Azide ions, oxidation

Diphenylthiirene 1-oxide reacts with hydroxylamine to give the oxime of benzyl phenyl ketone (79JA390). The reaction probably occurs by addition to the carbon-carbon double bond followed by loss of sulfur monoxide (Scheme 80). Dimethylamine adds to the double bond of 2,3-diphenylthiirene 1,1-dioxide with loss of sulfur dioxide (Scheme 81) (75JOC3189). Azide ion gives seven products, one of which involves cleavage of the carbon-carbon bond of an intermediate cycloadduct (Scheme 81) (80JOC2604). 

The effect of a substituent may be substantially modified by fast, concurrent, reversible addition of the nucleophile to an electrophilic center in the substituent. Ortho- and para-CS.0 and pam-CN groups have been found by Miller and co-workers to have a much reduced activating effect on the displacement of halogen in 2-nitrohaloben-zenes with methoxide ion [reversible formation of hemiacetal (143) and imido ester anions (144)] than with azide ion (less interaction) or thiocyanate (little, if any, interaction). Formation of 0-acyl derivatives of 0x0 derivatives or of A-oxides, hydrogen bonding to these moieties, and ionization of substituents are other examples of reversible and often relatively complete modifications under reaction conditions. If the interaction is irreversible, such as hydrolysis of a... 

The only examples of fully unsaturated tetrazoloazepines, e.g. 3, have been prepared by an unusual and intriguing reaction involving the action of azide ion on 4,7-disulfonylbenzofurazan 1-oxides, e.g. I.148 A mechanistic rationale involving intramolecular 1,3-dipolar cycloaddition of an azidonitrile intermediate, e.g. 2, has been proposed. 

The azide ion is a highly reactive polyatomic anion of nitrogen, N3 . Its most common salt, sodium azide, NaN3, is prepared from dinitrogen oxide and molten sodium amide ... 

There is an extensive chemistry associated with coordination compounds containing azide ions as a ligands. Like CN-, the azide ion is a pseudohalide ion, which means that it forms an insoluble silver salt, exists as the acid H-X, X-X is volatile, and it can combine with other pseudohalogens to give X-X. Although other pseudohalogens such as (CN)2 result from the oxidation of the CN- ion,... 

These solution NMR and X-ray crystallographic findings have been contradicted by X-ray structures solved by Rypniewski et al.32 The results show a reduced active site unchanged from the oxidized state and let these authors to propose a five-coordinate copper ion that exists throughout the oxidation and reduction process. In 2001 the Protein Data Bank listed 39 X-ray crystallographic and NMR solution structures for CuZnSOD, including oxidized, reduced, genetically modified, and other species with or without attached substrates or substrate mimics such as azide ion. The reader is advised to search the Protein Data Bank for additional and more up-to-date structural depositions and search the literature for further discussion of mechanism. 

Table 11 summarizes results of spin trapping experiments where PBN-Nu and other ST-Nu" systems have been oxidized anodically at platinum. Originally, all the reactions were suggested to proceed via Nu radicals (Janzen et al., 1980 Walter et al., 1982), but the fact that PBN is oxidized at a lower potential than Cl-, CNO and CN- (Tables 1 and 5) clearly shows that the faster electrochemical process must be PBN— PBN + at the potentials employed. On the other hand, azide ion is oxidized in a faster reaction than any of the spin traps used and thus azide radical is implicated as being trapped. The Cr 4MePyPBN [17] system is a case where possibly Cl is involved in view of the high pa of this spin trap. 

At least a part of the sulfur is chemically bonded to the surface and is not present in elementary form. This was proven by the catalysis in the oxidation of azide ions by iodine ... 

Hydroxyl radicals were generated radiolytically in NaO-saturated aqueous solutions of thiourea and tetramethylthiourea. Conductometric detection showed that HO and a dimeric radical cation were produced. The dimeric radical cation is formed by addition of a primary radical to a molecule of thiourea. In basic solution, the dimeric radical cation decays rapidly to a dimeric radical anion, which is formed via neutralization of the cation and subsequent deprotonation of the neutral dimeric radical (Scheme 16). This was not observed in tetramethylurea. These dimeric radical cations of thiourea and tetramethylurea are strong oxidants and readily oxidize the superoxide radical, phenolate ion, and azide ion. 

Azide ions are oxidised at low positive potentials and generate azide radicals. Azide radicals will add to an alkene. Thus the anodic oxidation of enol ethers in... 

Thermally unstable 1,2,3,4-thiatriazolines are reported as possible transient intermediates in the reaction between azide ion and thiobenzophenone (46) or thiobenzophenone 5-oxides (47) (Scheme... 

