Aqueous Acetone

Chromatographic Behaviour of log P = 3 Compounds in Aqueous Acetone. When the Xe value in aqueous methanol was nearly equal to that in aqueous acetonitrile (see above), the log A of ROH was about the same as that in aqueous acetonitrile but the corresponding predicted value with aqueous acetone (log k = 0.35) is very different to the equivalent aqueous acetonitrile (logfc = 0.53) (Table 4.3). However, when the Po and Xd values in aqueous acetonitrile are nearly equal to those in aqueous acetone, the predicted log A values of OH are about the same. To obtain the same log k as in 50% aqueous acetone it was necessary to use 59% aqueous acetonitrile for ROH, 61% for PAH, 56% for RB and 62% for ROB. 

Chromatographic Behaviour of log P = 3 Compounds in Aqueous Dimethylform-amide (DMF). DMF is a solvent with a strong dipole moment (Table 4.2). The same log A values in 50% aqueous DMF can be obtained at a concentration of 26% aqueous acetonitrile for ROH, 44% aqueous acetonitrile for PAH, 37% for RB, and 36% aqueous acetonitrile for ROB. When eluents with equivalent Po, Xe, Xd, or Xn values in 50% DMF were selected, different log A values were predicted in all three cases. 

The above results only demonstrate the chromatographic behaviour of compounds with logP = 3. Their relative retention factors thus are influenced by the properties of solvents in the eluent. The relative values cannot be controlled by only one property of the solvents and chromatographic behaviour therefore also depends on the properties of the analytes. 

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Urease is one of the enzymes which have been obtained in the crystalline state. This has been done by stirring jack bean meal with 30°o aqueous acetone, filtering and allowing the filtrate to remain at o for several hours. The urease which crystallises out is separated by centrifuging and is then recrystallised. Like crystalline pepsin and trypsin, it is a protein. 

By refluxing 54 and thioformamide for 16 hr m aqueous acetone solution, the expected compound 55 was obtained (Scheme 25). 55 in acetic medium, after treatment with hydrochloric add and zinc, gives 2-(4-thiazolyl)benziinida2ole derivatives 56 (554, 593). 

Benzylic halides resemble allylic halides m the readiness with which they form carbocations On comparing the rate of S l hydrolysis m aqueous acetone of the fol lowing two tertiary chlorides we find that the benzylic chloride reacts over 600 times faster than does tert butyl chloride... 

When chloro compounds are treated with sodium azide in ethanol or aqueous acetone the corresponding azides or tetrazolo[l,5-6]pyridazines are obtained. For example, 3-azido-and 4-azido-pyridazine 1-oxides are obtained from the corresponding chloro compounds ... 

Only 2-alkylthiopyrimidines are made by the Principal Synthesis, using 5-alkylthiourea as one component. For example, ethoxymethylenemalononitrile (877) and 5-benzylthiourea in aqueous acetone at 20 °C give 4-amino-2-benzylthiopyrimidine-5-carbonitrile (878) (61JOC79) and ethyl 2-allyl-2-formylacetate and 5-methylthiourea in aqueous ethanolic alkali give 5-allyl-2-methylthiopyrimidin-4(3H)-one (6UOC4425). 

Threo-2-Azldo-1,2-dlphenylethanol (2). A mixture ot cis-stilbene oxide 1 (3 92 g, 20 mmol) and NaNa (4 46 g, 70 mmol) in 50% aqueous acetone (60 mL) was relKixed lor 3h The solvent was removed in vacuum and the resxlue extracted with CHCI3 The organic solution was washed with water, dned (MgS04) and concentrated. Distillation of the resxlue afforded 3 70 g of 2 (77%) as a pale yellow oil, tsp 122°C/0 IS mm... 

F E R R I E R Chiral cyclohexanone synthesis Transtormatlon o< unsaturated glycosides into cyclohexanone derivatives by heating in aqueous acetone with mercury (II) salts... 

Water-soluble salts are best purified by preparing a concentrated aqueous solution to which, after decolorising with charcoal and filtering, ethanol or acetone is added so that the salts crystallise. They are collected, washed with aqueous ethanol or aqueous acetone, and dried. In some cases, water-soluble salts can be recrystallised satisfactorily from alcohols. Water-insoluble salts are purified by Soxhlet extraction, first with organic solvents and then with water, to remove soluble contaminants. The purified salt is recovered from the thimble. 

Diphenylguanidine [102-06-7] M 211.3, m 148°, pK 10.12. Crystd from toluene, aqueous acetone or EtOH, and vacuum dried. 

Nitroquinoline 1-oxide [56-57-5] M 190.2, m 157 . Recrystd from aqueous acetone [Seki et al. J Phys Chem 91 126 1987]. 

