Iodide anion

It is to be noted that N-vinylcarbazole (NVC) undergoes also living cationic polymerization with hydrogen iodide at —40 °C in toluene or at —78 °C in methylene chloride and that in this case no assistance of iodine as an activator is necessary 10d). NVC forms a more stable carbocation than vinyl ethers, and the living propagation proceeds by insertion between the strongly interacting NVC-cation and the nucleophilic iodide anion. 

The complex that is formed can dissociate to form a cation (n-tr-complex) and an iodide anion, with the iodide ion reacting with the excess iodine molecules that are present. In addition the decomposition of the n-cr-complex can lead to the formation of highly reactive iodine cations, which can initiate further reactions — e.g. oxidations or electrophilic substitutions of aromatic systems [11, 13]. 

In acidic media the /i-eriodide anions or periodide complexes these — like the iodide anion — are appreciably less reactive than the iodine cation [13]. 

Insulin derivatives lb 401 lodate anions la 188,190 lb 307 Iodine staining lb 278 Iodine-azide reaction lb 85,301-304 Iodide anions la 190 lb 76,77,128,129 Iodide vapor la 46,64,78 lodination la 66... 

The strong affinity of the hard potential trimethylsilyl cation for the hard N-oxide moiety and of the soff cyanide anion (or the soff iodide anion) for the ad-... 

Halogens, the elements in Group 17 of the periodic table, have the largest electron affinities of all the elements, so halogen atoms (a n readily accept electrons to produce halide anions (a a. This allows halogens to react with many metals to form binary compounds, called halides, which contain metal cations and halide anions. Examples include NaCl (chloride anion), Cap2 (fluoride anion), AgBr (bromide anion), and KI (iodide anion). 

Molecular iodine dissolves in a solution containing iodide anions to form triiodide anions ... 

Reaction of diazomethane with sulphinyl chlorides has been known since 1957. Effective procedures for the synthesis of -halogenosulphoxides 217 based on this reaction were reported by Venier and coworkers . Treatment of alkane or arenesulphinyl chlorides with diazomethane in ether solution gives a-chlorosulphoxides 217a in 70-90% yields. When the same reaction was carried out in the presence of iodide anion it yielded the corresponding iodo derivatives 217b in high yields (equation 123). Bromomethyl trichloromethyl sulphoxide was isolated in 15% yield after treatment of trichloro-methanesulphinyl bromide with diazomethane (equation 124). 

Fig. 9 Honeycomb-like architectures formed on self-assembly of halide anions (which work as tridentate XB acceptors and sit at the networks nodes) with 1,4-DITFB (which works as bidentate donor and forms network sides) (A). The angles formed by the XBs around the halide anions determine the corrugation of the honeycomb architecture, a more planar arrangement around the halide anions (as is the case of the iodide anions in adduct l,4-DITFB/Me4P+r (B) with respect to the bromide anions in adduct l,4-DITFB/Ph4P+Br (C)) results in a less corrugated honeycomb architecture...

The self-assembly of tridentate modules with bi- or tridentate partners may afford architectures other than the (6.3) nets described above. For instance, in the co-crystal l,4-DITFB/Ph4P+r the iodide anions work as... 

When one, or both, of the interactive modules are tetradentate, bi- or tridimensional (3D) architectures can be formed. An example of 2D architecture is the (4,4) network present in the complex diiodoacetylene/Ph4P+ Cl (and the analogous complexes formed by bromide or iodide anions) [194] as well as in the complex l,6-diiodoperfluorohexane/tetrakis(4-pyridyl)pentaerythritol [195]. In all these complexes, the XB acceptor works as the tetradentate tecton sitting at the node of the network and the XB donor works as the linear bidentate module that spaces the nodes. 

In related complexes of bromide and iodide anions with tetracyanoben-zene, the halide anions are also surrounded by four acceptor molecules [24], The coordination of the halides in two of these moieties is similar to that observed in TCP complexes, i.e., the anion is arranged above (or slightly outside) of the ring and forms close contacts with the cyano-bearing carbons. On the other hand, coordination with the third TCB occurs via the unsubstituted carbon, and the halide is positioned far outside the ring in this case The fourth acceptor moiety is hydrogen-bonded to the halide (Fig. 11). 

