Hexane alcohol mixture

Ethanol has also been utilized for oil extraction. Oil solubility in ethanol varies with temperature and water content. Soybean oil is completely miscible with absolute ethanol above 70 °C (Johnson and Lusas, 1983). As ethanol concentration decreases and water content increases, oil solubility is significantly reduced in the mixture. The higher cost and latent heat of vaporization are the major disadvantages of ethanol as a solvent for oilseed extraction. Recent developments in bioethanol production may reduce the cost of ethanol, making it a viable alternative to hexane. Solvent mixtures can also be used to extract oil. Hexane/alcohol azeotropes have been used for extraction of residual lipids from hexane-extracted meals to improve flavor and odor, specifically from soybean and peanuts. Grassy and beany flavors in oilseeds are associated with the presence of phosphatides, which can be easily extracted with hexane/alcohol mixtures. Similarly, hexane/alcohol azeotropes, specifically hexane/methanol, are very effective in extracting aflatoxin from meal. 

A. (1,3-Dibromo-3,3-difluoropropyl)trimethylsilane (Note 1). A 250-mL pressure tube (Note 2) equipped with a magnetic stirring bar is charged with vinyltrimethylsilane (20 g, 30.8 mL, 0.20 mol), ethanolamine (6.11 g, 6.04 mL, 0.10 mol), dibromodifluoromethane (83.9 g, 36.5 mL, 0.4 mol), copper(l) chloride (0.18 g, 1.8 mmol), and tert-butyl alcohol (15 mL) (Notes 3 and 4). The tube is sealed and stirred for 20 hr in an oil bath at 90°C (Note 5). The reaction mixture is combined with that from another run at the same scale and diluted with 40 mL of hexane (the mixture separates into a cloudy supernatant and a brown resin). The hexane layer is... 

One example is the separation of tricarboxylic acid cycle organic acids. These organic acids were originally separated on sulfonic acid-treated silica gel as the stationary phase material, and a chloroform and isopentyl alcohol mixture was used as the eluent. However, this eluent is not suitable for UV detection. A mixture of -hexane, THF, and ter/-butanol was therefore selected for the same separation.74... 

Typical NP conditions involve mixtures of n-hexane or -heptane with alcohols (EtOH and 2-propanol). In many cases, the addition of small amounts (<0.1%) of acid and/or base is necessary to improve peak efficiency and selectivity. Usually, the concentration of alcohols tunes the retention and selectivity the highest values are reached when the mobile phase consists mainly of the nonpolar component (i.e., n-hexane). Consequently, optimization in NP mode simply consists of finding the ratio n-hexane/alcohol that gives an adequate separation with the shortest possible analysis time [30]. Normally, 20% EtOH gives a reasonable retention factor for most analytes on vancomycin and TE CSPs, while 40% is more appropriate for ristocetin A-based CSPs. Ethanol normally gives the best efficiency and resolution with reasonable backpressures. Other combinations of organic solvents (ACN, dioxane, methyl tert-butyl ether) have successfully been used in the separation of chiral sulfoxides on five differenf glycopepfide CSPs, namely, ristocetin A, teicoplanin, TAG, vancomycin, and VAG CSPs [46]. 

Recently, three papers have reported the determination of risperidone and its active metabolite 9-hydroxyrisperidone using LLE and SPE technologies. The analytical columns used to separate these compounds were C4 or C18 bonded phases of 3 pm or 5 pm particle sizes with UV/VIS detection. Mobile phases consisted of phosphate bufiers (pH 3-4) in acetonitrile. The sample volumes used ranged from 200 pi to 1 ml, with extraction recoveries averaging 90%. The limits of quantitation ranged from 0.5 to 10 ng/ml in human plasma (Nagasaki et al., 1999 Avenso et al., 2000 Titier et al., 2002). A study by Titier showed the simultaneous determination of clozapine, olanzapine, haloperidol, risperidone, and its active metabolites by RP-HPLC in human plasma. The assay involved LLE with a hexane/isoamyl alcohol mixture... 

Arnett and Moe studied the protodelithiation of organolithiums with isopropyl alcohol in hexane/ether mixtures. These authors found protodelithiation enthalpies for n- and iec-butyl lithium of —209.2 4.2 and —220.9 2.9, respectively. The difference between their enthalpies of reaction, and so of the enthalpies of formation of the two organolithiums, is 11.7 5.1 kJmor, about half the difference between these species as found in Table 1. The protodelithiation enthalpy of terf-butyl lithium is —237.7 7.5 kJmoP. From equation 10 with n-butyl lithium as the benchmark species, and the butane hydrocarbons in their liquid reference states, the derived enthalpy of formation of ferf-butyl lithium is —87.5 kJmoP, in good agreement with that found before by Hohn . 

There remains little more for the operator to decide. Sometimes, alternative but similar solvent mixtures that have a lower viscosity or higher solute diffusivity could be selected. For example, a n-hexane/methanol mixture might be chosen as an alternative to the more viscous n-heptane/isopropyl alcohol mixture as it has similar elution properties. However, it will be shown later, that if a fully optimized column is employed the viscosity of the mobile phase does not seem to effect the column performance as it is taken into account in the optimization procedure. The operator would, under some circumstances, be free to choose less toxic or less costly solvents for example, in reverse phase chromatography the operator could select methanol/ water solvent mixtures as opposed to acetonitrile/water mixture on the basis of lower cost or less... 

