Intensity of the C≡N Stretching Vibration in Cyanoethylene Adducts of Levopimaric Acid

Abstract

The acrylonitrile adducts of levopimaric acid were prepared in this laboratory and reported previously (1). We have now prepared the fumaronitrile and the tetracyanoethylene adducts. The stereochemistry indicated in the structural formulas in Figures 1, 2, and 3 are based upon the logical assumption that the nitrile reagents attack the resin acid from the least hindered or α-side of the molecule (2). In such a situation, only one stereoisomer would be expected from the reaction of levopimaric acid and tetracyanoethylene; whereas, two trans stereoisomers should exist from the reaction of fumaronitrile and levopimaric acid. The distribution of the nitrile and hydrogen atoms is not known in the case of the fumaronitrile isomer isolated in the present case. The more probable distribution of the nitrile and hydrogen atoms in the mononitrile adduct has recently been suggested (3).