Organomercuric compounds require nucleophilic assistance by soft iodide anions (cf. Section 9.6.3.2.2) for participation in cross-coupling reactions.158 The reaction is useful for aryl-aryl cross-coupling in those cases in which the organomercury species are obtained by direct mercuration of aromatic compounds (38).159... 

Grasdalen, H. and Smidsrod, O. (1981) Iodide-specific formation of K-carrageenan single helices-1-127 NMR spectroscopic evidence for selective site binding of iodide anions in the ordered conformations. Macromolecules, 14, 1842-1845. 

Figure 12.1 Iodide anion in aqueous solution undergoes an equilibrium reaction process to form the reactive H20I+ species.

Figure 12.3 The strong oxidant chloramine-T can react with iodide anion in aqueous solution to form a highly reactive mixed halogen species. 125IC1 then can modify tyrosine and histidine groups in proteins to form radiolabeled products.

Figure 12.6 The immobilized glucose oxidase/lactoperoxidase system radioiodinates proteins through the intermediate formation of hydrogen peroxide from the oxidation of glucose. H2O2 then reacts with iodide anions to form reactive iodine (I2). This efficiently drives the formation of the highly reactive H2OI+ species that is capable of iodinating tyrosine or histidine residues (see Figure 12.2).

The slight steric differences between the alkyl groups of the cations lead to quite different far-orders of their polyiodide anion structures. In solid tBu2iPrPSeI7 [Figure 16(c)], one iodide anion bridges two of the iPr3PSeI+ cations and is in further contact with three I2 molecules the other I anion is in contact with five I2 molecules.59... 

Silver chloride is white silver bromide is pale yellow and silver iodide has a rich yellow colour. We might first think that the change in colour was due to Agl incorporating the iodide anion, yet Nal or HI are both colourless, so the colour does not come from the iodide ions on their own. We need to find a different explanation. 

In our laboratories, we have found that PdI2, in conjunction with an excess of iodide anions, constitutes an exceptionally efficient, selective and versatile catalyst for promoting a variety of oxidative carbonylation processes, leading to important acyclic as well as heterocylic carbonyl compounds. 

An unusual reaction of methoxythiocarbonyl chloride with tetra-n-butylammo-nium iodide in the presence of sodium thiosulphate leads to the formation of 0,5-dimethyl dithiocarbonate [49], The reaction appears to involve a reduction step, with the iodide anion being regenerated from the released iodine by the thiosulphate ions (Scheme 4.7). In the absence of the thiosulphate ions, the thiocarbonyl chloride decomposes to yield chloromethane and carbonyl sulphide. 

Johnson and McCants (161) were the first to show that the alkaline hydrolysis of alkoxysulfonium salts, obtained by 0-alkylation of sulfoxides, proceeds with inversion of configuration at sulfur. This method was employed to interconvert (/ )- and (5)-benzyl p-tolyl sulfoxides 37 as shown in Scheme 21. In contrast to the hydroxide anion, the chloride, bromide, and iodide anions as well as the nitrogen atom of pyridine react with chiral ethoxydiarylsulfonium salts, not at sulfur but at the a-carbon atom of the ethoxy group, yielding the starting sulfoxide with retained configuration (284). On the other hand, the nucleophilic attack of the fluoride anion is directed at sulfur as in the case of the hydroxide anion (285). 

As mentioned earlier (see page 373), methylation of (+)-(i )-ethyl phenyl sulfoxide 136 with methyl iodide in the presence of mercury iodide affords the corresponding oxosulfonium salt (+)-(/ )-l 35 (172). That its demethylation by iodide anion yields sulfoxide 136 with the same configuration as that of the starting one indicates that 5-methylation of sulfoxides occurs with retention of configuration. 

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