Iodine tris , reactions

Vicinal iodo carboxylates may also be prepared from the reaction of olefins either with iodine and potassium iodate in acetic acid/ or with N-iodosuccinimide and a carboxylic acid in chloroform. " A number of new procedures for effecting the hydroxylation or acyloxylation of olefins in a manner similar to the Prevost or Woodward-Prevost reactions include the following iodo acetoxylation with iodine and potassium chlorate in acetic acid followed by acetolysis with potassium acetate reaction with iV-bromoacetamide and silver acetate in acetic acid reaction with thallium(III) acetate in acetic acid and reaction with iodine tris(trifluoroacetate) in pentane. ... 

The use of tt trahydrofuryl derivatives for synthesis of racemic sugar derivatives has also been reported. It was found that iodine tris(tri-fluoroacetate) oxidizes tetrahydrofuryl trifluoroacetate, to yield a mixture of four diastereomeric 3-deoxypentofuranoses (413-416) in the ratios of 25 15 4 6. The main product, 3-deoxy-f/ireo-pentofuranose tris(trifluoroacetate) (413), readily crystallized out of the reaction mixture.269... 

Potassium iodide solution in the presence of concentrated hydrochloric acid, iodine is precipitated upon shaking the mixture with 1 -2 ml of chloroform, the latter is coloured violet by the iodine. The reaction may be used for the detection of arsenate in the presence of arsenite oxidizing agents must be absent. Excess of the reagent dissolves iodine to form tri-iodide ions. 

Catalysis of iodine-azide reaction test traces of thiocyanates act as powerful catalysts in the otherwise extremely slow reaction between tri-iodide (iodine) and sodium azide ... 

Tetrahydrofurfuryl alcohol was transformed directly into a mixture of diaster-eoisomeric 3-deoxypentofuranoses (183-186) by the action of iodine tris(trifluoroacetate). The main component the trifluoroacetate of 3-deoxy-a-DL-r/ireo-pentofuranose (183) crystallized out of the reaction mixture. ... 

Iodosyl fluorosulfate, OIOSO2F and the triflate, OIOTf, can be prepared as thermally stable, hygroscopic yellow solids by the reaction of iodine with iodine pentoxide or iodic acid in fluorosulfonic or trifluoromethanesulfonic acids, respectively [5]. Raman and infrared spectra of these compounds indicate a polymeric structure analogous to iodosyl sulfate [5], Iodine tris(fluorosulfate), I(0S02F)3 and tris(triflate), I(OTf)3, are also known [6,26]. I(0S02F)3 can be prepared by the reaction of iodine with peroxydisulfuryl ditluoride [26]. Salts such as KI(0S02F)4 have also been prepared and investigated by Raman spectroscopy [26,27]. I(OTf)3 was prepared from iodine tris(trifluoroacetate) and trifluoromethanesulfonic acid [6]. 

Aqueous solutions of I3 have an intense yellow to brown color. The vapor pressure of iodine is important even when it is in solution. Over time, aqueous solutions of iodine exhibit a spontaneous decrease in their concentrations by vaporization. Iodine is freely soluble in organic solvents. As a practical consequence of these properties, tri-iodide ions are used in direct iodometric titfations rather than aqueous solutions of I2. Due to the iodine/tri-iodide equilibrium, whose formation constant is weak, I3 solutions contain more and less free iodine I2, which is more and less liberated as the titration reaction evolves further. In a first approximation, tri-iodide ion solutions behave like iodine solutions. The formation of this ion complex has two interests. On the one hand, it (apparently) increases the solubility of iodine, permitting the attainment of I2 concentrations that allow practical titrations. On the other hand, the fact that iodine is in large part under the form of the tri-iodide complex rather than under the free form somewhat precludes its vaporization. However, the latter fact remains nonnegligible. 

This may be the explanation of the fact that tri-iodide ions appear again about the equivalence point of the iodine/thiosulfate reaction. 

