Diazonium species

The reaction of [B qH q] with excess nitrous acid gives an explosive iatermediate that can be reduced to the nonexplosive bis inner diazonium salt l,10-(N2)2B2QHg [66750-86-5] (eq. 42). This diazonium species is a useful synthetic iatermediate. 

For aryl amines the reaction mixture should be slightly acidic or neutral, in order to have a high concentration of free amine as well as arenediazonium ions. Aryl ammonium species—ArNH3+—are unreactive. The coupling of the diazonium species with aromatic amines proceeds by an analogous mechanism ... 

Certain aliphatic diazonium species such as bridgehead diazonium ions and cyclo-propanediazonium ions, where the usual loss of N2 would lead to very unstable carbocations, have been coupled to aromatic substrates. ... 

With diazonium species like 5, dinitrogen (N2) functions as a good leaving group. Loss of N2 from 5 generates a carbenium ion species 2, which rearranges by a... 

From a comparison of the model curves of the variation in log rate versus pH expected for reaction of possible diazonium species with possible amine and phenolic species (Figs. 1 and 2) with those obtained (Table 28) for the reaction of... 

Reduction of arenediazoninm salts provides the basis for a substantial number of chemical reactions. A notable application is the Sandmeyer reaction, which utilizes the diazo moiety to facilitate functionalization of aromatic systems and remains one of the most reliable transformations in organic chemistry. The general reaction involves the addition of the cuprate salt of the desired moiety to the diazonium species—ArN2 + CuX — ArX. 

Diazoalkanes add to PTAD by electrophilic addition. The intermediate diazonium species can lose nitrogen and the resulting dipole can be trapped by solvent or form a diaziridine (Scheme 15) <85CB28,85CB3396,88JCS(P2)1415>. In many cases the phenyl group on the PTAD can be replaced by a substituted benzene and the same type of reaction occurs (Scheme 16). 

Nitrosation, diazotation, and deamination processes take place in the reactions resulting in alcohols and N2 gas as final products. From the studies on the pH-dependence of the rate constants at different temperatures, a mechanism was proposed involving diazonium ions as intermediates. With the prediction that coordination to the metal could stabilize the otherwise extremely reactive diazonium species, the mechanism of these reactions are being studied in organic media. 

Aryl azides (such as 13) can be easily prepared from their corresponding amines (12) in one or two steps. Three examples are given in Scheme 2a. The most common method is the diazotization of the amine with sodium nitrite under acidic conditions (giving diazonium species 14), followed by addition of sodium azide in an aqueous medium (route i in Scheme 2a) [44], In 2003, the synthetic method was improved by application of triflyl azide (TfN3), which allowed a one-step conversion and gave improved yields (route ii in Scheme 2a) [45]. Recently, the development of sulfonyl azides 15 (with R = imidazole [46] or R = benzotriazole [47]) was reported these proved to be more stable reagents and allowed a conversion under mild conditions (route iii in Scheme 2a). 

Title Process for Derivatizing Carbon Nanotubes with Diazonium Species... 

Kirmse and coworkers have made an extensive study of rearrangements in deaminations of bicyclic cyclopropyl derivatives. An important process occurring in the deaminations when the diazonium species are formed by treatment of the corresponding iV-nitrosoureas (12) with aqueous or alcoholic base is the isomerization of exo-diazonium ions (13) to endo-diazonium ions (14) prior to loss of nitrogen. 

Generation of a diazonium intermediate (619) from nitrosourea (618) gave products, which are derived from intermediate 620 (equation 161). Surprisingly, in this special case the C(l)-C(2)-bond of the cyclopropane was cleaved. In contrast, diazonium species of a 3-oxa-bicyclo[4.1.0]heptyl or 3,5-dioxabicyclo[5.1.0]octyl system decomposed via an... 

Fortt, R., R.C.R. Wootton, and A.J. de MeUo, Continuous-flow generation of anhydrous diazonium species Monolithic microfluidic reactors for the chemistry of unstable intermediates. Organic Process Research and Development, 2003, 7 762-768. 

FIGURE 17.32 In the first step of this methyl estei forming reaction, diazomethane acts as a Bronsted hase and deprotonates the carboxylic acid. In the second step, the carboxylate does an Sn2 suhstitution on the very reactive methyl diazonium species. 

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