Methyl isopropyl ketone, condensation

Methyl Isopropyl Ketone. Methyl isopropyl ketone [563-80-4] (3-methyl-2-butanone) is a colorless Hquid with a characteristic odor of lower ketones. It can be produced by hydrating isoprene over an acidic catalyst at 200—300°C (150,151) or by acid-catalyzed condensation of methyl ethyl ketone and formaldehyde to 2-methyl-l-buten-3-one, foUowed by hydrogenation to the product (152). Other patented preparations are known (155,156). Methyl isopropyl ketone is used as an intermediate in the production of pharmaceuticals and fragrances (see Perfumes), and as a solvent (157). It is domestically available from Eastman (Longview, Texas) (47). 

Ketones do not condense readily with malonic ester. The condensation of acetone and diethyl malonate is brought about by heating for 24 hours with acetic anhydride and zinc chloride. The yield of diethyl isopropyl-idenemalonate is 52%. ° Under similar conditions methyl ethyl ketone condenses to the extent of only 19%. ° ... 

In an apparatus suitably protected against atmospheric moisture and fitted with a gas-inlet tube, mechanical stirrer, and an efficient reflux condenser, to a solution of 45 gm (0.45 mole) of ethyl isopropyl ketone and 5 gm of freshly distilled acetyl chloride is added, through the gas-inlet tube, 18 gm (0.24 mole) of ethyl nitrite at 45°-55°C over a 2 hr period. The reaction mixture is stored overnight in a refrigerator, whereupon 15.2 gm (48.7% based on ethyl nitrite used) of 2-methyl-2-nitroso-3-pentanone dimer (bimolecular ethyl a-nitroso-isopropyl ketone) deposits. The product is isolated by filtration, m.p. 122°-123°C. 

More precise information on the pathway of leucine catabolism was obtained from studies on the formation of ketone bodies in liver slices incubated with and C Mabeled leucine and isovaleric acid. In these experiments it was found that leucine-3-C yielded acetoacetate in which the label was virtually all contained in the methyl and methylene carbons, and to approximately the same extent in each of these. Only a trace of radioactivity was found in the carboxyl carbon. On incubation with leucine-4-Ci the label occurred solely in the carbonyl group. This suggested that the isopropyl group of the amino acid had been directly converted to acetone. The over-all conclusion was that the isopropyl group forms acetone, and carbons 2 and 3 of the amino acid yield a 2-car-bon fragment which can condense to acetoacetate. The acetoacetate formed from leucine-4-C was not symmetrically labeled, the isotope being present only in the carbonyl carbon. 

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