Reactions.—Alkanes can be oxidized by iodine tris(trifluoroacetate) to a mixture of mono and bis(trifluoroacetates). With certain alkanes, particularly those with tertiary carbon centres, the reaction can be of synthetic utility (Scheme 2). This... 

The reactions involved are similar in both cases, and closely parallel to those which give rise to chloroform. The sodium hypochlorite probably first oxidises the potassium iodide to potassium hypoiodite, which then oxidises the ethanol to acetaldehyde and then iodinates the latter to tri-iodo ... 

The reactions of trialkylboranes with bromine and iodine are gready accelerated by bases. The use of sodium methoxide in methanol gives good yields of the corresponding alkyl bromides or iodides. AH three primary alkyl groups are utilized in the bromination reaction and only two in the iodination reaction. Secondary groups are less reactive and the yields are lower. Both Br and I reactions proceed with predominant inversion of configuration thus, for example, tri( X(9-2-norbomyl)borane yields >75% endo product (237,238). In contrast, the dark reaction of bromine with tri( X(9-2-norbomyl)borane yields cleanly X(9-2-norbomyl bromide (239). Consequentiy, the dark bromination complements the base-induced bromination. 

The reaction of tris(trifluoromethyl)bismuthine with chlorine, bromine, or iodine, however, has been found to yield the corresponding bismuth trihahde and trifluoromethyl hahde (61) ... 

Trimethylarsine gives a 98% yield of trimethylarsine difluoride when treated with xenon difluoride [102] in fluorotrichloromelhane. and tnsfpentafluorophen-yl)arsine gives a 94% yield of tris(pentafluornphenyl)arsme difluoride after reaction with dilute fluorine in fluorotnchloromethane at 0 C [106] Other trivalent arsenic compounds have also been fluorinated with xenon difluoride [103] In addition, arsines have been oxidatively fluorinated by iodine pentafluoride [107] or electrochemically in 26-34% yield [108]... 

Tire condensation method (Section II,A,1) applied for 1,2,4-thiadia-zolium salts and phenylsubstituted imidazoles leads to the thia-tetraazaful-valenes 91 and 92 (70TL481). Moreover, 2,4,5-tris(ethylsulfanyl)imida-zolium chloride was converted to the unsymmetrical heterofulvalene 93 by a self-condensation reaction in the presence of potassium carbonate and elemental iodine (85PS223) (Scheme 37). 

It is, however, more likely that the discrepancies observed in the periodate oxidation of malonaldehyde concern mainly the hydroxylation step. In the mechanism proposed (5) for this reaction, it is the enol form of malonaldehyde which is hydroxylated. However, titrations of a solution of malonaldehyde, prepared by hydrolysis of an aqueous solution (33) of carefully distilled 1, 3, 3-tri-ethoxypropene (46, 47), both with strong base and with iodine, indicate that only about 80% of the enol form is present in the equilibrium solution. On the other hand, the thio-barbituric acid test (58, 59) gave consistently higher values for the malonaldehyde content of the solution. The fact that only about 80% of the enol form is present in the equilibrium solution is all the more important as it can be shown (56) by titration with strong base that the enolization is slow, and moreover does not seem to go to completion. 

The reaction has been extended (106) to the nucleoside field and provides a means for the direct iodination of suitably protected nucleosides. Thus treatment of 2,3-O-isopropylidene uridine (68) with tri-phenylphosphite methiodide in N,2V-dimethylformamide at room temperature afforded the corresponding crystalline 5-deoxy-5-iodo analog 69 in 77% yield. 

In most direct titrations with iodine (iodimetry) a solution of iodine in potassium iodide is employed, and the reactive species is therefore the tri-iodide ion 13. Strictly speaking, all equations involving reactions of iodine should be written with 13 rather than with I2, e.g. 

The cleavage of phenylmercuric iodide by iodine in the presence of excess iodide ion (to suppress free-radical reactions) at 25 °C in aqueous dioxan was reported to be first-order in both aromatic and tri-iodide ion, and faster than the reaction of alkylmercuric iodides724. A further study, together with bromodemercuration, both reactions being generally represented by... 

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