Ketone aqueous solution

CH2 CH C CH. Colourless gas with a sweet odour b.p. 5°C. Manufactured by the controlled low-temperature telomerization of ethyne in the presence of an aqueous solution of CuCI and NH Cl. Reduced by hydrogen to butadiene and, finally, butane. Reacts with water in the presence of HgSO to give methyl vinyl ketone. Forms salts. Forms 2-chloro-butadiene (chloroprene) with hydrochloric acid and certain metallic chlorides. 

Since hydroxylamine is usually available only in the form of its salts, e.g., the hydrochloride or sulphate, the aqueous solution of these salts is treated with sodium acetate or hydroxide to liberate the base before treatment with the aldehyde or ketone. Most oximes are weakly amphoteric in character, and may dissolve in aqueous sodium hydroxide as the sodium salt, from which they can be liberated by the addition of a weak acid, e.g., acetic acid. 

Sodium me/aperiodate (NalO ) in cold aqueous solution readily oxidises 1,2-diols with splitting of the molecule and the consequent formation of aldehydes or ketones thus ethylene glycol gives formaldehyde and pinacol gives acetone. In the case of a 1,2,3-triol, the central carbon atom of the triol... 

Note, (a) Aqueous solutions of formaldehyde and acetaldehyde give these addition products, which are so soluble that they rarely separate this reaction is therefore an unsatisfactory test for these aldehydes. (6) These addition products are also formed by ketones (p. 345). 

Dimedone derivatives. Dimedone or 6 6-dimethylci/cZohexane-1 3 dioiie j- in saturated aqueous solution J or in 10 per cent. alcohoUc solution gives crystalline derivatives (I) with aldehydes, but not with ketones. The reaction is ... 

A more complete recovery of the ketone from the aqueous solution may be obtained by repeated distillation of the aqueous layer until no appreciable amount of ketone is found in the distillate. The procedure outlined is, however, quite satisfactory. 

Unfortunately, addition of copper(II)nitrate to a solution of 4.42 in water did not result in the formation of a significant amount of complex, judging from the unchanged UV-vis absorption spectrum. Also after addition of Yb(OTf)3 or Eu(N03)3 no indications for coordination were observed. Apparently, formation of a six-membered chelate ring containing an amine and a ketone functionality is not feasible for these metal ions. Note that 4.13 features a similar arrangement and in aqueous solutions, likewise, does not coordinate significantly to all the Lewis acids that have been... 

With an excess of halocarbonyl reactant or a more reactive ketone like bromoketone, compounds of type 173 may result through reaction of the 2-mercaptothiazole (163a) with the excess of bromoketone (Scheme 88) (156, 199, 270, 291, 292, 519). Thus when Rj = phenyl and = hydrogen, 173 was obtained in 76% yield (292) in aqueous solution and in 20 to 40% in alcoholic solution (292, 519). 

Ketones are oxidized by potassium permanganate or by sodium hypochlorite (91) in aqueous solution to the corresponding acids. For example, oxidation of 5-acetylthiazole with aqueous KMnO at 70°C gives 5-thia-zolecarboxylic acid. 

FIGURE 18 1 Mechanism of acid catalyzed enolization of an aldehyde or ketone in aqueous solution... 

Although carbohydrates exist almost entirely as cyclic hemiacetals m aqueous solution they are m rapid equilibrium with their open chain forms and most of the reagents that react with simple aldehydes and ketones react m an analogous way with the carbonyl functional groups of carbohydrates... 

Aqueous solutions buffered to a pH of 5.2 and containing known total concentrations of Zn + are prepared. A solution containing ammonium pyrrolidinecarbodithioate (APCD) is added along with methyl isobutyl ketone (MIBK). The mixture is shaken briefly and then placed on a rotary shaker table for 30 min. At the end of the extraction period the aqueous and organic phases are separated and the concentration of zinc in the aqueous layer determined by atomic absorption. The concentration of zinc in the organic phase is determined by difference and the equilibrium constant for the extraction calculated. 

Reactions. Heating an aqueous solution of malonic acid above 70°C results in its decomposition to acetic acid and carbon dioxide. Malonic acid is a useful tool for synthesizing a-unsaturated carboxyUc acids because of its abiUty to undergo decarboxylation and condensation with aldehydes or ketones at the methylene group. Cinnamic acids are formed from the reaction of malonic acid and benzaldehyde derivatives (1). If aUphatic aldehydes are used acryhc acids result (2). Similarly this facile decarboxylation combined with the condensation with an activated double bond yields a-substituted acetic acid derivatives. For example, 4-thiazohdine acetic acids (2) are readily prepared from 2,5-dihydro-l,3-thiazoles (3). A further feature of malonic acid is that it does not form an anhydride when heated with phosphorous pentoxide [1314-56-3] but rather carbon suboxide [504-64-3] [0=C=C=0], a toxic gas that reacts with water to reform malonic acid. 

