Methanol, aqueous, solubilities

The most versatile derivative from which the free base can be readily recovered is the picrate. This is very satisfactory for primary and secondary aliphatic amines and aromatic amines and is particularly so for heterocyclic bases. The amine, dissolv in water or alcohol, is treated with excess of a saturated solution of picric acid in water or alcohol, respectively, until separation of the picrate is complete. If separation does not occur, the solution is stirred vigorously and warmed for a few minutes, or diluted with a solvent in which the picrate is insoluble. Thus, a solution of the amine and picric acid in ethanol can be treated with petroleum ether to precipitate the picrate. Alternatively, the amine can be dissolved in alcohol and aqueous picric acid added. The picrate is filtered off, washed with water or ethanol and recrystallised from boiling water, ethanol, methanol, aqueous ethanol, methanol or chloroform. The solubility of picric acid in water and ethanol is 1.4 and 6.23 % respectively at 20°. 

The peroxidase-catalyzed polymerization of m-alkyl substituted phenols in aqueous methanol produced soluble phenolic polymers. The mixed ratio of buffer and methanol greatly affected the yields and the molecular weight of the polymer. The enzyme source greatly affected the polymerization pattern of m-substituted monomers. Using SBP catalyst, the polymer yield increased as a function of the bulkiness of the substituent, whereas the opposite tendency was observed when HRP was the catalyst. 

Using such dielectric-based predictions, when the methanol-apparent solubility, log Sq versus wt% methanol is extrapolated to 0% cosolvent, the aqueous solubility, log So, can be estimated when log S(0 is extrapolated to 100% cosolvent, the membrane solubility, log iS cm, can be estimated. The approximate membrane partition... 

Substrate can be added to the cultures as a solid, a suspension, or a solution in DMSO, methanol, ethanol, acetonitrile or water. As the microbial culture generally has high tolerance toward organic solvents, there is less restriction on the choice and amount of solvent to be used for dispensing the substrate. Aqueous solubility of substrates normally will not affect compound loading, as a compound with poor aqueous solubility will likely be absorbed by the cells and still be subjected to biotransformation. 

The physical properties of the anhydrate form and two polymorphic monohydrates of niclosamide have been reported [61], The anhydrate form exhibited the highest solubility in water and the fastest intrinsic dissolution rate, while the two monohydrates exhibited significantly lower aqueous solubilities. In a subsequent study, the 1 1 solvates of niclosamide with methanol, diethyl ether, dimethyl sulfoxide, N,/V -dimethyl formamide, and tetrahydrofuran, and the 2 1 solvate with tetraethylene glycol, were studied [62], The relative stability of the different solvatomorphs was established using desolvation activation energies, solution calorimetry, and aqueous solubilities. It was found that although the nonaqueous solvates exhibited higher solubilities and dissolution rates, they were unstable in aqueous media and rapidly transformed to one of the monohydrates. 

The use of dissociable diastereomers for enantiomer resolution may be illustrated by the case where racemic mandelic acid is resolved using en-antiomerically pure a-methylbenzylamine. The n and p salts of a-methylbenzyl-amine mandelate have aqueous solubilities of 49.1 and 180 g/L, respectively, at 25°C [153], A more recent example, which focuses on the crystallographic origin of the solubility differences, is provided by the resolution of ( )-mandelic acid with (-)-ephedrine in water or methanol solution [154], In general, the relative solubilities of the n and p salt pairs are strongly influenced by the choice of solvent medium and temperature, which provide considerable flexiblity in optimizing the crystallization conditions and the efficiency of resolution. This process may be facilitated by the development of a full solubility phase diagram. 

Caco-2 model is easily affected by commonly used organic solvents or co-solvents [e.g., methanol, ethanol, polyethylene glycol (PEG), dimethyl sulfoxide (DMSO)] at relatively low concentrations (<1% v/v). Therefore, NCEs with poor aqueous solubility may not be adequately evaluated by this model. It has become a common practice in the pharmaceutical industry to test solubility of compounds before performing any other in vitro screens and eliminate NCEs with poor aqueous solubility, thus preventing false negatives due to this issue. 

Monohydrate, Ba(0H)2 H20 is a white powder density 3.743 g/cm shght-ly soluble in water soluble in dilute mineral acids. Octahydrate, Ba(0H)2 8H20 is a colorless monoclinic crystal density 2.18 g/cm at 16°C refractive index 1.50 melts at 78°C vapor pressure 227 torr loses seven molecules of water of crystallization when its solution is boiled in the absence of atmospheric CO2 forming solid monohydrate further heating produces anhydrous Ba(OH)2 melting at 407°C readily dissolves in water (3.76 g/100 g at 20°C and 11.7 g/100 g at 50°C) aqueous solution highly aUtahne also soluble in methanol shghtly soluble in ethanol insoluble in acetone. 

