Abstract-The pH dependence of the 13C chemical shifts (6) of the diazanaphthalenes has been recorded. From this dependence the pK. values have been determined using the Henderson-Hasselbach equation. The change in 13C chemical shifts under the influence of nitrogen protonation (Ad) has been predicted using the Ad values of quinoline and isoquinoline. The correlation between observed and expected A8 values of the symmetric diazanaphthalenes is very good. Assuming these changes in chemical shifts to be of general validity, the site of protonation in the asymmetric diazanaphthalenes has been determined by comparison of the expected A8 values for 01-and /?-nitrogen protonation with the observed ones. The site of protonation for 1,6-and 1,7-naphthyridine is the 8-nitrogen atom, whereas for cinnoline both monoprotonated species are present in a significant amount.
Abstract. Benzenesulfony 1 cyanide and six pora-substitution products were reduced electrochemically at a dropping mercury cathode, in DMF as solvent. A linear Hammett relation between the half-wave potentials of the first reduction wave and the 0,-values was observed. This suggests the reduction mechanism being andlogous for all molecules studied. The half-wave potentials could not be correlated with the electron affinities of these molecules, since for all compounds the first reduction wave is irreversible, due to the formation of mercurous intermediates. Performing electrochemical reduction within the ESR cavity spectra were obtained in some cases. For p-cyanobenzenesulfonyl and p-nitrobenzenesulfonyi cyanides these ESR spectra could be analysed and were assigned to the p-cyanobenzenesulfonyl and p-nitrobenzenesulfonyl dianion radicals, respectively. Prolonged reduction ofp-nitrobenzenesulfonyl cyanide in DMF yields two additional ESR spectra, which could be assigned to the p-nitrobenzenesulfinyl and p-nitrobenzenesulfenyl dianions. So the SO, group is reduced selectively in presence of the NO, group.
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