Insolubility, condition

Fig.1. Eh-pH diagram for the system Fe-U-S-C-H2O at 25 °C showing the mobility of uranium under oxidizing conditions, the relative stability of iron minerals, and the distribution of aqueous sulfur species. Heavy line represents the boundary between soluble uranium (above), and insoluble conditions (below), assuming 1 ppm uranium in solution.

In other experiments, too numerous to detail, the water was exposed to the action of a large surface of iron from twelve to forty-eight hours and as a general result it was found that by allowing water to remain in contact with a large surfaco of iron for about twelve hours, every trace of organic impurity was destroyed, or converted from the soluble to an insoluble condition, in which state it admitted of being effectually removed by ordinary filtration. 

Yields of the A-fraction by leaching at 70° agree with figures reported by Meyer, Brentano and Bernfeld. It appears that this mode of fractionation effects only a partial separation of the starch components. The soluble material is rather badly contaminated by B-fraction, especially at higher extraction temperatures." Correspondingly, a considerable portion of the A-fraction retrogrades to the insoluble condition and resists removal from the swollen residue. In comparison, fractionation... 

Ethoxylated alkyl sulfate amphoteric surfactant insoluble conditioning agent cellulosic cationic polymers synthetic esters... 

We restrict consideration here to insoluble surfactants. Note that though a surfactant may be soluble there are cases such that insolubility conditions can be used during a certain short period of the spreading process. Let us consider two characteristic time scales associated with the surfactant transfer (i) tj accoimts for the transfer from the liquid-air interface to the bulk, and (ii) Tq. from the bulk back to the interface. In both cases these characteristic time scales depend on an energy difference between corresponding states. For example, if we take water and a surfactant made of a hydrophilic head and a hydrophobic tail, then E/,h E,a, E,i are the energies (in kT units) of head-water, tail-air, and tail-water interactions. Using these notations... 

After the decomposition of the fatty or oily matter in the autoclave, the aqueous solution of glycerine is withdrawn, and instead of decomposing the lime soap with acids, as in the ordinary process of making stearine, the inventor employs for its decomposition strong caustio soda or potash leys, or a solution of carbonate of soda or potash. The hydrat or carbonate solution is used in about the proportion of 7 per cent, of the alkaline base to from 60 or 70 per cent, of the fatty acid, these proportions being varied within certain limits j in all cases care must be taken Hiat the alkali shall be sufficient to combine with or saturate the whole of the fatty acid. The decomposition of the lime soap by means of the hydrate or carbonate of soda will result in the production of a soda soap, and where the hydrate or carbonate of potash is used for such decomposition the product will be potash soap, the lime in either case being precipitated in a more or less insoluble condition. The soaps obtained by this process may be finished in a soap-copper in the ordinary manner. 

In tenns of an electrochemical treatment, passivation of a surface represents a significant deviation from ideal electrode behaviour. As mentioned above, for a metal immersed in an electrolyte, the conditions can be such as predicted by the Pourbaix diagram that fonnation of a second-phase film—usually an insoluble surface oxide film—is favoured compared with dissolution (solvation) of the oxidized anion. Depending on the quality of the oxide film, the fonnation of a surface layer can retard further dissolution and virtually stop it after some time. Such surface layers are called passive films. This type of film provides the comparably high chemical stability of many important constmction materials such as aluminium or stainless steels. 

The chromates of the alkali metals and of magnesium and calcium are soluble in water the other chromates are insoluble. The chromate ion is yellow, but some insoluble chromates are red (for example silver chromate, Ag2Cr04). Chromates are often isomorph-ous with sulphates, which suggests that the chromate ion, CrO has a tetrahedral structure similar to that of the sulphate ion, SO4 Chromates may be prepared by oxidising chromium(III) salts the oxidation can be carried out by fusion with sodium peroxide, or by adding sodium peroxide to a solution of the chromium(IIl) salt. The use of sodium peroxide ensures an alkaline solution otherwise, under acid conditions, the chromate ion is converted into the orange-coloured dichromate ion ... 

In the presence of excess iodide ions, copper(II) salts produce the white insoluble copper(I) iodide and free iodine, because copper(II) oxidises iodide under these conditions. The redox potential for the half-reaction ... 

In the Schotten-Baumann method of benzoylation, the hydroxyl- or amino-compound (or a salt of the latter) is dissolved or suspended in an excess of 10% aqueous sodium hydroxide solution, a small excess (about 10% more than the theoretical amount) of benzoyl chloride is then added and the mixture vigorously shaken. Benzoylation proceeds smoothly under these conditions, and the solid benzoyl compound, being insoluble in water, separates out. The sodium hydroxide then hydrolyses the excess of benzoyl chloride, giving sodium... 

R NHa + C.HjNCO = RNH CO NHC,Hj Traces of water will contaminate the product with diphenylurea (p. 336) if the solution is boiled hence the need for anhydrous conditions. i-Naphthylisocyanate reacts more slowly with water, and the i-naphthyl-urea derivative can often be obtained using a cold aqueous solution of an aliphatic amine it is particularly necessary in such cases to purify the product by recrystallisation from, or extraction with, boiling petroleum, leaving behind any insoluble di i-naphthylurea. Note that the amine must also be free from alcohols (p. 335) and phenols (p. 337). 

