Generation of Electrophilic Iodine from Iodine Monochloride in Neutral Media. Iodination and Protodeiodination of Carbazole

In reaction of iodine monochloride with CF₃COOAg, CH₃COONa or (CH₃COO)₂Pb in acetonitrile and acetic acid the chloride is bonded by metal cations, and electrophilic iodine is generated able to easily iodinate anthracene and carbazole. However at the iodination of anthracene in the presence of oxygen the prevailing process is anthracene oxidation to anthraquinone. In the presence of sulfuric acid protodeiodination of 3-iodocarbazole was found to occur resulting in rearranged products.     

Direct iodination of 3- and 4-nitropyrazoles with a reagent based on iodine monochloride and silver sulfate

The reagent obtained from iodine monochloride and silver sulfate in sulfuric acid easily iodinates I-methyl-3-nitropyrazole under mild conditions to give 4-iodo or 4,5-diiodo derivatives, 1-Methyl-4-nitropyrazole was also directly iodinated with this reagent for the first time. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1482–1484, August, 2000.     

Volumetric studies in oxidation-reduction reactions: Oxidation with chloramine-t. indirect determinations

Chloramine-T has been used as an oxidizing agent in hydrochloric acid medium for the indirect volumetric determination of hydrogen peroxide, lead dioxide, selenium dioxide, sodium formate, potassium meta-periodate, potassium permanganate and potassium dichromate using iodine monochloride as a catalyst, prcoxidizer and an indicator. Chloroform 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.     

Sodium meta-vanadate as volumetric reagent : Iodine monochloride method

Sodium meta-vanadate has been used as an oxidising agent in hydrochloric acid medium for the volumetric estimations of potassium iodide, sodium arsenite, mercurous chloride, potassium thiocyanate, sodium sulphite, sodium bisulphite, sodium thiosulphate, ferrous sulphate and hydrazine sulphate, using iodine monochloride as a catalyst and preoxidiser. Chloroform is used as an indicator. It is coloured pink due to the liberation, of iodine during the titration and becomes light pale yellow at the end-point due to the formation of iodine monochloride.     

Studies in oxidation-reduction reactions: Oxidation with chloramine-b,iodine monochloride method

Chloramine-B has been used as an oxidizing agent in hydrochloric acid medium for the volumetric estimations of potassium iodide, arsenious oxide, tartar-emetic, mercurous chloride, stannous chloride, potassium thiocyanate, ferrous ammonium sulphate, hydrazine sulphate and hydroquinone, using iodine monochloride as a catalyst and pre-oxidizer. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes light pale yellow at the end-point because of the formation of iodine monochloride.     

Studies in oxidation-reduction reactions: Oxidation with chloramine-b indirect determinations

Chloramine-B has been used as an oxidizing agent in hydrochloric acid medium for the indirect volumetric estimations of hydrogen peroxide, lead dioxide, manganese dioxide, selenium dioxide, sodium formate, sodium sulphide, sodium metavanadate, potassium iodate and copper sulphate using iodine monochloride as a catalyst and pre-oxidiser. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes light pale yellow at the end-point because of the formation of iodine monochloride.     

Volumetric studies in oxidation-reduction reactions: Oxidation with chloramine-t. iodine monochloride method

Chloramine-T has been used as an oxidizing agent in hydrochloric acid medium' for the volumetric estimations of potassium iodide, hydrazine sulphate, arscnious oxide, stannous chloride, mercurous chloride, tartar-emetic, potassium thiocyanate and ferrous ammonium sulphate, using iodine monochloride as a catalyst and pre-oxidizer. 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.     

Iodine monochloride in anhydrous acetic acid as an oxidizing agent

A systematic study of the redox reactions of iodine monochloride with various inorganic ions in glacial acetic acid medium is described. Sodium sulphite, mercury(I) perchlorate, antimony trichloride, arsenic trichloride and iron(II) perchlorate were examined. Potentiometric and amperometric methods were used to follow the reduction of iodine monochloride, which yields different products according to the type of reductant.     

