Diazo oxides salts

The most important results are given in Figure 4-1. The oxygen atom lies 244 pm from the N(l) atom of the diazonio group, well within the sum of the van der Waals radii. The diazonio group deviates by 10.4° from linearity. It seems that the 0(1) N(l) interaction is attractive, as indicated by the angle of 169.6° (instead of 180°) at N(l), but the 0(1) N(2) interaction is not. The NN distance (109.9 pm) is, however, not different from normal values found in diazonium ions. The same authors demonstrated later (Wallis et al., 1993) that this result is not unique for the quino-line-8-diazonium-l-oxide salt, as it was found also for two 1-naphthalenediazonium tetrafluoroborates substituted in the 8-position with the electron donors -SCH3 and -N(CH3)2 and - perhaps unexpectedly - for 8-nitronaphthalene-l-diazo-... 

Diazonium salts can also be converted to halides by processes involving aryl free radicals. In basic solutions, aryl diazonium ions are converted to radicals via the diazo oxide.102... 

In the classical procedure, base is added to a two-phase mixture of the aqueous diazonium salt and an excess of the aromatic that is to be substituted. Improved yields can be obtained by using polyethers or phase transfer catalysts with solid aryl diazonium tetrafluoroborate salts in an excess of the aromatic reactant.177 Another source of aryl radicals is A-nitrosoacetanilides, which rearrange to diazonium acetates and give rise to aryl radicals via diazo oxides.178... 

Dinitrobenzene diazo-oxide reacts with hydrazine hydrate to yield 2,4-dinitro-6-[tetrazene-(l)]-phenolhydrazine salt (XIV)... 

In comparison with diazonium salts (qv), diazo oxides are, more stable, more deeply colored, less soluble and less reactive. They do not readily couple to give azo colors except in strongly alkaline solns. Although diazo oxides are generally stable, some (such as 4,6-Dinitrobenzene-2-diazo- 1-oxide, Vol 2, p B59-L) are used as detonating expls Refs 1) G.T. Morgan J.W. Porter, JCS 107 I, 645-59 (Constitution of internal diazo oxides) 2) G.T. Morgan H.P. Tomlins,... 

There is a substantial group of diazonium salts to which the alkaline formaldehyde method, or any other deamination process requiring alkaline conditions, should not be applied, inasmuch as they are unstable in the presence of alkali. This instability is merely an extension of the hydrolytic cleavage reaction previously noted (pp. 274-276). Comparatively few diazonium salts are converted to the diazo oxides in aqueous mineral acid. As the acidity of the solution is decreased, however, diazo oxide formation is facilitated, and finally on the alkaline side many diazo compounds that are stable in acid media undergo hydrolytic cleavage.96 96 Thus, while 2,4-dinitrobenzenediazonium acid sulfate is stable to dilute aqueous sulfuric acid, in neutral or slightly alkaline solution it readily yields the diazo oxide.6 The reaction is not quantitative a poorly defined insoluble product is also formed in 14 to 20% yields. 

Symmetrical tribromo- and trichloro-benzenediazonium salts are rapidly transformed into the diazo oxides by ice-cold aqueous sodium hydroxide.97- 98... 

The para halogen atoms are less labile than those in the ortho positions about 20% of the molecules that yield diazo oxides lose an atom of bromine from the para position, whereas approximately 80% lose an ortho bromine.9 The more highly halogenated diazonium salts are more likely to undergo hydrolytic cleavage.109... 

It is reported that alkaline sodium hydrotulfite (Na2S204) is effective -in converting certain diazo compounds to the hydrocarbons,119 a statement supported solely by reference to the work of Grandmougin.130 Actually he obtained only a small yield of benzene from benzenediazonium salts but suggested that on further study the process might prove to be useful. Upon reduction with hydrosulfite, the diazo oxide XXIV is converted to the phenol XXV in 95% yield (crude product.)131... 

