Titrations with 0.1 N bromine

Readily Oxidizable Substances (as formic acid) Dissolve 15 g of sodium hydroxide in 50 mL of water, cool, add 6 mL of bromine, stirring to effect complete solution, and dilute to 2000 mL with water. Transfer 25.0 mL of this solution into a 250-mL glass-stoppered Erlenmeyer flask containing 100 mL of water, and add 10 mL of a 1 5 aqueous solution of sodium acetate and 10.0 mL of sample. Allow to stand for 15 min, add 5 mL of a 1 4 aqueous solution of potassium iodide and 10 mL of hydrochloric acid, and titrate with 0.1 N sodium thiosulfate just to the disappearance of the brown color. Perform a blank determination (see General Provisions), and make any necessary correction. The difference between the volume of 0.1 IV sodium thiosulfate required for the blank and that required for the sample is not more than 2.2 mL. 

Dilute 50 ml of syrup to 400 ml, precipitate with sodium hydroxide and a little bromine water, to oxidise any iron in the ferrous state. Bring the mixture to the boil and allow the precipitate to settle. After filtration on paper in a Gooch crucible, dissolve the precipitate in hydrochloric acid, reprecipitate with sodium hydroxide and redissolve in hydrochloric acid. Add potassium iodide and titrate with 0 1 N thiosulphate. 1 ml = 0 005585 g Fe. 

Procedure Transfer 25 ml of 0.1 N bromine solution with the help of a pipette into a 500 ml iodine flask and dilute it with 120 ml of DW. Add to it 5 ml of hydrochloric acid, moisten the glass-stopper with water and insert the stopper in the flask. Shake the contents gently. Now, add 5 ml of potassium iodide solution, again lace the stopper and allow the resulting mixture to stand for 5 minutes in the dark. Titrate the liberated iodine with previously standardized 0.1 N sodium thiosulphate solution, adding 3 ml of freshly prepared starch solution towards the end-point. Each ml of 0.1N sodium thiosulphate is equivalent to 0.01598 g... 

Procedure Weigh accurately about 0.2 g of ethacrynic acid, dissolve in 40 ml of glacial acetic acid in a 250 ml iodine flask. Add to it 20 ml of 0.1 N bromine and 30.0 ml of hydrochloric acid, immediately place in position the moistened stopper to the ffask, mix the contents vigorously and allow it to stand in a dark place for 60 minutes (to complete the reaction with bromine). Add to it 100 ml of water and 20 ml of KI Solution and titrate immediately with 0.1 sodium thiosulphate, employing freshly prepared starch solution as an indicator towards the end of the titration. Repeat an operation without the pharmaceutical substance (blank titration) thus the difference between the titrations represents the amount of bromine required by the ethacrynic acid. Each ml of 0.1 N bromine is equivalent to 0.01516 g of C13H12C1204. 

A sample (approximately 0.2 g.) is weighed accurately and dissolved in 25 ml. of water then 25 ml. of 0.1 N hydrochloric acid and 0.2 g. of potassium bromide are added. The solution is titrated with 0.017 M potassium bromate until a permanent yellow color is produced. Potassium iodide (0.1 g.) is added, and the solution is backtitrated to a starch end point with 0.1 N sodium thiosulfate. The blue color returns in about a minute since the high acidity promotes air oxidation of excess iodide. The accuracy is only slightly less if the appearance of a faint yellow bromine color is taken as the end point. One mole of potassium bromate is equivalent to 3 of sodium /8-styrenesul-fonate. 

Assay Transfer about 120 mg of sample, previously dried at 105° for 1 h and accurately weighed, into a 100-mL volumetric flask, dissolve in and dilute to volume with water. Transfer 50.0 mL of this solution into a 250-mL glass-stoppered iodine flask, add 50.0 mL of 0.1 N bromine and 20 mL of 2 A sulfuric acid, and stopper the flask. Place a few milliliters of a saturated solution of potassium iodide in the lip around the stopper, shake the flask well, and allow it to stand for 3 h. Place the flask in an ice bath for 5 min, then carefully remove the stopper, and allow the potassium iodide solution to be drawn into the flask. Add 2 g of potassium iodide dissolved in 10 mL of recently boiled water, shake the flask, and titrate the liberated iodine with 0.1 A sodium thiosulfate, using starch TS as the indicator. Each milliliter of 0.1 A bromine is equivalent to 2.311 mg of Mn(H2P02)2-... 

