Solubility in basic solution

SolubiHty is used in the refining of oilseed meals to give protein isolates and concentrates (18). Proteins are highly soluble in basic solutions and the... 

Divalent and tetravalent Pt probably form as many complexes as any other metal. The platinum(II) complexes are numerous with IV. S, halogens, and C. The letranitritoplatinum complexes are soluble in basic solution. Tetranitntoplatinum(II) ion is formed when a solution of plat-inum(II) chloride is boiled, at about neutral pH, with an excess of NaNO f. The ammonium salt may explode when heated. Generally, platinum-metal nitrites should be destroyed in solution. They never should be heated in the dry form. Pladnum(II) complexes most often have a coordination number of 4. Many compounds have been prepared with olefins, cyanides, nitriles, halides, isonitnles, amines, phosphines, arsines, and nitro compounds. 

As would be anticipated for a carboxylic acid, mandelic acid is known to exhibit a pH strong dependence in its aqueous solubility. This pH dependence was calculated using the solubility module of the ACD PhysChem computational program (version 6.0, Advanced Chemistry Development, Toronto, Canada), and these results are plotted in Figure 1. The results indicate that mandelic acid will be freely soluble in basic solution, which would be interpreted to imply that the sodium salt would be freely soluble as well. 

Novobiocin is a pale yellow, somewhat photosensitive compound that crystallizes in two chemically identical forms with different melting points (polymorphs). It is soluble in methanol, ethanol, and acetone but is quite insoluble in less polar solvents. Its solubility in water is affected by pH. It is readily. soluble in basic solutions, in which it deteriorates, and is precipitated from acidic solutions. It behaves as a diacid, forming two. series of salts. 

In basic solutions basic nitrates are formed which precipitate however. In the presence of excess acetate, basic lead acetate Pb(0H)C2H202 Is formed which Is soluble In basic solution and can be used to prevent precipitation or hydrolysis of lead In neutral or weakly basic solutions. 

One of the best qualitative tests for the carboxylic acid group is solubility in basic solutions. Carboxylic acids are soluble both in 1.5 M sodium hydroxide solution and in 0.6 M sodium bicarbonate solution, from which they are regenerated by acidification. Solubility properties are discussed in Section 25.3. 

The distinction between primary and secondary amines thus depends on the different solubility properties of their benzenesulfonamide derivatives. However, the potassium salts of certain primary sulfonamides are not completely soluble in basic solution. Examples usually involve primary amines of higher molar mass and those having cyclic alkyl groups. To avoid confusion and possible misassignment... 

In recent time the number of water-soluble cryptophanes reported in the literature has increased substantially. The main reason for this arises from the rapid development of the xenon-cryptophane complexes aimed at designing biosensors for MRI applications. Nevertheless, it seems important to distinguish between two types of water-soluble cryptophanes. The first series of water-soluble cryptophanes are made from a cryptophane skeleton, which has been properly modified in order to significantly enhance its solubility in water. For instance, the hexa-carboxylate cryptophane 1 (Fig. 21.2), whose synthesis is reported below (Scheme 21.1), is sparingly soluble in neutral water and very soluble in basic solution (Na0H/H20). The second class of water-soluble cryptophanes is made of lipophilic cryptophane cores, which have been adequately functionalized in order to make the whole molecule soluble in water. For example, cryptophanol-A 2, when suitably substituted by hydrosoluble moiety at the phenol function, belongs to this second class of molecule (Fig. 21.2). Original cryptophane biosensors have been prepared by this way and will be described in more detail below. 

Interestingly, some metal hydroxides can also act as acids— they are amphoteric. The ability of an amphoteric metal hydroxide to act as an acid inaeases its solubility in basic solution. For example, Al(OH)3(5 ) dissolves in basic solution according to the reaction ... 

This process leaves behind solid impurities such as Si02, Fe20s, and Ti02, which are not appreciably soluble in basic solution. After the solid impurities are removed, the pH of the solution is lowered, causing the pure aluminum oxide to re-form. It is then electrolyzed to produce aluminum metal (see Section 17.8). 

Aluminum compounds are soluble in acidic solution, where aluminum(III) exists as the complex ion [A1(H20)6], which is generally represented simply as Al " (aq). They are also soluble in basic solutions, where the aluminum(III) is present as the complex ion... 

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