INTERNAL-ROTATION OF THE OH GROUP IN DI-ANILS OF 2-HYDROXY-5-METHYL-ISOPHTHALDEHYDE

H-1, C-13 and N-15 NMR spectra of di-R-anils of 2-hydroxy-5-methyl-iso phthaldehyde (R=H, CH3, OCH3) were recorded in CDCl3 solution and the spectral assignments were performed. The variable temperature measurem ents over the range 310-223 K show evidence of a slowing down of the i nternal rotation of the OH group in comparison with the rotation of th e free OH group in phenols. The kinetic parameters of the OH group rot ation in the di-anils were determined by means of 1H NMR lineshape ana lysis. The conformational changes in molecules are discussed. (C) 1997 Elsevier Science B.V.