Bromine, 0.1 N (7.990 g Br per 1000 mL) Dissolve 3 g of potassium bromate (KBr03) and 15 g of potassium bromide (KBr) in sufficient water to make 1000 mL, and standardize the solution as follows Transfer about 25 mL of the solution, accurately measured, into a 500-mL iodine flask, and dilute with 120 mL of water. Add 5 mL of hydrochloric acid, stopper the flask, and shake it gently. Then add 5 mL of Potassium Iodide TS, restopper, shake the mixture, allow it to stand for 5 min, and titrate the liberated iodine with 0.1 N Sodium Thiosulfate, adding Starch TS near the end of the titration. Calculate the normality. Store this solution in dark, amber-colored, glass-stoppered bottles. 

Dilute 10 ml 40% fonnaldehyde with 50 ml distilled water. Dissolve 1 g sample in the diluted formaldehyde solution. Shake well and leave it to stand for 20 min. Dilute the solution to 500 ml. Take 50 ml out of the 500 ml solution and dilute it to 150 ml. Titrate the solution with 0.1 N aqueous bromine solution until a red brown colour appears. Back titrate the red brown solution with O.IN Na S O until a pale yellow colour is shown. Add 2-3 drops of 1% starch solution and continue to titrate until the blue colour disappears. Na S O concentration can be calculated using Equation [4.23] ... 

Dissolve about 0 4 g in water and make up to 250 ml. Pipette 25 ml of this solution into a stoppered flask, add 25 ml of 0 1 N bromine and 5 ml of concentrated hydrochloric acid . Shake the flask for one minute before allowing to stand for fifteen minutes, release the stopper carefully, since there is a slight pressure due to formation of nitrogen, add 2 g of potassium iodide and titrate with 0-1N sodium thiosulphate. 1 ml O lN bromine 0 003429 g CgHvONg. 

Transfer an aliquot part, containing from 0 03 to 0 04 g, of phenol in solution to a stoppered bottle. Add 30 ml of O IN bromine (2 784 g potassium bromate and 15 g potassium bromide per litre) and 5 ml of concentrated hydrochloric acid. Allow to stand with occasional shaking for fifteen minutes, add 5 to 10 ml of 20 per cent potassium iodide solution quickly to avoid loss of bromine and titrate the liberated iodine with 0 1 N sodium thiosulphate. Carry out a blank determination. 1 ml 0-lN = 0 001569 g. Starch indicator need not be used. 

Dissolve about 1 5 g in water and make up to 500 ml. Transfer a 25-ml aliquot to an iodine flask, add 50 ml of 0 1 N bromine, 50 ml of water and 5 ml of concentrated hydrochloric acid and immediately stopper the flask. Shake for one minute, allow to stand for two minutes and then add 5 ml of N potassium iodide, taking care to avoid loss of bromine vapour. Shake thoroughly, allow to stand for five minutes and remove the stopper, rinsing it and the neck of the flask with 20 ml of water into the flask. Titrate the liberated iodine, equivalent to the excess of bromine, with O IN thiosulphate using starch as indicator. 1 ml 0-lN = 0 001835 g. 

Boil about 01 g with 50 ml of N sodium hydroxide for thirty minutes under reflux. Cool, add 50 ml of 01N bromine and 10 ml of concentrated hydrochloric acid. Allow to stand for half an hour, shaking repeatedly during the first fifteen minutes, add 2 g of potassium iodide and titrate the liberated iodine with O IN sodium thiosulphate. 1 ml of 0 1 N bromine == 0 002536 g methyl hydroxybenzoate, CgHgOa 0 002902 g sodium salt of the methyl ester 0 003003 g propyl hydroxybenzoate, C10H12C3, and 0 003370 g sodium salt of the propyl ester. 

