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The second amendment to ‘German Rugulations on Consumer Goods’ states that azo dyestuffs, which can release one or more of the listed 20 carcinogenic amines, should no longer be used in dyeing consumer goods. Many acid and direct dyes which liberate harmful amines such as benzidine, o-tolidine and o-dianisidine after reduction are, however, still use. In this study, it was surprising to find that some dyestuffs or dyed substrates released carcinogenic amines such as 4-amino-diphenyl, 2-naphthylamine, 2,4-toluenediamine and 4,4′-diaminodiphenyl-methane, although such amines had not been employed as intermediates in the manufacture of the dyestuffs. Benzidine was also detected from a dyestuff which was not made from benzidine. The 2-naphthylamine residues were sourced as being due to the use of 1-naphthylamine contaminated with 2-naphthylamine. 4-Aminodiphenyl was formed by dediazoniation and a subsequent coupling reaction between the benzenediazonium ion and aniline. Benzidine was derived from dediazoniation and a subsequent self-coupling reaction of the diazonium ion of 4-nitroaniline. 2,4-Toluenediamine and 4,4′-diaminodiphenylmethane arose from the alkaline hydrolysis of the readily accessible moiety of the corresponding base units in PU foams or PU finishing agents.

Los análisis cinéticos realizados a diferentes temperaturas (20º C - 40º C) indican que el proceso de desdiazoación del ion bencenodiazonio (BZ) es de orden uno respecto a BZ siendo A = 2,3.1015 s-1 y Ea = 112,5 kJ.mol-1 en la ecuación de Arrhenius así como ΔH‡ = 110,0 kJ.mol-1 y ΔS‡ = 40,7 J.K-1.mol-1 para la ecuación de Eyring. Los resultados cromatográficos revelan que BZ se descompone por un proceso heterolítico mediado por el catión arilo. La presencia de sales Cu(I) o de Cu(II) y ácido ascórbico produce un cambio del mecanismo de reacción. Los compuestos intermedios originados en estas condiciones son especies estables que pueden ser transportadas en la sangre. El modelo estudiado sugiere una posible explicación para la localización descrita en la literatura para los tumores producidos por la administración de BZ a ratas., The kinetic analyses carried out at different temperatures (20ºC - 40ºC) indicate that the dediazoniation process of the benzenediazonium ion (BZ) is of the order of one, with BZ at A = 2,3.1015 s-1 and Ea = 112,5 kJ.mol-1 for the Arrhenius equation, and ΔH‡ = 110,0 kJ.mol-1 and ΔS‡ = 40,7 J.K-1.mol-1 for the Eyring equation. The chromatographic results reveal that BZ decomposes through a heterolytic process mediated by the aryl ion. The presence of Cu(I) or Cu(II) salts and ascorbic acid produce a change in the reaction mechanism. The intermediate compounds produced in these conditions are stable species that may be transported in the bloodstream. The model studied suggests a possible explanation for the localisation of tumours produced by the administration of BZ in rats., El presente trabajo ha sido financiado por la Junta de Andalucía Consejería de Educación y Ciencia (Acciones Coordinadas).

The interaction of aniline with nitrosonium hydrogensulfate then with nitric acid in concentrated sulfuric acid does not occur through diazotisation and subsequent nitration of the benzenediazonium ion, but instead involves nitrosonium ion catalysed nitration of anilinium ion in the para -position together with uncatalysed nitration in the meta - and para -positions followed by diazotisation on dilution with water.

Kinetics of parallel reactions contribute to the elucidation of poly-step mechanisms. Competing pathways in the reaction of benzenediazonium ion with azide anion helped to establish the occurrence of phenylpentazole. Steady state kine- tics clarified the competition between the interception of an intermediate and its return to the starting material. The Diels- Alder reactions of cyclooctatetraene and of diphenylbenzocyclo- butenes, and the thermal equilibration of aziridines with azo- methine ylides serve as examples. Kinetics and trapping experi- ments revealed a four-step sequence for the conversion of bro- mocyclooctatetraene to trans-8-bromostyrene.

Treatment of azoxybenzene with p-toluenesulfonic acid in acetic anhydride gave tosylates of 4- and 2-(phenylazo)phenols, and the corresponding acetates as by-product, besides azobenzene. However, a similar reaction of 4,4′-difluoroazoxybenzene gave 2-tosyloxy-4,4′-difluoroazobenzene as rearrangement product, besides 4-fluorophenyl tosylate and 4-fluorophenyl acetate. Meanwhile, the reaction of 4,4′-diacetoxyazoxybenzene afforded 4-acetoxyphenyl tosylate and hydroquinone diacetate in high yields. These unique reactions involve C–N bond cleavage, and may proceed through a pathway involving formation of benzenediazonium ion as the key intermediate.

The N(α), N(β)-rearrangement of the two N-atoms which can be observed in solutions of [β-15N]-labelled p-substituted benzenediazonium ions follows dual substituent parameter treatments. The reaction yields a negative field and a positive resonance reaction constant (pF =−3.35, pR = 2.47). The magnitude of these constants is, within experimental error, the same as the respective reaction constants for solvolytic dediazoniation. The exchange of the diazonio group of 15N-labelled p-substituted benzenediazonium ion yields, however, field and resonance reaction constants which are close to zero. This result is attributed to cancellation of the reaction constants for the forward and reverse steps in the complex mechanism of the exchange reaction.

