Water-methanol-acetic-acid-acetone-pyridine

Water with acetic acid, acetone, ethanol, methanol, or pyridine. 

Acetic acid, acetone, acetonitrile, benzenerwater (1 1), chloroform, cyclohexanone, dichloroacetice acid, dichloromethane, N,N-dimethylacetamide, dimethyUormainide, dimethylsulfoxide, dioxane, ethanol, ethylene glycol monomethyl ether, formamide, formic acid, 2-hydroxyethyl methacrylate, isopropanol, methanol, 2-methoxyethanol, methyl ether ketone, morphloline, 2,2 -oxydiethanol, 1-penlanol, phenol, 1,2-propanediol, 1-propanol, propylene glycol, pyridine, letrahydrcrfuran, trielhyl phosphate, trifluoroacelic acid, trimelhyl phosphate, water ... 

Certain solvents should be avoided with alumina or silica gel, especially with the acidic, basic, and highly active forms. For instance, with any of these adsorbents, acetone dimerizes via an aldol condensation to give diacetone alcohol. Mixtures of esters transesterify (exchange their alcoholic portions) when ethyl acetate or an alcohol is the eluent. Finally, the most active solvents (pyridine, methanol, water, and acetic acid) dissolve and elute some of the adsorbent itself. Generally, try to avoid going to solvents more polar than diethyl ether or methylene chloride in the eluent series (Table 19.2). 

Preparation of 9, 11 -Epoxy-17a-21 -Dihydroxy-16 -Methyl-4-Pregnene-3 0-Dione 21-Acetate To a stirred solution of 100 mg of the 9a-bromo-11(3,17a,2Ttrihydroxy-16 3-methyl-4-pregnene-3,20-dione 21-acetate in 3 ml of tetrahydrofuran and 1 ml of methanol under nitrogen was added 1.02 ml of 0.215 N methanolic sodium methoxide. After 10 minutes at 25°C, 0.2 ml of acetic acid was added and the methanol removed in vacuo. The residue was acetylated with 1.00 ml of pyridine and 0.5 ml of acetic anhydride at 60°C for 70 minutes. The mixture was taken to dryness in vacuo, water added, and the product extracted into chloroform. The residue was crystallized from ether-acetone to give pure 9(3,11 (3-epoxy-17a,21-dihydroxy-16(3-methyl-4-pregnene-3,20-dione 21-acetate. 

Kojic acid is readily soluble in water, ethanol, and acetone sparingly soluble in ether, ethyl acetate, chloroform, and pyridine and difficultly soluble in most other liquids.4-T It has been purified by recrystallization from acetone,7 ethanol-ether,20 and methanol-ethyl acetate26 also, by sublimation under diminished pressure at8-26-64 150-200°C. The m. p. (in °C.) has been given as 151-152,20-42 152,3-21-64 152.6,37 152-153,43 153-154,29 -31 and 154.6-6 The molecular weight was determined by the cryo-scopic method,4- 7-31 and the values obtained agreed well with the calculated value of 142. 

Cabon tetrachloride, n-hexane, chloroform, ACN, acetone, THF, pyridine, acetic acid, and their various mixtures were applied as mobile phases for adsorption TLC. Methanol, 1-propanol, ACN, acetone, THF, pyridine and dioxane served as organic modifiers for RP-TLC. Distilled water, buffers at various pH (solutions of and dipotassium hydrogen phosphate or potassium dihydrogen phosphate) and solutions of lithium chloride formed the aqueous phase. Carotenoids were extracted from a commercial paprika sample by acetone (lg paprika shaken with 3 ml of acetone for 30 min), the solution was spotted onto the plates. Development was carried out in a sandwich chamber in the dark and at ambient temperature. After development (15 cm for normal and 7cm for HPTLC plates) the plates were evaluated by a TLC scanner. The best separations were realized on impregnated diatomaceous earth stationary phases using water-acetone and water-THF-acetone mixtures as mobile phases. Some densitograms are shown in Fig.2.1. Calculations indicated that the selectivity of acetone and THF as organic modifiers in RP-TLC is different [14],... 

Many papers concerning salt effect on vapor-liquid equilibrium have been published. The systems formed by alcohol-water mixtures saturated with various salts have been the most widely studied, with those based on the ethyl alcohol-water binary being of special interest (1-6,8,10,11). However, other alcohol mixtures have also been studied methanol (10,16,17,20,21,22), 1-propanol (10,12,23,24), 2-propanol (12,23,25,26), butanol (27), phenol (28), and ethylene glycol (29,30). Other binary solvents studied have included acetic acid-water (22), propionic acid-water (31), nitric acid-water (32), acetone-methanol (33), ethanol-benzene (27), pyridine-water (25), and dioxane-water (26). 

The compound is sparingly soluble in water, soluble in methanol and ethanol, and readily soluble in acetone, nitroglycerine, nitrobenzene, aniline, pyridine, and acetic acid. It rapidly darkerns in sunlight. It is of interest for -> Lead-free Priming Compositions. 

In those cases where a compound is described in more than one paper, the reference number printed in bold type indicates the paper from which the physical constants have been taken. All references appear in a separate list, starting on p. 196. The abbreviations used to indicate the solvents in which [o]d values were determined are as follows A, acetone C, chloroform DMF, iV,V-dimethylformamide E, ethanol HO Ac, acetic acid M, methanol P, pyridine and W, water. 

