Iodine compounds using

Other Hypervalent Iodine Compounds Used for Oxidation... 

Iopanoic acid (3-amino-0(-ethyl-2,4,6-rn7o(3 o-hydrocinnamic acid) is a radiopaque iodine compound used as a contrast medium in cholecystography. Amiodarone (2-butyl-3-benzofuranyl) [4- [2- (diethylamino) ethoxyl]-3,5-diVocoronary vasodilator used in the control of ventricular arrhythmias, and in the management of angina pectoris. 

Iodine compounds are important in organic chemistry and very useful in medicine. Iodides, and thyroxine which contains iodine, are used internally in medicine, and as a solution of KI and iodine in alcohol is used for external wounds. Potassium iodide finds use in photography. The deep blue color with starch solution is characteristic of the free element. 

Iodine reacts with hydrocarbons to form iodine compounds, but compared to the other halogens, the equiUbria are unfavorable because the displacement step with the iodine atom is endothermic, requiring 4066.3 J (971.9 cal) for methane and 799.9 J (191.2 cal) for toluene. Hydrogen iodide can be used to reduce an alkah iodide to hydrocarbon plus molecular iodine. 

Catalysts. Iodine and its compounds ate very active catalysts for many reactions (133). The principal use is in the production of synthetic mbber via Ziegler-Natta catalysts systems. Also, iodine and certain iodides, eg, titanium tetraiodide [7720-83-4], are employed for producing stereospecific polymers, such as polybutadiene mbber (134) about 75% of the iodine consumed in catalysts is assumed to be used for polybutadiene and polyisoprene polymeri2a tion (66) (see RUBBER CHEMICALS). Hydrogen iodide is used as a catalyst in the manufacture of acetic acid from methanol (66). A 99% yield as acetic acid has been reported. In the heat stabiH2ation of nylon suitable for tire cordage, iodine is used in a system involving copper acetate or borate, and potassium iodide (66) (see Tire cords). 

A common contrast agent is barium sulfate [7727-43-7] although iodinated compounds have been used. Owing to the much higher linear attenuation coefficient of the contrast agent, a higher (120 keV) energy x-ray typically is used. 

Approximately half of the iodine consumed is used to make potassium iodide (see Iodine and iodine compounds). Production of KI is almost 1000 t/yr. Its main uses are in animal and human food, particularly in iodized salt, pharmaceuticals (qv), and photography (qv). 

Disinfectants. Several disinfecting agents can be used in hatcheries and two are of particular interest. Because they are not considered dmg or food additive uses by FDA, povidone—iodine compounds can be used to disinfect the surface of eggs (9). Benzalkonium chloride [68424-85-1] and benzethonium chloride (quaternary ammonium compounds), are allowed at 2 mg/L by FDA to disinfect water containing fish. These compounds are also known to have therapeutic properties, especially against external bacteria (9). 

Occurrence. Iodine [7553-56-2] is widely distributed in the Hthosphere at low concentrations (about 0.3 ppm) (32). It is present in seawater at a concentration of 0.05 ppm (33). Certain marine plants concentrate iodine to higher levels than occur in the sea brine these plants have been used for their iodine content. A significant source of iodine is caUche deposits of the Atacama Desert, Chile. About 40% of the free world s iodine was produced in Japan from natural gas wells (34), but production from Atacama Desert caUche deposits is relatively inexpensive and on the increase. By 1992, Chile was the primary world producer. In the United States, underground brine is the sole commercial source of iodine (35). Such brine can be found in the northern Oklahoma oil fields originating in the Mississippian geological system (see Iodine and iodine compounds). 

A primary use for iodine is as a catalyst in the production of acetic acid (qv) (39). Iodine is converted to compounds used in mbber, stabilizers, animal feed supplements, colorants, pharmaceuticals, sanitary products, and photographic products. 