Tetraethylammonium tetraphenylborate [12099-10-4] M 449.4. Recrystd from aqueous acetone. Dried in a vacuum oven at 60° for several days. Similarly for the propyl and butyl homologues. 

Tetra-n-propylammonium iodide [631-40-3] M 313.3, m >280 (dec). Purified by crystn from EtOH, EtOH/diethyl ether (1 1), EtOH/water or aqueous acetone. Dried at 50° under vacuum. Stored over P2O5 in a vacuum desiccator. 

Sodium 1-naphthalenesulfonate [130-14-3] M 230.2. Recrystd from water or aqueous acetone [Okadata et al. 7 Am Chem Soc 108 2863 1986]. 

Tetrasodium pyrene-l,3,6,8-tetrasulfonate [59572-10-0] M 610.5. Recrystd from aqueous acetone [Okahata et al. J Am Chem Soc 108 2863 1986]. 

Trisodium 8-hydroxy-l,3,6-pyrenetrisulfonate [6358-69-6J M 488.8, m >300(dec). Purified by chromatography with an alumina column, and eluted with -propanol-water (3 1, v/v). Recrystd from aqueous acetone (5 95, v/v) using decolorising charcoal. 

The reactor in Fig. 5 operates as follows. A feed solution containing a given concentration of pollutant is pumped to the adsorbent module at a fixed volumetric flow rate. The module is kept isothermal by a temperature control unit, such as a surrounding water bath. Finally, the concentration of the outlet solution is measured as a function of time from when the feed was introduced to the adsorbent module. These measurements are often plotted as breakthrough curves. Example breakthrough curves for an aqueous acetone solution flowing... 

Fig. 6. Breakthrough curves for aqueous acetone (10 mg 1" in feed) flowing through exnutshell granular active carbon, GAC, and PAN-based active carbon fibers, ACF, in a continuous flow reactor (see Fig. 5) at 10 ml min" and 293 K [64]. C/Cq is the outlet concentration relative to the feed concentration. Reprinted from Ind. Eng. Chem. Res., Volume 34, Lin, S. H. and Hsu, F. M., Liquid phase adsorption of organic compounds by granular activated carbon and activated carbon fibers, pp. 2110-2116, Copyright 1995, with permission from the American Chemical Society.

Various specific experiments support this general scheme. For example, in 80% aqueous acetone, the rate constant for lacemization ofp-chlorobenzhydiyl p-nitrobenzoate (/ ) and that for exchange of label in the carbonyl group can both be measured. At 100 C, kjk = 2.3. 

Steiic effects of another kind become important in highly branched substrates, in which ionization is facilitated by relief of steric crowding in going from the tetrahedral groimd state to the transition state for ionization. The ratio of the hydrolysis rates in 8OV0 aqueous acetone of t-butyl /F-nitrobenzoate and 2,3,3-trimethyl-2-butyl p-nitrobenzoate is 1 4.4. 

Another feature of systems that are subject to B-strain is their reluctance to form strained substitution products. The cationic intermediates usually escape to elimination products in preference to capture by a nucleophile. Rearrangements are also common. 2-Methyl-2-adamantyl p-nitrobenzoate gives 82% methyleneadamantane by elimination and 18% 2-methyl-2-adamantanol by substitution in aqueous acetone. Elimination accounts for 95% of the product from 2-neopentyl-2-adaman l p-nitrobenzoate. The major product (83%) from 2-r-butyl-2-adamantyl p-nitrobenzoate is the rearranged alkene 5. 

Apply sample followed by 5% potassium carbon- [16] ate solution in aqueous acetone, dry, apply 50% methyl iodide in acetone. Allow to react for 3 h at 50 °C in an atmosphere of methyl iodide — acetone (1 + 4), dry and develop. Oleanonic acid, for example, yields its methyl ester. 

Ergotamine crystallises from a variety of solvents but always with the solvent, e.g., from aqueous acetone, which is recommended as a medium, it separates in rectangular plates, B. 2H2O. 2C3HgO, decomposes at 180° and has, for solvent free base, [a] ° — 160° and — 192° (c = 1 CHCl3)or 12-7°and [a] 4g°—8-6°(c= 1 pyridine). Kdder ... 