AB + B Usually + H bonds broken and formed Dioxane + water (min), formic acid + dioxane (max), methanol + acetone (min), 2-butanone + butylamine (min), acetic acid + pyridine (max), methylamine + 1,3-butadiene (min), methanol + ethyl formate (min), methanol + benzene (min)... 

Furthermore, it is seen that a hydroxyl group in the molecule does not necessarily reduce the Rf value as the chromatographic behavior of serine with respect to glycine on both layers of silica gel and cellulose shows (see Table 1). Some of the numerous eluents that have been used for the separation of amino adds on silica gel are acetone-water-acetic acid-formic acid (50 15 12 3), ethylacetate-pyridine-acetic acid-water (30 20 6 11), 96% ethanol-water-diethylamine (70 29 1), chloroform-formic acid (20 1), chloroform-methanol (9 1), isopropanol-5 % ammonia (7 3), and phenol-0.06M borate buffer pH 9.30 (9 1). On cellulose plates, ethylacetate-pyridine-acetic add-water (5 5 1 3), n-bu-tanol-acetic acid-water (4 1 1 and 10 3 9), n-butanol-acetone-ammonia-water (20 20 4 1), collidine-n-bu-tanol-acetone-water (2 10 10 5), phenol-methanol-water (7 10 3), ethanol-acetic acid-water (2 1 2), and cyclohexanol-acetone-diethylamine-water... 

Throughout the Tables, the following abbreviations are used A, acetone AcOH, acetic acid B, benzene Bu, 1-butanol C, cyclohexane Ch, chloroform D, 1,4-dioxane Dch, dichloromethane Dip, diisopropyl ether E, ethanol EA, ethyl acetate Et, ether Ip, 2-propanol M, methanol Me2SO, dimethyl sulfoxide P, 1-propanol Pe, petroleum ether Py, pyridine Tch, tetrachloromethane T, toluene and W, water. 

Water can be removed from methanol by a membrane of polyvinyl alcohol cross-linked with polyacrylic acid, with a separation factor of 465.204 A polymeric hydrazone of 2,6-pyridinedialdehyde has been used to dehydrate azeotropes of water with n- and /-propyl alcohol, s- and tort butyl alcohol, and tetrahydrofuran.205 The Clostridium acetobutylicum which is used to produce 1-butanol, is inhibited by it. Pervaporation through a poly(dimethyl-siloxane) membrane filled with cyclodextrins, zeolites, or oleyl alcohol kept the concentration in the broth lower than 1% and removed the inhibition.206 Acetic acid can be dehydrated with separation factors of 807 for poly(4-methyl-l-pentene) grafted with 4-vinylpyridine,207 150 for polyvinyl alcohol cross-linked with glutaraldehyde,208 more than 1300 for a doped polyaniline film (4.1 g/m2h),209 125 for a nylon-polyacrylic acid membrane (5400 g/m2h), and 72 for a polysulfone.210 Pyridine can be dehydrated with a membrane of a copolymer of acrylonitrile and 4-styrenesulfonic acid to give more than 99% pyridine.211 A hydrophobic silicone rubber membrane removes acetone selectively from water. A hydrophilic cross-linked polyvinyl alcohol membrane removes water selectively from acetone. Both are more selective than distillation.212... 

This widely applicable method involves condensing the pyridine-3,4-diamine moiety with the a-dioxo function of the reaction partner. Reported conditions are 0°C in aqueous ethanol,112 room temperature in methanol,44 acetone/water,53 methanolic sodium methoxide,15 dilute sulfuric acid,97 or dilute hydrochloric acid.47 Others are heating at 60-100 C in water,113 aqueous acetic acid.114 ethanol/acetic acid,115 or ethanol.42,97,116,117... 

Plates from hot benzene + methanol, rop 206 -206.5. [n) J —36,3 (c = 3.8 in ethanol), uv max (ethanol) 223, 272, 304.5 nm (< 11,300 6350 5100). Sol in ethanol, methanol, dioxane, acetone, pyridine, coned HjSO( moderately sol in acetic acid, ether sparingly sol in benzene, petr ether, chloroform, water. Gives yellow solns with aq ammonia, sodium carbonate, and sodium hydroxide. Alkaline solns darken rapidly in air, eventually becoming purple. 

Coral-like clusters from pyridine + acetone, mp 230-240 with sintering at 180-190. [ ]Jf —10.8 (c = 2 in pyridine). Practically insol in water, cold methanol, acetone, cold acetic acid, ether, acetonitrile. Soluble in pyridine, chloroform, hot methanol, hot acetic acid. Dissolves readily in chloroform + methanol mixtures of high chloroform content. 

Needles from methanol, mp 215°. [a]g —121 (chloroform). uv max (ethanol) 231 nm (log e 4.24). Very slightly So] in water slightly sol in petr ether, methanol, ethanol. More sol in hot methanol, ethanol sol in chloroform, acetone, ethyl acetate, benzene, pyridine, glacial acetic acid, dioxane, ether. 

One gram dissolves in 50 1 water- Sol in form amide, dimeth -ylformatnide at 60°. Slightly so] in methanol, hot glacial acetic acid. Almost insol in acetone, benzene, chloroform. Freely sol in dil alkalies, pyridine,... 

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