Solubility characteristic solution

Solubility and Solution Properties. Poly(vinyhdene chloride), like many high melting polymers, does not dissolve in most common solvents at ambient temperatures. Copolymers, particularly those of low crystallinity, are much more soluble. However, one of the outstanding characteristics of vinyUdene chloride polymers is resistance to a wide range of solvents and chemical reagents. The insolubiUty of PVDC results less from its... 

This derivative was used to improve the solubility characteristic of an argininal semicarbazone for solution-phase peptide synthesis. 

One of the key factors controlling the reaction rate in multiphasic processes (for reactions talcing place in the bulk catalyst phase) is the reactant solubility in the catalyst phase. Thanks to their tunable solubility characteristics, the use of ionic liquids as catalyst solvents can be a solution to the extension of aqueous two-phase catalysis to organic substrates presenting a lack of solubility in water, and also to moisture-sensitive reactants and catalysts. With the different examples presented below, we show how ionic liquids can have advantageous effects on reaction rate and on the selectivity of homogeneous catalyzed reactions. 

The sulfonylated and acylated PPO presents solubility characteristics which are completely different from those of the parent PPO. Table V presents the solubility of some modified structures compared to those of unmodified PPO. It is very important to note that, after sulfonylation, most of the polymers become soluble in dipolar aprotic solvents like dimethyl sulfoxide (DMSO), N,N— dimethylformamide (DMF) and N,N-dimethylacetamide (DMAC). At the same time it is interesting to mention that, while PPO crystallizes from methylene chloride solution, all the sulfonylated polymers do not crystallize and form indefinitely stable solutions in methylene chloride. Only some of the acetylated polymers become soluble in DMF and DMAC, and none are soluble in DMSO. The polymers acetylated with aliphatic acid chlorides such as propionyl chloride are also soluble in acetone. 

Chitosan features far more than chitin in research into applications. This is largely due to their difference in solubility characteristics, chitosan being more amenable to practical manipulation. Chitin is in fact rather more intractable than cellulose, since it is insoluble in those solvents, such as cuprammonium hydroxide, that are commonly used to dissolve cellulose. Chitin is soluble in hot concentrated solutions of certain inorganic salts capable of... 

Because the product and also its solutions in chloroform are so highly colored, it is difficult to judge when complete solution has been achieved. The checker, operating on a scale one-third of that reported, dissolved 13.5 g. of crude product in 180 ml. of hot chloroform, filtered the solution, and added 360 ml. of ethanol. The product did not precipitate at room temperature, but 6.1 g. of material could be isolated after the solution had been chilled. An additional 3.1 g. of product was isolated after reduction of the volume of solvent to 70 ml. The combined crops constitute the yield claimed. It is recommended that the solubility characteristics of this complex which are given in Table I (p. 48) be used as a guide for dissolution of the crude product. 

The comonomer composition distributions of these two materials are also indicative of the block architecture of the OBC. A comparison of solution solubility characteristics as revealed by TREF is shown in Fig. 25. The physical blend displays a peak at 96 °C with a soluble fraction of 56 wt%, consistent with a physical blend of HDPE and VLDPE. The trace from the diblock OBC reveals a peak at a slightly lower temperature, 93 °C, with no evidence of a shoulder at higher temperature that could be attributed to uncoupled HDPE. In contrast to the blend, the majority of this sample, 84 wt%, elutes at this high temperature, while only 13 wt%... 

Deoxoartemisinin and carboxypropyldeoxoartimisinin have also been shown to have anti-tumour activity and, NMR studies on solution conformations have been reported <00BBR359>. One of the problems with artemisinin use is its poor water solubility characteristics. An attempt to rectify this, and to overcome stability problems associated with sodium artesunate in solution, has involved the introduction of amino group functionality as in 127 (eg. R = 0(CH2)3NR r2 where NR r2 = morpholine). The maleate salt of this compound has reasonable water solubility and aqueous solutions are stable at room temperature for an extended time. However activity against Plasmodium knowlesi in rhesus monkeys after oral administration was poorer compared with artesunic acid <00JMC1635>. 