The ureas are less soluble than the corresponding urethanes, but their separation is not always easy. For this reason the urethanes are generally prepared from alcohols which are insoluble in water and can therefore be easily obtained in the anhydrous condition. 

There are, however, practical limitations to minimizing RSS. Precipitates that are extremely insoluble, such as Fe(OH)3 and PbS, have such small solubilities that a large RSS cannot be avoided. Such solutes inevitably form small particles. In addition, conditions that yield a small RSS may lead to a relatively stable supersaturated solution that requires a long time to fully precipitate. For example, almost a month is required to form a visible precipitate of BaS04 under conditions in which the initial RSS is 5. ... 

Furfural reacts with ketones to form strong, crosslinked resins of technical interest in the former Soviet Union the U.S. Air Force has also shown some interest (42,43). The so-called furfurylidene acetone monomer, a mixture of 2-furfurylidene methyl ketone [623-15-4] (1 )> bis-(2-furfurylidene) ketone [886-77-1] (14), mesityl oxide, and other oligomers, is obtained by condensation of furfural and acetone under basic conditions (44,45). Treatment of the "monomer" with an acidic catalyst leads initially to polymer of low molecular weight and ultimately to cross-linked, black, insoluble, heat-resistant resin (46). 

Under acidic conditions, furfuryl alcohol polymerizes to black polymers, which eventually become crosslinked and insoluble in the reaction medium. The reaction can be very violent and extreme care must be taken when furfuryl alcohol is mixed with any strong Lewis acid or Brn nstad acid. Copolymer resins are formed with phenoHc compounds, formaldehyde and/or other aldehydes. In dilute aqueous acid, the predominant reaction is a ring opening hydrolysis to form levulinic acid [123-76-2] (52). In acidic alcohoHc media, levulinic esters are formed. The mechanism for this unusual reaction in which the hydroxymethyl group of furfuryl alcohol is converted to the terminal methyl group of levulinic acid has recendy been elucidated (53). 

The alkene is allowed to react at low temperatures with a mixture of aqueous hydrogen peroxide, base, and a co-solvent to give a low conversion of the alkene (29). These conditions permit reaction of the water-insoluble alkene and minimise the subsequent ionic reactions of the epoxide product. Phase-transfer techniques have been employed (30). A variation of this scheme using a peroxycarbimic acid has been reported (31). 

This is essentially a corrosion reaction involving anodic metal dissolution where the conjugate reaction is the hydrogen (qv) evolution process. Hence, the rate depends on temperature, concentration of acid, inhibiting agents, nature of the surface oxide film, etc. Unless the metal chloride is insoluble in aqueous solution eg, Ag or Hg ", the reaction products are removed from the metal or alloy surface by dissolution. The extent of removal is controUed by the local hydrodynamic conditions. 

The standard methods (26) of analysis for commercial lecithin, as embodied in the Official and Tentative Methods of the American Oil Chemists Society (AOCS), generally are used in the technical evaluation of lecithin (27). Eor example, the AOCS Ja 4-46 method determines the acetone-insoluble matter under the conditions of the test, free from sand, meal, and other petroleum ether-insoluble material. The phosphoHpids are included in the acetone-insoluble fraction. The substances insoluble in hexane are determined by method AOCS Ja 3-87. 

Metallic magnesium and water [7732-18-5] react. Under normal atmospheric conditions or in pure or chloride-free water of high pH, the reaction is suppressed by the formation of an insoluble magnesium hydroxide [1309-42-8] film. 

Metals and Metallic Ions. Under appropriate conditions, ozone oxidizes most metals with the exception of gold and the platinum group. When oxidized by ozone, heavy metal ions, such as Fe and Mn , result in the precipitation of insoluble hydroxides or oxides upon hydrolysis (48—50). Excess ozone oxidizes ferric hydroxide in alkaline media to ferrate, and Mn02 to MnO. ... 

Compositions having an oxide ratio, i < 2, eg, in equation 11, can dehydrate to form more highly condensed phosphates beyond the pyrophosphate. Conditions must therefore be controlled to prevent complete dehydration. Insoluble pyrophosphates are obtained by treatment of a soluble salt of the desired cation using a sodium pyrophosphate solution. 

Calcium Pyrophosphates. As is typical of the pyrophosphate salts of multiple-charged or heavy-metal ions, the calcium pyrophosphates are extremely insoluble ia water. Calcium pyrophosphate exists ia three polymorphic modifications, each of which is metastable at room temperature. These are formed progressively upon thermal dehydration of calcium hydrogen phosphate dihydrate as shown below. Conversion temperatures indicated are those obtained from thermal analyses (22,23). The presence of impurities and actual processing conditions can change these values considerably, as is tme of commercial manufacture. 

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