Arenediazonium chlorides

When aqueous solutions are mixed with arenediazonium chlorides, the corresponding salts are formed. These salts decompose between 80 and 120 C with a release of mtrogen and formation of aryloxyfluorooxosulfomobis(fluorosuLfonyl)meth-... 

Some observations are important for improvement of the yield and for the elucidation of the mechanism of the Meerwein reaction. Catalysts are necessary for the process. Cupric chloride is used in almost all cases. The best arylation yields are obtained with low CuCl2 concentrations (Dickerman et al., 1969). One effect of CuCl2 was detected by Meerwein et al. (1939) in their work in water-acetone systems. They found that in solutions of arenediazonium chloride and sodium acetate in aqueous acetone, but in the absence of an alkene, the amount of chloroacetone formed was only one-third of that obtained in the presence of CuCl2. They concluded that chloroacetone is formed according to Scheme 10-50. The formation of chloroacetone with CuCl2 in the absence of a diazonium salt (Scheme 10-51) was investigated by Kochi (1955 a, 1955 b). Some Cu11 ion is reduced by acetone to Cu1 ion, which provides the electron for the transfer to the diazonium ion (see below). 

Horner and Stohr (1952) found that in methanol the photolytic formation of the aryl methyl ether is rather a minor process, the main reaction being a hydro-de-di-azoniation. In a comparison between thermal and photolytic dediazoniation in water, Lewis et al. (1969 b) analyzed the percentages of chloro-de-diazoniations for three arenediazonium chlorides in aqueous solution in the presence of various concentrations of NaCl under both thermal and photolytic conditions. The authors came to the conclusion that these processes do not involve the same intermediates. 

Arenediazonium chlorides and hydrogen sulfates react with tetram-ethyltin in aqueous acetonitrile in the presence of a catalytic amount of palladium acetate to give high yields of substituted toluenes.130 One-pot hydrostannylation/Stille couplings with catalytic amounts of... 

Replacement by fluoride ion When arenediazonium chloride is treated with fluoroboric acid, arene diazonlum fluoroborate is... 

TeCl4 in concentrated hydrochloric acid reacts with arenediazonium chlorides giving bis(arenediazonium) hexachlorotellurates that are decomposed by copper powder in acetone to give diaryltellurium dichlorides in low to medium yields. ... 

Silver acetylides have also been used to form bonds with non-carbon centers to produce synthetically useful compounds. Sladkov and coworkers report the reaction of silver acetylides to arenediazonium chlorides to give areneazoethynes.125,126 A necessary condition for the reaction was the presence of para or ortho electron acceptor substituents on the aromatic ring of the diazonium salt (Scheme 1.56). 

Phenacyl selenocyanate and arenediazonium chlorides afford 5-benzoyl-2-imino-2,3-dihydro-l,3,4-selenadiazoles (182 Scheme 76) (80BCJ1185). 4-Substituted 3-selenosemicar-bazides (183), by a cyclocondensation reaction with carbon diselenide, afford 5-substituted 3H-l,3,4-selenadiazoline-2-selones (168) and (170). Compound (183 R = p-tolyl) and thiophosgene give (169 Scheme 77) (77JOC3725). 

Arenetellurolates, prepared from diaryl ditellurium compounds via reduction with sodium borohydride in organic media, interact with arenediazonium chlorides2 and arenediazonium tetrafluoroborates3 to produce unsymmetrical diaryl tellurium products in yields below 50%. The arenediazonium chlorides were added as aqueous solutions to the tellurolates. Arenediazonium tetrafluoroborates were used as solids. 

Arenediazonium chlorides react with elemental tellurium to form diaryl tellurium dichlorides in yields not exceeding 40%. The diazonium salts were prepared from aromatic amines and amyl nitrite14. 

Arenediazonium tetrafluoroborates were unreactive towards tellurium3 under conditions that had produced diaryl tellurium dichlorides from arenediazonium chlorides. However, addition of lithium chloride to a mixture of tellurium and 4-nitrobenzenediazonium tetrafluoroborate led to the formation of bis[4-nitrophenyl] tellurium dichloride in 33% yield2. 

