Sodium metavanadate as volumetric reagent : Determination of organic derivatives of hydrazine,iodine monochloride method

Sodium metavanadate has been used as an oxidising agent in hydrochloric acid medium for the volumetric determination of semicarbazide hydrochloride, benzalazine, benzalsemicarbazone, aminoguanidine hydrochloride, o-hydroxybenzalsemicarbazone, p-methoxybenzalsemicarbazone, chloralhydrazine, o-chlorobenzalsemicarbazone and ethyl methyl ketone semicarbazone, using 10-dine monochloride as a catalyst and preoxidiser Chloroform was used as an indicator. It was coloured violet due to the liberation of iodine during the titration and became light pale yellow at the end-point owing to the formation of iodine monochloride Eachhydrazino group in these compounds was oxidised quantitatively with a four-electron change to nitrogen with sodium metavanadate as an oxidant in hydrochloric acid solution.     

Volumetric studies in oxidation-reduction reactions : Oxidation with sodium hypochlorite iodine monochloride method

Alkaline sodium hypochlorite was used as an oxidant to determine arsenious oxide, hydrazine sulphate, ferrous ammonium sulphate, stannous chloride, sodium sulphite, potassium iodide, mercurous chloride, thallous chloride and tartar emetic, by a volumetric method, using iodine monochloride as catalyst and preoxidizer. During these titrations, the normality of the solution with respect to hydrochloric acid was kept between 5N and 7N, Chloroform was used as an indicator. Its pink colour due to the liberation of iodine during the titration turns very pale yellow at the end-point because of the formation of iodine monochloride     

Diethylenetetra-ammonium sulphatocerate as volumetric reagent: Iodine monochloride method

The method of preparation of diethylenetetra-ammoniuin sulphatocerate is described. This substance has been used as an oxidant to determine potassium iodide, ferrous ammonium sulphate, arsenious oxide, stannous chloride, hydrazinc sulphate, thallous chloride. hydroquinone and potassium ferrocyanide by a volumetric method, using iodine inonochloride as catalyst and preoxidizer. During these titrations, normality of the solution with respect to hydrochloric acid has been kept at about 6N. Chloroform is used as an indicator. It is 'coloured pink owing to the liberation of iodine during the titration and becomes very pale yellow at the end-point because of the formation of iodine monochloride.     

New chiral hypervalent iodine(V) compounds as stoichiometric oxidants

The synthesis and application of some new hypervalent iodine compounds bearing chiral and achiral ester motives derived from easily accessible starting materials is presented. The oxidation is carried out using dimethyldioxirane as an oxidant providing the desired compounds in moderate to high yields. A crystal structure analysis for one iodine(V) derivative is investigated. The λ⁵-iodanes are applied as stoichiometric reagents in the oxidation of thioanisole to phenylmethyl sulfoxide, benzyl alcohol to benzaldehyde, and meso-hydrobenzoine to benzaldehyde, benzyl, and benzoin.     

Mechanism and reaction rate of the karl-fischer titration reaction: Part I. Potentiometric measurements

The reaction rate of the coulometric variant of the Karl-Fischer titration reaction (in which electrolytically generated triiodide is used as oxidant instead of iodine) has been measured in methanol. The reaction is first order in water, sulfur dioxide and triiodide, respectively. For pH<5 the reaction rate constant decreases logarithmically with decreasing pH. Addition of pyridine solely influences the pH (by fixing it to a value of about 6) and has no direct influence on the reaction rate. A linear relation exists between the reaction rate constant and the reciprocal value of the iodide concentration, from which we can calculate the individual reaction rates for the oxidation by iodine and triiodide, respectively. While the reaction rate constant for triiodide is relatively small (k₃≈350 l² mol^?2s^?1), the reaction rate constant for iodine is much larger (k₃≈1.5×10⁷ l² mol^?2 s^?1.     

