Methanol aqueous solution data

Table 2 Substrate specificity lor 1-catalyzedhydrolysis ofp-nitrophenyl alkanoates (NPAlk) in 1 1 methanol-aqueous solution in the presence of polymer 1 aggregates. (Data from Ref. [76]) ...

Many of the properties oj -hydroxypyridines are typical of phenols. It was long assumed that they existed exclusively in the hydroxy form, and early physical measurements seemed to confirm this. For example, the ultraviolet spectrum of a methanolic solution of 3-hydroxypyridine is very similar to that of the 3-methoxy analog, and the value of the dipole moment of 3-hydroxypyridine obtained in dioxane indicates little, if any, zwitterion formation. However, it has now become clear that the hydroxy form is greatly predominant only in solvents of low dielectric constant. Comparison of the pK values of 3-hydroxypyridine with those of the alternative methylated forms indicated that the two tautomeric forms are of comparable stability in aqueous solution (Table II), and this was confirmed using ultraviolet spectroscopy. The ratios calculated from the ultraviolet spectral data are in good agreement with those de-... 

Solutes in Methanol Solution. In Table 23 we have seen that for four solutes in methanol the viscosity //-coefficients are positive. This is the case even for KC1 and KBr, for which the coefficients are negative in aqueous solution. In Sec. 88 it was pointed out that it would be of interest to see whether this inversion is likewise accompanied by a change in sign for the ionic entropy. Although no accurate values for the entropy of solution of salts in methanol arc available, reliable estimates have been made for KC1, KBr, and NaCl.1 Since the /1-coefficients of KC1 and KBr have been determined both in methanol and in water, all the required data are available for these two solutes. The values of A/S" given in Table 29 have been taken from Table 34 in Chapter 12, where the method of derivation is explained. The cratie term included in each of these values is 14 cal/deg, as already mentioned in Sec. 90. 

High Performance Liquid Chromatographic (HPLC) Analysis. A Waters HPLC system (two Waters 501 pumps, automated gradient controller, 712 WISP, and 745 Data module) with a Shimadzu RF-535 fluorescence detector or a Waters 484 UV detector, and a 0.5 pm filter and a Rainin 30 x 4.6 mm Spheri-5 RP-18 guard column followed by a Waters 30 x 3.9 cm (10 pm particle size) p-Bondapak C18 column was used. The mobile phase consisted of a 45% aqueous solution (composed of 0.25% triethylamine, 0.9% phosphoric acid, and 0.01% sodium octyl sulfate) and 55% methanol for prazosin analysis or 40% aqueous solution and 60% methanol for naltrexone. The flow rate was 1.0 mL/min. Prazosin was measured by a fluorescence detector at 384 nm after excitation at 340 nm (8) and in vitro release samples of naltrexone were analyzed by UV detection at 254 nm. 

Pedrosa, A. and Serrano, M.L. Solubilities of sodium gluconate in water and in aqueous solutions of ethanol and methanol, /. Chem. Eng. Data, 45(3) 461-463, 2000. 

Thomas JK (1967) Pulse radiolysis of aqueous solutions of methyl iodide and methyl bromide. The reactions of iodine atoms and methyl radicals in water. J Phys Chem 71 1919-1925 Tsang W, Hampson RF (1986) Chemical kinetic data base for combustion chemistry, part I. Methane and related compounds. J Phys Chem Ref Data 15 1086-1279 UlanskiP, von Sonntag C (1999) The OFI-radical-induced chain reactions of methanol with hydrogen peroxide and with peroxodisulfate. J Chem Soc Perkin Trans 2 165-168 Ulanski P, Bothe E, Hildenbrand K, von Sonntag C, Rosiak JM (1997) The influence of repulsive electrostatic forces on the lifetimes of polyfacrylic acid) radicals in aqueous solution. Nukleonika 42 425-436... 

Strelyuk described a thin-layer chromatographic method for the qualitative detection of dipyridamole [62], Data were presented on the use of various reagents for the detection by solution color change and precipitate formation in the thin-layer chromatography of dipyridamole. Thin-layer chromatography was on silica gel-calcium sulfate dihydrate, with methanol aqueous ammonia or benzene-dioxane being used as the mobile phase with detection at 270-330 nm. The Rvalues were 0.7-0.75 and 0.5-0.55 for the two solvent systems, and the detection limit was... 