Diethylenetetra-ammonium sulphatocerate as volumetric reagent: Iodine monochloride method. Indirect determinations

In presence of 4N to N hydrochloric acid, diethylenetetra-ammnonium sulphatocerate was used as a volumetric reagent to determine indirectly potassium iodate, potassium metaperiodate, potassium dichromate, potassium bromate, ceric sulphate, hydrogen peroxide, lead dioxide and chloramine-B by the iodine monochloride method. An excess of potassium iodide added to each of the substances in the acid medium was, titrated back with a standard solution of diethylene-tetra-ammonium suphatocerate. Chloroform was used as an indicator. It was coloured violet owing to the liberation of iodine during the titralion and became very pale yellow at the end-point because of the formation of iodine monochloride.     

Diethylenetetra-ammonium sulphatocerate as volumetric reagent : Determination of organic derivatives of hydrazine by the iodine monochloride method

Diethylenetetra-ammonium sulphatocerate has been used as an oxidising agent in hydrochloric acid medium for the volumetric determination of semicarbazide hydrochloride, benzalazine, benzalsemicarbazone, aminoguanidme hydrochloride, chloralhydrazinc, P-methoxybcnzalsemicarbazonc, o-chlorobenzalsemicarbazone and acetonesemicarbazone, using iodine monochloride as a catalyst and preoxidiser Chloroform was used as an indicator. It was coloured violet owing to the liberation of iodine during the titration and became very pale yellow at the end-point owing to the formation of iodine monochloride Each hydrazino group in these compounds was oxidised quantitatively with a four-electron change to nitrogen with diethylenetctra-ammonium sulphatocerate as an Oxidant in hydrochloric acid solution.     

Determination of isoniazid in drugs

A titrimetric method is described for the determination of isoniazid in pharmaceutical preparations. Samples are treated with an excess of iodine monochloride, and the iodine produced is titrated with iodine trichloride to an Andrews end-point. p-Aminosalicylic acid undergoes only nuclear iodination and does not interfere. Mixtures of isoniazid with vitamin C or methionine are analysed by first titrating both compounds by the Andrews method and then determining either vitamin C alone by titration with iodine monochloride or methionine by a second Andrews titration after destruction of isoniazid with nitrous acid. In both cases, isoniazid is obtained by difference. A mixture of isoniazid, methionine and vitamin C can also be analysed.     

Potassium persulphate as volumetric reagent

Summary Potassium persulphate has been used as volumetric reagent for the direct determination of hydrazine sulphate, phenyl hydrazine hydrochloride, semicarbazide hydrochloride, thiosemicarbazide, acetone semicarbazone, benzal semicarbazone, benzalazine, aminoguanidine hydrochloride, 4-phenyl semicarbazide hydrochloride, ethylmethyl ketone semicarbazone and 4-hydroxy-3-methoxy benzal semicarbazone in hydrochlorid acid medium at room temperature, using iodine monochloride as a catalyst and preoxidiser. Chloroform was used as an indicator. It was coloured violet owing to the liberation of iodine during the titration and became very pale yellow at the end-point due to the formation of iodine monochloride. Normality of the solution with respect to hydrochloric acid was kept between 6.0 and 7.5 N in these redox titrations.     

Sodium hypochlorite as volumetric reagent

Summary Sodium hypochlorite solution has been used as an oxidising agent for the volumetric determination of semicarbazide hydrochloride, phenylhydrazine hydrochloride, benzalazine, benzalsemicarbazone, o-chlorobenzalsemicarbazone, acetonesemicarbazone, aminoguanidine hydrochloride, thiosemicarbazide, o-hydroxy benzalsemicarbazone, 3,4-methylenedioxy benzalsemicarbazone and p-methoxy benzalsemicarbazone, using iodine monochloride as catalyst and preoxidizer. During these titrations normality of the solution with respect to hydrochloric acid has been kept between 2.0 N and 3.5 N. Chloroform is used as an indicator. It is coloured pink due to the liberation of iodine during the titration and becomes very pale yellow at the end-point owing to the formation of iodine monochloride. Each hydrazino group in these compounds is oxidised quantitatively with a four-electron change to nitrogen with sodium hypochlorite as an oxidant in hydrochloric acid solution.     

Pharmaceutical analysis of some tranquillizers and antidepressants with iodine monochloride

A titrimetric method for the evaluation of some tranquillizers and antidepressants is proposed. The method is based on the oxidation of these drugs by iodine monochloride, in strong acid medium, the iodine liberated being titrated with potassium iodate by the Andrews method. The proposed method is applied successfully for the determination of 9 phenothiazines, 1 thioxanthene, 2 acid hydrazides and 1 dibenzazepine containing a double bond (Opipramol). Tablets, solutions for injection, and drops are also determined by the proposed method. The mechanism of oxidation for each species is suggested and the results obtained agree with these suggestions. Some official and non-official methods for the evaluation of the drugs have been compared with the iodine monochloride method, which is found to be superior in specificity, sensitivity and speed.     

