Experimental Study of Tautomeric Equilibria of 2-Cyanobenzoic Acids in Gas, Solution and Solid Phase

2-cyanobenzoic acids are very important compounds in several sciences, and it is because of this that studying their tautomeric equilibria is of great interest. Ring-chain tautomeric equilibria of 2-, 3- and 4- cyanobenzoic, 3-benzyl-2-cyanobenzoic and 1-cyano-2-naphthoic acids were studied in gas phase by means of mass spectrometry (MS). Furthermore, evidences of ring-chain tautomerism of 2-cyanobenzoic acid were found in solution using 1H and 13C nuclear magnetic resonance and in solid phase by infrared spectroscopy.