System acetic acid-acetone

The largest errors in predicted compositions occur for the systems acetic acid-formic acid-water and acetone-acetonitrile-water where experimental uncertainties are significantly greater than those for other systems. 

The oxidation of a secondary alcohol to a ketone is usually accomplished with a solution of the alcohol and aqueous acidic chromic acid in either acetone or acetic acid, with a solution of sodium dichromate in acetic acid, or by reaction of the alcohol with aqueous acidic chromic acid as a heterogeneous system. An example is the oxidation of the substituted cyclohexanol below (Reaction XXXV) with sodium dichromate in sulfuric acid (55). 

Dziewinski et al. [71] have reported current efficiencies greater than 90% at 80°C for isopropanol, acetone, and acetic acid, whereas methanol, chloroform, and carbon tetrachloride were converted into carbon dioxide at room temperature with ca. 100% current efficiency. The predicted order of ease of oxidation is alcohols < aldehydes, ketones < carboxylic acids. Thus, the complete conversion to carbon dioxide, in particular for large organic molecules, is expected only at elevated temperatures. To avoid the use of a separator, Farmer et al. [72,75] employed C0SO4 in sulfuric acid. A scheme of the system is shown in Fig. 17. Both electrodes, the anode and the cathode, are usually of a Pt-containing surface layer, although other materials such as Au, steel, graphite, Ti, Nb, Ir, or tin oxide can also be used. H2 is evolved at the cathode because the deposition of the mediator takes place... 

Figure 2. CD spectra obtained within the n->w band system of the carbonyl chromophore upon dissolution of (a) acetone, (b) acetic acid, (c) acetamide, and (d) urea in (2R,3R)-2,3-butanediol (data adapted from reference [7]).

Phospholipase A2 Action. Incubation of phosphatidylserine with phospholipase A2 obtained from Crotalus adamanteus or Naja Naja snake venom will show that the serine-containing phosphoglyceride was smoothly and completely converted to a lysophosphatidylserine with liberation of 1 mol of fatty acid per mole of lipid P. The experimental procedure was the same as the one described before in this and in the previous chapter. The products of the reaction can be recovered by thin-layer chromatography on Whatman K6 plates in a solvent system of chloroform-acetone-methanol-acetic acid-water (4.5 2 1 1.3 0.5, v/v). 

The main use of TLC in analysis of amoxicillin and its formulated products is as an identity test. A major study [105] using silica gel and silanised silica gel plates with thirty five different mobile phases and iodine vapour detection produced a system, on silanised plates with ammonium acetate/acetone mobile phase, in which amoxicillin was separated from all the other penicillins studied. A slightly modified version of this system was subsequently introduced into the European and British Pharmacopoeia monographs for amoxicillin trihydrate and sodium salt [2]. The British [57,58] and US [9] Pharmacopoeias specify other TLC systems for identification of amoxicillin in formulated products. Simple TLC methods have been developed for identification of several compounds on the WHO essential drugs list, to help combat counterfeiting [106]. For amoxicillin, systems using ethyl acetate/acetic acid/water or acetone/toluene/acetic acid/water with silica gel plates were recommended. 

Fig. 1 Typical chromatograms of (A) the cream sample on the Multi-K CS5 TLC plate after development in solvent system B i ethanol in water), and (B) the cream sample and standards, tretinoin and 13-cw-retinoic acid (13-c -Ra), after development in solvent system A (diethyl ether-cyclohexane acetone-glacial acetic acid, 40 60 2 1). The spotting areas are designated as follows S = sample A and B = tretinoin standard stock solution at the beginning of analysis and just before development in direction 2, respectively C and D = 13-cri-RA standard test solutions. The broken lines represent solvent fronts. The Rp values in (A) are 0.81 for plar excipients, 0.42 for tretinoin and 13-cfr-RA, and 0.36 for hutylated hydroxytoluene (bHT). In (B), the Rp values are 0.25 for polar excipients, 0.34 for tretinoin, 0.39 for 13-cfr-RA, and 0.68 for BHT.

Two-dimensional systems are often used to separate complex phospholipid mixtures in plant and animal tissues. See reviews in Mangold (98) and Rouser et al. (99) for details. The first development is typically in chloroform-methanol-water (65 25 4), and development in the second direction is often in either n-butanol-acetic acid-water (60 20 20) or chloroform-acetone-methanol-acetic acid-water (5 2.1 1 0.5). Although 2-D procedures may increase the resolution of some spots, it often results in large spots with tails. Figure 6 shows a 2-D separation of phospholipids from snail tissue, and Fig. 7 shows a 2-D separation of serum lipids. Table 7 lists frequently used 2-D solvent systems for complex lipid mixtures. 

Elution of parafHn oil-impregnated starch thin-layer with acetone-conc. acetic acid (30 20, by vol) resulted in a separation of all the above mentioned compounds except K3, K4, and K5, which migrated as a single spot with the front. Under these conditions, untreated talc and impregnated starch, cellulose, or talc were complementary systems for the separation of this complex mixture of fat-soluble vitamins. 

Savescu, V Cioroianu, D. lonescu, L Simoiu, L. Liquid-vapor equilibrium in binary systems of cro-tonaldehyde with acetone and acetic acid [Rom]. Rev. Chim. (Bueharest) 1991, 42, 402-405. 

CeUulose triacetate is insoluble in acetone, and other solvent systems are used for dry extmsion, such as chlorinated hydrocarbons (eg, methylene chloride), methyl acetate, acetic acid, dimethylformamide, and dimethyl sulfoxide. Methylene chloride containing 5—15% methanol or ethanol is most often employed. Concerns with the oral toxicity of methylene chloride have led to the recent termination of the only triacetate fiber preparation faciHty in the United States, although manufacture stiH exists elsewhere in the world (49). 

Thin layer chromatography of (-)-DAG on Silica Gel G using the solvent system, benzene methanol acetone acetic acid (70 20 5 5), shows one spot with Rf 0.7. 

York, R. and Holmes, R. C. (1942) Ind. Eng. Chem. 34, 345. Vapor-liquid equilibria of the system acetone-acetic acid-water. 

Equilibrium data for the system acetone-acetic acid, at 760 mmHg, mol... 

The explosion limits have been determined for liquid systems containing hydrogen peroxide, water and acetaldehyde, acetic acid, acetone, ethanol, formaldehyde, formic acid, methanol, 2-propanol or propionaldehyde, under various types of initiation [1], In general, explosive behaviour is noted where the ratio of hydrogen peroxide to water is >1, and if the overall fuel-peroxide composition is stoicheiometric, the explosive power and sensitivity may be equivalent to those of glyceryl nitrate [2],... 

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