STUDY OF THE ASSOCIATION OF 2-OXOINDOLINES IN CARBON-TETRACHLORIDE SOLUTIONS BY IR-SPECTRA, DIPOLE-MOMENTS AND AVERAGE MOLECULAR-WEIGHT MEASUREMENTS

Dipole moments, average molecular weights and IR spectra of 2-oxoindoline (I), 2-oxo-3-methylindoline (II) and 2-oxo-3,3-dimenthylindoline (III) and their N-methyl-substituted analogues were studied in CCl4 solutions at various concentrations. It was shown that the molecules with an N-H bond associate exclusively to cyclic dimers. The values of the association constants (K) were determined by IR spectrometry. Other methods gave too broad intervals of possible K values. The spectroscopic association constants of compounds I-III are very similar, 380, 350 and 370 dm3 mol-1, respectively. The v(s)(NH) band shift on association is 275 cm-1.