| abstract |
The invention provides oil-soluble multivalent metal ion salts of a compound of the formula XNR<1>R<2>, in which R<1> and R<2> are the same or different and each are selected from hydrogen and hydrocarbon based radicals having from 1 to 30 carbon atoms, X is an acyl radical of an aromatic ortho-hydroxy carboxylic acid having a ring substituent which is a hydrocarbon based radical having at least 4 carbon atoms, and their use, as additives, in lubricating oils. The compounds may be prepared by reacting a compound of formula XY with an amine of formula HN R<1>R<2>, in which Y is OR<3>, in which R<3> is hydrogen, alkyl, aryl or acyl or Y is halogen, followed by the reaction of the amide with a multivalent compound. The metal compound may be added in greater than stoichiometric amount for neutralising the phenolate moiety to give an overbased product, the process preferably including a carbonation step. |