Ketone hydrolysis

Ketonic Hydrolysis. Hot dilute caustic alkalis or hydrochloric acid first hydrolyse off the ethyl group, and then remove carbon dioxide, a mono- or di-substituted acetone being thus obtained ... 

It follows therefore that ethyl malonate can be used (just as ethyl aceto- acetate) to prepare any mono or di-substituted acetic acid the limitations are identical, namely the substituents must necessarily be alkyl groups (or aryl-alkyl groups such as CjHjCHj), and tri-substituted acetic acids cannot be prepared. Ethyl malonate undergoes no reaction equivalent to the ketonic hydrolysis of ethyl acetoacetate, and the concentration of the alkali used for the hydrolysis is therefore not important. 

By the ketonic hydrolysis of substituted acetoacetic esters this is brought about by the action of dilute alkali in the cold, followed by acidification and boiling. The free substituted acetoacetic acid is produced, which readily undergoes decarboxylation (since it has a carboxyl and a carbonyl group on the same carbon atom) to give a ketone, for example ... 

Ketonic hydrolysis with a mixture of sulphuric and acetic acids of the ethyl Mobutyryltsobutyrate 3uelds di-tso-propyl ketone ... 

Ketonic hydrolysis to di-iso-propyl ketone. Mix 15 g. of the ester with 30 ml. of glacial acetic acid, 10 ml. of water and 10 ml. of concentrated sulphuric acid, and reflux in a flask coimected by a ground glass joint... 

Commercially, pure ozonides generally are not isolated or handled because of the explosive nature of lower molecular weight species. Ozonides can be hydrolyzed or reduced (eg, by Zn/CH COOH) to aldehydes and/or ketones. Hydrolysis of the cycHc bisperoxide (8) gives similar products. Catalytic (Pt/excess H2) or hydride (eg, LiAlH reduction of (7) provides alcohols. Oxidation (O2, H2O2, peracids) leads to ketones and/or carboxyUc acids. Ozonides also can be catalyticaHy converted to amines by NH and H2. Reaction with an alcohol and anhydrous HCl gives carboxyUc esters. 

Acetylisothiazoles have been prepared by ketonic hydrolysis of the jS-ketoesters derived from the Claisen condensation on 5-ethoxycar-bonylisothiazoles. 5-Acetyl-3-methylisothiazole is also obtained from the reaction of 5-cyano-3-methylisothiazole with methylmagnesium iodide. ... 

Keratin, 5, 39 Ketene, 4, 3g 8, 124 Ketone hydrolysis, 7, 60 Ketone-splitting of acetoacetic ester, 7, 60... 

Carbohydrate lactones have been used as the carbonyl reagent in the Reformatsky reaction. Thus, 2,3 5,6-di-O-cyclohexylidene-D-mannono-1,4-lactone [44, obtained by oxidation of the mannofuranose derivative (49)] reacted with ethyl bromoacetate and zinc to give the protected 2-deoxy-3-octulosonic acid ethyl ester (45a) in 69% yield (50). Ketonic hydrolysis with potassium hydroxide in aqueous methanol, followed by acidification and heating, afforded the 1-deoxyheptulose derivative 45b. Similarly, starting from compound 44, the 1-C-substituted allyl and propar-gyl lactols were prepared on reaction with allyl or propaigyl bromides in the presence of zinc (51). 

All evidence presented here indicates that the methoxime-to-ketone reaction is enzymatic, but the nature of the reaction is unclear. Hydrolysis by an uncharacterized hydrolase, as postulated by the authors, is a valid assumption. However, one should not dismiss another possibility, namely oxidative O-demethylation to the oxime, followed by spontaneous oxime-to-ketone hydrolysis, and stereospecific reduction, as explained above. 

This synthetic route is based on ring closure by Dieckmann condensation of 1,2-bis-carbalkoxyalkylpyrrolidines. It has gained special importance during the last few years, after application to several total syntheses of naturally occurring pyrrol izidine bases. The usual starting compounds employed in this route are esters of a-pyrrolidineacetic acid, proline, and their homologues, which are converted into N-substituted dialkyl dicarboxylates. The esters of the dicarboxylic acids are subjected to Dieckmann condensation and subsequent ketonic hydrolysis the resultant ketones are used in further reactions. 

The synthesis of l-methylpyrrolizid-7-one49 was very important for final confirmation of the structure of the naturally occurring pyrrolizi-dine bases. The starting ethyl ester of 3-methylproline (80), obtained by analogy with proline,50 was condensed with ethyl acrylate and the condensation product (81) converted into l-methylpyrrolizidine-7-one (82) by cyclization and ketonic hydrolysis. A similar route starting with the ethyl ester of 3-methyl-L-proline afforded optically active... 

