Sodium iodate extraction

Iodine is produced in large scale from Chilean nitrate. Iodine occurs in this mineral as sodium iodate, NalOs. The iodate extract of the mineral becomes more concentrated in iodate after sodium nitrate crystaUizes out. The mother liquor is then treated with sodium bisulfite solution to give sodium iodide ... 

Formerly all the iodine was made from the ash of seaweed, and potash was a remunerative appendix to the iodine industry but just as the Stassfurt salts killed those industries which extracted potash from other sources, so did the separation of iodine from the caliche mother-liquors threaten the industrial extraction of iodine from seaweed with extinction. Iodine in a very crude form was exported from Chili in 1874—e.g. a sample was reported with iodine 52-5 per cent. iodine chloride, 3-3 sodium iodate, 13 potassium and sodium nitrate and sulphate, 15 9 magnesium chloride, 0 4 insoluble matter, 1 5 water, 25-2 per cent. About that time much of the iodine was imported as cuprous iodide. This rendered necessary the purification of the Chilian product but now the iodine is purified in Chili before it is exported. The capacity of the Chilian nitre works for the extraction of iodine is greater than the world s demand. It is said that the existing Chilian factories could produce about 5100 tons of iodine per annum whereas the... 

To a cooled solution of dithiane (1) (2.00 g, 16.7 mmol) in methanol (125 ml) was added an aqueous solution (35 ml) of sodium periodate (3.68 g, 17.5 mmol) at such a rate (approximately 30 min) to maintain the temperature at 20°C. Stirring and cooling were continued for an additional 30 min. The reaction mixture was then filtered to remove sodium iodate, and the resulting solution taken to near dryness on a rotary evaporator. Extraction of the solids with chloroform produced a solution which was dried over sodium sulfate, and filtered. Evaporation left the crystalline sulfoxide (2) (2.13g, 94%), m.p. 86-87°C. 

In a 500 ml round-bottomed flask equipped with a magnetic stirrer are placed 22 5 g (0 105 mole) of powdered sodium metaperiodate and 210 ml of water The mixture is stirred and cooled m an ice bath (Note 1), and 12 4 g (0 100 mole) of thio-anisole (Note 2) is added The reaction mixture is stirred for 15 hours at ice-bath temperature and is then filtered through a Buchner funnel The filter cake of sodium iodate is washed with three 30-ml portions of methylene chloride The wrater methylene chloride filtrate is transferred to a separatory funnel, the lower methylene chloride layer is removed, and the water layer is extracted with three 100-ml portions of methylene chloride The combined methylene chloride extracts are treated with activated carbon (Note 3) and dried over anhydrous sodium sulfate (Note 4) The solvent is removed at reduced pressure to yield 13 6-13 9 g of a slightly yellow oil (Note 5) which crystallizes on cooling The crude sulfoxide is transferred to a 25 ml distillation flask with the aid of a small amount of methylene chloride After removal of the solvent, a pinch of activated carbon is added to the distillation flask (Note 6) Simple vacuum distillation (Note 7) of the crude product through a short path still affords 12.7-12 8 g (91%) of pure methyl phenyl sulfoxide, b p 78-79° (0 1 mm ), m p. 33-34° (Notes 8 and 9)... 

Stir 2.35 g (0.011 mol) of sodium metaperiodate (Section 4.2.55, p. 454) in 45 ml of a 1 1 mixture of water and methanol held at 0°C. Add portionwise 2.14 g (0.01 mol) of dibenzyl sulphide (Expt 5.204) and continue to stir the mixture at 0 °C for several hours, preferably overnight. Extract the reaction mixture (which contains precipitated sodium iodate) with three 20 ml portions of chloroform. Dry the combined chloroform extracts over magnesium sulphate and remove the solvent on a rotary evaporator. Recrystallise the product from ethanol. The yield of dibenzyl sulphoxide is 2.2 g (96%), m.p. 135 °C. 

Iodine also occurs in seawater and in numerous seaweeds including kelp, from which iodine has been extracted on a commercial scale. The greater part of the iodine of commerce is obtained from sodium iodate (NalOs) and sodium periodate (NaI04), both of which are associated with the enormous deposits of sodium nitrate in Chile. 

