Dioxane-Ethanol

Norethindrone may be recrystakhed from ethyl acetate (111). It is soluble in acetone, chloroform, dioxane, ethanol, and pyridine slightly soluble in ether, and insoluble in water (112,113). Its crystal stmcture has been reported (114), and extensive analytical and spectral data have been compiled (115). Norethindrone acetate can be recrystakhed from methylene chloride/hexane (111). It is soluble in acetone, chloroform, dioxane, ethanol, and ether, and insoluble in water (112). Data for identification have been reported (113). The preparation of norethindrone (28) has been described (see Fig. 5). Norethindrone acetate (80) is prepared by the acylation of norethindrone. Norethindrone esters have been described ie, norethindrone, an appropriate acid, and trifiuoroacetic anhydride have been shown to provide a wide variety of norethindrone esters including the acetate (80) and enanthate (81) (116). 

In benzonitrile both types of processes occur in parallel with similar efficiencies. In hydrogen-donating solvents (toluene, ether, dioxane, ethanol), hydrogen abstraction processes prevail [toluene (114) -> (123)]. 

Hydroxy-B-homo-5a-cholestan-7-one acetate (54b) A solution of 3/3-hydroxy-5a-cholestan-7-one acetate (51b 5 g mp 146-148°) in dioxane-ethanol (100 ml, 1 1) is placed in a 250 ml three-necked flask equipped with a mechanical stirrer and thermometer and is cooled to 0° (iee-salt bath). Powdered potassium cyanide (7.3 g) is added portionwise with stirring. Acetic acid (8 ml) is then added dropwise with constant stirring over 30 min. The resultant mixture is stirred for 1 hr at 0° C and for an additional 2 hr at room temperature. It is then poured into ice water (200 g ice, 100 ml water) and after standing for 1 hr the precipitate is collected by filtration. The product is dissolved in ether (100 ml), the ether solution is washed with 5% sodium bicarbonate, water and dried over anhydrous sodium sulfate. The filtrate is evaporated at reduced pressure and the solid residue (5.1 g) is crystallized from ethyl acetate (30 ml) to yield 2.8 g of cyanohydrin (52b) mp 160-164° repeated crystallization from the same solvent gives a product mp 164-167°. An alternative method of isolation of the cyanohydrin is used when 100 g or larger quantities are worked up. The reaction mixture is poured directly into a mixture of ice water and sodium bicarbonate, the precipitate (mp 155-156°) is washed well with water, dried and used directly for the next step. 

In 1988 Masoud and Ishak demonstrated that ( -arenediazo methyl ethers do not react with 2-naphthol in dry organic solvents such as dioxan, ethanol, 2-propanol, but only in the presence of water. The reactions are catalyzed by hydrochloric acid (even in the absence of water). Under such conditions almost quantitative yields of azo compounds were obtained. A careful and extensive kinetic investigation of the HCl-catalyzed dediazoniation of substituted benzenediazo methyl ethers, varying the HC1 concentration and the diazo ether/2-naphthol ratio (the latter either absent or in large excess), and comparing the observed rate constants with Hammett s acidity functions for dioxane and ethanol (see Rochester, 1970) indicated the mechanism shown in Schemes 12-8 to 12-10 (DE = diazo methyl ether, D+ = diazonium ion). 

X-Y CH2CI2 THF Dioxan Ethanol Propanol Octanol DMSO DMF Mean... 

Returning to the higher member of the homologous series but nevertheless changing the sulfonate type and solvent as compared to the above case of the cyclobutane-1,1,2,2-tetratosylate 37 the corresponding tetramesylate 18 affords the dithioether 45 instead of the ether-thioether 43 (dioxan/ethanol 77%). 

A specific assay of bromocriptine mesilate in the dosage form may be carried out by tic followed by uv-spectrophotometry (26)(The system can also serve for identification purposes). The drug substance is extracted with methanol in the absence of light, the chromatographic conditions are Merck plates F 254, mobile phase dichloromethane/dioxane/ ethanol abs./conc. ammonia 180 15 5 0.1 per volume. 

In this example a productivity of 100 kg/m3, yield of >85% and Maximum solids fraction at isolation of 0.3 are specified. The solvents that match these constraints are 1,4-dioxane, Ethanol, Isobutanol, Pentanol, Propanol, Isopropyl alcohol, 1,1,1-Trichloroethane and Water. On the basis of these results the first choice of a cooling crystallization from a single solvent appears feasible and an antisolvent addition should not be required. From this list the alcohols and water are certainly the best choices from a health, safety and environmental... 