Tellurium tetrachloride and arenediazonium chlorides react to form bis[arenediazoniuin] hexachlorotellurates(IV) that can be decomposed in an acetone suspension in the presence of copper powder1. 

Similar reactions of adenine with arenediazonium chlorides however afforded 8-aryladenines but via an internal free radical process from an aryltriazene (see Section 4.09.5.4.5). 

After the formation of an arylpentazole from an arenediazonium chloride and sodium azide, the accompanying aryl azide is soluble in the petroleum ether, and the sodium chloride stays in the aqueous methanol, whereas generally the arylpentazole is not soluble in any one of the two solvent phases (56AG705, 57CB2914, 58CB2324). The pentazole can be collected by filtration. Note that the crystalline arylpentazoles tend to explode violently at temperatures above their decomposition points (see Table 3) they should be handled with great care, in small amounts and at low temperatures. 

Similarly to 5-hydroxypyrazoles which react with arenediazonium salts to afford 4-arylazo-5-hydroxypyrazoles <84CHEC-I(5)167>, some 4-hydroxypyrazoles yield l-aryl-3-phenylsulfonyl-4-hydroxy-5-arylazopyrazoles on reaction with arenediazonium chlorides using pyridine as solvent <92JHC543>. 

There are many examples of reaction (a) e.g., arenediazonium chlorides add to acrylic and methacrylic acids esters, and nitriles giving / -aryl-chloro-propionic acids, esters, and nitriles 242-244 and <%,/ -unsaturated aldehydes afford 3-aryl-2-chloropropionaldehyde and the analogous 2-bromo aldehydes.245,246 Butadiene undergoes 1,4-addition.247-249 Phenylacetylene and a benzenediazonium chloride solution that has been neutralized with sodium carbonate solution gives, at 25-30°, a 46.5% yield of <%-chlorostilbene.250... 

One of the principal syntheses of the pharmacologically interesting aryl-arsonic acids is provided by treatment of arenediazonium chlorides with sodium arsenites (the Bart reaction), e.g. ... 

According to Waters results,27,28 the formation of aryl-metal compounds on decomposition of arenediazonium chlorides in the presence of metals such as mercury, antimony, bismuth, lead, and tin also occurs by way of radicals, in contrast to the Nesmeyanov reaction. 

In a variant of this process arenediazonium chlorides are decomposed directly by finely divided metallic mercury at 0-5° 181... 

Good yields of triarylarsines are further obtained when arenediazonium chlorides or their double salts (ArN2)2ZnCl4 decompose in the presence of arsenic trichloride or chloroarsines in a suspension of zinc dust in acetone 510... 

Arenediazonium chloride-antimony pentachloride double salts decompose in the presence of cuprous chloride in acetone in the following manner 527... 

Zinc is considered to be a borderline transition metal. ZnCl2 is used as an additive to arenediazonium chlorides because it increases the inertness ( kinetic stability ) towards explosive dediazoniation. Three X-ray investigations of such so-called double salts (ArNi )2ZnCl4 (see Zollinger, 1994, p. 24) reveal that the two diazonium ions are not coordinated to the metal atom (Mostad and Romming, 1968). These compounds are not, therefore, complexes containing aryldiazenido ligands. 

Thiiran reacts with arenediazonium chlorides to give 2-(arylthio)ethyl radicals. Thiirans have been proposed as intermediates in the reaction of sulphines with thiophilic reagents, in the low-yield synthesis of tetracyclo[ 12.4.1.1 l ]hen-icosanonaene, and in the conversion of (51) into (52) by sodium ethoxide in DMF or by concentrated sulphuric acid. ... 

Arenediazonium salts can be precipitated as their tetrafluorobo-rate salts by addition of a cold solution of HBF4 to a solution of the initial arenediazonium chloride. 4-Methoxybenzenediazonium tetraduoroborate is thus obtained in 94—98% yield. The ary-lamine can be diazotized with Sodium Nitrite in the presence of HBF4, and the diazonium fluoroborate then precipitates directly. 3-Nitroaniline, when treated in this manner, provides a 90-97% yield of 3-nitrobenzenediazonium tetrafluoroborate (eq 1). Diazotizations of arylamines and heteroarylamines in organic solvents can be conveniently conducted using HBF4-OEt2 and alkyl nitrites. ... 

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