GB235540A - A process for the preparation of mono-cyclic ketones with more than nine ring members - Google Patents

Abstract

Carbocyclic ketones having more than nine ring members are prepared by treating dicarboxylic acids having more than ten carbon atoms, or their salts or alkyl derivatives, by ketone preparation methods, preferably by employing the thorium or cerium salts. In one method, the thorium salt of the dicarboxylic acid, e.g. tetradecane-1 : 14-dicarboxylic acid, is heated to 300 DEG -400 DEG C., preferably in a vacuum, and the cyclic ketone, e.g. cyclopentadecanone, is obtained from the distillate by repeatedly fractionally distilling or by forming the semicarbazone. The preparation of the cyclic ketones from cycloundecanone to cyclopentadecanone and cycloheptadecanone by this method, starting with the corresponding acid, is described. Cyclopentadecanone may also be obtained by starting with the cerium salt or by heating tetradecane-1 : 14-dicarboxylic acid in the presence of thorium oxide. The cyclic ketones obtained have a characteristic smell, that of cyclopentadecanone and the adjacent ketones resembling musk and civet in place of which they can be used. The cyclic ketones on oxidation with chromic acid give each a dicarboxylic acid, e.g. cycloundecanone gives nonane-1 : 8-dicarboxylic acid. The Specification as open to inspection under Sect. 91 (3) (a) comprises also the preparation of cyclodecanone, cyclohexadecanone, and cyclooctadecanone from the thorium salts of the corresponding dicarboxylic acids; the addition of a good conductor of heat, such as copper or iron turnings, and heating to above 400 DEG C. in the preparation of the cycloketones from the thorium salts, and their isolation by fractionally distilling and then forming the semicarbazone; the recovery from the mother liquid of the semicarbazones of a mixture of semicarbazones from which a mixture of ketones, mostly isomeric with the cycloketones, can be obtained; the preparation of cyclopentadecanone by heating tetradecane-1 : 14-dicarboxylic acid alone or in the presence of cerium or of acetic anhydride, or by gradually heating its anhydride alone or in the presence of thorium oxide, the temperature being raised to over 400 DEG C. and a vacuum being preferably employed towards the end, or from a mixture of the thorium and cerium salts of the acid; and the preparation of mixtures of the cycloketones starting with mixtures of the thorium salts of the corresponding dicarboxylic acids. This subject-matter does not appear in the Specification as accepted.