The aqueous solubility of brinzolamide is pH dependent, with minimal solubility existing at neutral pH and increased solubility at more acidic and basic pH values. In the alcohol series, maximal solubility is observed with methanol. Solubilities of brinzolamide observed in this laboratory are listed in Table 2. 

The ternary hydride was purified by reprecipitation from aqueous methanolic sodium hydroxide. Na2ReH9 was soluble in water and methanol, slightly soluble in ethanol, and insoluble in 2-propanol, acetonitrile, ether, and THF. Decomposition started at approximately 245°C when heated in a vacuum, with the evolution of hydrogen and sodium as the temperature increased. Na2ReH9 was a precursor for the preparation of the tetraethylammonium salt, the potassium salt, and the mixed potassium sodium salt of nonahydridorhenate(VII). 

Rao et al. (1990) investigated the effect of nonpolar cosolutes (trichloroethylene, toluene p-xylene), polar cosolutes (1-octanol, chlorobenzene, nitrobenzene, o-cresol) and polar cosolvents (methanol and dimethyl sulfoxide) on sorption of several polycyclic aromatic hydrocarbons (PAHs). The nonpolar cosolutes did not significantly influence PAH sorption, while the polar cosolutes (nitrobenzene, o-cresol), having sufficiently high aqueous solubilities, caused a significant decrease in PAH sorption. 

Equation (11) estimates sunlight photoreaction rate constants using computed or tabulated values for Zk or tabulated values of L> at the appropriate latitude and time of year (Zepp and Cline, 1977 Mill and Mabey, 1985 Leifer, 1988), together with measured values of > and <1>. Equation (2) can be used to estimate values of > from a uv spectrum measured in water or, if aqueous solubility is low, a polar organic solvent such as acetonitrile or methanol. Absorbance values are converted into ex values at wavelength centers corresponding to those Table 15.1 lists. 

Figure 15.12. XH NMR spectra of aqueous soluble species from (A) coarse air particles with diameters of 33-4.7mm (pH 6.55) (B) fine air particles with diameters of 0.65-1.1 mm (pH 3.92). Compounds identified in the spectra include 1, acetic acid 2, monomethylamine 3, succinic acid 4, dimethylamine 5, methanesulfonic acid 6, methanol 7, monomethyl hydrogen sulfate 8, hydroxymethanesulfonic acid 9, phthalic acid 10, terephthalic acid. Reprinted from Suzuki, Y., Kawakami, M., and Akasaka, K. (2001). JH NMR application for characterizing water-soluble organic compounds in urban atmospheric particles. Environ. Sci. Technol. 35, 2656-2664, with permission from the American Chemical Society.

A pKa of 4.5 for the carboxyl group of indomethacin was calculated from aqueous solubility data(30). Potentiometric titration data for indomethacin in 50% methanol-water yielded pKa of 4.5 using a correction factor for the solvent(31). 

Bevan et al. [97] have developed a solubility screen for. small amounts of compounds (10 pi of a 10 mM DMSO solution) on a 96 well plate format by applying reversed-phase HPLC with a fast gradient elution. The DMSO solutions of the compounds are dispensed into a 96 well microtitre plate format at a known concentration (typically 10 mM). Duplicate plates are prepared each containing 10 pi of a 10 mM DMSO solution. For the so-called standard plate the DMSO solution is diluted with known amounts of solvent possibly dissolving the compounds (methanol or DMSO). The wells on the so-called sample plate are diluted with the same known amounts of aqueous buffer used in the enzyme-assay screens. The compounds having poor aqueous solubility will eventually precipitate out in the wells of the sample plates. The precipitation and the equilibrium formation between the saturated solution and the solid can be promoted by applying sonication. Before HPLC analysis of the wells of the standard... 

Solubility practically insoluble in water soluble in methanol freely soluble in 50% aqueous ethanol, propylene glycol, chloroform, ether, hexane, cottonseed oil, peanut oil, soybean oil, glyceryl monooleate, and lard, and in solutions of alkali hydroxides. 

Properties Light-red, oily liquid fatty odor. D 0.93, iodine value 65-75, titer below 0C, pH 7.7-8.2 (25C) (5% aqueous dispersion). Soluble in ethanol, naphtha, ethyl acetate, methanol partly soluble in cottonseed oil insoluble in water. Combustible. 

Properties White to brown crystalline solid. Bulk d 15-16 lb/gal (20C),mp indefinite (decomposes), pH of 0.1 molar aqueous solution 1.6. Very hygroscopic soluble in water and methanol slightly soluble in alcohol. 

