Oxidation with Diazonium Salts

As Schaffer has found 2.4.6-triphenyl-X -phosphorin 22 and other 2.4.6-tri-substituted X -phosphorins react smoothly with aryl diazonium salts in benzene. Nitrogen develops and the aryl residue bonds with the phosphorus. In presence of alcohols as nucleophiles, l-alkoxy-l-aryl-2.4.6-triphenyl-X -phosphorins 100 can be isolated. The aryl diazonium-tetrafluoroborate without any nucleophile in DMOE yields l-aiyl-l-fluoro-2.4.6-triphenyl-X -phosphorin 70i. As with other oxidants like halogen or mercury-Il-acetate, we suppose that in the first step triphenyl-X -phosphorin radical cation is formed. This could be shown by ESR spectroscopy. The next step may be a radical-radical addition to the X -phosphorin cation or a nucleophile ation addition to the X -phosphorin radical these than are transformed to the endproducts by a nucleophilic or radical addition respectively  

These reactions are related to the reaction of aryl diazonium salts with iodide yielding iodoaryls, the mechanism of which seems to be a one-electron transfer (radical) reaction and not a nucleophilic displacement. Just as iodide is easily oxi- zed to iodine by the aryl diazonium cation, 2.4.6-triphenyl-X -phosphorin is oxidized to the radical cation 58. 

When 2.4.6-triphenyl-X -phosphorin 22 is treated with an excess of the diazonium salt, for instance, 2-methyl-4-nitro-phenyl-diazonium-tetrafiuoroborate 102 in benzene/methanol, a doubly atylated X -phosphorin 103 can be isolated 

Compounds prepared by these methods are summarized in Table 14. The substance 100 was also prepared by Markl via pyrylium salt and phenylphosphine, s. Table 23, p.98. 

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Alkyl and aryl arenediazoates ( diazoethers ) are generally unstable and even explosive compounds. They are produced by interaction of alcohols with (explosive) bis(arenediazo) oxides, or of -blocked phenols with diazonium salts. The thio analogues are similar. Individually indexed compounds are ... 

Since A,A -disubstituted hydrazines are readily available from a variety of sources (see Volume I, Chapter 14), their dehydrogenation constitutes a widely applicable route to both aliphatic and aromatic azo compounds. Such oxidative procedures are of particular value in the aliphatic series because so many of the procedures applicable to aromatic compounds, such as the coupling with diazonium salts, have no counterpart. The oxidation reactions permit the formation not only of azoalkanes, but also of a host of azo compounds containing other functional groups, e.g., a-carbonyl azo compounds [83], a-nitrile azo compounds [84], azo derivatives of phosphoric acid [85], phenyl-phosphoric acid derivatives [86],... 

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,... 

Diselenides are generally prepared by the aerial oxidation of selenols or selenolates (see Section 2) or by the reaction of Li2Sc2, Na2Se2, or other 802 species with alkyl or aryl halides. In the latter case, elevated temperatures and DMF as the solvent are recommended. Aryl diselenides may also be obtained from the reaction of 802 with diazonium salts (Scheme 6). Relatively few unsymmetrical diselenides have been reported. Triselenides are also known but have not been as widely studied. 

SAFETY PROFILE Poison by intravenous route. Moderately toxic by ingestion and intraperitoneal routes. Human teratogenic effects by ingestion developmental abnormalities of the endocrine system. Experimental teratogenic and reproductive effects. Mutation data reported. Explosive reaction with charcoal + ozone, trifluoroacetyl hypofluorite, fluorine perchlorate. Violent reaction or ignition on contact with diazonium salts, diisopropyl peroxydicarbonate, bromine pentafluoride, chlorine trifluoride. Incompatible with oxidants, BrFs, FCIO, metallic salts, calomel. When heated to decomposition it emits very toxic fumes of K20 and I . See also IODIDES. 

