Iodide removal

In the chemical industry, iodine and/or iodine compounds are often used as catalysts and/or catalytic promoters for the production of value-added organic chemicals. As with other catalytic reactions, the catalyst or promoter must be removed from the products after completing the reaction. However, removing trace amounts of organic iodide contaminates from the product by conventional distillation techniques is difficult primarily due to the fact that iodine compounds are unstable and split off into various boiling ranges. 

Ag exchanged zeolite is used to remove iodine compounds. More recently Ag-LZ-210 , an Ag-exchanged zeoUte-Y adsorbent developed by UOP and having a high silica/alumina ratio (Si/Al 5), has been used commercially to remove iodide from acetic acid streams [250-252]. 

Trace aromatics removal from linear paraffins in the Ciq-Cis range is an important step in producing linear alkylbenzene (LAB) which in turn is used to make linear alkylbenzene sulfonate (LAS) an important constituent of detergents. High purity linear paraffins are required to produce superior detergent properties. For this application, MgY and NaX adsorbents are reported to be effective adsorbents in removing aromatics from Cio-C n-paraffins [265-267]. 

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Before coupling, excess nitrous acid must be destroyed. Nitrite can react with coupling components to form nitroso compounds causiag deHterious effects on the final dyestuff. The presence of nitrite can be detected by 4,4 -diamiQO-diphenyHnethane-2,2 -sulfone [10215-25-5] (Green reagent) or starch—iodide. Removal of nitrite is achieved by addition of sulfamic acid or urea [57-13-6], however, sulfamic acid [5329-14-6] has been more effective ia kinetic studies of nine nitrous acid scavangers (18). 

Metyrosine Metyrosine, (-)a-methyltyrosine (12.3.11), is synthesized in a few different ways, the simplest of which is the synthesis from 4-methoxybenzylacetone, which is reacted with potassium cyanide in the presence of ammonium carbonate to give the hydan-toin (12.3.9). Treating this with hydrogen iodide removes the methyl-protecting group on the phenyl hydroxyl group and the product (12.3.10) is hydrolyzed by barium hydroxide into a racemic mixture of a-methyl-D,L-tyrosine, from which the desired L-isomer is isolated (12.3.11) [83-86]. 

Washing with hydrochloric acid and potassium iodide removes 2,2,6,6-tetramethylpiperidin-1-oxyl from the organic phase.6 Because of its volatility, the catalyst cannot be eliminated in the distillation of crude aldehyde. 

Tellurophthalide in benzene solution was hardly affected by irradiation with 300 nm light, with phenyl magnesium bromide diphenyl ditellurium was formed. Methyl iodide removed tellurium from the heterocycle yielding trimethyl telluronium iodide1. 

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 potassium iodide removes mercury as tetraiodomercurate(II) [Hgl4]2, whilst the sodium thiosulphate dissolves lead and silver as complex thiosulphates. 

Reactor effluent liquid is withdrawn and flash-vaporized in the Flasher (2). The vaporized crude acetic acid is sent to the dehydration column (3) to remove water and any light gases. Dried acetic acid is routed to the finishing column (4), where heavy byproducts are removed in the bottom draw off. The finished acetic-acid product is treated to remove trace iodide components at the iodide removal unit (5). 

This compound is formed as a white precipitate from the interaction of ammonium aci-nitro-acetate and mercuric chloride in aqueous solution. It sublimes when carefully heated, detonates when strongly heated, and when ignited burns with a luminous flame,. In bases it dissolves readily, but is almost insoluble in boiling water. Treatment with bromine in potassium bromide solution forms ethyl dibromonitro-acetate, and potassium iodide removes the mercury from the anhydride as mercuric iodide. 

Iodide removal using zeolite-based reactive adsorption... 

Iodide removal using zeolite-based reactive adsorption S. Kulprathipanja and B. Spehlmann... 

Cellulose acetate membrane [69] and cellulose fiber [70] were coated on PPy to remove gold iodide and Cr(VI), respectively. Ionic exchange was ascribe for the gold iodide removal and the reduction of Cr(VI) to Cr(III), followed by adsorption. A covalently immobilized heparin-PPy/ poly(ethylene glycol) methacrylate composite was also fabricated for biological applications to reduce the protein and thrombus formation [71]. 

A soln. of methyl l-(l,3-dithian-2-ylmethyl)-c/5-l-methylcyclohex-2-ylacetate and methyl iodide stirred 12 hrs. at room temp., excess methyl iodide removed in vacuo, the soln. of the intermediate crude sulfonium salt in tetrahydrofuran added to NaH in tetrahydrofuran, and stirred 2.5 hrs. methyl l-(3,7-dithia-rran5--l-octenyl)-cw-l-methylcyclohex-2-ylacetate. Y 86%. F. method s. J. A. Marshall and D. E. Seitz, J. Org. Chem. 40, 534 (1975). 

Dissolve about 100 mg of sample in 52 ml of ethanol and add 40 ml of 2 per cent w v aqueous solution of potassium iodide and 2 ml of a freshly prepared 0 25 per cent solution of gelatin. Mix, cool and make up to 100 ml with the 2 per cent potassium iodide. Remove the oxygen from a portion of the solution by passing through nitrogen previously passed through a solution of 50 per cent v/v ethanol in water. 

Triphenylphosphinehydrocinnamoylmethoxycarbonylmethylmethylene refluxed 40 hrs. in benzene in the presence of benzoic acid, methyl iodide added, refluxing continued 2 hrs., and the resulting methyltriphenylphosphonium iodide removed by filtration methyl 3-hydrocinnamoylacrylate. Y 80%. F. e. s. H.-J. Bestmann, G. Graf, and H. Hartung, A. 706, 68 (1967). 

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