Media Acetone, benzene, benzyl alcohol, butanol, 2-butanol, carbon tetrachloride, cetane, chlorocyclohexane, chloroform, cyclohexane, cyclohexanone, diehloroeihane, di-chloromethane, dioxane, ethanol, ether, ethyl acetate, hexane, methanol, 2-propa-nol, pyridine, letrachloromethane, toluene, water, xylene... 

An experimental check of the conclusions of the theory was. performed for neutral PAA gel and also for a weakly charged PAA network containing 1.88 mol % of the anionic SMA links synthesized in dilute solution of monomers. The mixtures of water with dioxane, ethanol, and methanol were used as a solvent [48]. 

Note. Both the rearrangement In t-Butanol) and the double bond isomerization of (114) In Benzene) are quenched in a diffusion-controlled process by suitable triplet acceptors (e.g., naphthalene or 2,5-dimethylhexa-2,4-diene). The rearrangement (114) - (118) + (120) is also observed on irradiation in pyridine, the double bond isomerization (114) -> (122) in trifluorotoluene. In benzonitrile both types of processes occur in parallel with similar efficiencies. In hydrogen-donating solvents (toluene, ether, dioxane, ethanol), hydrogen abstraction processes prevail [toluene (114) - (123)]. 

PS-PB-PS 33-80% Dioxane + ethanol THF + allyl alcohol (selective for PS) Solubilization of PB and PS-PB-PS triblock Micellar structure with solubilizate SLS Tuzar et ai (1982)... 

The acetates of 2-hydroxyglycals are soluble in ethanol, ether, chloroform, benzene, and ethyl acetate moderately soluble in hot water and insoluble in petroleum ether or cold water.2 2,3,4,6-Tetra-0-methyl-(2-hydroxy-D-glucal) is soluble in water, acetone, ether, dioxane, ethanol, and chloroform.29... 

The polymers (+ )polyfthio- l-(N-sec butyl,N-methyl-aminomethyl)ethylene] and (—)poly[thio-l-(N-methyl,N-(l-phenylethyl)aminomethyl)ethylene] seem to be able to give complexes with Cu2 + in dioxane/ethanol 1 9. The nature of these complexes is not yet fully established however, an interaction between Cu2+ ions and sulphur atoms probably occurs 29). 

This can be purified by crystallization from n-butanol, dioxan, ethanol or ethyl acetate. 

Several approaches have been used to circumvent these problems. First, scintillation cocktails have been developed that will accept more water and associated hydrophilic compounds. Bray s solution (4 g PPO, 0.2 g POPOP, 60 g naphthalene, 20 ml ethylene glycol, 100 ml methanol, and dioxane up to 1 liter), Kinard solution (xylene, p-dioxane, ethanol (5 5 3) containing 0.5% PPO, 0.005% a-NPO, and 6% naphthalene), and ethanol systems (e.g., 3 parts ethanol, 4 parts 0.8% PPO, 0.01% POPOP in toluene) are notable examples. In these examples, PPO denotes 2,5-diphenyloxazole, POPOP denotes l,4-bis-2-(5-phenyloxazolyl)-benzene, and a-NPO denotes 2-(l-naphthyl)-5-phenyloxazole. (POPOP and a-NPO are secondary fluors and can usually be omitted with modern scintillation counters.)... 

Metal /3-diketonates are generally synthesized from the neutral /3-diketones and the appropriate bulk metal or metal salt are synthesized in solvents such as water, dioxane, ethanol, or neat diketone. The use of the bulk metal is limited to the more electropositive elements such as the group 1 and 2 metals, although the method is more widely apphcable with more acidic /3-diketones, such as those with perfluoroalkyl substituents. Electrochemical syntheses... 

Corresponding increases in —60 are observed upon the addition of similar amounts of other weakly protic, hydrocarbon-miscible, nonaqueous solvents to protein solutions in H2O (Tanford et al., 1960 Tanford and De, 1961). Among the solvents so far examined which exhibit this effect are dioxane, ethanol, dimethylformamide, iV-methylpropionamide, and 1-propanol. There is therefore nothing unique about 2-chloroethanol in this respect except its solubilizing capacity for proteins (Section 111,11) which is not nearly as extensively exhibited by the other pure solvents. 