In typical processes, the gaseous effluent from the second-stage oxidation is cooled and fed to an absorber to isolate the MAA as a 20—40% aqueous solution. The MAA may then be concentrated by extraction into a suitable organic solvent such as butyl acetate, toluene, or dibutyl ketone. Azeotropic dehydration and solvent recovery, followed by fractional distillation, is used to obtain the pure product. Water, solvent, and low boiling by-products are removed in a first-stage column. The column bottoms are then fed to a second column where MAA is taken overhead. Esterification to MMA or other esters is readily achieved using acid catalysis. 

Alkaline Degradation. At high pH, sucrose is relatively stable however, prolonged exposure to strong alkaU and heat converts sucrose to a mixture of organic acids (mainly lactate), ketones, and cycHc condensation products. The mechanism of alkaline degradation is uncertain however, initial formation of glucose and fructose apparendy does not occur (31). In aqueous solutions, sucrose is most stable at —pH 9.0. 

Oxo Ion Salts. Salts of 0x0 ions, eg, nitrate, sulfate, perchlorate, hydroxide, iodate, phosphate, and oxalate, are readily obtained from aqueous solution. Thorium nitrate is readily formed by dissolution of thorium hydroxide in nitric acid from which, depending on the pH of solution, crystalline Th(N02)4 5H20 [33088-17 ] or Th(N02)4 4H20 [33088-16-3] can be obtained (23). Thorium nitrate is very soluble in water and in a host of oxygen-containing organic solvents, including alcohols, ethers, esters, and ketones. Hydrated thorium sulfate, Th(S0 2 H20, where n = 9, 8, 6, or 4, is... 

Zinc chloride melts at 275°C, bods at 720°C, and is stable in the vapor phase up to 900°C. It is very hygroscopic, extremely water-soluble, and soluble in organic Hquids such as alcohols, esters, ketones, ethers, amides, and nitrides. Hydrates with 1, 1.5, 2.5, 3, and 4 molecules of water have been identified and great care must be exercised to avoid hydration of the anhydrous form. Aqueous solutions of zinc chloride are acidic (pH = 1.0 for 6 M) and, when partially neutralized, can form slightly soluble basic chlorides, eg, ZnCl2 4Zn(OH)2 [11073-22-6] and Zn(OH)Cl [14031-59-5]. Many other basic chlorides have been reported (58). 

Organic solutions of HOCl can be prepared in near quantitative yield (98—99%) by extraction of CU -containing aqueous solutions of HOCl with polar solvents such as ketones, nitriles, and esters (131). These organic solutions of HOCl have been used to prepare chlorohydrins (132) and are especially useful for preparation of water-insoluble chlorohydrins. Hypochlorous acid in methyl ethyl ketone has also been used to prepare Ca(OCl)2, by reaction with CaO or Ca(OH)2 (133), and hydrazine by reaction with NH3 (134). 

Dihydrostreptomycin sesquisulfate [5490-27-7] M 461.4, m 250 (dec), 255-265 (dec), [a]p -92.4 (c 1, H2O), pKgsJd)-- 9.5 (NMe), pKes,(2,3) 13.4 (guanidino). It crystallises from H2O with MeOH, -BuOH or methyl ethyl ketone. The crystals are not hygroscopic like the amorphous powder, however both forms are soluble in H2O but the amorphous solid is about 10 times more soluble than the crystals. The free base also crystallises from H20-Me2C0 and has [a]p -92° (aqueous solution pH 7.0). [Solomons and Regina Science 109 515 7949 Wolf et al. Science 109 515 7949 McGilveray and Rinehart J Am Chem Soc 87 4003 1956]. 

Strong acids in aqueous solution convert allenes to ketones via an enol intermediate. This process also involves protonation at a terminal carbon. 

The exceptions are formaldehyde, which is nearly completely hydrated in aqueous solution, and aldehydes and ketones with highly electronegative substituents, such as trichloroacetaldehyde and hexafluoroacetone. The data given in Table 8.1 illustrate that the equilibrium constant for hydration decreases with increasing alkyl substitution. 

Because of the unfavorable equilibrium constant in aqueous solution and the relatri e facility of the hydrolysis, acetals and ketals are rapidly converted back to aldehydes and ketones in acidic aqueous solution. 

---