Sodium thiosulfate reaction with iodine

Sodium thiosulfate reacts with alkyl halides to form salts of the type RSSOjNa (Bunte salts). Alkyl disulfides may be obtained from these salts by pyrolysis or reaction with iodine or hydrogen peroxide. The yields range from 47% to 6S>%. Cyano and carboxyl groups do not interfere. Benzoylation of sodium thiosulfate produces benzoyl disulfide in 58% yield. ... 

A range of iodine concentrations was used with controlled potassium iodide concentrations and equilibrated over known weights of carbon. To know extents of adsorption of iodine by the carbon, the latter was centrifuged from the solution and the equilibrated iodine desorbed from the carbon by shaking the carbon with benzene and titrating the benzene with sodium thiosulfate solution. Total iodine concentrations ([I2] + [I ]) were measured by direct titration, with sodium thiosulfate, of the solution as separated from the carbon. Concentrations of I2 were calculated from the equilibrium constant for the reaction [I2 + 1 I ] taken as 870 L mol at 298 K. 

Another method suitable for the determination of small amounts of iodine in organic materials involves the amplification technique. The iodide ions obtained after decomposition of the sample are oxidized to iodate by the addition of bromine in an acetate buffer. Excess bromine is removed with formic acid. Then the iodate is determined by liberation of iodine on addition of iodide in sulfuric acid solution, followed by titration of the liberated iodine with standardized sodium thiosulfate solution with starch as the indicator. The sequence of reactions can be depicted as follows ... 

Iodide ion, a moderately effective reducing agent, is used extensively for the deterrnination of oxidants. In such appHcations, the iodine Hberated by reaction between the analyte and the unmeasured excess of potassium iodide is ordinarily titrated with a standard solution of sodium thiosulfate. The reaction is as foHows ... 

Liquid phosgene is assayed by an iodometric method which iavolves the foUowiag reaction (52). The released iodine is titrated with sodium thiosulfate. 

In this reaction, iodine is liberated from a solution of potassium iodide. This reaction can be used to assess the amount of ozone in either air or water. For determination in air or oxygen, a measured volume of gas is drawn through a wash bottle containing potassium iodide solution. Upon lowering the pH with acid, titration is effected with sodium thiosulfate, using a starch solution as an indicator. There is a similar procedure for determining ozone in water. 

The amount of sodium hypochlorite in a bleach solution can be determined by using a given volume of bleach to oxidize excess iodide ion to iodine CIO- is reduced to Cl-. The amount of iodine produced by the redox reaction is determined by titration with sodium thiosulfate, Na2S203 I2 is reduced to I-. The sodium thiosulfate is oxidized to sodium tetrathionate, Na2S406. In this analysis, potassium iodide was added in excess to 5.00 ml of bleach d = 1.00 g/cm3). If 25.00 mL of 0.0700 MNa2S203 was required to reduce all the iodine produced by the bleach back to iodide, what is the mass percent of NaCIO in the bleach ... 

For instance, in order to characterize the mixing performance of any transparent reactor, the reaction of discoloration of an iodine solution with sodium thiosulfate could be used according to the following reaction scheme ... 

Periodate and iodate ions may both be removed by reaction with iodide ion in acid solution this yields free iodine which can be removed by extraction209 or by centrifugation210-—or the iodine can be converted to iodide ion by titration with sodium thiosulfate.211 Periodate and iodate ions are also readily removed from solution by use of an anion-exchange resin.211a... 

A sample of iodine-128 was produced in a Szilard-Chalmers reaction by irradiating a sample of ethyl iodide in a neutron source. The radio-iodine was extracted with sodium thiosulfate solution and then counted in a Geiger counter at various time Intervals. Use the tabulated data of t in minutes against C counts/min to find the rate equation and the half time. 

The sulfur formed in this reaction mainly consists of Sg and Sg with small amounts of larger even-membered rings of which S12, a-Sjg cmd S20 could be isolated The iodine can be recycled by reaction with stoichiometric amoimts of sodium thiosulfate, and the sulfur mixture is separated by precipitation with pentane and recrystallization from CS2 yield of Sg 36 % Sg forms orange-yellow crystals... 