Oxidimetric methods for the volumetric estimation of sulphite

1. The use of permanganate, ceric sulphate, and dichromate for the estimation of sulphite has been reinvestigated, although these reagents have heen discarded as useless by earlier investigators. By using catalysts under controlled acid concentration, we have been able to develop conditions for the quantitative oxidation of sulphite to sulphate at room temperature by any one of these oxidizing agents, avoiding the formation of dithionate. Copper sulphate and iodine monochlonde have been found useful as catalysts with potassium permanganate and dichromate; but only iodine monochloride with ceric sulphate. 2. Sodium sulphite is also oxidized quantitatively to sulphate at room temperature, when added to excess of sodium vanadate solution containing 5 to 6N hydrochloric acid and iodine monochloride as catalyst.     

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     

Simple spectrophotometric and titrimetric methods for the determination of sulfur dioxide.

The proposed work describes a simple spectrophotmetric as well as a titrimetric method to determine sulfur dioxide. The spectrophotometric method is based on a redox reaction between sulfur dioxide and iodine monochloride obtained from iodine with chloramine-T in acetic acid. The reagent iodine monochloride oxidizes sulfur dioxide to sulfate, thereby reducing itself to iodine. Thus liberated iodine will also oxidize sulfur dioxide and reduce itself to iodide. The obtained iodide is expected to combine with iodine to form a brown-colored homoatomictriiodide anion (460 nm), which forms an ion-pair with the sulfonamide cation, providing exceptional color stability to the system under an acidic condition, and is quantitatively relatd to sulfur dioxide. The system obeys Beer's law in the range 5 - 100 microg of sulfur dioxide in a final volume of 10 ml. The molar absorptivity is 5.03 x 10(3) l mol(-1)cm(-1), with a relative standard deviation of 3.2% for 50 microg of sulfur dioxide (n = 10). In the titrimetric method, the reagent iodine monochloride was reduced with potassium iodide (10%) to iodine, which oxidized sulfur dioxide to sulfate, and excess iodine was determined with a thiosulfate solution. The volume difference of thiosulfate with the reagent and with the sulfur dioxide determined the sulfur dioxide. Reproducible and accurate results were obtained in the range of 0.1 - 1.5 mg of sulfur dioxide with a relative standard deviation of 1.2% for 0.8 mg of sulfur dioxide (n = 10).     

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.     

Sodium meta-vanadate as volumetric reagent: Iodine monochloride method

In hydrochloric acid medium sodium meta-vanadate was used as a volumetric reagent for the determination of copper, zinc, cobalt, mercury, and lead. Cu⁺², Zn⁺² and Co⁺²were precipitated as complex mercurythiocyanates, Hg⁺² as mercuric zinc thiocyanate and Pb⁺² as Iodide. The thiocyanates were dissolved in concentrated hydrochloric acid and titrated against standard sodium meta-vanadate solution in the presence of iodine monochloride as a pie.oxidizer and catalyst. In titration of the iodide against the meta-vanadate. it was not necessary to add iodine monochloride to the titrant because it is formed during the titration. Chloroform was used as an indicator. It was pink owing to the liberation of iodine during the titration and became pale yellow at the end-point because of the formation of iodine monochlonde.     

Iodine trichloride as an analytical reagent for determination of some organic compounds

Procedures are described for the determination of organic compounds with iodine trichloride under Andrews's titration conditions. Samples are directly titrated with iodine trichloride or first reacted with an excess of iodine monochloride, with subsequent titration of the iodine formed. The direct titration is done initially in feebly acid medium, then the acidity is raised (biotin, methionine, cystine and thiomersal). Pre-oxidation with iodine monochloride is used if the organic compound reacts slowly [tryptophan and arsenic(III) compounds] or is determined in bicarbonate medium (hydroxylamine and thiosemicarbazide). The ferrocyanide formed by the reduction of ferricyanide (by thiourea and allylthiourea) can also be titrated. Arsenic(V) compounds are determined after reduction to arsenic(III), and iodine in organic compounds is converted into iodide by alkaline fusion into iodide and the iodide titrated.