Patent GB-960011-A (GB)
Title: Carboxylation of unsaturated aliphatic compounds
IPC: C07D309/30
Filed: 1961-06-16
Abstract: The invention comprises a process for the carboxylation of olefinically unsaturated aliphatic compounds, in which the unsaturation is in a non-terminal position in the molecule, having a chain of at least 12 carbon atoms which comprises (1) admixing the unsaturated compound with concentrated sulphuric acid containing 2-7% by weight of water and having carbon monoxide dispersed therein to provide a liquid phase having a molar ratio of water to unsaturated compound of from 4.5:1 to 12:1 and a molar ratio of sulphuric acid to unsaturated compound of at least 30:1 and (2) contacting the liquid phase with a further quantity of CO at a temperature below 50 DEG C. and at a pressure of from atmospheric to 20 atmospheres until a carboxylated derivative of the unsaturated compound is produced; esters may be prepared from the carboxylated derivatives. The invention also comprises carboxy octadecanols of the general formula <FORM:0960011/C1/1> where x is an integer from 6 to 9, and esters of these acids with alkanols containing not more than 4 carbon atoms. The unsaturated compounds to be carboxylated may be olefines, carboxylic acids, alcohols or esters and are preferably compounds having the general formula R-CH= CH-(CH2)7-M, wherein R represents an alkyl, substituted alkyl or alkenyl group containing 4, 6, 8 or 10 carbon atoms and M is the grouping -CO2H, -CH2OH or -CO2X where X is an alkyl group containing not more than 4 carbon atoms.  The carbon monoxide used in the carboxylation may be gaseous CO or may be formed in situ by addition of anhydrous formic acid to the sulphuric acid, allowance being made for the water so liberated. The carboxylation mixture may thereafter be poured on to ice and water and the carboxylated derivative recovered therefrom by extraction with ether or other like solvent; however, the carboxylated derivative of an olefinic alcohol is obtained in the form of its sulphuric acid ester which requires hydrolysis in boiling dilute sulphuric acid before it can be extracted. The carboxylated derivatives may be converted into their methyl esters by reacting with methanol and dimethyl sulphate; the resulting methyl esters may be converted into other esters by transesterification with a desired alcohol, e.g., ethanol, propanol or butanol, in the presence of an alkali metal or alkoxide thereof as catalyst. The above mentioned carboxy octadenols and esters thereof are derived from oleyl alcohol. Oleic acid yields a mixture of carboxy stearic acid CH3. (CH2)x.CH(COOH).(CH2)15-xCOOH where x is an integer from 6 to 9 which contains mainly the 9- and 10- carboxy stearic acids but also some 8- and 11- carboxy compounds: their di-C1- 4 alkyl esters are said to be novel and useful as plasticisers, lubricants and hydraulic fluids. Methyl ricinoleate on carboxylation yields a mixture of CH3.(CH2)5.CH(OH).(CH2)y. CH(COOH).(CH2)z.COOH3 wherein y is 1 or 2 and y+z=9, and lactones of these hydroxy acid-esters; these compounds and the methyl esters thereof are stated to be novel and utilisable as lubricants. Linoleic acid on carboxylation yields a mixture of dibasic acids CH3.(CH2)4.CH= CH.(CH2)y.CH(COOH).(CH2)z.COOH wherein y is 1 or 2 and y+z is 9 and inner esters of these acids; these compounds and their C1- 4 alkyl esters are stated to be novel and the esters may be used as drying oils.  Examples describe (1) the carboxylation of oleic acid, oleyl alcohol, methyl ricinoleate and linoleic acid; (2) the conversion of the products of (1) into their methyl esters by reaction with methanol and dimethyl sulphate; (3) the preparation of the dibutyl esters of the carboxylated oleic acid of (1) by transesterification of their dimethyl esters or by reaction with butanol in the presence of cymene or toluene.  Specification 743,597 is referred to.