Replacement of diazo groups

Thus, the replacement of diazo group by other groups is helpful in... 

Reduction with loss of nitrogen. Replacement of diazo group with H. Benzene diazonium chloride. C.Hs- -N—(Cl lit N H)—H (C2H6—OH or SnCh) CsH Benzent. Hydrocarbon. 

Replacement of diazo group with CtHi. Ditto C.Hj- -N—(Cl III N H)—CsHs ( + AICI1) CeHs—CsHs Duphenyl. Hydrocarbon. 

Diazonium compounds have been treated with a great variety of reducing agents, some of which have become incorporated into procedures for replacing the diazo group by hydrogen. The more important of these processes involve reduction by ... 

Replacement of Diazo Sulfide Groups with Fluorine in the Silver(l) Ion Promoted Acid Decomposition of Aryl Diazo Sulfides... 

A quite important process for the preparation of aromatic nitriles is certainly the substitution of diazo groups by a cyanide function (equation 18). Following this route, the nitro or a primary amino group is, in principle, replaced by a CN ligand. The most important procedures are summarized in review articles and in some shorter accounts. ... 

As mentioned earlier, this reaction is extremely useful, because many different reagents will replace the diazo group, allowing for a simple procedure for installing a wide variety of groups on an aromatic ring ... 

The diazonium salts usually decompose when warmed with water to give a phenol and nitrogen. When treated with CuCl, CuBr, KI, the diazo group is replaced by chlorine, bromine or iodine respectively (Sandmeyer reaction). A diazonium sulphate and hydroxyl-amine give an azoimide. The diazonium salt of anthranilic acid (2-aminobenzoic acid) decomposes to give benzyne. ... 

When a solution of a diazonium salt is heated, the diazo group is replaced by hydroxyl and nitrogen is evolved ... 

Quinone diazides can also be obtained by the diazo group transfer reaction of 4-tosyl azide. For example, 9-diazo-10-anthrone (2.55) is formed from anthrone (2.54) if the reaction is carried out in an ethanol-piperidine mixture. On the other hand, if ethanol is replaced by pyridine, dimerization with loss of molecular nitrogen takes place and the azine 2.56 is isolated (Scheme 2-32 Regitz, 1964 Cauquis et al., 1965). In the preceding discussion tosyl azide was shown to be an electrophilic reagent. It therefore seems likely that it is not the anthrone 2.54 but its conjugate base which reacts with tosyl azide. 

The structure elucidation of the kinamycins was a formidable challenge, and the information presented below draws from the work of several research groups over a period of more than 20 years. As will be shown, the originally proposed structure of the kinamycins contained a cyanamide rather than a diazo function. Subsequent synthetic and biosynthetic studies led to replacement of the cyanamide with a diazo function. The structural elucidation was challenging, in part, because of the high degree of unsaturation of the kinamycins, which limits the utility of H and 2D NMR analysis. In addition, because these structures were unprecedented, there were no clear benchmarks for comparison at the time. The pathway from isolation to determination of the correct structure is described below. 

Although practically important in other cases, the replacement of an NH2-group by hydrogen via the diazo-compound naturally has none in the example here given. Thus m-nitrotoluene (and from it m-toluidine) is obtained from p-toluidine by nitration of the acetylated base and replacement of the NH2-group (after elimination of the acetyl) by H, as shown above. 

Aryldiazonium salts, usually obtained from arylamines, undergo replacement of the diazonium group with a variety of nucleophiles to provide advantageous methods for producing aryl halides, cyanides, phenols and arenes by reductive removal of the diazo group. Coupling reaction of aryldiazonium salts with phenols or arylamines give rise to the formation of azo dyes. 

Whatever method is used, the replacement of an amino group by fluorine, via a diazo derivative, implies two reaction steps diazotization (to give 1) and dediazoniation (to give 2). The diazo intermediate can be isolated or not depending upon the substrate, the reagents, and the reaction conditions however, some general mechanistic features are common to all cases. 

The replacement of an aromatic diazo group by fluorine can be performed ... 

The monovalent azide group, Ns, is closely related to the divalent diazo group and can be regarded as derived from the latter by replacement of a tetravalenr carbon atom by... 

Hydroxyphenylarsonic acid may be prepared by diazotiza-tion of arsanilic acid and replacement of (he diazo group by... 

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