Methanol solubility coefficients

Dihydrochloride, C HjiNjOj-IHCI, crystals from tnetha -nol + ether, dec 280-287 (Free base, mp 83"). Freely soluble in water, methanol. Solubility in ethanol 8 mg/g. pH of at] solos 2.0 to 2.5. Solns are stable at pH 3.5 and below. At pH 4 and higher the insol free base is precipitated, uv max (pH 7 in 90% methanol contg phosphate buffer) 235, 289 nm (A, 293, 34.5). Distribution coefficient between water at pH 3.6 and n-butanol = 0.9. 

Kumbar, S.G., Kulkarni, A.R., Dave, A.M., and Aminabhavi, T.M. An assessment of solubility profiles of structurally similar hazardous pesticide in water + methanol mixture and co-solvent effect on partition coefficient, J. Haz. Mater., 89 (2-3) 233-239, 2002. 

Figure 5.6 Illustration of the effect of a completely water-miscible solvent (CMOS, i.e., methanol) on the activity coefficient of organic compounds in water-organic solvent mixtures decadic logarithm of the activity coefficient as a function of the volume fraction of methanol. Note that the data for naphthalene (Dickhut et al., 1989 Fan and Jafvert, 1997) and for the two PCBs (Li and Andren, 1994) have been derived from solubility measurements whereas for the anilins (Jayasinghe etal., 1992), air-water partition constants determined under dilute conditions have been used to calculate y,f.

Little attention has so far been paid to studying exchange energy-transfer processes in media so viscous that a steady-state is no longer established. Butler and Pilling [200] specifically sought experimental evidence for time-dependent rate coefficients of the form of eqn. (98). They chose to study triplet phenanthrene in methanol—water mixtures and used cupric chloride as the acceptor since it is readily soluble and a very efficient quencher of triplet phenanthrene. To observe even the t 1/2 dependence of the time-dependent rate coefficient, concentrations [A] > 10-2 are required that is with Re 1 nm and [A] > 10 mmol... 

Miscible organic solvents, such as methanol and ethanol, have been shown to increase solubility of hydrophobic organics and to decrease sorption (Nkedi-Kizza, 1985 Fu and Luthy, 1986 Nkedi-Kizza et al., 1987 Walters and Guiseppi-Elle, 1988 Wood et al., 1990 Lee et al., 1991). This is presumably the result of (i) reducing the activity coefficient of the sorbate chemical in the aqueous phase, and (ii) competition for sorbing sites. 

Palytoxin is a white, amorphous, hydroscopic solid that has not yet been crystallized. It is insoluble in nonpolar solvents such as chlorophorm, ether, and acetone sparingly soluble in methanol and ethanol and soluble in pyridine, dimethyl sulfoxide, and water. The partition coefficient for the distribution of palytoxin between 1-butanol and water is 0.21 at 25°C based on comparison of the absorbance at 263 nm for the two layers. In aqueous solutions, palytoxin foams on agitation, like a steroidal saponin, probably because of its amphipathic nature. The toxin shows no definite melting point and is resistant to heat but chars at 300°C. It is an optically active compound, having a specific rotation of -i-26° 2° in water. The optical rotatory dispersion curve of palytoxin exhibits a positive Cotton effect with [a]25o being -i-700° and [a]2,j being +600° (Moore and Scheuer 1971 Tan and Lau 2000). 

The Rectisol process [667], [707], [711]-[715] seems to be the prime choice in partial oxidation plants. The process, invented by Lurgi and developed further by Linde, operates with chilled methanol, a cheap and readily available solvent, in which carbon dioxide, hydrogen sulfide and carbonyl sulfide (COS) are readily soluble at low operating temperatures of below - 30 °C. The Henry absorption coefficient for H2S is about six times higher than for C02-... 

British Pharmacopoeia 2009 and European Pharmacopoeia 6.0 [3,7] specify fhat glimepiride is insoluble in water but it is soluble in dimethylforma-mide, slightly soluble in methylene chloride and very slightly soluble in methanol. Further, its log partition coefficient in octanol-water is 3.81, with log distribution coefficient in octanol-phosphate buffer pH 7.4 valued for 2.38 [8]. The value of glimepiride was found fo be 6.2 0.1 at 37 °C [2]. 

