Benzenediazonium acetate

N N.0.N0 C(N02)2 mw 255.15, N 27.45% yel prisms(from acet+eth), mp- expl violently ca 40° sol in acet or hot w diffc sol in cold w almost insol in ale, eth, chlf or benz. Can be prepd by reacting in the cold aq solns of benzenediazonium acetate and K trinitromethane. This compd is fairly stable in the pure state, but very unstable when impure. It expl when heated or on impact... 

AW-Diethyl-2,6-dimethylaniline (154), a highly hindered tertiary amine, has been considered. This is illustrated by the decomposition o iV-nitrosoacet-anilide (169) and benzenediazonium acetate by two competing routes to give converted into (154) in four steps. 

In the context of this section it is important that Ruchardt and Tan (1970 a) found that (solid) benzenediazonium fluoroborate gave benzyne adducts with potassium acetate in the presence of aryne trapping agents such as tetracyclone or anthracene. This is, however, not the case if water is present (Cadogan, 1971). As a consequence of these observations, Cadogan et al. (1971) simplified the formation of arynes from diazonium ions by converting aniline or its substitution products into arynes in a... 

A suitable catalyst for carboxy-de-diazoniations was found by Matsuda s group in their work on arylations of alkenes. As in the case of alkene arylations (Sec. 10.9), they used Pd11 acetate (2 mole %) and carbon monoxide (9 atm) for reactions with benzenediazonium tetrafluoroborate and sodium acetate in acetonitrile as solvent at room temperature (Nagira et al., 1980 82-85% yield). Similar results were obtained... 

Ring transformation involving the intramolecular reaction of a hydrazone or in situ formed hydrazone also appeared. The transformation of 6-methyl-2//-pyran-2,3,4-trione 3-arylhydrazones 332 into l-aryl-6-methyl-4-oxo-l,4-dihydropyridazine-3-carboxylic acids 333 is an example of the former (Scheme 82). Compound 332 are formed via reaction of 4-hydroxy-6-methyl-27/-pyran-2-one 331 with substituted benzenediazonium chlorides. These are normally not isolated and immediately used further <2005EJM1325>. An example where a hydrazone is formed in situ is the reaction of 2-amino-5-aryldiazenyl-4-oxo-6-phenyl-4//-pyran-3-carbonitriles 334 with H2SO4 in glacial acetic acid, yielding 2-aryl-6-benzoyl-3-hydroxy-5-oxo-2,5-dihydropyridazine -carbonitriles 335 (Scheme 83) <2001T6787>. 

Attention has previously been drawn (Section 6.7.1, p. 922) to the fact that unless an excess of hydrochloric (or mineral) acid is used in the diazotisation process, coupling occurs between the diazonium salt and the amino group in the amine to give diazoamino compounds. Thus benzenediazonium chloride and aniline yield diazoaminobenzene. This substance may be conveniently prepared by dissolving two equivalents of aniline in three equivalents of hydrochloric acid, and adding one equivalent of sodium nitrite in aqueous solution followed by two equivalents of sodium acetate (Expt 6.86). 

Reactions of benzenediazonium chloride with 3-bromomethylbenzo-[sodium acetate afforded the hydrazonoyl bromides 35 [90ZN(B)1067]. 

Coupling, of benzenediazonium chloride with acetoacetic acid, 32, 84 of diazotized 3,5-dichloro-2-amino-benzoic acid to give 4,4, 6,6 -tetra-chlorodiphenic acid, 31, 96 of diphenyldichloromethane to tetra-phenylethylene, 31, 104 Crotonaldehyde, diethyl acetal, 32, 5 Cyanoacetamide, 32, 34 Cyanoacetic acid, 31, 25 -Cyanobenzaldehyde, 30, 100 3-Cyano-5,6-dimethyl-2(l)-pyridone,... 

Diazotization in organic solvents allows solid diazonium salts to be isolated. Diazotization can be carried out using an ester of nitrous acid, such as pentyl nitrite, in a solvent such as acetic acid or methanol. A procedure has also been described for isolating diazonium tetrafluoroborates, in excellent yield, by carrying out the diazotization with boron trifluoride etherate and f-butyl nitrite in ether or dichlorometh-ane at low temperature. Another method for the preparation of a variety of diazonium salts in a nonaqueous medium makes use of the chemistry of bis(trimethylsilyl)amines (8). These compounds react in dichloromethane with nitrosyl chloride and other nitrosating agents which are generated in situ. Thus, benzenediazonium chloride was isolated (96%) from bis(trimethylsilyl)aniline. 

Electrophilic Amination of Ketene Silyl Acetals with Benzenediazonium Tetrafluoroborate... 

Benzenediazonium tetrafluoroborate has also been investigated as an electrophilic aminating reagent in the reaction with the ketene silyl acetal 2 derived from the /1-hydroxy ester 119. 

Biaryls are produced in low yields by several related coupling reactions. When benzenediazonium chloride is treated with aqueous sodium hydroxide in the presence of benzene, nitrogen is eliminated and biphenyl is formed in 22% yield. Better results are sometimes obtained when the sodium hydroxide is replaced by sodium acetate or when stabilized diazonium salts are employed. In the former modification the aryl-diazoacetate, ArN = NOCOCHj, is an intermediate product. The tautomeric forms of the aryldiazoacetates are N-nitrosoamides, ArN(N0X30CH, which are obtained by the action of nitrous fumes or nitrosyl chloride on... 

B) Preparation of 2,4-Dihydroxyazobenzene. Dissolve 2.0 g of resorcinol in 5 ml of water and add to it 15 ml of the benzenediazonium chloride solution stir, and add 2 g of sodium acetate dissolved in 8 ml of water. Allow to stand in the cold later, filter the dye, wash repeatedly with water, and place on paper to dry. The yield is about 3 g. 

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