Process for the preparation of detergent dispersants of high alkalinity for lubricating oils and the product obtained therefrom

A process of preparing detergent-dispersant compositions containing at least about 2 percent magnesium, from an alkylphenol, an alkaline-earth metal alkylbenzenesulfonate, an alkylene glycol, sulfur, and carbon dioxide, which process comprises:

• (1) reacting sulfur at a temperature between about 100.degree. C. and 190.degree. C., with an alkylphenol bearing one or more C.sub.6 -C.sub.60 alkyl substituents, in the presence of a dilution oil, a magnesium and/or calcium alkylbenzenesulfonate of a molecular weight of more than about 300 and a TBN of less than or equal to about 150, an alkaline-earth component selected from among calcium hydroxide, mixtures of magnesium oxide, and calcium hydroxide, and an alkali metal hydroxide and an alkylene glycol;
• (2) superalkalinizing and carbonating the resultant sulfurized medium with magnesium oxide or a mixture of magnesium oxide and calcium hydroxide, in the presence of an alkylene glycol, at a temperature of between about 100.degree. C. and 250.degree. C., with carbon dioxide;
• (3) at any stage of the superalkalinization/carbonation step, treating the reaction medium with 0 to about 10 percent by weight of water, referred to the weight of the said medium, at a temperature between about 100.degree. C. and 150.degree. C.;
• (4) removing the excess alkylene glycol and recovering the detergent-dispersant composition of high alkalinity.