The most suitable solvents for extracting SPA from fats are acetonitrile (113,125,126, 139,142) and water-alcohol mixtures. The fat is usually dissolved in hexane or petroleum ether, and SPA are extracted into acetonitrile (105,110-113,125,126,128). The disadvantages of acetonitrile extraction are that (a) BHT recovery is low and (b) moderately high levels of interfering compounds are coextracted. The advantage of aqueous methanolic extraction of SPA from nonpolar solvent is that the fat is mostly excluded (99,114). Hammond (99) described a methanolic extraction of a melted fat sample, heated to 40-50°C, followed by transfer of the mixture to a deep freeze for a few hours to aid the solidification of any excess fat from methanol. The methanol layer was then decanted and filtered prior to the addition of an internal standard and direct injection. 

Polysaccharide-based CSPs are effective for chiral aromatic hydrocarbons without polar substituents (Figure 14). For example, racemates 31 were resolved on OD using hexane-2-propanol as the eluent.79 Compound 32 was not resolved with the mixture of hexane-alcohol and pure hexane, but it was completely separated on OD using... 

Analytical Properties Ionically bonded to silica, this phase provides good resolution of enantiomeric quasiequatorial frans-dehydriols of unsubstituted and methyl- and bromo-substituted benz[a]anthracene derivatives covalently bonded to silica, this phase provides good resolution of enantiomeric pairs of quasidiaxial frans-dihydrodiols of unsubstituted and methyl- and bromo-substituted benz[a]anthracene derivatives by addition of a third solvent (chloroform) to the classical binary mixture (hexane-alcohol) of the mobile phase, resolution of enantiomers of tertiary phosphine oxides is possible Reference 31-33, 36, 37... 

The Step 7 product (0.2 mmol) and 1M NaOH (0.22 nM) dissolved in 5 ml ethyl alcohol was stirred 3.5 hours at 25°C and then diluted with diethyl ether/hexanes. The mixture was cooled and a precipitate isolated. The precipitate was washed with ethyl alcohol/diethyl ether/hexanes, dried, and the product isolated in 73% yield as a brown solid. 

In order to maximize such interactions, these stationary phases can be used in conjunction with mobile phases containing mixtures of hexane/alcohols. It was found that linear alcohols such as ethanol and n-propanol produced a longer retention time than the branched alcohols. The reason for such a phenomenon is attributed to the behavior of linear alcohols, which self-associates in the presence of a nonpolar solvent such as hexane. Such association is at the expense of the interaction of these alcohols with the stationary phase. 

The cinchona alkaloid-based stationary phases are chiral stationary phases where quinine/ quinidine are chemically bonded to a silica gel matrix. The interaction between the selectand and selector is based on charge transfer n-n interactions as well as ion pairing with the selector. They operate under aqueous-organic mobile phases or mixtures of organic solvents such as hexane-alcohols. 

Table lists the results of the additions of both chiral and achiral alkoxytrialkylaluminates (20) to chiral a-keto esters (21). Some trends arc readily tqiparent (i) sodium is a superior cation as compared to lithium and potassium (entries 11-14) (ii) the configuration of the chiral moiety of the ester substrate dictates the facial preference (entries 1-7) and the preference follows the dictates of Prelog s rule (iii) there is an observable solvent effect with a preference for hexane/ether mixtures (iv) either (+)- or ( )-(2S,3/ )-4-dimethylamino-l,2-diphenyl-3-methyl-2-butanol (Darvon alcohol or (Zhirald) is the best of the... 

Complex multiphase process waste streams are generated in the production of active substances in the chemical industry. A number of standard types of chemistry reactions currently carried out in the pharmaceutical industry would generate complex waste solvent mixtures containing tetrahydrofuran, hexane, alcohols and water. 

Neutralization of the Isolated Polymeric Acid. The isolated polymeric acid was redissolved in a mixture of toluene/ methanol or hexane/alcohol at a concentration of 50 to 100 g/L. Neutralization was effected through the addition of a solution of metal acetate in water or water/methanol. 

Ethanol and tt-hexane form two liquid phases at many temperatures. Assuming that the activity coefficients for /I-hexane-ethyl alcohol mixtures can be represented by the equation... 

Phenyl-Substituted Phenols VII. General procedure. To a solution of 26.2 g (0.1 mol) of 2,6-diphenylhydroquinone(III) in 200 mL of the appropriate alcohol there was added, while stirring, 5 mL of concentrated sulfuric acid over 3 hr. After additional stirring for 1 hr at 65°-130°C, depending upon the alcohol used, the reaction mixture was diluted with 200 mL of chloroform and was washed with water. After evaporation of the chloroform, a light yellow syrup was obtained which gave the 4-alkoxy-2,6-diphenylphenol after crystallization from a hexane/toluene mixture (95 5). Vila, yield 87% mp 67.6°-68.1°C Vllb, yield 72% mp 89.1°-89.9°C Vile, yield 55% mp 34.2° 35.3°C Vile, yield 84% mp 56.9°-60.3°C. The identity and purity of the phenyl-substituted phenols... 

Some laboratories prepare successive extracts of each organism using solvents of increasing polarity. This affords some measure of preliminary separation of components. Organisms are first extracted exhaustively with a nonpolar solvent such as diethyl ether, hexanes, ethyl acetate, or a halogenated solvent (dichloromethane, chloroform), then exhaustively with an alcohol (methanol or ethanol), and then exhaustively wifli water or water-alcohol mixtures. Some groups use acetone for extraction, but care must be taken that adducts are not formed. 

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