NATURE OF HYDROGEN-BONDS FORMED BY SIMPLE AMIDES AND SULFONIC-ACIDS IN INERT SOLVENT .1. H-1-NMR LOW-TEMPERATURE STUDIES

For the first time direct spectroscopic evidence was found that amides (B) are the O and N bases. H-1 NMR low-temperature investigations show that sulfonic acids (AH) form with amides AH-O(B)N and AH-O(B)N-HA hydrogen-bonded complexes. The latter can exist in two different tautomeric states with exchange between them governed by the electron structure rearrangement of the complexed amide. The OHO proton in the AH-O(B)N complexes probably occupies only one position inside the hydrogen bridge (one tautomeric state of the complex) which is sensitive to the acid-base interaction strength and to the solvation. These phenomena are monitored by its chemical shifts.