Ketones tee under Aliphatic ketones and Aromatic ketones Ketonic hydrolysis, 475, 480, 481 Ketose, 437... 

The acid catalyzed conversion of oximes over different acidic solids in "dry media under soft conditions gives as major products the amide (Beckmann rearrangement) and the ketone (hydrolysis). The... 

Reaction LXVH. (a) Ketonic Hydrolysis of Alkyl Derivatives of Ethyl Acetoacetate. (A., 138, 211.)—This reaction illustrates one of many synthetical uses of acetoacetic ester. When that ester or its mono- or dialkyl derivatives is boiled with dilute aqueous or alcoholic alkalis or baryta water, or sulphuric acid, ketonic hydrolysis occurs, and acetone or its mono- or di-substituted derivatives is formed—... 

It is not possible to perform the acid hydrolysis without some ketonic hydrolysis occurring. This reaction and the preceding one are important in many syntheses of aliphatic ketones and acids. They might have been included equally well in the decomposition section (p. 411) in fact they are often referred to as the ketonic and acid decomposition of acetoacetic ester. The malonic ester synthesis of fatty acids may be compared with the present reaction (p. 135). 

Ketonic hydrolysis to di-isopropyl ketone. Mix 14 g (0.75 mol) of the ester with 30 ml of glacial acetic acid, 10 ml of water and 10 ml of concentrated sulphuric acid, and boil under reflux until evolution of carbon dioxide ceases. Dilute the cooled solution with 180 ml of water, add 100 ml of ether and render alkaline to phenolphthalein with 20 per cent sodium hydroxide solution. Separate the ether layer, extract the aqueous layer with two 50 ml portions of ether, dry the combined ether layer and extracts with anhydrous sodium sulphate, distil off the ether and fractionate the residue. The yield of di-isopropyl ketone (2,4-dimethylpentan-3-one), b.p. 123-124 °C, is 6.5 g (76%). 

The synthesis may thus be seen to be an intramolecular Claisen ester condensation, which is known as the Dieckmann reaction. The procedure is an important method for the synthesis of five- and six-membered ring systems, and the cyclic /2-keto ester product may be converted into the corresponding cyclic ketone by hydrolysis followed by decarboxylation (ketonic hydrolysis, see Section 5.8.5, p. 619). The base catalyst used in Expt 7.8 is sodium ethoxide, but sodium hydride as a 50 per cent dispersion in oil is a recommended alternative. 

Boiling with dilute acid or dilute alkali brings about ketonic hydrolysis chiefly ... 

Laurone has been prepared by hydrating and decarboxylating decylketene dimer.3 It has also been prepared by distilling calcium laurate 4 by heating lauric acid with phosphorus pent-oxide 5 by heating barium laurate under reduced pressure 6 by the ester condensation of ethyl laurate with sodium ethoxide 7 or of methyl laurate with sodium hydride 8 followed by ketonic hydrolysis by catalytic ketonization of lauric acid over a chromate catalyst 9 or by passing lauric acid over thorium dioxide at 400°.10... 

Most recently, B-halo-l-alkenyl-9-BBN s have revealed to undergo a 1,4-addition reaction to ae,P-unsaturated ketones such as methyl vinyl ketone. Hydrolysis of the initially formed intermediates produces the corresponding (Z)-5-halo-y,5-unsaturated ketones in good yields stereospecifically (>98%),88). In the reaction with methyl vinyl ketone, the major products isolated after hydrolysis are not the expected halo-enones but the aldol adducts, which are readily converted into the halo-enones by treatment with sodium hydroxide, as depicted in Scheme 3. No aldol adducts are formed in the case of enones other than methyl vinyl ketone. 

Sulfuric or phosphoricacids are used for the ketonic hydrolysis, as in the preparation of methyl n-amyl ketone. Also, the hydrolysis is brought about by boiling with acetic-sulfuric acid mixture, hot 5% potassium hydroxide solution, or hydriodic acid if the hydrolysis is especially difficult. Benzyl ace tone, QH, CHjCHjCOCH, is formed by hydrolysis of the corresponding /8-keto ester with water at 150-250° and 200 atm. Diaikylated /S-keto esters are stable to this treatment therefore, a single ketone can be obtained from a mixture of mono- and di-alkylated /3-keto esters. ... 

Monoalkylation of ethyl acetoacetate and subsequent ketonic hydrolysis gives methyl ketones of the type CHjCOCHjR (acetoacetic ester synthesis). 

AUylcyclohexanone has been prepared from the sodium derivative of cyclohexanone by alkylation with allyl bromide or with allyl iodide, and by ketonic hydrolysis of ethyl l-allyl-2-ketocyclohexanecarboxylate. - ... 

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