Patent GB-859740-A (GB)
Title: Saturated long chain aliphatic dicarboxylic acid polyketones
IPC: C07C51/373
Filed: 1958-03-12
Abstract: Saturated aliphatic poly-keto dicarboxylic acids containing an average of 3-30 keto groups per molecule are prepared from a saturated aliphatic dicarboxylic acid containing at least 7 carbon atoms or a mixture of such acids, by heating a substantially pure cadmium salt of said acid or mixture of acids, containing at least one atom of cadmium per molecule of acid, to a temperature of between 280 DEG  and 350 DEG C. and maintaining, the reaction mixture at this temperature with constant stirring. for 5-90 mins. and treating the resultant mass with at least one strong mineral acid or suitable organic acid to liberate the free poly-keto dicarboxylic acids therefrom.  A dibasic acid HOO C (CH2)n COO H wherein n is at least 5 yields a product H OO C-(CH2)n-[CO-(CH2)n]p COOH wherein p is from 3 30.  The cadmium salt generally has a purity of at least 98% by weight.  The acid treatment may be effected with sulphuric, nitric, hydrochloric or a lower aliphatic acid such as acetic acid.  Examples describe the ketonisation of neutral cadmium salts of sebacic acid, brassylic acid and a mixture of aliphatic diabasic acids containing 10-14 carbon atoms to poly-ketone dicarboxylic acids of the above defined type wherein p ranges from 3,3 to 10.ALSO:Saturated aliphatic poly-keto dicarboxylic acids containing an average of 3-20 keto groups per molecule are prepared from a saturated aliphatic dicarboxylic acid containing at least 7 carbon atoms or a mixture of such acids, by heating a substantially pure cadmium salt of said acid or mixture of acids, containing at least one atom of cadmium per molecule of acid, to a temperature of between 280 DEG  and 350 DEG C. and maintaining the reaction mixture at this temperature for 5-90 mins. with constant stirring and treating the resultant mass with at least one strong mineral acid or suitable organic acid to liberate the free poly-keto dicarboxylic acids therefrom.  The ketonisation may also yield minor amounts of cyclic ketones.  A dibasic acid HOOC-(CH2)n-COOH yields a poly-keto dicarboxylic acid. HOOC-(CH2)n-[CO-(CH2) n]p COOH wherein n is at least 5 and p is a number from 3 to 20.  The cadmium salt is preferably the neutral salt, and generally has a purity of at least 98% by weight.  The dibasic acid starting materials may be the acids obtained by the nitric acid oxidation of saturated aliphatic acids containing at least 7 carbon atoms. The acid treatment may be effected with sulphuric, nitric, hydrochloric or lower aliphatic carboxylic acids such as acetic acids.  A preferred working up comprises boiling the crude reaction mass with acetic acid, filtering and then cooling whereupon the desired products precipitate out.  The residual solution may be basified to precipitate cadmium hydroxide which may be reconverted into the salt of a dibasic acid to be ketonised.  In another procedure, a suitable volatile organic acid is used to liberate the polyketone dibasic acids and the residual mother liquor is then treated with dibasic acids to be ketonised and the volatile organic acid liberated is distilled off to leave neutral cadmium salts of the dibasic acid to be ketonised.  In typical examples: (1) cadmium sebacate is ketonised yielding poly-ketone dibasic acids containing 10 keto-groups; (3) cadmium brassylate similarly yields a product containing 3,3 keto groups per mole and during the ketonisation some cyclo dodecanone is formed and distilled off; (4) cadmium salts of a mixture of dibasic acids containing 10-14 carbon atoms, obtained by nitric acid oxidation of stearic and palmitic acid methyl esters, similarly yields products containing 6-10 keto-groups.