Transition metal free one pot synthesis of aryl carboxylic acids via dehomologative oxidation of styrenes

Iodine/NaOH-catalyzed one-pot dehomologative oxidation of styrenes to aryl carboxylic acids has been reported. A wide range of carboxylic acids are obtained using iodine (I₂) as a catalyst, tert-butyl hydroperoxide (TBHP) as an oxidant and sodium hydroxide (NaOH) as a base. This reliable conversion involves dehomologation of styrene to aromatic aldehyde which on subsequent oxidation affords aryl carboxylic acid. This protocol was used for gram-scale synthesis as it is free from chromatographic purification. This is the first report for the oxidative transformation of styrenes into aryl carboxylic acids under transition metal-free conditions.     

Tandem Catalytic C(sp3)H Amination/Sila‐Sonogashira–Hagihara Coupling Reactions with Iodine Reagents

A new tandem C? N and C? C bond‐forming reaction has been achieved through Rh^II/Pd⁰ catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by‐product is used as a coupling partner. The overall process demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations.     

Tandem Catalytic C(sp3)?H Amination/Sila‐Sonogashira–Hagihara Coupling Reactions with Iodine Reagents

A new tandem C N and C C bond‐forming reaction has been achieved through Rh^II/Pd⁰ catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by‐product is used as a coupling partner. The overall process demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations.     

A new hypervalent iodine(iii/v) oxidant and its application to the synthesis of 2H-azirines

The reaction of o-nitroiodobenzene and mCPBA in acetic acid was found to afford a novel hypervalent iodine compound, in the structure of which both iodine(iii) and iodine(v) moieties coexist. The nitro groups at the ortho phenyl positions were found to be crucial in stabilizing this uncommon structure. This novel hypervalent iodine(iii/v) oxidant is proved to be effective in realizing the synthesis of 2-unsubstitued 2H-azirines via intramolecular oxidative azirination, which could not be efficiently achieved by the existing known hypervalent iodine reagents.

The reaction of o-nitroiodobenzene and mCPBA in AcOH was found to afford a novel hypervalent iodine compound which both iodine(iii) and iodine(v) moieties coexist. This new reagent is proved to be effective in realizing the synthesis of 2H-azirines.     

Mild regioselective iodination of pyrazoles using <Emphasis Type="Italic">n</Emphasis>-butyltriphenylphosphonium peroxodisulfate

A practical, efficient and inexpensive method of synthesis of iodopyrazoles by the reaction of pyrazoles with iodine using n-butyltriphenylphosphonium peroxodisulfate as an oxidant at room temperature is reported. The use of n-butyltriphenylphosphonium peroxodisulfate is feasible due to its easy preparation and handling, high stability and activity.     

Ultrasound-assisted tandem synthesis of tri- and tetra-substituted pyrrole-2-carbonitriles from alkenes,TMSCN and N,N-disubstituted formamides

An energy-saving and eco-friendly method for the efficient construction of various tri- and tetra-substituted pyrrolecarbonitriles through ultrasound-assisted multicomponent tandem reaction of readily available alkenes, TMSCN and N,N-disubstituted formamides within 40 min under metal-, solvent-free and mild conditions was developed. The dual role of iodine (catalyst and oxidant) notably simplified the reaction conditions and reduced the chemical waste generated     

An efficient chlorination of aromatic compounds using a catalytic amount of iodobenzene

An efficient method was developed for chlorination of aromatic compounds with electron-donating groups using iodobenzene as the catalyst and m-chloroperbenzoic acid as the terminal oxidant in the presence of 4-methylbenzenesulfonic acid in THF at room temperature for 24 h,and a series of the monochlorinated compounds was obtained in good yields.In this protocol,the catalyst iodobenzene was first oxidized into the hypervalent iodine intermediate,which then treated with lithium chloride and finally reacted with aromatic compounds to form the chlorinated compounds.     

A synthetic approach to carbazoles using electrochemically generated hypervalent iodine oxidant

Carbazoles were successfully synthesized by oxidative cyclization of the corresponding diaryl derivatives using electrochemically generated hypervalent iodine oxidant. Electron-withdrawing nitro and donating methoxy groups at the para position of the acetamide group interfered with cyclization. Glycozoline (8) was successfully synthesized in five steps with 50% overall yield.     