P-o 3-ketal in 130 ml of glacial acetic acid and 130 ml of water is maintained at 80° for 30 min, poured onto ice, made alkaline with sodium hydroxide and extracted with methylene dichlofide. The extracts are washed once with water, dried over magnesium sulfate, filtered, and evaporated to a residue. A solution of this residue in 240 ml of pyridine and 120 ml of acetic anhydride is kept at room temperature for 1.25 hr and then poured into hydrochloric acid-ice water. The mixture is extracted with methylene dichloride and the methylene dichloride solution is washed until neutral, dried over magnesium sulfate and filtered. The filtrate is evaporated to dryness to yield 13 g. Crystallization from aqueous acetone yields 11.8 g (92%) mp 251-255° [ ]d —1° (dioxane). 

Oxidations usually proceed in the dark at or below room temperature in a variety of solvents ranging from aqueous bicarbonate to anhydrous benzene-pyridine. Base is quite commonly used to consume the hydrogen halide produced in the reaction, as this prevents the formation of high concentrations of bromine (or chlorine) by a secondary process. The reaction time varies from a few minutes to 24 hours or more depending on the nature of the reagent and the substrate. Thus one finds that NBS or NBA when used in aqueous acetone or dioxane are very mild, selective reagents. The rate of these oxidations is noticeably enhanced when Fbutyl alcohol is used as a solvent. In general, saturated, primary alcohols are inert and methanol is often used as a solvent. 

The residue from the neutral fraction is crystallized from aqueous acetone to yield 3.4 g (94%) of 3a,21,21-trihydroxy-5j -pregnane-ll,20-dione, mp 153-155°. 

Acetoxyandrost-5-en-17-one (59) is converted into the ethylene ketal (60) by treatment with ethylene glycol, triethylorthoformate and p-toluenesulfonic acid. The ketal is brominated with pyridinium bromide perbromide in THF and then treated with sodium iodide to remove bromine from the 5 and 6 positions. This gives the 16a-bromo compound (61) which is hydrolyzed in methanol to the free alcohol (62). Dehydrobromination is effected with potassium Fbutoxide in DMSO to give the -compound (63). Acid catalyzed hydrolysis of the ketal in aqueous acetone gives the title compound (64). ... 

The use of A -enol ethers as substrates for dehydrogenation is often attractive. Aqueous acetone at room temperature gives yields ranging from 70 to 88% other systems with acid catalysis have also been used, e.g. ... 

Androst-4-ene-3,17-dione (83) is converted into the enol ether (84) by reaction with triethyl orthoformate. Treatment of the enol ether (84) with DDQ in aqueous acetone gives the title dienone (85). This method is particularly suitable for A" -3-ketones substituted at the 6-position. 

Rj, R2 = O) by treatment with silver perchlorate in aqueous acetone or boron trifluoride etherate in formic acid at 0°. 

A-Homo-estra-l 0),2,4c[-triene-4,ll-dione (45) by solvolysis of the l-keto dibromocarbene adduct (43a).A mixture of monoadduct (43a 0.25 g) and silver perchlorate (0.3 g) in aqueous acetone (1 4, 30 ml) is heated under reflux for 30 min. The reaction mixture is filtered to remove the precipi-... 

A-Homo-estra-, 4, )-triene-3, l-dione (50). A solution of bromo ketone (49 0.2 g), silver perchlorate (0.5 g) and 20% aqueous acetone (30 ml) is heated at reflux with stirring for 30 min and then allowed to cool to room temperature. The mixture is filtered to remove precipitated silver bromide (ca. 0.19 g) and the filtrate is diluted with water (200 ml) and then extracted with chloroform. The chloroform extracts are washed, successively with water, 5% sodium bicarbonate solution, water and saturated salt solution. After being dried over anhydrous magnesium sulfate, the solvents are removed at reduced pressure to give a solid. Recrystallization from ethyl acetate gives A-homo-estra-l,4,5(10)-triene-3,17-dione (50 0.17 g) mp 193-197°. 

Alternatively, treatment of the monodibromocarbene adduct (48 0.7 g) with silver perchlorate (1.4 g) in refluxing 20% aqueous acetone (30 ml) for 30 min followed by the workup described above affords A-homo-estra-l,4,5(10)-triene-3,17-dione (50) in nearly quantitative yield. 

Reactions that occur with the development of an electron deficiency, such as aromatic electrophilic substitutions, are best correlated by substituent constants based on a more appropriate defining reaction than the ionization of benzoic acids. Brown and Okamoto adopted the rates of solvolysis of substituted phenyldimeth-ylcarbinyl chlorides (r-cumyl chlorides) in 90% aqueous acetone at 25°C to define electrophilic substituent constants symbolized o-. Their procedure was to establish a conventional Hammett plot of log (.k/k°) against (t for 16 /wcra-substituted r-cumyl chlorides, because meta substituents cannot undergo significant direct resonance interaction with the reaction site. The resulting p value of —4.54 was then used in a modified Hammett equation. 

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