Iodine Transfer about 20 g of sample, accurately weighed, into a 600-mL beaker, and dissolve in about 300 mL of water. Add a few drops of methyl orange TS, neutralize the solution with 85% phosphoric acid, and then add 1 mL excess of the acid. Add 25 mL of bromine TS and a few glass beads, boil until the solution is clear, then boil for an additional 5 min. Add about 50 mg of salicylic acid crystals, 1 mL of phosphoric acid, and 10 mL of a 1 20 potassium iodide solution, and titrate to a pale yellow color with 0.01 N sodium thiosulfate. Add 1 mL of starch TS, and continue the titration to the disappearance of the blue color. Each milliliter of 0.01 N sodium thiosulfate is equivalent to 0.2767 mg of potassium iodide (KI). 

The bromine index can be measured by electrometric and coulomelric titration. In the electrometric titration method, a sample is titrated with bromide-bromate solution (0.1 N solution of mixture of potassium bromide and potassium bromate) until the end-point increase in potential remains steady for 30 s. In coulometric titration, a potassium bromide solution is used to titrate the solvent until the bromine concentration increases because it is no longer being consumed by the unsaturation of the solvent. ... 

Destroy the organic matter in 0 2 to 0-4 g by heating with small quantities of an oxidising mixture of strong sulphuric, nitric and perchloric acids. When a colourless liquid results and fumes of sulphuric acid appear, cool, add 0 25 g of hydrazine sulphate and heat the liquid for ten minutes to reduce the arsenic to the trivalent form and to decompose any excess of reducing agent. Add 20 ml of water and cool add 0-1 to 0 2 g of potassium bromide and titrate with potassium bromate solution until a faint yellow colour of free bromine is obtained. 1 ml 0 1 N bromate = 0 003746 g. As. 

For salicylic acid, dissolve exactly 2 5 g in ether and extract completely with saturated sodium bicarbonate solution, washing each extract with ether. After cautious acidification with dilute hydrochloric acid, extract with ether, evaporate carefully, dissolve the residue in N sodium hydroxide and determine by bromination (see p. 558). 1 ml O IN bromine = 0 002302 g. Calculate the ml of O IN sodium hydroxide equivalent to the salicylic acid found (1 ml 0 1 N == 0 01381 g) and deduct from the titration figure for total acidity. 1 ml 0 1N = 0 01221 g benzoic acid. 

Procedure Weigh accurately about 0.8 g of granulated zinc, dissolve by gentle warming in 12 ml of dilute hydrochloric acid and 5 drops of bromine water. Boil to remove excess bromine, cool and add sufficient DW to produce 200 ml in a volumetric flask. Pipette 20 ml of the resulting solution into a flask and neutralize carefully with 2 N sodium hydroxide. Dilute to about 150 ml with DW, add to it sufficient ammonia buffer (pH 10.0) to dissolve the precipitate and add a further 5 ml quantity in excess. Finally add 50 mg of Mordant Black II mixture and titrate with the disodium edetate solution until the solution turns green. Each 0.003269 g of granulated zinc is equivalent to 1 ml of 0.05 M disodium ethylenediaminetetracetate. 

Method S(when acardite II and diphenylamine. are present) a)Extract ca lOg of finely divided propellant with methylene chloride or with chlf, evap the solvent and dry and weigh the extracted residue (P = x + y, where x is the wt of acardite II and y is the wt of DPhA in propellant) b)Dissolve the extracted material in 50cc chlf, add 300cc water and an excess of K bromide-bromate soln of known concn c)After brominating for 4 hrs at RT, add aq soln of KI and titrate the liberated iodine with N/10 Na thiosulfate (lcc of thiosulfate is required for 0.0021 g of DPhA) d)If the ealed wt of DPhA is equal to P, mol wt of DPhA = 1 ( 9 and wt of 2 mols of acardite II is equal to 452, the P1 ... 

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