R. King
Nov 1, 1974
Citations
0
Influential Citations
7
Citations
Journal
Annals of the New York Academy of Sciences
Abstract
One of the most rewarding areas of organic chemistry has been the study of hydrocarbon derivatives in which all or most of the hydrogen atoms are replaced by another atom or group that conveys unusual chemical and physical properties on the resulting molecule. The best-known class of such compounds comprises the fluorocarbons, which are related to the hydrocarbons by replacement of all or most of the hydrogen atoms with fluorine atoms. Fluorocarbon chemistry has been of fundamental importance since about 1940 in the development of novel heat-resistant and chemically inert polymers, notably Teflon, which are now of considerable importance to science, technology, and defense. Many laboratories throughout the world have active research programs involving various aspects of fluorocarbon chemistry. The success of du Pont in the development of the fluorocarbon polymer Teflon in the 1940s led a group of investigators there to investigate another still different class of organic compounds-the cyanocarbons. Cyanocarbons are related to the hydrocarbons by replacement of all or most of the hydrogen atoms with cyano (nitrile) groups. Of particular interest were the unusual chemical properties of the simplest percyanoolefin, tetracyanoethylene.' Furthermore, certain cyanocarbon derivatives appeared to be of importance in thermoelectric devices2 and semiconducting polym e r ~ . ~ Although the basic du Pont publications on cyanocarbon chemistry' have now been in print about 15 years, very few chemists have used cyanocarbon chemistry in their research other than for the preparation and study of Diels-Alder adducts, metal complexes, or charge transfer derivatives of tetracyanoethylene. The very unusual chemistry of tetracyanoethylene and related cyanocarbon derivatives made this class of compounds of considerable interest to us, because of our interest in compounds with unusual properties. It appeared that the potential for stabilizing unstable and even unisolable hydrocarbon derivatives by complete replacement of the hydrogen atoms with the cyano group had never been properly exploited. Presently available information4 suggests that the principles affecting the stability of cyanocarbon derivatives are so drastically different from the principles affecting the stability of hydrocarbon derivatives that cyanocarbon analogues of unstable hydrocarbons may be stable and vice versa. A simple example of the drastic difference between cyanocarbon and hydrocarbon chemistry is the chemical stability of saturated hydrocarbons relative to unsaturated hydrocarbons but the chemical instability of saturated cyanocarbons such as hexacyan~ethane~ and 1,1,2,2,-tetracyanoethane6 relative to unsaturated cyanocarbons such as tetracyanoethylene.' Another key feature in cyanocarbon chemistry is the close relationship between many compounds containing a dicyanomethylene [C(CN)z] group and the corre-