In addition to relatively small amounts of iodine that are extracted from the ashes of kelp, the great bulk of iodine produced commercially is obtained from sodium iodate. This compound occurs along with sodium nitrate (Chile saltpeter), and the iodine is extracted by treating the iodate with sodium hydrogen sulfite ... 

Bromides and iodides interfere because of the liberated halogen the test is not trustworthy in the presence of chromates, sulphites, thiosulphates, iodates, cyanides, thiocyanates, hexacyanoferrate(II) and (III) ions. All of these anions may be removed by adding excess of nitrate-free Ag2S04 to an aqueous solution (or sodium carbonate extract), shaking vigorously for 3-4 minutes, and filtering the insoluble silver salts, etc. 

Thioanisole (methyl phenyl sulfide) (12.4 g, 0.1 mol) is added to 210 mL (0.105 mol) of a 0.5 M solution of sodium metaperiodate at 0 °C, and the mixture is stirred in an ice bath overnight. The precipitated sodium iodate is filtered, and the filtrate is extracted with chloroform. The extract is dried over anhydrous magnesium sulfate, and the solvents are evaporated under reduced pressure. The residue (13.9 g, 99% yield) is distilled at 83-85 °C at 0.1 mm of Hg to give pure methyl phenyl sulfoxide, mp 29-30 °C. 

The mother liquors now contain about 40 lbs. of nitrate per cubic foot, and are used in the systematic lixiviation of the caliche described above, being run (in addition to the weak liquor from the final exhaustion of the caliche) on to the subsequent caliche. These mother liquors, however, contain much iodine in the form of sodium iodate, from which the iodine must first be recovered in the manner described ia the section on Iodine in Martin s Industrial Chemistry, Vol. II. From the iodine house the mother liquors are passed on to the lixiviating tanks, to lie used once more, as above described, m extracting crude caliche. The iodine recovered in this way is now an important article of commerce. 

General directions for oxidation of sulfides to sulfoxides 604 A mixture of a 0.5M-solution (210 ml, 0.105 mole) of sodium metaperiodate in water and of the sulfide (0.1 mole) is stirred at 0° for 12 h. The precipitated sodium iodate is filtered off and the solution is extracted with chloroform. The chloroform is removed in a vacuum and the residual product is purified by distillation, crystallization, or sublimation. Yields of sulfoxide are about 90%. 

Most of the world s production of iodine comes from the saltpeter deposits in Chile and natural brines in Japan. In Chile, calcium iodate is found in caliche deposits extracted from open pit mines in the Atacama Desert. Applying an alkaline solution to the caliche yields sodium iodate and iodine is obtained from the sodium iodate by reduction with sulfur dioxide. In Japan, iodine is a by-product of the production of natural gas, which is extracted from brine deposits a mile or two below ground. Iodine is recovered from the brines by one of the following two methods. In the blowout process elemental iodine is liberated as a result of the reaction of chlorine with sodium iodide in the brines. Elemental iodine is blown out of the brine with air and then purified in subsequent reaction steps. The second method, ion exchange, involves recovery of dissolved iodine from oxidized brines using anion-exchange resins packed in columns. In 2010, Chile produced 18 000 metric tons of iodine, compared to Japan s output of 9800 metric tons. Chile has reserves of 9 million metric tons, some 60% of the world s total reserves of iodine [10],... 

Iodine was determined by an iodometric titration adapted from White and Secor.(3) Instead of the normal Carius combustion, iodide was separated from the samples either by slurrying in 6M NaOH, or by stirring the sample with liquid sodium-potassium (NaK) alloy, followed by dissolving excess NaK in ethanol. Precipitated plutonium hydroxides were filtered. Iodine was determined in the filtrate by bromine oxidation to iodate in an acetate buffer solution, destruction of the excess bromine with formic acid, acidifying with SO, addition of excess KI solution, and titrating the liberated iodine with standard sodium thiosulfate. The precision of the iodine determination is estimated to be about 5% of the measured value, principally due to incomplete extraction of iodine from the sample. 

