NMR-spectroscopic investigation of o-nitrosobenzoic acid.
The synthesis of o-nitrosobenzoic acid 2 has been known for more than 100 years, and the photochemical preparation from o-nitrobenzaldehyde 1 became a textbook example for [1,5]-hydrogen shifts. However, neither the (1)H-NMR spectra nor the (13)C--{(1)H}-NMR of this compound have been reported so far. This fact can most likely be attributed to the monomer-dimer equilibrium of the nitrosobenzoic acid, which leads to rather complex, concentration-dependent NMR spectra. In this paper, we report a thorough investigation of these spectra. In the (13)C-{(1)H}-NMR spectra, all 21 lines could be assigned to the monomeric form, the E-dimer, and the Z-dimer.
Institut für Makromolekulare und Organische Chemie I, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany. schaper@klaus-schaper.de
Klaus
K
Schaper