The tetracyclines are well known for their ability to form complexes with polyvalent cations. This property changes their solubility characteristics in the mobile solvents and often results in troublesome streaking. To overcome this difficulty, Selzer and Wright used paper dipped in Mcllvaine s buffer (pH 3.5) which contains citrate ions capable of binding the metallic ions. The chromatograms were developed with a mixture of nitromethane, chloroform, and pyridine (20 10 3) on paper still damp from the treatment with the buffer solution. 

Dissolution of carbonates can only occur if the solution is thermodynamically undersaturated, pH is an important variable affecting the saturation ratio (Appendix 8.1 gives a brief review of the CaC03 solubility characteristics in open and closed systems). 

Once the required ligands have been obtained, the formation of complexes is usually straightforward. Metal complexes can often be prepared by direct reaction in solution between the ligand and a metal salt, generally at pHs above seven so that the hydroxypyranone or hydroxypyridinone is in its anionic form. There can be difficulties with purification, as solubility characteristics of ligands and their respective complexes may be inconveniently similar, but recrystallization is usually effective. In cases of difficulty sublimation may successfully separate unreacted ligand from the complex. 

Free and glycine-conjugated BAs are only slightly soluble in acid solutions. As the pH is increased, the solubility will increase. This is a very important characteristic since it describes the solubility characteristics of the major BAs, and, it also explains their potential to enter the epithelium at physiological pH ranges. 

Organic matter extracted from earth materials usually is fractionated on the basis of solubility characteristics. The fractions commonly obtained include humic acid (soluble in alkaline solution, insoluble in acidic solution), fulvic acid (soluble in aqueous media at any pH), hymatomelamic acid (alcohol-soluble part of humic acid), and humin (insoluble in alkaline solutions). This operational fractionation is based in part on the classical definition by Aiken et al. (1985). It should be noticed, however, that this fractionation of soil organic matter does not lead to a pure compound each named fraction consists of a very complicated, heterogeneous mixture of organic substances. Hayes and Malcom (2001) emphasize that biomolecules, which are not part of humic substances, also may precipitate at a pH of 1 or 2 with the humic acids. Furthermore, the more polar compounds may precipitate with fulvic acids. 

The solubility characteristics of the a- and /J-isomers are distinctly different. When a-lactose is added in excess to water at 20°C, about 7 g per 100 g water dissolve immediately. Some a-lactose mutarotates to the fS anomer to establish the equilibrium ratio 62.7/J 37.3a therefore, the solution becomes unsaturated with respect to a and more a-lactose dissolves. These two processes (mutarotation and solubilization of a-lactose) continue until two criteria are met 7g a-lactose in solution and a / /a ratio of 1.6 1.0. Since the /J/a ratio at equilibrium is about 1.6 at 20°C, the final solubility is 7 g + (1.6 x 7) g = 18.2 g per 100 g water. 

These solvents include tetrahydrofuran (THF), 1,4-dioxane, chloroform, dichloromethane, and chlorobenzene. The relatively broad solubility characteristics of PSF have been key in the development of solution-based hollow-fiber spinning processes in the manufacture of polysulfone asymmetric membranes (see Hollow-fibermembranes). The solvent list for PES and PPSF is short because of the propensity of these polymers to undergo solvent-induced crystallization in many solvents. When the PES structure contains a small proportion of a second bisphenol comonomer, as in the case of RADEL A (Amoco Corp.) polyethersulfone, solution stability is much improved over that of PES homopolymer. 

Citrates (like tartrates) in solution change silver of amnmnio-silver nitrate into metallic silver. Calcium citrate, due to its solubility characteristics. is of importance in the separation and recovery of citric acid. Calcium ciiraic plus dilute H.SOj yields citric acid plus calcium sulfate, and the latter may he separated by filtration. Citric acid may be obtained by evaporation of Ihc filtrate. 

The general solubility characteristics of the protein, including its behavior in different pH and ionic strength environments, its behavior in urea solutions, its behavior... 

Selection of solvents for adsorption chromatography. The choice of solvent for transferring the mixture to be chromatographed to the column will naturally depend upon the solubility characteristics of the mixture. If it is already in solution, for example as an extract, this is usually evaporated to dryness under reduced pressure and the residue dissolved in the minimum volume of the most non-polar solvent suitable. As concentrated a solution as possible is desirable to achieve a compact band at the top of the column of adsorbent, so that during subsequent development the separation will hopefully proceed with formation of discrete bands. 

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