Crystallization salting

A furtlier problem is tire influence of tire ratlier unusual—from tire physiological viewpoint—salt conditions necessary for crystallization. It should not be presumed tliat proteins embedded in a crystal are in tlieir most common native stmcture. It is well known tliat, witli tire exception of sodium or potassium chloride, which are not very useful for inducing crystallization, salts change key protein parameters such as tire melting temperature [19]. 

The most important manganese(V) compound is K MnO, a key intermediate in the manufacture of potassium permanganate. Potassium manganate(V) is an easily crystallized salt obtained by reduction of potassium permanganate using sodium sulfite in strong sodium hydroxide solution. This was the first compound to be recognized as exclusively pentavalent. 

Compounds of Tl have many similarities to those of the alkali metals TIOH is very soluble and is a strong base TI2CO3 is also soluble and resembles the corresponding Na and K compounds Tl forms colourless, well-crystallized salts of many oxoacids, and these tend to be anhydrous like those of the similarly sized Rb and Cs Tl salts of weak acids have a basic reaction in aqueous solution as a result of hydrolysis Tl forms polysulfldes (e.g. TI2S3) and polyiodides, etc. In other respects Tl resembles the more highly polarizing ion Ag+, e.g. in the colour and insolubility of its chromate, sulfide, arsenate and halides (except F), though it does not form ammine complexes in aqueous solution and its azide is not explosive. 

On evaporation of the ethyl ether from the ethyl ether solution, the benzhydryl ether was recovered as a pale yellow oil. The benzhydryl ether was dissolved in 60 ml of isopropanol and the isopropanol solution acidified to a pH of 3 with dry hydrogen chloride-methanol solution. The acidic propanol solution was then diluted with ethyl ether until a faint turbidity was observed. In a short time, the crystalline hydrochloride salt of the benzhydryl ether separated from the propanol solution. The crystallized salt was recrystallized once from 75 ml of isopropanol with the aid of ethyl ether in order to further purify the material. A yield of the pure hydrochloride salt of 1-methylpiperidyl-4-benzhydryl ether of 24.5 grams was obtained. This was 39% of the theoretical yield. The pure material had a melting point of 206°C. 

There are other soUd states which sometimes confuse the measurement and definition of solubiUty. The dmg may crystaUize as a hydrate, i.e. under inclusion of water molecules. If the hydrate form is more stable than the pure form it may be difficult to measure the intrinsic solubility of the drug at all. Often drugs tend to precipitate in an amorphous form, often under the inclusion of impurities. As with metastable polymorphs, such amorphous precipitates may lead to erroneously high solubility measurements. CommerciaUy, drugs are often crystallized in salt form, e.g. as the hydrochloride salt, a cation with a chloride anion. In these co-crystallized salts, a much lower solubility than the intrinsic solubility will typi-... 

Figure 7.28. Molecular representations of the crystallized salts (a) 78s-(S)-PEA and (b) 79s-(S)-PEA, from the X-ray structure data. (Taken from reference 179.)...

The new chromium(iii) isocyanato-complex (Ph4As)3[Cr(NCO)e] has been prepared and its i.r. and electron spectra are consistent with N-bonded ligands. ° A mixture of K3[Cr(NCS)e] and m-xylidine (m-xyl) at 100 °C for 4—5 h gives (m-xyl)[Cr(NCS)4(m-xyl)2] as purple crystals. Salts with other cations have also been isolated, and p-xylidine forms the analogous derivatives. ... 

The metal dissolves in dilute and concentrated mineral acids. Evaporation crystallizes salts. At ordinary temperatures, ytterbium, similar to other rare earth metals, is corroded slowly by caustic alkalies, ammonium hydroxide, and sodium nitrate solutions. The metal dissolves in liquid ammonia forming a deep blue solution. 

For salt-out, add solute which reduces effective solubility of component to be crystallized (salt having common ion is usual choice) salting-out compound should be cheap, as maybe difficult to recover. 

