Sodium thiosulfate, reaction with hydrochloric acid

Sodium thiosulfate reacts with chlorine to form sodium bisulfate and hydrochloric acid. This reaction removes chlorine from aqueous solutions ... 

Cyclophosphamide Cyclophosphamide or ifosfamide may be destroyed using alkaline hydrolysis in the presence of dimethylformamide or refluxing with hydrochloric acid, neutralizing, or reaction with sodium thiosulfate. The... 

Reaction of phenylenediamine with an excess of sodium thiosulfate, followed by treatment with hydrochloric acid and then basification gave (128) (mp 22 °C, imax 491 nm, log e 4.02) as deep red crystals (Scheme 12) <87JOCi874>. The product had originally been identified as the 1,4-dithioquinone (129) <03JCS1201> and then as the 1,2-dithioquinone (130) <68JOC2132>. The red color is thought to be due to (130), which is in equilibrium with (128) (Scheme 12) <87J0C1874>. 

A mixture of 17 g of the methiodide and 32 ml of a 40 % aqueous potassium hydroxide solution is heated with stirring in a flask fitted with a condenser. The heating bath should be kept at 125-130°, and the heating should be continued for 5 hours. The cooled reaction mixture is then diluted with 30 ml of water and washed twice with 25-ml portions of ether. The aqueous layer is cautiously acidified in the cold with concentrated hydrochloric acid to a pH of about 2 and then extracted five times with 25-ml portions of ether. The combined extracts are washed twice with 10% sodium thiosulfate solution and are dried (magnesium sulfate). Removal of the solvent followed by distillation affords about 3 g of 4-cyclooctene-l-carboxylic acid, bp 125-12671-1 mm. The product may solidify and may be recrystallized by dissolution in a minimum amount of pentane followed by cooling in a Dry-Ice bath. After rapid filtration, the collected solid has mp 34-35°. 

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. 

The reaction between sodium thiosulfate and hydrochloric acid can also be used to study the effect of temperature on the rate of a reaction. Figure 7.11 shows some sample results of experiments with sodium thiosulfate and hydrochloric acid (at fixed concentrations) carried out at different temperatures. You can see from the graph that the rate of the reaction is fastest at high temperatures. 

Assays of bromate and perbromate concentrations are required during the procedure. Bromate concentrations that are at least comparable to the perbromate may be determined iodometrically by reaction with sodium iodide in acid solution containing molybdate, followed by titration with standardized thiosulfate. After reduction of the bromate the solution should be ca. 0.1 M each in H+ and in free iodide ion. Perchloric, hydrochloric, or sulfuric acids may be used. The molybdenum(VI) concentration should be ca. 10 3 M. 

To a stoppered tube (22 mm diameter, 200 mm long) pour 25.0 mL of starch substrate and 10.0 mLof 0.2 M acetate buffer solution. Stopper the tube, mix the contents, and place in a water bath at 25°C. When the temperature of the mixture has reached 25°C, add 2.0 mL of the enzyme solution and record the time of addition. Mix thoroughly and replace in the water bath. After exactly 10 min, add 4 mL of 1 N hydrochloric acid to stop the reaction. Transfer the contents of the tube to a 300-mL stoppered flask, rinse the tube with 20 mL of water, and add the washings to the flask. While stirring continuously, add 10.0 mL of 0.1 N iodine and immediately afterwards 25.0 mL of 0.25 N sodium hydroxide. Allow to stand in the dark at 15-25°C for 15 min. Add 4 mL of the 20% sulfuric acid solution and titrate using a microburette with 0.05 N sodium thiosulfate. Repeat the procedure but add the 4 mL of N hydrochloric acid before the addition of the solution of the sample being examined. 

Mercaptoacetic acid 149a 277 Monochloroacetic acid is neutralized with 3N-sodium hydroxide solution, treated with the equivalent amount of sodium thiosulfate, and heated for an hour on the water-bath. The end of the reaction is recognized when a sample no longer becomes turbid (separation of sulfur) when acid is added. Hydrolysis of the reaction mixture with 25 % hydrochloric acid for 2 h affords a 95 % yield of mercaptoacetic acid, which can be isolated by extraction with ether and subsequent distillation in a vacuum. 

Transfer 5 ml of the test solution to a 50 ml beaker. Add 1 ml of N hydrochloric acid and then 0.5 ml of sodium acetate buffer solution and 1 drop of fluorescein solution. Mix thoroughly and then add 1 drop of chloramine T solution. Mix by swirling and set aside for 30 seconds, then stop the reaction by adding 2 drops of alkaline thiosulfate reducing agent. Treat the blank solution in a similar manner. When bromine is present in the sample, a rose-pink colour will be developed in the test solution compared with the yellow-green blank solution. (Note Iodine also gives a positive result with this test.)... 

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