Iodide salts, solubility

Lithium Halides. Lithium haHde stabiHty decreases with increasing atomic weight of the halogen atom. Hence, the solubiHty increases from the sparingly soluble Hthium fluoride to the very soluble bromide and iodide salts. The low melting points of Hthium haHdes are advantageous for fluxes in many appHcations. 

When a salt dissolves in water, it produces cations and anions. Lead(II) nitrate and potassium iodide are soluble salts. Lead(II) nitrate dissolves in water to generate Pb cations and NO3 anions. Potassium iodide dissolves in water to generate K and I ions. Mixing the solutions combines all four types of ions. A precipitate forms if any of the new combinations of the ions forms a salt that is insoluble in water. The new combinations when these two solutions mix are K combining with NO3 or Pb combining with I ... 

Ewing et al. (2) noted that C. bowiei, a small shrub in New South Wales and southern Queensland and a tree growing to about 10 m (30 feet) in northern Queensland, afforded alkaloids which were different but structurally closely related. Methods of isolation were essentially the same, and the alkaloids were obtained as sparingly soluble iodide salts after addition of potassium iodide. (—)-Cryptaustoline iodide (C20H24NO4I) was obtained from extracts of the bark of larger northern trees, and (-)-cryptowoline iodide (C,gH2oN04l) was found to be present in the smaller southern shrubs. 

With these process factors in mind, a continuous, homogeneous reaction process concept was developed in which the starting epoxide 1 is fed as a liquid to the reactor containing the soluble Lewis acid and iodide salt while continuously removing the 2,5-DHF and crotonaldehyde by distillation. Continuously, or as needed, the catalysts are recovered from the reaction mixture by extraction with an alkane and the undissolved oligomer is discarded. 

Quaternary ammonium iodides are attractive choices because they generally have good activity, low cost, and solubility in the reaction and recovery processes. Simple quaternization of the wide variety of available tri(n-alkyl) amines with n-alkyl iodides allows optimization of the tetra(n-alkyl) ammonium iodide salt properties ... 

Quaternary phosphonium iodides are also good choices for the iodide salt catalyst component because they are highly active and, in some cases, soluble in the reaction and recovery processes. The simple quaternization of tri(n-alkyl)phosphines or triarylphosphines with n-alkyl iodides produces a wide variety of low cost phosphonium iodide salts ... 

Cadmium iodide is soluble in such organic solvents as alcohol, ether, and acetone. The salt may be formulated as cadmium (II) tetraiodocadmate (II) to explain this behavior. 

A solution of 8.70 g. (29.8 mmoles) of the iodide salt in 50 ml. of water is warmed to about 80°C., and a warm solution of NH4PF6 (11.8 g. threefold excess) in 75 ml. of water is added slowly while the mixture is stirred with a glass rod. Precipitation of the sparingly soluble hexafluorophosphate starts immediately and is completed by cooling in an ice bath. 

The iodide salt is insoluble in benzene, alkanes, carbon tetrachloride, or diethyl ether but is easily soluble in water, methanol, acetone, or methylene chloride. It can be recovered from methylene chloride in nearly quantitative yield by precipitation with ether. The hexafluorophosphate dissolves in the same solvents as does the iodide, with, the exception of cold water, in which it is only slightly soluble (about 0.01 M). The cation is stable in aqueous HC1 or NaOH but rapidly loses trimethyl-amine in pyridine solution. It can be chlorinated or brominated on boron by the elements in methylene chloride. The hexa-... 

The salt is a white solid, soluble in w ater, acetonitrile, methylene chloride, and alcohol. The cation is stable in neutral and acidic aqueous solution, but it is degraded in aqueous base. Because the cation is stable in aqueous solution, many of its salts can be readily prepared by metathesis or ion exchange. Principal infrared absorption bands of the iodide salt, run as a mineral-oil mull (exclusive of that in common with the mineral oil), occur at 2410(m), 2380(m), 1300(m), 1065 (w), 1037(w), 990(m), 950(s), 900(m), 855(w), 772(m), and 740(m) cm.-1. 

All chlorides, bromides, and iodides (salts containing CP, BP, or P) are soluble. Halides where Ag+, Pb2+, Hg22+, are the cations are insoluble. 

This equation only shows the ions that are actually involved in the reaction. It also helps to point out other reactions that are possible. For example, any soluble lead salt, when combined with any soluble iodide salt, will produce the insoluble lead (II) iodide. 

IV.16 IODIDES, I Solubility The solubilities of the iodides are similar to the chloride and bromides. Silver, mercury(I), mercury(II), copper(I), and lead iodides are the least soluble salts. These reactions can be studied with a O 1m solution of potassium iodide, KI. 

The chloride, bromide, bromate, perchlorate, nitrate, acetate, and iodide salts are all soluble in water, the sulfates sparingly soluble, and the fluorides, carbonates, oxalates, and phosphates insoluble. 