The ethereal solution is usually dark but should not have a purple color. A purple color indicates the presence of iodine. Iodine can arise by light-catalyzed reaction in the latter stages of the reaction and during isolation of the product. For this reason the reaction should be shielded from strong light. In addition it is advisable for the ether employed in the reaction mixture to be peroxide-free. If iodine is present in the reaction product, it must be removed by extraction with aqueous sodium thiosulfate solution since an adequate separation is not obtained by distillation. 

Hydrolysis An aliquot of the reaction mixture is quenched with saturated aqueous ammonium chloride solution eind extracted with ether, then injected on GC to verify that al the 4-bromobenzonifrile has been consumed, lodolysis An aliquot of the reaction mixture is added to a dry vial containing iodine after 10 min ether is added and the ethereal solution is washed with an aqueous solution of sodium thiosulfate. The organic phase is injected on... 

A flask containing 15.0 gm (0.25 mole) of sodium azide in 100 ml of acetonitrile is stirred and cooled in an ice bath while 18.3 gm (0.113 mole) of iodine monochloride is added over a 10-20 min period. After stirring for an additional 5-10 min, 5.6 gm (0.1 mole) of isobutylene is added and then the reaction is allowed to warm to room temperature for 20 hr. The red-brown slurry is poured into 250 ml of water, extracted with 100 ml of ether three times, washed with 150 ml of 5 % sodium thiosulfate, washed four times with 250 ml portions of water, and dried over magnesium sulfate. The ether is removed at reduced pressure, leaving a slightly orange oil. Distillation behind a barricade yields 13.5 gm (60%), b.p. 68°-69°C (7 mm), n% 1.5292. 

To a stirred solution of 120 ml of methylene chloride, 18 ml of dry pyridine, and 5 ml of iodine pentafluoride maintained at —10°C to —20°C in a Dry Ice-carbon tetrachloride slurry is added a solution of 13.5 gm (0.1 mole) of cumyl-amine in 10 ml of methylene chloride over a 1 hr period. The reaction mixture is stirred for another hour at —10°C, and then for 1 hr at 0°. After this time, water is added to the reaction mixture and stirring is continued until the yellow solid which had formed is dissolved. The lower organic layer is separated and washed in turn with water, 1 N hydrochloric acid, a saturated sodium thiosulfate solution, and again with water. After drying with anhydrous magnesium sulfate and filtration, the product solution is partially evaporated by means of a rotary evaporator at a temperature below 30°C. The brown solid obtained on cooling is separated and recrystallized twice from methylene chloride yield 4.75 gm (17.9%), m.p. 86.9°-88.7°C. 

A mixture consisting of the step 2 product (37 g) and 800 ml trimethyl phosphate were charged into a flask and treated with iodine (10.6 g) and the dropwise addition of bromine (19 g) dissolved in 70 ml trimethyl phosphate. After stirring for 4 hours additional bromine (9.5 g) dissolved in 35 ml of trimethyl phosphate was added and the mixture stirred overnight. The reaction liquid was then poured into water, extracted with chloroform, and washed with aqueous solutions of sodium thiosulfate and brine. The solution was then dried, concentrated, the residue purified by silica gel chromatography using cyclohexane/toluene, 20 1, respectively, and... 

This method can be used for the determination of the ozone concentration in the gas and/or liquid phase. The measurement takes place in the liquid phase, though, so that to measure a process gas containing ozone, the gas must first be bubbled through a flask containing potassium iodide KI. For the measurement of the liquid ozone concentration, a water sample is mixed with a KI solution. The iodide F is oxidized by ozone. The reaction product iodine 12 is titrated immediately with sodium thiosulfate Na2S203 to a pale yellow color. With a starch indicator the endpoint of titration can be intensified (deep blue). The ozone concentration can be calculated by the consumption of Na2S203. 

The peroxy group is detemiined by treatment with sodium iodide. The liberated iodine is then titrated with standard sodium thiosulfate solution. The reaction is... 

