Synthesis of Isopropyl 2'-Formyldiphenyl-2-carboxylate
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Synthesis of Isopropyl Ester of 2′-Formyldiphenyl-2-carboxylic Acid
I. L. KHALFINA
(Presented by the scientific-methodological seminar of the Faculty of Chemical Technology)
Biological tests of a number of complex alkyl esters of 2′-formyldiphenyl-2-carboxylic acid showed that some of them, in particular the isopropyl ester synthesized by us earlier [1], exhibit high fungicidal activity.
The aim of the present work was to study the conditions under which a good yield of isopropyl ester of 2′-formyldiphenyl-2-carboxylic acid is achieved. Sulfuric acid, orthophosphoric acid, and also gaseous hydrogen chloride were tested as catalysts for the esterification reaction.
The results of the experiments are given in the table.
| Series no. of experiments | Catalyst | Reaction temperature | Reaction time (h) | Molar ratio of alcohol and acid | Average ester yield, % |
|---|---|---|---|---|---|
| 1 | gaseous HCl | 82,2 | 6 | 2:1 | 34,6 |
| 2 | H₃PO₄ | 82,2 | 6 | 2:1 | 43,8 |
| 3 | H₂SO₄ | 82,2 | 6 | 2:1 | 50 |
The influence on the ester yield of the amount of catalyst and the esterification time was also studied.
The results are presented in Figures 1 and 2.
Fig. 1. Dependence of ester yield on the amount of catalyst.
Fig. 2. Dependence of ester yield on reaction time.
The experiments showed that isopropyl ester of 2′-formyldiphenyl-2-carboxylic acid can be obtained in 50% yield if the pro-
esterification should be carried out for six hours in the presence of sulfuric acid, taken in an amount of 8%, calculated relative to the excess isopropyl alcohol introduced into the reaction [2]. A further increase in the amount of sulfuric acid and in the reaction time leads to a decrease in the product yield.
The results of the experiments also showed that, for the successful performance of the reaction, a twofold excess of isopropyl alcohol relative to the acid taken into the reaction may be used.
A series of alkyl esters of 2′-formyldiphenyl-2-carboxylic acid, synthesized by us under analogous conditions, was obtained in high yields.
Experimental Part
Starting reagents. 2′-Formyldiphenyl-2-carboxylic acid was obtained by hydrolysis of the final product from ozonization of technical phenanthrene—3,8-dimethoxy-4, 5, 6, 7-dibenzo-1,2-dioxycyclooctane—and had m.p. 131–132°.
Isopropyl ester of 2′-formyldiphenyl-2-carboxylic acid. 10 g of the acid, 6.8 ml of isopropyl alcohol, and 0.23 ml of conc. sulfuric acid were introduced into a flask fitted with a reflux condenser. The contents of the flask were heated on a water bath for six hours. Fifteen minutes after the start of heating, the acid had completely dissolved and the reaction was carried out at the boiling temperature of isopropyl alcohol. After heating was completed, the mass was poured into a beaker with water; the oily precipitate that formed was separated, washed with water and with a 10% solution of caustic soda. The solidified light-brown product was filtered off and recrystallized from diluted isopropyl alcohol. Product yield: 5.92 g (50% of theoretical), m.p. 78°.
Conclusions
- The influence of conditions on the yield of the isopropyl ester of 2′-formyldiphenyl-2-carboxylic acid was investigated.
It was shown that, under optimal conditions, the ester can be obtained in a yield of 50% (of theoretical).
LITERATURE
- A. G. Pechenkin, I. L. Khalfin. Journal of the All-Union Chemical Society named after Mendeleev, vol. 8, No. 6, 703, 1963.
- E. Fischer, Speier, Ber. 28, 3252, 1895.