Evaluation of solvent-sensitive properties requires well-defined referena i ran eis. A macroscopic parameter, dielectric constant, does not always give interpretable correlations of data. The first microscopic measure of solvent polarity, the Y-value, based on the solvolysis rate of t-butyl chloride, is particularly valuable for correlating solvolysis rates. Y-values are tedious to measure, somewhat complicated in physical basis, and characterizable for a limited number of solvents. The Z-value, based on the charge-transfer electronic transition of l-ethyl-4-carbomethoxy-pyridinium iodide , is easy to measure and had a readily understandable physical origin. However, non-polar solvent Z-values are difficult to obtain b use of low salt solubility. The Et(30)-value , is based on an intramolecular charge-transfer transition in a pyridinium phenol b ne which dissolves in almost all solvents. We have used the Er(30)-value in the studies of ANS derivatives as the measure of solvent polarity. Solvent polarity is what is measured by a particular technique and may refer to different summations of molecular properties in different cases. For this reason, only simple reference processes should be used to derive solvent parameters. 

Addition of excess iodide to the insoluble Hgl2 results in the formation of soluble mercury iodo complex [Hgl3] , with a trigonal planar structure. The ion is solvated in water and converts to a tetrahedral structure. Further, addition of H leads to tetrahedral [Hg ] ". Reaction of iodide salts with Hg can be used to produce mercury iodo complexes. Other halide and pseudohalides also form [HgXj] and [HgX4] . The tetrahalo anions see Anion) are usually tetrahedral, while the trihalo ions readily add solvent molecules to form distorted tetrahedral or Trigonal Bipyramidal structures. 

Ammonia possesses similar physical properties to that of water, which is similarly highly associated. It is a good solvent for many compounds. Owing to the lower dielectric constant (NH3 16.9, H2O 78.3 at 298 K) of ammonia in comparison with water, less polar compounds are more soluble in ammonia and polar compounds, for example, salts, are more soluble in water. Organic compounds tend to have a higher solubihty in ammonia than in water. Armnonium salts, nitrates, nitrites, cyanides, and thiocyanates dissolve readily in ammonia. The solubihty increases from fluorides to chlorides, bromides, and iodides. Salts with higher charged ions dissolve only poorly in ammonia. This results in the reversal of some precipitation reactions in ammonia compared to water. 

Formation of Complex Ions.—In certain cases the solubility of a sparingly soluble salt is greatly increased, instead of being decreased, by the addition of a common ion a familiar illustration of this behavior is provided by the high solubility of silver cyanide in a solution of cyanide ions. Similarly, mercuric iodide is soluble in the presence of excess of iodide ions and aluminum hydroxide dissolves in solutions of alkali hydroxides. In cases of this kind it is readily shown by transference measurements that the silver, mercury or other cation is actually present in the solution in the form of a complex ion. The solubility of a sparingly soluble salt can be increased by the addition of any substance, whether it... 

Other Alkylation Experiments. In other experiments lithium and sodium were used in place of potassium. Biphenyl and anthracene were used in place of naphthalene. 1,2-Dimethoxyethane was used in place of tetrahydrofuran. Butyl chloride, butyl bromide, butyl mesylate, butyl triflate, methyl iodide, and octyl iodide were used in place of butyl iodide. The conditions used in these experiments were very similar to the conditions used in the procedures described in the previous paragraphs. The isolation procedure was modified in those cases where the ionic salt, e.g., sodium iodide, was soluble in tetrahydrofuran. In these instances the tetrahydrofuran-soluble product was washed with water to remove the salt prior to further study. 

Water-soluble ruthenium complexes RuHCl(tppts)3, RuCl2(tppts)3, RUH2 (tppts)3, or the rhodium complex RhCl(PTA)3, are also effective catalysts for the hydrogenation of the carbonyl function of aldehydes [16], carbohydrates [17], and keto acids [13], provided that the iodide salt Nal is added for ruthenium complexes. 

Carbonylation of methanol catalyzed by soluble Group IX transition metal complexes remains the dominant method for the commercial production of acetic acid. The Monsanto process stands as one of the major success stories of homogeneous catalysis, and for three decades it was the preferred technology because of the excellent activity and selectivity of the catalyst. It has been demonstrated by workers at Celanese, however, that addition of iodide salts can significantly benefit the process by improving the catalytic reaction rate and catalyst stability at low water concentrations. Many attempts have been made to enhance the activity of... 

For salt formation by salt exchange, the salt of the drug substance is combined with a salt containing the desired counterion in specific molar ratios in a suitable solvent system. As described above, there must be adequate solubility of each reactant in the solvent system. If the desired salt of the drug substance is less soluble than the starting materials, it will precipitate out and can be isolated by filtration. If no precipitate is obtained, other isolation methods can be employed. A method that was described for iodide salts (19) involved precipitation of the unwanted counterion first. In this case silver salts were used for the counterions (silver sulfate, silver orf/tophosphate, silver lactate) and a silver iodide precipitate was isolated first by filtration. The desired salt of the drug substance was then precipitated from the filtrate by addition of an antisolvent. 

The characteristics of the iodide salts are either identical (cation exchange chromatographic behavior) or close (IR and electronic spectra, solubilities) to those of the related bromides (Section A). 

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