Treatment of acylhydrazines with diazonium salts gives rise to tetrazenes (199) which can be readily dehydrated with base to give 1,5-disubstituted tetrazoles (Scheme 33). The reaction is also effective with 1,2-diacylhydrazines since one of the acyl groups is cleaved during the dehydrative cyclization, which may be conveniently carried out in situ without isolation of the tetrazene. This reaction can be useful for the synthesis of 1-aryltetrazoles using 1,2-diformylhydrazine as substrate (B-67MI41300). Mesoionic tetrazolium 5-oxides (8a) are obtained on treatment of bis(alkylsulfonyl)methanes with diazonium salts. Hydra-zones of type (200) are also obtained from these reactions and the tetrazenes... 

Bulka et al.,22 during the attempted preparation of selenazole formazans, found that the hydrazones of the selenazoles with unsubstituted 5-positions reacted with diazonium salts to give 5-azo derivatives preferentially. Thus coupling 2-benzylidenehydrazino-4-phenyl-selenazole with diazotized o-phenetidine afforded two compounds that could be separated chromatographically on aluminum oxide. The main product (67%) was 2-benzylidenehydrazino-4-phenyl-5-(o-ethoxybenzeneazo) selenazole (7), which formed ruby red prisms with a green surface sheen, mp 206°C.29 The desired formazan formed the minor product (see Section II,B,6). 

Dialkyl cyanomethylphosphonates, possessing both an active methylene gronp and an electrophilic cyano group, react under basic conditions with arylazidcs, arylnitrile oxides, 5 diazonium salts of indazoles, pyrazoles, and triazoles and isatoic anhydride to produce intermediates that spontaneously cyclize, giving heterocyclic systems. 

The initial intent to cover the subject exhaustively had to be abandoned because of the overwhelming amount of relevant literature. The following reactions are not covered but are briefly discussed, with references to reviews and seminal papers, in the section on Comparison with Other Methods reactions of carbanions and enolates and their surrogates with nitrogen oxides, nitrite and nitrate esters, and nitroso and nitro compounds reactions of enolates with diazonium salts, including the Japp-Klingemann reaction the diazo transfer reaction except as it interferes with the synthesis of azides the animation of boranes and the Neber rearrangement. 

Some more reactions comprising the oxidation or reduction of nanotubes are described in the sections on side-wall functionalization. They include, for example, the ozonization, the electrochemical reaction with diazonium salts, and the hydrogenation with various reagents. Furthermore nanotubes are either reduced or oxidized, depending on the bonding partner, in the formation of charge transfer complexes. Examples can be found in Sections 3.5.4.2 and... 

Silver fluoborate, reaction with ethyl bromide in ether, 46, 114 Silver nitrate, complexing with phenyl-acetylene, 46, 40 Silver oxide, 46, 83 Silver thiocyanate, 46, 71 Sodium azide, reaction with f-butyl chloroacetate, 46, 47 reaction with diazonium salt from fi-amino-/> -nitrobiphenyl, 46,... 

SULFURE de METHYLE (French) (75-18-3) Forms explosive mixture with air (flash point -36°F/-38°C). Reacts with water, steam, acids, acid fumes, producing hydrogen sulfide fumes, which can explode in air. Reacts violently with strong oxidizers, chlorobenzene-diazonium salts, mercurous chloride. Incompatible with zinc acetate. Flow or agitation of substance may generate electrostatic charges due to low conductivity. 

Many easily oxidized organic sulfides exist, but, of these, tetrathiafulvalene [2] (TTF) has been more extensively researched than most, because of interest in the electrical properties of its salts. Its oxidation potential makes it a reasonable electron donor [3]. Arenediazonium salts were chosen as the partner reagents since their electron-accepting properties had been well explored [4, 5]. Furthermore, reaction of TTF with diazonium salts had recently been discussed in the Russian literature [6], but this reported only the formation of the radical-cation, TTF+. We were keen... 

Examples of postprocess systems under evaluation include surface oxidation using ozone, hydrogen peroxide, or nitric acid. Such approaches are used in the production of conductive blacks. Reaction with diazonium salts, plasma treatment, and polymer grafting are also under investigation. 

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