An aqueous solution (20 mL) of [Rh(en)2(C204)]C104- H20 (0.10 g, 0.25 mmole), acidified with 5 mL of concentrated HC1 (12 M) is allowed to heat at reflux for 3 minutes. The solution, cooled and reduced in volume to about 5 mL, is kept at ice temperature for several hours. The yellow precipitate that forms is collected by filtration, washed carefully with cold water and methanol, and finally air dried. Yield 0.05 g (64% based on Rh). The checkers obtained 71% (after removing a small amount of /rans-isomer, as described below). Electronic and infrared spectra agree with published data.6 Anal. Calcd. for [Rh(en)2Cl2] Cl H20 C, 13.8 H, 5.2 N, 16.1. Found C, 13.7 H, 5.5 N, 16.0. 

It is unfortunate that there has been so little work devoted to quantitative measurements of cation-pseudobase equilibria in methanol and ethanol since these media have several advantages over water for the determination of the relative susceptibilities of heterocyclic cations to pseudobase formation. The enhanced stability of the pseudobase relative to the cation in alcohols compared to water is discussed earlier this phenomenon will permit the quantitative measurement of pseudobase formation in methanol (and especially ethanol) for many heterocyclic cations for which the equilibrium lies too far in favor of the cation in aqueous solution to allow a direct measurement of the equilibrium constant. Furthermore, the deprotonation of hydroxide pseudobases (Section V,B) and the occurrence of subsequent irreversible reactions (Sections V,C and D), which complicate measurements for pKR+ > 14 in aqueous solutions, are not problems in alcohol solutions. Data are now available for the preparation of buffer solutions in methanol over a wide range of acidities.309-312 An appropriate basicity function scale will be required for more basic solutions. The series of -(substituted phenyl)pyridinium cations (163) studied by Kavalek et al.i2 should be suitable for use as indicators in at least some of the basic region. The Hm and Jm basicity functions313 should not be assumed90 to apply to methoxide ion addition to heterocyclic cations because of the differently charged species involved in the indicators used to construct these scales. 

Given in the literature are vapor pressure data for acetaldehyde and its aqueous solutions (1—3) vapor—liquid equilibria data for acetaldehyde—ethylene oxide [75-21-8] (1), acetaldehyde—methanol [67-56-1] (4), sulfur dioxide [7446-09-5]— acetaldehyde—water (5), acetaldehyde—water—methanol (6) the azeotropes of acetaldehyde—butane [106-97-8] and acetaldehyde—ethyl ether (7) solubility data for acetaldehyde—water—methane [74-82-8] (8), acetaldehyde—methane (9) densities and refractive indexes of acetaldehyde for temperatures 0—20°C (2) compressibility and viscosity at high pressure (10) thermodynamic data (11—13) pressure—enthalpy diagram for acetaldehyde (14) specific gravities of acetaldehyde—paraldehyde and acetaldehyde—acetaldol mixtures at 20/20°C vs composition (7) boiling point vs composition of acetaldehyde—water at 101.3 kPa (1 atm) and integral heat of solution of acetaldehyde in water at 11°C (7). 

Reference Solution. Prepare an aqueous solution containing 0,2 mg/ml of each of ethanol, methanol, isopropyl alcohol, and propMiol, and inject 1 jiil on to the column. The retention data for these compounds are listed in Table 14,... 

From the numerous correlations for Eq reported in the literature only two will be given here. Akita and Yoshida ( ) correlated their data for water and aqueous solution of glycol, glycerol, methanol, NaCl and Na2S03 by... 

Experimental data fit well with kinetic expressions that are first order in both phenol and hydrogen peroxide [47]. Observed rate constants were significantly larger in water than in methanol and acetone. This was ascribed to the stronger adsorption of phenol from an aqueous solution in TS-1 (Table 18.6) [47, 48]. Surprisingly enough, in the presence of methanol or acetone the concentration of phenol in the pores was about the same as that in the external solution. 

Second-order rate coefficients, kH (= rate/[S] [H30+]), for the hydrolyses of some typical acetals, ketals, and orthoesters in purely aqueous solutions are collected in Table 12. In a compilation of data from one single source [162], ftH values can be found for the reactions of a large number of diethyl acetals and ketals in 50 % dioxane—water at 25 °C. In more recent studies, kH values have been determined for the hydrolyses of substituted benzaldehyde diethylacetals [163] and benzophenone diethyl-ketal [164] in the same solvent (Table 13). The hydrolyses of para-substituted methyl orthobenzoates have been studied in 70 % methanol-water [169]. A large amount of other work is concerned with various special examples. 

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