Patent GB-578945-A (GB)
Title: Improvements in or relating to the production of halogenated keto fatty acids and esters
IPC: C23F11/12
Filed: 1944-11-20
Abstract: Higher keto fatty acids, or esters thereof, chlorinated or brominated in the positions alpha to the keto group are prepared by reacting keto fatty acids containing from 8 to 30 carbon atoms, or esters thereof, with elementary chlorine or bromine.  The products are generally alpha, alpha dihalogen compounds, but may contain three or even four halogen atoms in the alpha positions according to the amount of halogen used and the reaction time. The keto compound may be reacted upon in solution in an inert organic solvent such as chloroform, carbon tetrachloride, hexane or petroleum ether, or simply in the molten state.  The chlorine is best introduced by bubbling gaseous chlorine through a solution or molten mass of the keto compound; bromine may be introduced similarly as a vapour, but is preferably supplied as a solution in an inert organic solvent. The reaction temperature is maintained, in general, at between about -20 DEG  and 100 DEG  C., and preferably between about 0 DEG  and about 75 DEG  C.  The alpha, alpha dihalogen keto compounds will occur in four stereoisomeric forms and the dl mixtures of the two pairs of optical antipodes may be separated by crystallisation from solvents.  The products may be used as additives to lubricants for pour point lowering, imparting extreme pressure properties and the like; and as constituents of rust-proofing compositions (see Group III).  In examples: (1)-(3) 12-keto stearic acid is chlorinated in carbon tetrachloride solution, in petroleum ether, and in the molten state respectively, yielding 11 : 13-dichlor-12-keto stearic acid; (4) mixed 13- and 14-keto behenic acids in petroleum ether solution are chlorinated to yield a mixture of dichlor 13- and 14-keto behenic acids; (5) mixed 9- and 10-keto stearic acids are similarly chlorinated in petroleum ether to give the dichloroderivatives; (6) 4-keto stearic acid in chloroform is chlorinated in three stages to give 3 : 5-dichlor 4-keto stearic p  acid; (7) 12-keto stearic acid in petroleum ether is chlorinated for a longer period than in (1) above, yielding trichlor 12-keto stearic acid; (8) the product of (7) above is further chlorinated in carbon tetrachloride to yield a product corresponding to the tetrachloro derivative; (9) 12-keto stearic acid in chloroform is reacted with bromine added as a solution in chloroform and the 11 : 13-dibromo 12-keto stearic acids so obtained are separated into the two dl mixtures by fractional crystallization from petroleum ether; (10) mixed 13- and 14-keto behenic acids are brominated as in (9) above yielding mixed dibromo 13- and 14-keto behenic acids; (11) mixed 9- and 10-keto stearic acids are brominated similarly to yield mixed dibromo 9- and 10-keto stearic acids; (12) 4-keto stearic acid is likewise brominated yielding the dibromo derivative.  Other specified starting materials are 9-chlor 10-keto stearic acid, and the acids derived from hardened castor oil which has been subsequently dehydrogenated by oxidation or catalytically; esters of the above acids with aliphatic or araliphatic alcohols such as methanol, glycerol and benzyl alcohol, and esters produced from natural glyceride oils by treatment with, for example, chromic anhydride in glacial acetic acid in known manner to develope keto groups in the acyl chains thereof.