A magnesium phenate is prepared by a process which comprises reacting (1) magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium bicarbonate or a magnesium carboxylate with (2) a phenol, a methylene bis-phenol or a sulphurised phenol in the presence of (3) a solvent comprising an organic compound containing one or more alcoholic hydroxyl groups e.g. an alkoxy alcohol and (4) a promoter selected from a ketone, diketone such as α or β diketone, aldehyde or carboxylic acid and (5) optionally a diluent oil. This magnesium phenate may be used as a detergent for a lubricating oil.
The present invention provides a heat sensitive composition, comprising a) at least one colour forming compound, b) at least one developer, c) at least one stabiliser of the formula (II) wherein R1 and R2 are independently from each other C1-C2o=cycloalkyl, unsubstituted or substituted aralkyl of from 7 to 10 carbon atoms or unsubstituted or substituted phenyl, R¿3 and R4 are independently from each other hydrogen or C1-C20alkyl or C3-C10cycloalkyl, wherein R3 and R4 are not in ortho-position to the hydroxyl group, and n is 0, 1 or 2.