Jaenicke and Schweitzer [224], who studied the kinetics of the electrode reaction of the Zn(II)/Zn(Hg) system in mixtures of water with dioxane, ethanol, acetonitrile, tetrahydrofuran, and acetone, initiated and gave impetus to the practical study of electrode kinetics in mixed solvents. Their kinetic results are given in Fig. 11, where one may observe a decrease in the exchange current when the concentration of organic component increases in the mixture. This decrease is not large in the case of dioxane, but it amounts to 2.5 orders of magnitude when acetone is added to water. 

The salt is prepared efficiently by reaction oftrimethylamine with methylene iodide in dioxane ethanol. I he product (I) is then heated at about 150° for about 12 min. in tetrahydrothiophenc dioxide dimethyl(methylene)ammonium iodide (2) is obtained in 81 % yield. ... 

Fig. 11.4. Plm of log/t predicied by Eq. (II.14 against cxporiincnial data determined on a diol column for 36 ehalcone derivatives with heptane eluent containing O.Sfif tetrahydrofuran. dioxane. ethanol, propanol, trctanol or dimeihylformamide. (Reprinted with permission from K. A//aoui and L. Morin-Allory. Chromatographia. 42 (1996). 389. Copyright Friedr. Vieweg and. Sohn.)...

What we have just proposed is admittedly a working hypothesis whose limitations must be specified. Certainly, there are exceptions. The highest rates are usually, but not inevitably, found in the most polar solvents in the addition of ethanol to diacetylene the rates are in the order A (dioxane-ethanol)>A (ethanol)>A (ethanol-heptane) . The highest antifsyn addition ratios are usually, but not inevitably found in the most polar solvents in equation (19), the fraction of Z isomer in the product... 

In Nonaqueous Solution. The use of a nonaqueous solvent in which both the metal salt and the /3-keto imine are soluble eliminates many of the problems of contamination due to hydrolysis, the presence of extraneous ions, and unfavorable equilibria. Halides such as ECU, AICI3, SiCU, GeCU, ZrCU, ThCU, NbCU, and TaCU, which are soluble in an inactive organic solvent, have been used in the reaction with 1,3-diketones but apparently not with /3-keto imines. However, the reaction of metal acetates with /3-keto imines has been effected successfully in dioxane, ethanol, - or methanol. ... 

Dissolving metal reductions remain the method of choice, and are frequently the only viable method, for the reduction of sterically hindered cyclohexanones to equatorial alcohols. In the early 1950s it was found that reduction of 11-keto steroids using either Na-propan-l-oP or Li-NHs-dioxane-ethanol gave good yields of the equatorial I la-alcohol. 11-Keto steroids, such as androstan-11-one (29 equation 12) have two axial methyl groups in a 1,3-relationship to the carbonyl group and afford exclusively the axial 11 P-ol (30) on reduction with metal hydrides. 

Besides methanol, many other polar and nonpolar modifiers have also been used to successfully improve the separation in SFC. These modifiers include acetone, acetonitrile, acetic acid, butane, butanol, n-butyl chloride, carbon tetrachloride, dioxane, ethanol, formic acid, heptane, hexane, n-hexylamine, methylene chloride, nitromethane, propanol, proprionitrile, tetrahy-drofuran, toluene, triethanolamine, trifluoroacetic acid, trifluoroethanol, trimethyl phosphate, and water. 

The isotherms for 1,4-dioxane, ethanol, heptane, and octane are shown in Figure 7. The temperatures at which the isotherm curves were obtained are 24.3°C for 1,4-dioxane, ethanol and heptane, and 25°C for octane. Though the temperature for octane is slightly higher than that for the other organic vapors, the difference in the temperature seems to be small enough to make the comparison of these adsorption Isotherms meaningful. Furthermore, relative pressure (vapor pressure/saturation vapor pressure) was used for the pressure scale instead of the vapor pressure itself. The amount of adsorbed vapor decreases in the order 1,4-dioxane > ethanol > heptane > octane. 

Figure 7. Adsorption isotherms of 1,4-dioxane, ethanol, heptane, and octane on cellulose polymer. Temperatures were 24.3 C, except for the octane isotherm, which was obtained at 25 C.

Data in Table 7 show that acetonitrile, dioxane, ethanol, and water are very poor solvents for humic acids. Humic acids are, by definition, insoluble in water, although traces of the H -exchanged substances are invariably dissolved in it. Similar trace amounts were dissolved in ethanol. Pyridine and formic acid (90%) were also poor solvents for humic substances. The extent of dissolution in pyridine was less than would be predicted from the data quoted for the H -exchanged soil in Table 4. However, the Glade humic... 

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