Iodine. Iodine has been important for many years, primarily as an antiseptic (see Iodine and iodine compounds). In the American Civil War physicians used it to treat battie wounds. Elemental iodine is not very soluble in water, but dissolves readily when sodium iodide is added, forming triiodide + I I Iodine may thus be used as an aqueous solution but it has generally been used as a tincture of 2% iodine in 70% alcohol. Tests on... 

On a smaller scale, the largest producer of iodine is Japan where it is extracted from. seaweed containing more than 0.05 parts per million. The most important industrial iodine compound is silver iodide used with silver bromide in photography. Iodine is important in medicine for treating thyroid problems by adding it to table salt. It is used directly as a disinfectant, and a component of d vs. Crystalline silver iodide is used for cloud seeding. 

In addition to its uses in photography and medicine, iodine and its compounds have been much exploited in volumetric analysis (iodometry and iodimetry, p. 864). Organoiodine compounds have also played a notable part in the development of synthetic organic chemistry, being the first compounds used in A. W. von Hofmann s alkylation of amines (1850), A. W. Williamson s synthesis of ethers (1851), A. Wurtz s coupling reactions (1855) and V. Grignard s reagents (1900). 

Synthesis of heterocyclic compounds using hypervalent iodine reagents 98AHC(69)1. 

The alkaline solution of thymol is made up to 100 or 200 c.c. as the case may require, using a 5 per cent, soda solution. To 10 c.c. of this solution in a graduated 500 c.c. flask is added a normal iodine solution in shgbt excess, whereupon the thymol is precipitated as a dark reddish-brown iodine compound. In order to ascertain whether a sufficient quantity of iodine has been added, a few drops are transferred into a test tube and a few drops of dilute hydrochloric acid are added. When enou iodine is present, the brown colour of the solution indicates the presence of io ne, otherwise the liquid appears milky by the separation of thymol. If an excess of iodine is present, the solution is slightly acidified with dilute hydrochloric acid and diluted to 500 c.c. From this 100 c.c. are filtered,off, and the excess of iodine determined by titration with normal solution of sodium thiosulphate. For calculation, the number of cubic centimetres required is deducted from the number of cubic centimetres of normal iodine solution added and the resultant figure multiplied by 5, which gives the number of cubia centimetres of iodine required by the thymol. 

Thus, despite all the work carried out on starch-iodine, the exact nature of the guest iodine atoms is still not totally resolved. Teitelbaum, Ruby and Marks 156) have examined the compound using Raman and 129I Mossbauer spectroscopy and concluded that the pentaiodide ion 1 was the major chromophore present. However work based on iodine compounds of cyclodextrins 3-134 135) has shown that a variety of polyiodide species is possible, and the starch-iodine inclusion compound could conceivably involve I2 If, I2 I- I2, or I5 species 157). The anhydrous amylose-iodine compound has recently been found to exhibit semiconductor behaviour 158). 

Varvoglis A (2003) Preparation of Hypervalent Iodine Compounds. 224 69-98 Verkade JG (2003) P(RNCH2CH2)3N Very Strong Non-ionic Bases Useful in Organic Synthesis. 223 1-44... 

Varma and coworkers have explored the use of hypervalent iodine compounds on solid support for the first time and developed a facile oxidative procedure that rapidly converts alcohols to the corresponding carbonyl compounds using alumina-sup-ported IBD under solvent-free conditions and MW irradiation in almost quantitative yields [108]. The use of alumina as a support improved the yields markedly as compared to neat IBD (Scheme 6.33). 1,2-Benzenedimethanol, under these conditions, undergoes cyclization to afford l(3H)-isobenzofuranone. 

The oxidation of acetylthiourea and phenylthiourea to afford the corresponding 1,2,4-thiadiazoles has been reported using [bis(acyloxy)iodo]arenes as the oxidants. The proposed mechanism involves the formation of a polyvalent iodine compound 74. After the elimination of iodobenzene, the 1,6-dip he nyl-dithioformamidine 75 is formed, which is set up to undergo a further oxidation to give the bis 3,5-diamino-l,2,4-thiadiazole 76 (Scheme 7) <2003T7521>. 

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