Showing papers on "Triazene published in 1970"
41 citations
TL;DR: Several triazene 1-oxide chelates of nickel(II), palladium(II) and copper(II)) are described in this article, where the pmr spectra of the partially paramagnetic complexes show small contact shifts.
10 citations
TL;DR: It is concluded that triazenes with tissue aliamino groups play no significant part in the final color effect of azo coupling with the diazonium salts used.
Abstract: The suggestion that triazenes formed by union of alkalized diazonium salts with aliphatic amino groups contribute to the azo color reaction of tissue proteins is rejected. Deaminations of formaldehyde-fixed and other tissues were sufficient to render the previously oxyphil elements of these tissues basophilic to azure A-eosin B at the same pH level. After these deaminations there was no detectable difference in intensity or distribution of the azo coupling reaction. Freshly diazotized safranin 0, dimethylphenosafranin (methylene violet) and the diazosulfanilic acid, azure A sequence technic were used as testing methods. Acid extraction even when prolonged to 24 hr and when acid concentration raised from 0.1 N to 0.24 N does not alter the intensity or distribution of the several azo coupling reactions as compared with unextracted preparations. Deliberate creation of triazenes by admixture of proline, diethylamine, hydroxylamine, hydrazine sulfate, glycine and uric acid, added to the diazo in stoichiometric excess, more or less completely inhibited azo coupling of all tissue elements. Uric acid and hydrazine were the most eflective, and then hydroxylamine, proline and diethylamine in that order. Reacidification of the uric acid compound to pH 2.2-2.5 for 10 mm, filtration to remove liberated uric acid and realkalinization moderately restored the azo coupling capacity of diazosafranin. This illustrates acid destruction of a triazene of this diazotate. It is concluded that triazenes with tissue aliamino groups play no significant part in the final color effect of azo coupling with the diazonium
10 citations
TL;DR: In this paper, it was shown that the bimolecular rate constants obey Hammett law for the sum of the Hammett σ values for the substituents in both benzene rings.
Abstract: The oxidation of diazoaminobenzenes with peroxybenzoic acid in ether gives diaryltriazene 1-oxides in good yield. An electron-releasing substituent on one of the benzene nuclei directs the oxygen to the nearest nitrogen atom. With diazoaminobenzenes carrying substituents of similar polarity on the two benzene nuclei the two possible isomers are formed in comparable amounts. The plot of logarithms of isomer ratios against the difference between Brown and Okamoto's σ+ values for the two substituents in a triazene is a straight line (ρ–1·3). Kinetic studies show that the bimolecular rate constants obey the Hammett law for the sum of the Hammett σ values for the substituents in both benzene rings (ρ–0·87). Analysis of the effect of substituents on the rate and the isomer ratio suggests a mechanism which involves the rate-determining formation of a metastable intermediate, in which the oxygen atom from peroxybenzoic acid is tentatively regarded as bonded to both nitrogen atoms 1 and 3, and which rapidly collapses to isomeric N-oxides in a ratio determined by the nature of the substituents.
5 citations