To a freshly prepared catalyst (1 g, 0.2 mmol of iodine) under stilling, a mixture of benzaldehyde la (2 mmol) and ethane-1,2-dithiol (2.2 mmol) was added and stirring continued for 10 min or till the reaction was complete. For TLC monitoring, a small amount of the solid reaction mixture was taken out with a spatula and washed with a little amount of ethyl acetate to get a solution. On completion the reaction mixture was loaded on a short column of silica gel (60 to 120 mesh) and eluted with ethyl acetate. The organic layer was washed with a dilute solution of sodium thiosulfate followed by water and dried over anhydrous sodium sulfate. Evaporation of the solvent under reduced pressure and purification of the residue by column chromatography yielded the pure product. 

Iodometric titration involves the reaction of iodine with a known amount of reducing agent, usually sodium thiosulfate (Na2S203) or phcnylarsine oxide (PAO). Starch solution is used as an indicator to detect the end point of the titration. Thus, the exact amount of iodine that would react with a measured volume of sodium thiosulfate of known strength is determined. From this, the concentration of the analyte in the sample, which is proportional to the amount of iodine reacted with thiosulfate or PAO, is then calculated. 

A measured volume of sample is added to a known quantity of standard iodine solution estimated to be in excess over the amount of analyte (e.g., sulfide) in the sample. The standard iodine solution should contain an excess of potassium iodide. The analyte reacts with iodine. This would cause a lowering of strength of iodine solution after the reaction. The normality of iodine is then determined from titration against a standard solution of sodium thiosulfate. Concentration of analyte in the sample, which is proportional to the amount of iodine consumed, is calculated as follows ... 

Special test Catalysis of iodine-azide reaction solution of sodium azide (NaN3) and iodine reacts with a trace of a sulfide to evolve nitrogen thiosulfates and thiocyanates act similarly and therefore must be absent... 

To a mixture of glucopyranose (0.22 mmol) in dry cyclohexane (24 ml) under an argon atmosphere were added iodosylbenzene (0.43 mmol) and iodine (0.22 mmol) at room temperature. The mixture was stirred for 20 h at the same temperature. After the reaction, the reaction mixture was poured into water and extracted with ether. The organic layer was washed with aq. sodium thiosulfate solution, water, and dried over Na2S04. After removal of the solvent, the residue was chromatographed on silica gel (eluent hexane/ethyl acetate = 65/35) to give D-arabinose derivative in 86% yield [68]. 

Sodium Chlorite. An accurately weighed sample of about 2.0 g. of sodium chlorite is dissolved in 1 1. of water a 25-ml. aliquot serves as the sample for analysis. Two milliliters of 50 % potassium iodide and 10 ml. of acetic acid are added to the aliquot, and the ensuing reaction is allowed to proceed in the dark for 5 minutes. The liberated iodine is then titrated with 0.1 A standard sodium thiosulfate solution, using starch as an indicator. The equations for the reactions are written below.1... 

Effluent-gas Analysis.4 This method of analysis gives an estimate both of the chlorine (IV) oxide produced and of the unreacted chlorine present in the effluent-gas mixture. The gas is collected in an opaque 600-ml. Hempel tube it is then absorbed in a neutral 10% solution of potassium iodide. Starch indicator is added to this solution or to an aliquot, which is then titrated with 0.1 AT sodium thiosulfate solution (titration A). The amount of sodium thiosulfate used is equivalent to all the chlorine gas in the sample plus one-fifth of the chlorine(IV) oxide. The solution is then acidified with an excess of 30% acetic acid, causing a second release of iodine, which is then titrated with sodium thiosulfate solution (titration B). The amount of sodium thiosulfate used in titration B is equivalent to four-fifths of the chlorine (IV) oxide in the sample. The equations for the reactions involved are shown below.4... 

It was found impossible to measure the rate of decomposition by the evolution of gases because the release of these gas bubbles is very slow and erratic. The course of the reaction was followed by analyzing samples for the ammonium ion. Small amounts of the decomposing amalgam were forced through a capillary tube into a chilled solution of an iodate. The ammonium reacted with iodate ion to give iodide ion. The solution was then acidified with acetic acid and the iodine distilled out, collected and titrated with sodium thiosulfate. The method was checked with samples... 

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