Cuprous Iodine

Chemical Designations - Synonyms Cuprous Iodine Marshite Chemical Formula Cul. Ohservahle Characteristics - Pfo .rfca/State (as normally shipped) Solid Color Beige Odor. None. Physical and Chemical Properties - Physical State at 15 and I atm. Solid Molecular Weight 190.4 Boiling Point at I atm. 2,354, 1,290, 1,563 Freezing Point 1,121, 605, 878 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 5.62 at 20°C (solid) Vapor (Gas) Density Not pertinent Rtuio cf Specific Heats of Vapor (Gas) Not pertinent Latent Heat of Vaporization Not pertinent Heat cf Combustion Not pertinent Heat cf Decomposition Not pertinent. 

Iodides. Iodides range from the completely ionic such as potassium iodide [7681-11-0] KI, to the covalent such as titanium tetraiodide [7720-83-4J, Til. Commercially, iodides are the most important class of iodine compounds. In general, these are very soluble in water and some are hygroscopic. However, some iodides such as the cuprous, lead, silver and mercurous, are insoluble. 

Iodized Salt. Iodized table salt has been used to provide supplemental iodine to the U.S. population since 1924, when producers, in cooperation with the Michigan State Medical Society (24), began a voluntary program of salt iodization in Michigan that ultimately led to the elimination of iodine deficiency in the United States. More than 50% of the table salt sold in the United States is iodized. Potassium iodide in table salt at levels of 0.006% to 0.01% KI is one of two sources of iodine for food-grade salt approved by the U.S. Food and Dmg Administration. The other, cuprous iodide, is not used by U.S. salt producers. Iodine may be added to a food so that the daily intake does not exceed 225 p.g for adults and children over four years of age. Potassium iodide is unstable under conditions of extreme moisture and temperature, particularly in an acid environment. Sodium carbonate or sodium bicarbonate is added to increase alkalinity, and sodium thiosulfate or dextrose is added to stabilize potassium iodide. Without a stabilizer, potassium iodide is oxidized to iodine and lost by volatilization from the product. Potassium iodate, far more stable than potassium iodide, is widely used in other parts of the world, but is not approved for use in the United States. 

Ofner Method. This method is for the determination of invert sugar in products with up to 10% invert in the presence of sucrose and is a copper-reduction method that uses Ofner s solution instead of Fehling s. The reduced cuprous oxide is treated with excess standardized iodine, which is black-titrated with thiosulfate using starch indicator. 

Another process using butadiene as the starting material was developed by Esso. This involved the reaction of butadiene with iodine and cuprous cyanide to give the cuprous iodide complex of dehydroadiponitrile. This is further reacted with HCN to give a high yield of dehydroadiponitrile and regeneration of the iodine and cuprous iodide. 

Most of the iodine can be recovered as potassium iodide mixed with some potassium carbonate. A little cuprous iodide is also present. 

Potassium iodide is added as a nutrient to prevent goiter, a thyroid problem caused by lack of iodine, and to prevent a form of mental retardation associated with iodine deficiency. A project started by the Michigan State Medical Society in 1924 promoted the addition of iodine to table salt, and by the mid-1950s three-quarters of U.S. households used only iodized salt. Potassium iodide makes up 0.06 percent to 0.01 percent of table salt by weight. Sometimes cuprous iodide—iodide of copper—is used instead as the source of iodine. 

Iodinations can be carried out by mixtures of iodine and various oxidants such as periodic acid,26 I205,27 N02,28 and Ce(NH3)2(N03)6.29 A mixture of a cuprous iodide and a cupric salt can also effect iodination.30... 

Tetrahydrofuran freshly distilled from lithium aluminum hydride should be used. A commercial product with a peroxide content giving a positive iodine test must be treated with about 0.3% of cuprous chloride (boiling for 30 minutes and distillation) before the addition of the hydride. 