As already mentioned, the Krichevsky equation (eq 1) is valid when the binary mixtures 1—2 and 2—3 (gas solute/pure solvents) and the ternary mixture 1—2—3 are ideal. However, these conditions are often far from reality. Let us consider, for example, the solubility of a hydrocarbon in a water—alcohol solvent (for instance, water—methanol, water—ethanol, etc.). The activity coefficient of propane in water at infinite dilution is 4 X 10 , whereas the activity coefficients of alcohols and water in aqueous solutions of simple alcohols seldom exceed 10. It is therefore clear that the main contribution to the nonideality of the ternary gas-binary solvent mixture comes from the nonidealities of the gas solute in the individual solvents, which are neglected in the Krichevsky equation. 

We only give basic directions for the choice of a solvent system. If the polarities of the solutes are known, the classification established by Ito [1] can be taken as a first approach. He classified the solvent systems into three groups, according to their suitability for apolar molecules ( apolar systems), for intermediary polarity molecules ( intermediary system), and for polar molecules ( polar system). The molecule must have a high solubility in one of the two immiscible solvents. The addition of a third solvent enables a better adjustment of the partition coefficients. When the polarities of the solutes are not known. Oka s [8] approach uses mixtures of n-hexane (HEX), ethyl acetate (EtOAc), n-butanol (n-ButOH), methanol (MeOH), and water (W) ranging from the HEX-MeOH-W, 2 1 1 (v/v/v) to the n-BuOH-W, 1 1 (v/v) systems and mixtures of chloroform, methanol, and water. These solvent series cover a wide range of hydrophobicities from the nonpolar n-hexane-methanol-water system to the polar n-butanol-water system. Moreover, all these solvent systems are volatile and yield a desirable two-phase volume ratio of about 1. The solvent system leading to partition coefficients close to the unit value will be selected. 

Chemical structures of sporaviridins are described in Fig. 1. They are only soluble in polar solvents such as water, methanol, and n-butanol. Therefore, a two-phase solvent system containing n-butanol was examined. A nonpolar solvent such as diethyl ether has been added to the n-butanol-water system to decrease the solubility of molecules in n-butanol and to obtain partition coefficients close to 1. The partition coefficients, K, are defined as the ratio of the solute concentration in the upper phase (butanol rich) to its concentration in the lower one (water rich). A two-phase solvent system oin-butanol-diethyl ether-water (10 4 12, v/v/v) was selected because it allows one to obtain the almost equally dispersed partition coefficients among six components (C2, B2, A2, Cl, Bl, Al). The preparative separation of six components from sporaviridin complex by HSCCC was performed in 3.5 h (500 mL of elution volume). The six components were eluted in the order of their partition coefficients, yielding pure components Al (1.4 mg), A2 (0.6 mg), Bl (0.7 mg), B2 (0.5 mg). Cl (1.1 mg), and C2 (1.4 mg) from 15 mg of the sporaviridin complex. 

Solvent activity coefficients for a small number of polar solutes, referred to the standard state of unimolar solute in DMF, are given in Table 3. In the absence of more detailed observations, and applying many of my qualitative observations on the solubility of organic com-poimds, it is tentatively suggested that many polar organic compounds, which are not strong H-bond donors or acceptors, are from 2 to 60 times more solvated by DMF than by methanol or formamide. 

Phenol was successfully extracted from water using pure supercritical carbon dioxide at pressures up to 31 MPa for two isotherms 298 and 323 K. The distribution coefficient increased with increasing pressure, but decreased with increasing temperature. This is expected since increasing the temperature severely drops the carbon dioxide density and hence the solubility of the phenol in it. Increased volatility at the higher temperature is not sufficient to off-set the density effect, since phenol has a low vapor pressure. Benzene was foimd to be a suitable entrainer since its solubility in water is very small and it enhances the distribution of phenol into the supercritical phase. The presence of methanol was found to have no effect. Since methanol is polar and completely soluble in water, it favors the aqueous phase and therefore does not change the characteristics of the supercritical phase. Others have found that the distribution of short chain alcohols between water and supercritical carbon dioxide highly favors the aqueous phase (ifl). 

Properties White flakes. Mp 72-74C, d 0.89 (90C), bp 280-302C, hydroxyl coefficient 259-275. Insoluble in hot and cold water limited solubility in alkalies soluble in 1 1 mixture of methanol and 50% aqueous potassium hydroxide, also in alcohol, acetone, fixed oils. Combustible. 

Graaf et al (27,2reaction rate for methanol syn esis in gas-catalyst phases and extended it to three phase methanol synthesis using gas-liquid solubilities in thermodynamical equilibrium described by Henry s law. The rates for the three reactions (ZY= 3) in liquid phase are given by equations T12 and T13. Where, a. represents the stoichiometric coefficient of yxth species in the rth reaction of liquid phase and M- represents the molecular weight of yxth species. rix (mol/Kgcat sec) is the rate of reaction on catalyst surface for three reactions. 

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