Use ofwater/DMSO mixed solvent can enhance solubility of salts in the stock solution and avoid missing valuable compounds with good aqueous solubility. Typically 1 1 water/DMSO is used to dissolve salts. Besides DMSO, water mixable solvents can sometimes be used to dissolve certain classes of compounds, such as methanol, ethanol, acetonitrile, THF, pyridine and DMF (Buchli et al., 2005). Tolerance for different organic solvents needs to be carefully evaluated for each assay during assay method development. 

Aqueous Solubility Organic Solubility (1) Methanol Organic Solubility (2) Ethyl acetate Organic Solubility (3) Chloroform Matrix Water ... 

Development Worksheet for SPE (Fig. 3.2). The structure for atrazine shows that it contains a triazine ring with two secondary amines. The aqueous solubility is 33 mg/L, and the compound is quite soluble in methanol, ethyl acetate, and chloroform. List these solvents on the worksheet in Figure 3.2 as possible elution solvents. The pA", of atrazine is not given in the Merck Index, but a quick literature search shows that the is less than 2.0. Furthermore, the compound is stable in water and the pH range of samples will be from 5 to 8. This information may be recorded on the worksheet together with the pAT, and pH of the sample. 

These compounds are nonionic and moderately polar to polar herbicides (Fig. 7.14). They are analyzed by liquid chromatography rather than by gas chromatography. Their more labile nature and lack of volatility lend these compounds to an approach using C-18 followed by elution with a polar solvent, such as methanol. Because of the aqueous solubility of some of these compounds, SDB may be substituted for the C-18 sorbent to increase the sorption capacity. 

These compounds are examples of nonionic, polar herbicide metabolites (Fig. 7.15). The examples shown below are degradation products of the triazine compounds shown in Section 7.10.4. They are nonionic compounds that are formed in soil by the dealkylation of the parent compounds. They are considerably more soluble than the parent compounds with aqueous solubilities equal to or greater than 1000 mg/L. Therefore, the sorbent to choose in this case is the styrene-divinylbenzene or graphitized carbon. The compounds are soluble in ethyl acetate or methanol, either of which may be used as an elution solvent. The C-18 sorbent may also be used with good recovery of either deethylatrazine or deisopropylatrazine, but with no recovery of the didealky-latrazine. 

Owing to the limited aqueous solubility of GPANA and BTPNA, it was necessary to use water-miscible organic solvents to increase the substrate solubility in these solutions. For the initial reaction rate studies, GPANA was dissolved in 10% by volume methanol and BTPNA was dissolved in 20% by volume acetone. For the NMR studies, GPANA was dissolved in 10% by volume deuterated methanol and BTPNA was dissolved in 60% by volume deuterated methanol. 

Dithizone is also used for the determination of metallic compounds such as copper (II) (Fig. 28). Because of the slight aqueous solubility of this compound, UV-visible spectra have been acquired in methanol/water (50/50) solution (Fig. 29). In strong acid medium (pH = 2.0), the maximum of absorption in the visible region is located at X = 588 nm (e = 13,700 Lmol-1 cm-1). A protonation may occur on the sulphur atom. The coloration of the solution is dark blue. In basic medium (pH = 12.0), the colour turns to orange X = 472 nm, e = 8100 Lmol-1 cm-1). Two isosbestic points, located at X = 425 nm and X = 517 nm, confirms this phenomenon. 

Hydroxylamine-O-sulfonic acid is a white, hygroscopic, microcrystalline solid, melting with decomposition at 210 to 211°. The solid acid is stable for long periods of time if it is stored in a moisture-free atmosphere, but the compound decomposes very slowly in aqueous solutions below 25°. It is rapidly destroyed in solutions above this temperature. The decomposition is also markedly affected by pH and by the presence of traces of copper ion.4 Decomposition in acidic media yields hydroxylammonium and hydrogen sulfate ions. In alkaline solution the products are nitrogen, ammonia, and sulfate ions. Hydroxylamine-O-sulfonic acid is soluble in cold water and methanol, slightly soluble in ethanol, and insoluble in chloroform, ethyl ether, and carbon tetrachloride. It reacts with ammonia and amines to give hydrazine and substituted hydrazines, respectively. 

Stackman and Hurley (49) used turbidimetric measurements and dissolution experiments to characterize the aqueous solubility characteristics of various acrylate-acrylic acid copolymers prepared by solution polymerization in methanol. When phase diagrams of percent neutralization versus percent acrylic acid were generated, the phase boundaries for solubility fell on nearly the same line. This result allowed approximation of the neutralization requirement for other acrylate ester-AA copolymers. 

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