Replacement of the diazonium group by iodine does not require the presence of cuprous halide and is done simply by shaking the diazonium salt with potassium iodide. 

The jacketed addition funnel is removed and 1.5 g of cuprous bromide-dimethyl sulfide complex (Note 7) is added through a powder funnel. A 500-mL, pressure-equalizing addition funnel (long-tipped) is attached to the flask and flushed with argon. As the anion solution is cooled in a dry ice-isopropyl alcohol bath, a solution of 530 g (2.08 mol) of sublimed iodine in 500 mL of anhydrous tetrahydrofuran is placed in the addition funnel. This solution is added dropwise to the cooled slurry over approximately 90 min (Note 8). The solution is stirred for about 15 min at low temperature. 

This mechanism can be illustrated by the reaction of ferrous ions with hydrogen peroxide (42), the reduction of organic peroxides by cuprous ions (63), as well as by the reduction of perchlorate ions by Ti(III) (35), V(II) (58), Eu(II) (71), The oxidation of chromous ions by bromate and nitrate ions may also be classified in this category. In the latter cases, an oxygen transfer from the ligand to the metal ion has been demonstrated (8), As analogous cases one may cite the oxidation of Cr(H20)6+2 by azide ions (15) (where it has been demonstrated that the Cr—N bond is partially retained after oxidation), and the oxidation of Cr(H20)6+2 by 0-iodo-benzoic acid (6, 8), where an iodine transfer was shown to take place. 

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... 

In 1862, E. C. C. Stanford proposed the carbonization of the drift-weed in closed retorts so as to recover tar and ammoniacal liquor in suitable condensers. This modification did not flourish because of the subsequent difficulties in extracting soluble iodides from the charcoal. V. Vincent (1916) claims that soln. containing aluminium sulphate extract the alkali iodides from seaweed leaving behind the organic matter which prevents the direct precipitation of iodine or iodides. The alkali iodide soln. is treated with copper sulphate for cuprous iodide, or by soln. of sulphites for iodine. M. Paraf and J. A. Wanklyn proposed to heat the drift-weed first with alkali hydroxide so as to form oxalic and acetic acids, which could be crystallized from the lixivium. The economical treatment of seaweed for iodine has been discussed by A. Puge. 

Apart from cuprous acetylide, with the formula Cu2C2, there are complex cuprous salts prepared by the action of acetylene on certain cuprous salts in a neutral or slightly acidic medium e.g. Bhaduri [110] obtained a cuprous acetylide containing a thiosulphate group by the action of acetylene on cuprous thiosulphate, and in the presence of potassium iodide Scheiber and Reckleben [104] precipitated an acetylide containing iodine. 

To estimate arsenite and arsenate when present together, the former may first be determined in a portion of the solution by titration with iodine in the presence of sodium bicarbonate. Another portion is acidified strongly with hydrochloric acid, some ferrous sulphate and potassium bromide are added and the whole of the arsenic is distilled off as chloride and collected in water.2 The reduction may also be accomplished by cuprous chloride.3 The arsenious acid in the aqueous distillate is determined as above and the arsenic acid found by difference. 

Cupric iodide is very unstable, and readily yields up iodine, forming cuprous iodide. On mixing cupric chloride with potassium iodide, the cuprous iodide is precipitated + + +- + + -... 

Iodine Calcium iodate, iodobehenate, cuprous iodide, 3,5-diiodosalicylic... 

Reformatsky reactions have a bad reputation as being difficult to entrain. To the authors experience, however, the reactive donors such as alkyl bromo-acetates do not pose particular problems even under rather conventional conditions. Commercial zinc dust activated by pre-treatment with either iodine of preferentially with cuprous chloride (i.e. Zn(Cu)) readily inserts into these halocarbonyl compound with formation of the corresponding zinc enolates. Protocols 1 and 2 describe prototype examples for Reformatsky reaction in the conventional two-step or Barbier-type set-up, respectively. 

---