The reaction of benzenediazonium ion generated from α-azohydroperoxide with 1-naphthol gave a diazoether which rearranged to 2- and 4-phenylazo-1-naphthols.

The preparation and spectral properties of twenty-five arylazocyanoacetarylamides (VI–VIII) are investigated. Analysis of the IR and UV spectra of such compounds (VI–VIII) shows that they are of the hydrazo rather than the azo form. The reaction of benzenediazonium ion and the arylazo derivatives (VI and VII) in the presence of sodium hydroxide (and not in the presence of sodium acetate) produces 3-cyano-1,5-diarylformazans (IX). A mechanism is suggested for the formation of formazans (IX). Reaction of (VI–VII) with Grignard reagents results in 1,2-addition to the cyanide group with the formation of arylazoiminoacylacetanilides (X), which were hydrolysed to the corresponding arylazoacylacetanilides (XI). The UV spectral properties of compounds X and XI are compared.

The electronic states of diazomethane, ketene, diazocyclopentadiene and benzenediazonium ion were studied by the semi-empirical ASMO LCAO SCF CI method. Both π- and \barπ-systems were taken into consideration. Two types of approximations, Mulliken’s formula and a new semitheoretical formula, were used in the evaluation of the core resonance integrals. The latter gives satisfactory results though it contains no arbitrary adjustable parameters. The longest wavelength singlet-singlet transition of diazomethane, ketene or diazocyclopentadiene is 1π–1\barπ, and that of benzenediazonium ion 1π–1π.

The reaction of benzenediazonium ion generated from α-azohydroperoxide with 1-naphthol gave a diazoether which rearranged to 2- and 4-phenylazo-1-naphthols.

Treatment of azoxybenzene with p-toluenesulfonic acid in acetic anhydride gave tosylates of 4- and 2-(phenylazo)phenols, and the corresponding acetates as by-product, besides azobenzene. However, a similar reaction of 4,4′-difluoroazoxybenzene gave 2-tosyloxy-4,4′-difluoroazobenzene as rearrangement product, besides 4-fluorophenyl tosylate and 4-fluorophenyl acetate. Meanwhile, the reaction of 4,4′-diacetoxyazoxybenzene afforded 4-acetoxyphenyl tosylate and hydroquinone diacetate in high yields. These unique reactions involve C–N bond cleavage, and may proceed through a pathway involving formation of benzenediazonium ion as the key intermediate.

The N(α), N(β)-rearrangement of the two N-atoms which can be observed in solutions of [β-15N]-labelled p-substituted benzenediazonium ions follows dual substituent parameter treatments. The reaction yields a negative field and a positive resonance reaction constant (pF =−3.35, pR = 2.47). The magnitude of these constants is, within experimental error, the same as the respective reaction constants for solvolytic dediazoniation. The exchange of the diazonio group of 15N-labelled p-substituted benzenediazonium ion yields, however, field and resonance reaction constants which are close to zero. This result is attributed to cancellation of the reaction constants for the forward and reverse steps in the complex mechanism of the exchange reaction.

3 Mol p-Chlorbenzoylnitrit (III) reagieren mit der Hydrazonform (II) von l-Phenylazonaphthol-(2) (I) in Benzol bei Raumtemperatur zur N-Nitrosoverbindung (IV), die uber den Diazoather (V) in (VI) und (VII) zerfallt.

The conversion of p -CH 3 OC 6 H 4 N 2 + to the hydrazine and then to the benzaldehyde hydrazone gave a stable substance in which the proton NMR could be used to locate a 15 N label. In contrast to an earlier study on benzenediazonium ion by a similar method, this analysis showed that the α- 15 N label in the diazonium salt migrates during hydrolysis to the β position to about the extent indicated by a degradative method.

Contrary to previous reports, we find the aromatic ring in the 4-morpholinobenzenediazonium cation in (II) to be considerably distorted compared with that in the benzenediazonium ion (I), very much in the manner in which substitution of a 4-dialkylamino-group distorts the ring in nitrobenzene. These new data are used in a critique of the frequently expressed view that the electronic ground-state of a 4-dialkylaminobenzenediazonium cation is quinoidal in nature rather than aromatic: SCF calculations by several methods, while predicting a shortening of the C-2 to C-3 bond of (II), fail to reproduce the observed bond distances. Crystals of (II) are monoclinic, space group P21/c, a= 13.675(4), b= 10.686(4), c= 8.982(2)A, β= 106.72(2)°, Z= 4. The structure was refined to R 0.065 for 1 674 observed reflections. Mean bond distances are: C(1)–C(2)(systematic numbering) 1.395(1), C(2)–C(3) 1.371(1), C(3)–C(4) 1.424(1), C(1)–N(diazonium) 1.381(1), C(4)–N(morpholino) 1.352(1), and N–N 1.100(1)A.

1-Phenyl-3,3-dimethyltriazene (1; X = H) is a stable source for the benzenediazonium ion which is in eaquilibrium with the betaine (2) and hence can kgive rise to products derived from benzyne and phenyl radicals: on the other hand, the analogous 2,3,4,5-tetrahalogenophenyltriazenes (1; X = F or Cl) do not lead to arynes.

Presents a more convenient approach to studying the kinetics of the hydrolysis of benzenediazonium ion.