Sulfite, reaction with iodide

Troy, R. C., and D. W. Margerum, Non-Metal Redox Kinetics—Hypochlorite and Hypochlorous Acid Reactions with Iodide and with Sulfite and the Hydrolysis of Bromosulfate, Inorg. Chem.,... 

A detailed procedure for the use of MCPBA recently appeared in Reagents for Organic Synthesis by Fieser and Fieser. The commercially available MCPBA (Aldrich) is 85% pure the contaminant, m-chlorobenzoic acid, can be removed by washing with a phosphate buffer of pH 7.5. The epoxidation is usually performed as follows a solution of 3 -acetoxy-5a-androst-16-ene (2.06 g, 6.53 mmoles) in 25 ml of chloroform (or methylene dichloride) is chilled to 0° in a flask fitted with a condenser and drierite tube and treated with a solution of commercial MCPBA (1.74 g, 20% excess) in 25 ml chloroform precooled to the same temperature. The mixture is stirred and allowed to warm to room temperature. After 23 hr (or until TLC shows reaction is complete) the solution is diluted with 100 ml chloroform and washed in sequence with 100 ml of 10% sodium sulfite or sodium iodide followed by sodium thiosulfate, 200 ml of 1 M sodium bicarbonate and 200 ml water. The chloroform extract is dried (MgS04) and evaporated in vacuo to a volume of ca. 10 ml. Addition of methanol (10 ml) followed by cooling of the mixture to —10° yields 0.8 gof 16a,17a-epoxide mp 109.5-110°. Additional product can be obtained by concentration of the mother liquor (total yield 80-90%). 

Free and total sulfite in wines were determined using the induced oxidation of manganese(ll) and FIA system [1]. Sulfur dioxide as a product of the reaction of the examined sample with sulfuric acid diffused through a PTFE membrane to a solution of Mn(ll) in acetate buffer of pH 5.5. The oxidized Mn formed reacted with iodide to form iodine that was detected at 352 nm. The DL of 1 mg f was reported. 

HgjCU Noncombustible solid. Violent reaction with sodium. Slow decomposition in light, forming mercury and mercuric chloride. Incompatible with acetylene, alkali chlorides, ammonia, bromides, azides, carbonates, chlorine dioxide, cocaine hydrochloride, cyanides, copper and copper salts, hydrogen peroxide, hydroxides, iodides, iodine, iodoform, lead salts, lithium, potassium iodide, mbidium, silver salts, sodium carbide, sulfates, sulfides, sulfites. On small fires, use any kind of extinguishers. 

Miura, Y. Hatakeyama, M. Hosino, T. Haddad, P.R. Rapid ion chromatography of L-ascorbic acid, nitrite, sulfite, oxalate, iodide and thiosulfate by isocratic elution utilizing a postcolunm reaction with cerium(IV) and fluorescence detection. J. Chromatogr. A, 2002, 956,11-8A. 

A mixture of 0.16 g.-atom of red P, 0.3 g.-atom of iodine, and 0.3 mole of benzyl chloride heated in an oil bath until an exothermic reaction starts at 110°, kept for another 20 min. at 120° after the reaction has subsided, cooled, and treated with Na-sulfite (or 2 N NaOH) soln. with gentle heating tribenzyl-phosphine oxide. Y 87%. F. e. with iodides, and procedures s. E. S. Levchenko, Y.V.Piven, and A. V. Kirsanov, 7K. 30, 1976 (1960) G. A. 55, 6418L... 

In the fractional precipitation method for the separation of radioiodide, radioiodate, and radioperiodate (27,45), the sample was dissolved in aimonia water and iodine carriers were added. (The basic nature of the solution prevents redox reactions which might occur between the oxo species and iodide in an acidic or neutral medium.) Silver iodide was then precipitated from the ammo-niacal solution. The solution which remained was acidified with nitric acid and silver lodate precipitated. The periodate, which was left in solution, was reduced to iodide by means of sulfite and the iodide precipitated as the silver salt. The separation is not entirely satisfactory high results for periodate are generally obtained because some iodate appears in the periodate fraction as a result of the slight solubility of silver iodate. 

C7H2N3F306 mw 281.11 N 14.95% OB to C02 -51.23% white ndls mp 87°, 88.6-91.2°, 88.3—91.0°, 89.5—90° (separate values). Sol in hot trichlorethylene, Prepn is by reacting a soln of Na iodide in acet/glacial acetic acid with a soln of 3-chloro-2,4,6-trinitrobenzotrifluoride in acet at RT with stirring for 24 hrs. The reaction mixt is then drowned in an aq soln of Na sulfite. This procedure serves to separate an oily product-containing layer which is then extracted with hot... 

The reaction is catalyzed by divalent heavy metal ions, especially by Cu2+ and Co2+. It follows zeroth order, so it is independent of the concentration of the reactants Na2S03 and 02( ) but only depends on the rate of mass transfer. The remaining sulfite is oxidized to sulfate by the addition of iodine and the iodide generated is back-titrated with thiosulfate [Eqs. (8.37), (8.38)]. 

Reduction of the copper(II) halides to copper(I) halides may be carried out using sulfite or copper metal. If the reduction with copper metal is carried out in concentrated HC1 solution, the solution takes on an intermediate black color before fading to the colorless CuCl ion. The black color is probably due to dimeric or polymeric ions having copper in both the +1 and +2 states, for example, Cl—Cu—Cl—CuC12(H20) . The reduction of divalent copper by cyanide to form the cyano complex, Cu(CN)73, was mentioned in Chapter 10, and the reaction between cupric and iodide ions is similar to this, releasing iodine and forming the very insoluble copper iodide ... 

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