.0 mol/L. In this case the process is reversible, and the rate of the reverse reaction (decomposition of ethylidene diacetate) is proportional to the concentration of catalyst, both mercury acetate and sulfuric acid (see Table 2), and directly proportional to the reaction temperature (see Table 3).
Table 2
Effect of catalyst concentration on the acidity of the medium
| Sulfuric acid concentration × 10³, mol/L | Mercury acetate concentration × 10³, mol/L | Acidity of the medium 3 min after introduction of the catalyst, mol/L |
|---|---|---|
| 0.7 | 1.0 | 1.165 |
| 2.3 | —"— | 1.172 |
| 4.6 | —"— | 1.266 |
| 6.8 | —"— | 1.240 |
| 4.6 | 4.0 | 1.220 |
| —"— | 8.0 | 1.250 |
Experimental conditions: acetone — 50 ml (0.68 M); vinyl acetate — 7.0 ml (0.075 M); acetic acid — 4.4 ml (0.077 M); temperature — 50°C.
Table 3
Effect of the medium temperature on the acidity of the vinyl acetate–acetic acid–catalyst system
| Medium temperature, °C | Acidity of the medium 3 min after introduction of the catalyst, mol/l |
|---|---|
| 20 | 1.164 |
| 30 | 1.179 |
| 40 | 1.198 |
| 50 | 1.220 |
Experimental conditions: acetone — 50 ml (0.68 M); vinyl acetate — 7.0 ml (0.075 M); acetic acid — 4.4 ml (0.077 M); mercury acetate — 0.06 g (\(1.9 \cdot 10^{-5}\) M); sulfuric acid — 0.006 ml, 96% (\(1.1 \cdot 10^{-5}\) M).
The data obtained made it possible to select more correctly the conditions for the synthesis of P-9-VK-O.
Conclusions
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The reaction of vinyl acetate with acetic acid in an acetone medium in the presence of catalysts—mercury acetate and sulfuric acid—has been studied.
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It has been shown that the process of interaction of vinyl acetate with acetic acid is reversible, and an increase in the concentration of catalysts and in the temperature of the medium leads to a shift of the equilibrium toward the starting substances.
Literature
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V. P. Lopatinskii, E. E. Sirotkina. Izv. Tomsk. polit. in-ta, III, 44, 1961.
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S. N. Ushakov. Polyvinyl Alcohol and Its Derivatives, vol. 1, Moscow, Publishing House of the Academy of Sciences of the USSR, 1960; A. M. Shur, V. F. Filimonov. Uch. zapiski Kishinevskogo un-ta, 56, 67, 1960.