Potassium iodide can also be obtained from the aq. extract of kelp or from the mother liquid remaining after the separation of sodium chloride and potassium sulphate from sea-water by evaporation. In E. Allary and J. Pellieux process,8 the liquid is evaporated to dryness and roasted in a special furnace so as to avoid a loss of iodine. The product is fractionally extracted with cold water, when a soln. is obtained which on evaporation gives a residue with 50 per cent, of alkali iodide. This product is extracted.in a special digester with 50 per cent, alcohol. The solvent dissolves little more than the iodides. The alcohol is distilled off, and on evaporation a residue containing about 34 per cent, of potassium iodide, and 66 per cent, of sodium iodide is obtained. To convert the latter into potassium iodide, the proper quantity of a soln. of potassium carbonate is added and carbon dioxide passed into the liquid whereby sodium bicarbonate is precipitated. The precipitate is separated by a filter press, and the small amount of sodium bicarbonate remaining in the soln. is separated by the addition of a little hydrochloric acid and the sodium chloride and potassium iodide separated by fractional crystallization. In E. Sonstadt s process, the mother liquid is treated with chlorine mixed with potassium chlorate or permanganate so as to convert the iodine into iodate. A soln. of a barium salt is added, and the barium iodate treated with potassium sulphate. Barium sulphate is precipitated, and the soln. of potassium iodate is evaporated to dryness and calcined to convert the iodate to iodide. The latter is purified by crystallization. 

Grind together 12 g (0.05 mol) of iodylbenzene (Expt 6.33), and 11 g (0.05 mol) of iodosylbenzene (Expt 6.32) with 25 ml of water, add 100 ml of 1 m sodium hydroxide solution and stir for 24 hours in a 1-litre vessel. Dilute with 500ml of cold water, stir thoroughly, allow to settle and decant the supernatant solution of diphenyliodonium iodate, through a fluted filter paper. Extract the solid residue with two 250 ml portions of water, and decant the extract... 

Bromide and iodide in the presence of each other and of chloride The presence of a chloride does not interfere with the reactions described below. To the soda extract, strongly acidified with dilute hydrochloric acid add 1-2 drops of chlorine water (the solution obtained by carefully acidifying a dilute solution of sodium hypochlorite with dilute hydrochloric acid may also be used) and 2-3 ml chloroform or carbon tetrachloride shake a violet colour indicates iodide. Continue the addition of chlorine water or of acidified sodium hypochlorite solution drop by drop to oxidize the iodine to iodate and shake after each addition. The violet colour will disappear, and a reddish-brown colouration of the chloroform or carbon tetrachloride, due to dissolved bromine (and/or bromine monochloride, BrCl), will be obtained if a bromide is present. If iodide alone is present, the solution will be colourless after the violet colour has disappeared. 

Test for iodide in the neutralized soda extract or in a solution of the sodium salts by the addition of a few drops of chlorine water (or acidified sodium hypochlorite solution) and 2-3 ml chloroform or carbon tetrachloride the latter is coloured violet. Add excess silver sulphate solution to another portion of the neutral solution and filter off the silver iodide remove the excess silver sulphate with sodium carbonate solution. Pass sulphur dioxide into the filtrate to reduce iodate to iodide, boil off the excess sulphur dioxide, and add silver nitrate solution and dilute nitric acid. A yellow precipitate of silver iodide confirms the presence of iodate in the original substance. 

The presence of iodate in the soda extract can be readily detected as follows. Treat 2 ml of the solution with silver nitrate solution until precipitation ceases, heat to boiling for 2-3 minutes and filter. Render the filtrate strongly acid with hydrochloric acid, add 2 ml of 0-5m iron(II) sulphate solution (or 0 5m sodium sulphite solution) and shake it with 2 ml carbon tetrachloride. A purple colouration of the organic layer indicates iodate. 

The extraction of iodine from caliche.—The mother-liquor—aqua vieja— remaining after the extraction of sodium nitrate from caliche in Chili, contains sodium nitrate, chloride, sulphate, and iodate as well as magnesium sulphate. The iodine content of this liquid amounts up to about 0 3 per cent, as the original caliche has about 0 02 per cent., the iodine thus accumulates in the mother liquid during the extraction of the nitrate. The mother liquid is run into wooden vats,... 

---