Hydrates are more often obtained by crystallizing salts from water and are very familiar compounds. A large number of salts are soluble in liquid ammonia, and from that solvent they usually crystallize as ammonates. 

In crystallizing salts from solution, it frequently happens that it is possible to obtain more than one hydrate. In all such cases, a perfectly definite temperature can be found above which the one hydrate will deposit, and below which the other one with a larger number of molecules of water of hydration appears. Thus, above 38°, zinc sulfate deposits crystals of the composition ZnS04 6H20, while crystals deposited below that temperature have the formula ZnS04-7H20. This is also called a transition point. 

Crystals of carbonate of soda have also been obtained containing eight equivalents of water, Na 0, CO, 8 HO, in the form of rectangular prisms, terminated by four-sided summits. These aro produced when the ordinary crystallized salt cools from a state of fusion, or from a saturated aqueous solution at a particular temperature. 

Prior to discharge, the condensate flows to the on-site federally owned treatment works, which includes an activated-sludge sewage treatment plant. The crystallized salts are shipped to an off-site commercial treatment, storage, and disposal facility. 

Ionic substances are written in the ionic form only if the ions are separated from each other in the reaction medium (most often water). NaCl would be the conventional notation for reactions involving solid salt, because the ions in the solid are bound together in the crystal. Salt reactions in solution, however, would... 

A mixture of 46 g of l-methyl-4-piperidinol (0.4 mol), 49.4 g of benzhydryl bromide (0.2 mol) and 100 ml of xylene was refluxed for approximately 24 hours. The reaction mixture separated into two phases with the upper phase containing the desired ether compound dissolved in xylene. The lower phase consisted of the hydro bromide salt of the excess l-methyl-4-piperidinol. The upper phase was separated from the lower phase and the desired benzhydryl ether recovered in the crude state by distilling off the xylene under reduced pressure. The crude benzhydryl ether was a clear reddish oil. It was dissolved in 75 ml of 20% hydrochloric acid and the aqueous acid solution then washed three times with 50 ml portions each of ethyl ether. The aqueous acid solution was then decolorized with activated carbon and thereafter slowly admixed with 75 ml of 28% aqueous ammonia. The benzhydryl ether separated as an oily material and was removed from the aqueous mixture by extraction with three 50 ml portions of ethylether. On evaporation of the ethyl ether from the ethyl ether solution, the benzhydryl ether was recovered as a pale yellow oil. The benzhydryl ether was dissolved in 60 ml of isopropanol and the isopropanol solution acidified to a PH of 3 with dry hydrogen chloride-methanol solution. The acidic propanol solution was then diluted with ethyl ether until a faint turbidity was observed. In a short time, the crystalline hydrochloride salt of the benzhydryl ether separated from the propanol solution. The crystallized salt was recrystallized once from 75 ml of isopropanol with the aid of ethyl ether in order to further purify the material. 

In the second column the behavior of the crystallized salt when it is exposed to the air of the laboratory is indicated s = stable, i.e. unchanged by exposure to atmosphere e = efflorescent d = deliquescent d, e = deliquescent or efflorescent, according as to whether the humidity is above or below the average C02 = absorbs carbon dioxide and falls to a white powder Ox - compound is oxidized, especially in presence of moisture Hyd = hydrolyzed, even by the water vapor of the air. 

Salt. Formula of crystallized salt. Color (White unless otherwise specified) Behavior when exposed to atmosphere. Solubility in Grams anhydrous salt per 100 grams water in a saturated solution at 0° 25° 100° Vater F. W. per liter of solution at laboratory temperature. 

The diaquabis(oxalato)chromate(III) anion forms a large number of well-crystallized salts with various cations. Their constitution was first established by Rosenheim and Cohn1 and by Werner and Surber.2 The salts occur in two geometrically isomeric series—cis, reddish violet, and trans, pinkish red—which are formed by reduction of dichromates by oxalic acid the specific conditions of the reaction determine which isomer is formed.2,3... 

The resulting powder is either used directly or the metal salts are calcined at a temperature that decomposes the crystallized salts and converts them to very fine crystalites of the desired ceramic powder. 

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