GB749749A - Diketene-ketone adducts - Google Patents

Abstract

The invention comprises adducts of diketene with ketones containing no polar groups other than the reacting CO group and which have the general formula R1COR2 where R1 and R2 are alkyl groups or one is an alkyl and the other an aryl group, at least one of the said alkyl groups in the dialkyl ketones and the alkyl group in the alkyl aryl ketones having at least two carbon atoms on the carbon adjacent the carbonyl group and the aryl groups having no substituents adjacent the carbonyl group or wherein R1 and R2 taken together with the carbonyl carbon atom form a cyclo-alkyl group, at least one of the a -carbon atoms of which has two hydrogen atoms attached thereto. The compounds are believed to be 2:2-disubstituted-4 - methyl - 6 - keto - 1:3 - dioxenes, the substituents being the respective two alkyl groups, the alkyl and aryl groups or the cycloalkyl group. They are prepared by reacting diketene with the respective ketone, generally under reflux in the presence of an acid esterification catalyst, e.g. an aryl sulphonic acid, zinc chloride or stannic chloride. The ketone is preferably used in excess, the unchanged ketone being recovered thereafter by distillation or by crystallization of the adduct when the latter is a solid. Adducts of the higher boiling ketones may be prepared by ketone exchange with the adduct of a lower boiling ketone by adding excess of the higher boiling ketone to the adduct in the presence of an organic acid having a dissociation constant less than 10-4 such as acetic acid, or a very small quantity of a strong mineral acid and distilling off the liberated lower ketone. Examples describe the preparation of (1) acetone adduct C7H10O3; (2) acetophenone adduct C12H12O3; (3) methyl ethyl ketone adduct C8H12O3; (4) dibenzyl adduct C19H18O3; (5) cyclohexanone adduct; and (6) methyl isobutyl ketone adduct. The adducts may be used for the same syntheses as is diketene; thus, the adducts react with alcohols to produce aceto acetic esters and with primary amines to produce aceto acetamides and on heating the adducts in a suitable solvent, dehydro acetic acid is formed; further examples describe the reaction of the acetone-adduct with (9) dry ethanol in the presence of triethanolamine catalyst at 90-100 DEG C. yielding ethyl aceto acetate; and (10) aniline in presence of di-ethanolamine catalyst yielding acetoacetanilide; and (11) formation of dehydroacetic acid by heating the acetone-adduct in toluene in presence of a little calcium acetate.