Crystalline salts aqueous solubility

Aquo-pentammino-chromic Nitrate, [Cr(NH3)5H20](N03)3, may be formed by a method similar to that for the bromide, or it may be produced by treating cliloro-pentammino-ehromie chloride in aqueous solution with 1-4 nitric acid and allowing the mixture to stand at 0° C. The solution is filtered and treated with a further portion of nitric acid and allowed to stand at 0° C., when the aquo-salt crystallises out.2 It is a yellowish-red crystalline salt, easily soluble in water, and decomposes if heated to 100° C. 

Physical properties. Majority are liquids except p toluidine and 1- and 2-naphthylamine. All are colourless when pure, but rapidly darken on exposure to air and light. All are very sparingly soluble in water, but dissolve readily in dilute mineral acids (except the naphthyl-amines, which are only moderately soluble in adds). They form colourless crystalline salts e.g., CjHjNH2,HCl) which are soluble in water these aqueous solutions usually have an add reaction owing to hydrolysis, and give the reactions of both the amine and the acid from which they are derived. Addition of alkali to the acid solution liberates the amine. 

Note. PRIMARY ALIPHATIC AMINES. The lower amines are gases or low-boiling liquids (b.ps. CHjNH, 7 CiHjNH, 17 CH,(CH2,>,NH 49 (CHg)jCHNHa, 34 ) but may be encountered in aqueous or alcoholic solution, or as their crystalline salts. They are best identified as their benzoyl, or toluene-/>-sulphonyl derivatives (c/. (C) above), and as their picrates when these are not too soluble. This applies also to benzylamine, CjHsCHjNH, b.p. 185 also to ethylenediamine, usually encountered as the hydrate, NHj (CHj)j NH2,HjO, b.p. 116 , for which a moderate excess of the reagent should be used to obtain the di-acyl derivative. (M.ps., pp. 55 55 )... 

The chlorides, bromides, nitrates, bromates, and perchlorate salts ate soluble in water and, when the aqueous solutions evaporate, precipitate as hydrated crystalline salts. The acetates, iodates, and iodides ate somewhat less soluble. The sulfates ate sparingly soluble and ate unique in that they have a negative solubitity trend with increasing temperature. The oxides, sulfides, fluorides, carbonates, oxalates, and phosphates ate insoluble in water. The oxalate, which is important in the recovery of lanthanides from solutions, can be calcined directly to the oxide. This procedure is used both in analytical and industrial apptications. 

Physical and Chemical Properties. Ammonium nitrate is a white, crystalline salt, df = 1.725, that is highly soluble in water, as shown in Table 3 (7). Although it is very hygroscopic, it does not form hydrates. This hygroscopic nature compHcates its usage in explosives, and until about 1940, was a serious impediment to its extensive use in fertilizers. The soHd salt picks up water from air when the vapor pressure of water exceeds the vapor pressure of a saturated aqueous ammonium nitrate solution (see Table 4). 

Methylpyrrole gives only amorphous polymeric material with HCl or picric acid in ether.In contrast with the pyrroles just mentioned, 2,5- and 3,4-dimethyl-, 2-methyl-5-ethyl-, 3-methyl-4-ethyl-, and 2-methyl-4-ethyl-pyrrole do not form crystalline salts, either monomeric or dimeric, and 2,4-dimethyl- and 4-methyl-2-ethyl-pyrrole form only monomeric salts. The dialkylpyrroles in this latter group all dissolve in aqueous sulfuric acid to form relatively stable solutions (e.g., references 14 and 15). The various tri- and tetra-akylpyrroles are likewise soluble in aqueous mineral acid to form stable solutions, and either do not react with HCl or picric acid... 

Crystalline salts of many organic acids and bases often have a maximum solubility in a mixture of water and water-miscible solvents. The ionic part of snch a molecule requires a strongly polar solvent, snch as water, to initiate dissociation. A mixture of water-miscible solvents hydrates and dissociates the ionic fraction of pollutants at a higher concentration than wonld either solvent alone. Therefore, from a practical point of view, the deliberate nse of a water-soluble solvent as a cosolvent in the formnlation of toxic organic chemicals can lead to an increased solnbility of hydrophobic organic contaminants in the aqueous phase and, conse-qnently, to a potential increase in their transport from land surface to groundwater. 

In aqueous media lutetium occurs as tripositive Lu3+ ion. All its compounds are in +3 valence state. Aqueous solutions of all its salts are colorless, while in dry form they are white crystalline solids. The soluble salts such as chloride, bromide, iodide, nitrate, sulfate and acetate form hydrates upon crystallization. The oxide, hydroxide, fluoride, carbonate, phosphate, and oxalate of the metal are insoluble in water. The metal dissolves in acids forming the corresponding salts upon evaporation of the solution and crystallization. 

Aquo-pentammino-chromic Bromide, [Cr(NH3)5H20]Br3, is prepared from the chloride by treating an aqueous solution of the salt with hydrobromic acid. The solution is evaporated to dryness and the residue taken up in water, filtered to remove any bromo-pentammino-chromic bromide formed, and the filtrate treated with concentrated hydrobromic acid to precipitate the aquo-salt, which is then washed with alcohol. It forms a yellow crystalline powder, easily soluble in W ater, and much more stable than the corresponding chloride. At 100° C. it loses water, and is transformed into bromo-pentammino-cliromic bromide. 

It is a white crystalline solid, slightly soluble in water, but soluble in acidic aqueous solutions and soluble in organic solvents, such as chloroform and diethyl ether. It is available in the illicit market as hydrochloride salt or free base (crack). Cocaine is usually mixed with other substances used as excipients. 

This latter behavior differs from fhaf observed in fhe crystalline diastereomers of mandelic acid wifh 1-phenylefhylamine [63]. Here the n-salt crystallized in the triclinic PI space group, while the p-salt crystallized in the monoclinic P2i space group. The crystallographic structures of the two diastereomers revealed the existence of fairly equivalent hydrogen-bonding patterns, but at the same time substantially different conformations for fhe two molecular ions making up fhe donor-acceptor complex were noted. These structural differences became manifest in the relative solubilities of fhe two diastereomers, where the aqueous solubility of fhe p-salf was much less fhan fhaf of fhe n-salt. 

Aminosalicylic Add. 4-Aminosalieylie acid (PAS) occurs as a white to yellowish-white crystalline solid that darkens on exposure to light or air. It is slightly soluble in water but more soluble in alcohul. Alkali metal salts and the nitric acid salt are. soluble in water, but the salts of hydrochloric acid and sulfuric acid arc not. The acid undergoes decarboxylation when heated. An aqueous solution has a pH of. T2. 

Penicillin G procaine suspension is an aqueous preparation of the crystalline salt that is only 0.4% soluble in water. Procaine combines with penicillin mole for mole a dose of 300,000 units thus contains approximately 120 mg procaine. When large doses of penicillin G procaine are given (e.g., 4.8 million units), procaine may reach toxic concentrations in the plasma. If the patient is believed to be hypersensitive to procaine, 0.1 mL of 1% solution of procaine should be injected intradermally as a test. The anesthetic effect of the procaine accounts in part for the fact that injections of penicillin G procaine are virtually painless. 

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