PREPARATION OF POLYVINYL ACETAL BASED ON 2-FORMYLBIPHENYL-2′-CARBOXYLIC ACID AND POLYVINYL ALCOHOL

A. G. PECHENKIN, A. M. SEDOV, V. B. GOLUB

(Submitted by the scientific seminar of the departments and laboratories of organic synthesis, CTF)

At the Department of Technology of Organic Synthesis and in the problem laboratory for the synthesis of medicinal substances of the Tomsk Polytechnic Institute, ozonolysis of technical phenanthrene has yielded: diphenic acid, 2-formylbiphenyl-2′-carboxylic acid, diphenic anhydride, and other substances that may serve as starting materials for the preparation of a number of valuable products.

Thus, the synthesized esters of diphenic acid proved to be good plasticizers for polyvinyl chloride; a number of derivatives of 2-formylbiphenyl-2′-carboxylic acid exhibited high fungicidal activity.

In order to further seek ways of rational utilization of phenanthrene ozonolysis products, we decided to obtain polyvinyl acetal based on 2-formylbiphenyl-2′-carboxylic acid and polyvinyl alcohol according to the scheme:

\[ \begin{aligned} &{-}\mathrm{CH_2{-}CH(OH){-}CH_2{-}CH(OH){-}CH_2{-}CH(OH)}{-} \\ &\quad +\ \mathrm{O{=}CH{-}C_6H_4{-}C_6H_4{-}COOH} \longrightarrow \\[4pt] &{-}\mathrm{CH_2{-}CH{-}CH_2{-}CH{-}CH_2{-}CH}{-} \\ &\qquad\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \diagup\!\!\mathrm{O}\quad\quad\mathrm{O}\!\!\diagdown \\ &\qquad\qquad\qquad\qquad\ \ \mathrm{CH{-}C_6H_4{-}C_6H_4{-}COOH} \end{aligned} \]

The starting substances for obtaining polyvinyl acetal were: 2-formylbiphenyl-2′-carboxylic acid, obtained by ozonolysis of technical phenanthrene, with m.p. 131–132°; polyvinyl alcohol from the Kuskov Chemical Plant, containing 1.36% acetate groups.

The reaction of polyvinyl alcohol with 2-formylbiphenyl-2′-carboxylic acid was carried out by the method of homogeneous acetalization with stirring of the reaction mass [1]. The reaction medium was 93% acetic acid; the ratio of polyvinyl alcohol to 2-formylbiphenyl-2′-carboxylic acid was 1:1 by weight; the concentration of polyvinyl alcohol in the solution was 3%.

The influence of the reaction duration and temperature on the degree of acetalization (% acetalization) was studied.

The acetalization products were precipitated by adding water to the acetic-acid reaction solution. After washing with alcohol and water, the polyvinyl acetals were dried and analyzed for the content of acetal groups according to the method of [2]. The experimental results are given in Tables 1 and 2.

Table 1

Dependence of the percentage of acetalization
on the reaction duration
(reaction temperature 60°C)

Table 2

Dependence of the percentage of acetalization
on the reaction temperature
(reaction duration 10 h)

The polyvinyl acetals synthesized with various degrees of acetalization are solid white substances, soluble in an alcohol–benzene mixture (1:1), pyridine, and benzyl alcohol; insoluble in ethyl alcohol and acetone.

The data obtained on the acetalization of polyvinyl alcohol with 2-formylbiphenyl-2′-carboxylic acid are consistent with the calculations of Flory, who showed that the percentage substitution of hydroxyl groups in polyvinyl alcohol by acetal groups cannot exceed 86% [3]. The resulting polyvinyl acetal may be of interest for ion-exchange purposes as a weakly acidic cation exchanger.

Conclusions

1. Acetalization of polyvinyl alcohol with 2-formylbiphenyl-2′-carboxylic acid was carried out.

2. The dependence of the degree of acetalization (% acetalization) on the temperature and duration of the reaction was determined. The greatest percentage substitution of hydroxyl groups in polyvinyl alcohol by acetal groups (82%) is achieved at a temperature of 100°C and a reaction duration of 10 h.

REFERENCES

1. S. N. Ushakov. Polyvinyl Alcohol and Its Derivatives. Vol. 1, Publishing House of the Academy of Sciences of the USSR, Moscow, p. 398, 1960.

2. I. P. Losev, O. Ya. Fedotova. Laboratory Manual on the Chemistry of High-Molecular Compounds. Goskhimizdat, Moscow, pp. 74–77, 1959.

3. Flory. J. Am. Chem. Soc. 61, 1518 (1939).