Certain diazonium salts, however, are unstable in the presence of water. Thus, 2-methoxy-4,6-dinitroaniline when diazotized in sulfuric acid containing an equal volume of water gives, in addition to the expected diazonium salt, a diazo oxide (XVII). Apparently the nitro group imdergoes hydrolytic cleavage, a hydroxybenzenediazonium salt (XVI) being intermediate in the diazo oxide formation. 

Unexpected products are sometimes obtained in the l horr reaction for example, during an attempt to synthesize an alkaloid, thermolysis of the diazo-nium salt (79.7) gave a triazinone, the carbonyl group probably arising from the oxidation of the methylene by nitrous acid. 

CIANOGUANIDINA (Spanish) (461-58-5) Mixtures with many compounds form explosive compounds, including strong oxidizers, diazo, nitrocompounds, salts of diazonium or hydrazinium, azides, tetrazenes, tetrazoles, triazenes, and triazoles. Reacts with strong acids, forming hydrogen cyanide. 

Without additional reagents Hydrazinophosphonium salts from diazo oxides via phosphazines... 

The 2-hydroxybenzenediazonium ion is in acid-base equihbrium (pIQ = 1.14) with 2-diazocyclohexa-3,5-dien-l-one 5 (the diazo-oxide form). Diazo-oxides show absorption maxima at longer wavelengths than the corresponding diazonium salt form. Thus, l-diazo-2-oxo-l,2-dihydrobenzene has 395 nm... 

In a 1 5 or 2-Utre rovmd-bottomed flask, prepare cuprous chloride from 105 g. of crystallised copper sulphate as detailed in Section 11,50,1. Either wash the precipitate once by decantation or filter it at the pump and wash it with water containing a httle sulphurous acid dissolve it in 170 ml. of concentrated hydrochloric acid. Stopper the flask loosely (to prevent oxidation) and cool it in an ice - salt mixture whilst the diazo-tisation is being carried out. 

Oxidative Couplings of Heterocyclic Hydrazones. This method has opened the way to the preparation of azo derivatives of diazo compounds unobtainable by other means, ie, heterocycHc compounds ia which the diazotizable amino group is conjugated with the heterocycHc nitrogen atom as ia 2- and 4-amiQopyridine, compounds which do not normally yield stable diazonium salts (38). The reaction occurs as illustrated by equation 7 for the iateraction of (A/-methylcarbostyryl)hydrazone [28219-37-6] and dimethyl aniline the overall process is oxidation. 

The aza-transfer reaction between 3-hydrazinopyridazines and aromatic diazonium salts or heterocyclic diazo compounds affords the corresponding tetrazolo[l,5-6]pyridazines, while 3-hydrazinopyridazine 1-oxide gives 3-azidopyridazine 1-oxide (76TL3193, 76X725). 

Acridizinium salts, 8-diazo-7-oxo-in lithography, 2, 570 Acridizinium salts, 7,10-dihydroxy-oxidation, 2, 539... 

Diazo compounds Diazoniiim sulfides and derivatives, Xanthates 1,2-epoxides Halo-aryl metals Haloarenemetal TC-complexes Halogen oxides Hydraziniiim salts Hyjiohalites... 

The major problem of these diazotizations is oxidation of the initial aminophenols by nitrous acid to the corresponding quinones. Easily oxidized amines, in particular aminonaphthols, are therefore commonly diazotized in a weakly acidic medium (pH 3, so-called neutral diazotization) or in the presence of zinc or copper salts. This process, which is due to Sandmeyer, is important in the manufacture of diazo components for metal complex dyes, in particular those derived from l-amino-2-naphthol-4-sulfonic acid. Kozlov and Volodarskii (1969) measured the rates of diazotization of l-amino-2-naphthol-4-sulfonic acid in the presence of one equivalent of 13 different sulfates, chlorides, and nitrates of di- and trivalent metal ions (Cu2+, Sn2+, Zn2+, Mg2+, Fe2 +, Fe3+, Al3+, etc.). The rates are first-order with respect to the added salts. The highest rate is that in the presence of Cu2+. The anions also have a catalytic effect (CuCl2 > Cu(N03)2 > CuS04). The mechanistic basis of this metal ion catalysis is not yet clear. 

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