Hydrazinofluorophosphines, 13 393 Hydrazoic acid, 9 134 reaction mechanisms, 22 131-135 of coordinated azide ion, 22 133-135 oxidation by metals, 22 131, 132 by nonmetals, 22 132, 133 thermal decomposition of, 14 121 Hydrides... 

This mechanism can be illustrated by the reaction of ferrous ions with hydrogen peroxide (42), the reduction of organic peroxides by cuprous ions (63), as well as by the reduction of perchlorate ions by Ti(III) (35), V(II) (58), Eu(II) (71), The oxidation of chromous ions by bromate and nitrate ions may also be classified in this category. In the latter cases, an oxygen transfer from the ligand to the metal ion has been demonstrated (8), As analogous cases one may cite the oxidation of Cr(H20)6+2 by azide ions (15) (where it has been demonstrated that the Cr—N bond is partially retained after oxidation), and the oxidation of Cr(H20)6+2 by 0-iodo-benzoic acid (6, 8), where an iodine transfer was shown to take place. 

Similar reactivity is known for divalent sulfur nucleophiles (75JA3850). For 3,3-dimethyl-1,2-dioxetane, initial attack at carbon by azide ion has been postulated to explain the formation of acetone and nitrogen and imine TV-oxide (Scheme 40) (71TL749,72JA1747). 

I7.S. The production of pseudohalcgens requires mild oxidizing conditions (Eq. I7.7S). Why do you suppose that it has never been possible to oxidize the azide ion to hexanitrogen (di.izyl) ... 

G. Miscettaneous Nwdeopkilic Additions (1) Azide ion. The ready cleavage of ethylene oxide rings by N. ion is in acoordanoe with its recognized nucleophilic character. Alllums-Ii so far limited to three,6 8-127 -1778 publications devoted to this reaction have explored the behavior of a wide assortment of epoxides. Jt. is customary to characterize 0-azido alcohol obtained on treatmml of epoxides with aqueous sodium azide by reduction to /1-atnirm aa-o-hok.iwo. ins aa shown in Eq. (896). 

The azides, except those of mercury) ), Hg(l,i, thalliura(l), 11(1), copper. Cu, silver, Ag, and lead, Pb, are readily prepared from hydrazoic acid and the oxide or carbonate of the metal, or by metathesis of the metal sulfate with barium azide. They are all thermally unstable, giving nitrogen and free metal or occasionally nitride. The azide ion appears to resonate between four structures ... 

Azide ion also reacts with the dication [RuCl(NO)(bipy)2]2+ above) but leads to complete removal of the nitric oxide group. It is possible that an intermediate is first formed, containing a N40 group, and this then decomposes. The overall reaction is shown in equation (24). 

Lead azide is dissolved by an aqueous solution of ammonium acetate, but it is not destroyed by it. The solution contains azide ions and lead ions, the latter quantitatively precipitable as lead chromate, PbCr04, by the addition of potassium dichromate solution. Lead azide in aqueous suspension is oxidized by ceric sulfate with the quantitative production of nitrogen gas which may be collected in an azotometer and used for the determination of the azide radical. 

Cyclic sulfites (68) also are opened by nucleophiles, although they are less reactive than cyclic sulfates and require higher reaction temperatures for the opening reaction. Cyclic sulfite 77, in which the hydroxamic ester is too labile to withstand ruthenium tetroxide oxidation of the sulfite, is opened to 78 in 76% yield by reaction with lithium azide in hot DMF [82], Cyclic sulfite 79 is opened with nucleophiles such as azide ion [83] or bromide ion [84], by using elevated temperatures in polar aprotic solvents. Structures such as 80 generally are not isolated but as in the case of 80 are carried on (when X = N3) to amino alcohols [83] or (when X = Br) to maleates [84] by reduction. Yields are good and for compounds unaffected by the harsher conditions needed to achieve the displacement reaction, use of the cyclic sulfite eliminates the added step of oxidation to the sulfate. 

Sr(N3)j is not discussed by Sax (Ref 24) but its effects should be considered similar to those of the alkali and alkaline earth azides Sr azide was first prepd in 1898 by Dennis Benedict (Ref 1) and in the same year by Curtius Rissom (Ref 2) by the action of HNj on the oxide, hydroxide or carbonate of Sr. Its prepn has also been described by Mellor (Ref 7), Gmelin (Ref 9), Audrieth (Ref 10) and others (Refs 11, 15, 18, 19 25). The cryst structure of Sr(N3)2 was investigated to a limited extent by A.C.Gill (cited in Ref 1) and in detail by Llewellyn Whitmore (Ref 15) who established its orthorhmb nature as ionic, with a linear sym azide ion, N N 1.12A, and Sr to N distance of 2.63 to 27lX. Kahovec Kohlrausch (Ref 16) detd, from the Raman Effect, both on cryst powd and in soln, frequencies which corresponded to sym. oscillation in a linear triatomic molecule. 

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