Approach for the Direct Synthesis of β-Dichlorosubstituted Acetanilides Using Iodine Trichloride (ICl3) as the Oxidant and Catalyst

A reliable method for direct synthesis of β‐dichlorosubstituted acetanilides is reported. The key transformation involves the oxidative and catalytic cleavage of a carbon‐carbon bond in the presence of iodine trichloride (ICl₃). In this protocol ICl₃ is used not only as the catalyst but also as the oxidant which widely broadens the scope of its application in organic synthetic chemistry.     

Preparation of chiral bipyridine bis-N-oxides by oxidative dimerization of chiral pyridine N-oxides

The direct preparation of chiral 2,2′-bipyridine bis-N-oxides has been developed. The method involves two stages, first, the deprotonation of substituted chiral pyridine N-oxides and second, the oxidative dimerization of the resulting 2-lithiopyridine N-oxides. Optimization of the reaction conditions led to the selection of LiTMP in THF for the deprotonation and molecular iodine as the oxidant. The corresponding 2-iodopyridine N-oxide is invariably formed as a by-product. A series of 11 chiral pyridine N-oxides was prepared that bear substituents at the C(2) and C(5) positions. Oxidative dimerization of these mono-N-oxides proceeded in 33–77% yield. In all cases, the dimerization was highly diastereoselective for the formation of the P-configuration of the chiral axis.     

Aerobic oxidative iodination of organic molecules activated by sodium nitrite

Aerobic oxidative iodination activated by sodium nitrite occurs effectively and selectively with 100% iodine atom economy with air as the oxidant. Silica-supported sulfuric acid was used for the activation of the catalyst and iodination. Thus, I₂/NaNO₂/air/silica-supported H₂SO₄ in acetonitrile iodinated aromatics, ketones and aldehydes effectively at ambient temperature.     

Simple and regioselective oxyiodination of aromatic compounds with ammonium iodide and Oxone

A simple method for the iodination of aromatic compounds using NH₄I as the iodine source and Oxone^® as the oxidant is described.     

The Multiple Facets of Iodine(III) Compounds in an Unprecedented Catalytic Auto‐amination for Chiral Amine Synthesis

Iodine(III) reagents are used in catalytic one‐pot reactions, first as both oxidants and substrates, then as cross‐coupling partners, to afford chiral polyfunctionalized amines. The strategy relies on an initial catalytic auto C(sp³)?H amination of the iodine(III) oxidant, which delivers an amine‐derived iodine(I) product that is subsequently used in palladium‐catalyzed cross‐couplings to afford a variety of useful building blocks with high yields and excellent stereoselectivities. This study demonstrates the concept of self‐amination of the hypervalent iodine reagents, which increases the value of the aryl moiety.     

An efficient and mild oxidant for the synthesis of s-tetrazines

PhI(OAc)₂ serves as a mild and effective oxidant for the synthesis of s-tetrazine derivatives—molecules of emerging significance to the field of bioorthogonal chemistry. This reagent serves as a complementary oxidant to harsher nitrous reagents. The use of PhI(OAc)₂ improves the synthesis of 5-amino-di(pyridin-2-yl)-s-tetrazine, a molecule that has been broadly used for cellular imaging and nuclear medicine. The generality of PhI(OAc)₂ as the oxidant for tetrazine synthesis is demonstrated for nine tetrazines in 75–98% yield.     

Hypervalent iodine(III)-mediated tandem oxidative reactions: application for the synthesis of bioactive polyspirocyclohexa-2,5-dienones

In 2002, we reported the first total syntheses of potent antimalarial natural products, the aculeatins, employing the concept of tandem oxidative reactions mediated by hypervalent iodine(III) reagent to access to polyspirocyclohexa-2,5-dienone cores in very concise manner. Efforts in this field have allowed to identify cyclohexa-2,5-dienone group as a new potent class of pharmacophoric group for treating malaria disease. This article sums up recent contributions devoted to the synthesis of complex and diverse polycyclic structures using the concept of tandem oxidative activations, with p-phenol as co-reactant. More recently, we have explored a variant of the new tandem oxidative reactions that employs a catalytic amount of 4-iodotoluene in the presence of mCPBA as the stoichiometric oxidant (Kita’s procedure).