Hydrogen iodide purification

Rhodium catalyzed carbonylations of olefins and methanol can be operated in the absence of an alkyl iodide or hydrogen iodide if the carbonylation is operated in the presence of iodide-based ionic liquids. In this chapter, we will describe the historical development of these non-alkyl halide containing processes beginning with the carbonylation of ethylene to propionic acid in which the omission of alkyl hahde led to an improvement in the selectivity. We will further describe extension of the nonalkyl halide based carbonylation to the carbonylation of MeOH (producing acetic acid) in both a batch and continuous mode of operation. In the continuous mode, the best ionic liquids for carbonylation of MeOH were based on pyridinium and polyalkylated pyridinium iodide derivatives. Removing the highly toxic alkyl halide represents safer, potentially lower cost, process with less complex product purification. 

The purification unit consists of three valve-tray columns. The production medium for AA in the purification stage at 130-200 °C contains up to 16% water, 26% methyl iodide, and other components, such as methyl acetate (MA), methanol (MeOH), hydrogen iodide (HI), formic acid (FA), and propionic acid (PA) (PEP Report, 1994). The fractionation column removes the light components and portions of water in the mixture, and the dehydration column treats both water and FA. The last column, which is an SSC, produces the final AA product from the side draw by cutting off the remaining light and heavy components from... 

While several of the approaches are fast, the copper-catalyzed iodination of terminal alkynes using Al-iodomoiphoUne-hydrogen iodide is fast and requires only minimal purifications to isolate pure material [261]... 

The iodate is a poison potassium iodide, however, is used in foodstuffs. Thus the iodate must be completely removed frequently by a final reduction with carbon. After re-solution in water, further purification is carried out before recrystallization. Iron, barium, carbonate, and hydrogen sulfide are used to effect precipitation of sulfates and heavy metals. 

Purification. The metal obtained from both electrolytic processes contains considerable oxygen, which is beheved to cause brittieness at room temperature. For most purposes the metal as plated is satisfactory. However, if ductile metal is desired, the oxygen can be removed by hydrogen reduction, the iodide process, calcium refining, or melting ia a vacuum ia the presence of a small amount of carbon. 

Dimethylphenylsilyl lithium (1 mmol, above THF solution) was added to copper(i) iodide (0.5 mmol) at — 23 °C, and the mixture was stirred at this temperature for 4h. The enone (0.75-0.5mmol) was then added, and stirring was continued at —23 °C for 0.5 h. The mixture was then poured on to ice(25 g)/HCl(5 ml), and extracted with chloroform (3 x 25 ml). The combined extracts were filtered, washed with HCI (25ml, 3m), water (25 ml), saturated sodium hydrogen carbonate solution (25 ml) and water (25 ml), and dried. Concentration and purification by preparative t.l.c. (eluting solvent 3 7 ether petrol) gave the /J-silylketone (40-99%). 

Methyl n-amyl carbinol. 247, 254 Methyl n-amyl ketone, 482 Methylaniline (mono), pure, from commercial methylaniline, 562, 570 P-Methylanthraquinone, 728, 740 Methyl benzoate, 780, 781 p-Methyl benzyl alcohol, 811,812 Methyl benzyl ketone, 727, 735 Methyl y-bromocrotonate, 926, 927 2-Methyl-2-butene, 239 Methyl n-butyl carbinol, 247,255 Methyl n-butyl ether, 314 Methyl n-butyl ketone, 475, 481 4-Methylcarbostyril, 855 p-Methylcinnamic acid, 719 4-Methylcoumarin, 853, 854 Methyl crotonate, 926, 927 Methylethylacetic acid, 354, 358 Methylethylethynyl carbinol, 468 Methyl ethyl ketone, 335, 336 purification of, 172 Methyl n-hexyl ether, 314 Methyl n-hexyl ketone, 335, 336 Methyl n-hexyl ketoxime, 348 Methyl hydrogen adipate, 938 Methyl hydrogen sebacate, 938,939 4-Methyl-7-hydroxycoumarin, 834 Methyl iodide, 287 Methyl isopropyl carbinol, 247,255 Methyl 4-keto-octanoate, 936... 

Bismuth(III) iodide has been prepared in the absence of solvents by the reaction of iodine with elemental bismuth1,2 or with bismuth (III) sulfide.3 Alternative methods involve precipitation of bismuth(III) iodide from aqueous solutions of bismuth salts by adding alkali-metal iodides,4 and the addition of bismuth (III) oxide to a solution of iodine and tin(II) chloride in saturated hydrogen chloride.5 In either case the initial product is purified by sublimation, usually in an atmosphere of carbon dioxide. The product obtained by precipitation requires several resublimations for complete purification.6... 

Plutonium Purification. The same purification approach is used for plutonium separated from sediments or seawater. In case reduction may have occurred, the plutonium is oxidized to the quadrivalent state with either hydrogen peroxide or sodium nitrite and adsorbed on an anion exchange resin from 8M nitric acid as the nitrate complex. Americium, curium, transcurium elements, and lanthanides pass through this column unadsorbed and are collected for subsequent radiochemical purification. Thorium is also adsorbed on this column and is eluted with 12M hydrochloric acid. Plutonium is then eluted from the column with 12M hydrochloric acid containing ammonium iodide to reduce plutonium to the non-adsorbed tervalent state. For seawater samples, adequate cleanup from natural-series isotopes is obtained with this single column step so the plutonium fraction is electroplated on a stainless steel plate and stored for a-spectrometry measurement. Further purification, especially from thorium, is usually needed for sediment samples. Two additional column cycles of this type using fresh resin are usually required to reduce the thorium content of the separated plutonium fraction to insignificant levels. 

Improvements to the basic commercial process also involve modifications to the purification stage and implementation of chemical treatment applications within that section, such as treatment with ozone, peroxides, or hydrogen [116-126]. These improvements are designed specifically to remove low levels of iodides, acetaldehyde, and acetaldehyde-derived impurities (i.e., crotonaldehyde and 2-ethylcrotonaldehyde) to reduce the concentration of these impurities in the final product. Removal of these impurities improves the acetic acid product quality [116-126]. 

Octadecylmethyl sulfoxide (OMS) was prepared in the following manner 15 g of octadecyl bromide and 3.5 g of thiourea were dissolved in 150 cm3 of ethanol. The mixture was refluxed for 1 hr after which 100 cm3 of ethanol were removed by distillation. The residue, after cooling, was made alkaline by an ethanol/sodium hydroxide solution (5 g sodium hydroxide in a minimum volume of ethanol). Methyl iodide, 3.7 g, was then added, and the mixture was left to stand overnight. The resulting thioether was recovered by filtration and washed with cold ethanol. The thioether was dissolved in glacial acetic acid then small quantities of 20 vol % hydrogen peroxide, constituting the stoichiometric amount, were added over several hours. The product was precipitated with water, and the precipitate was collected by filtration. The crude product was washed successively with water, ice-cold ethanol, and a small quantity of diethyl ether it was finally dried at 70°C. OMS was purified by successive recrystallization from benzene purification was... 

The preparation and purification of hydrogen chloride, bromide, and iodide were reported on pages 119-121. 

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