The study of kinetic NMR on bis-substituted piperidyl disulfides showed that there is a remarkable increase of free energy of activation for the inversion of piperidine ring in comparison with piperidine itself. It was also observed that, within the mol. of bis-substituted piperidyl disulfides, one half of the ring in which the 3,4- and 5-ring atoms are located undergoes inversion about 4 times faster than the other half of the ring, in which the 1,2- and 6-ring atoms are located. This clearly demonstrates the influence of the large substituent group on the N atom of piperidine ring. A comparison of the potential barrier for ring inversion of bispiperidyl disulfides and the corresponding trisulfides shows that the steric hindrance within the disulfide mol. has also some influence upon the ring inversion process.

Key words: PIPERIDINE P, REACTION KINETICS, PROTON MAGNETIC RESONANCE SPECTROMETRY, DISULFIDE, CHEMICAL SHIFT, STERIC EFFECT, CONFORMATION