The tail section, an oleophilic group, serves as a solubilizer in the base fluid, while the polar group is attracted to contaminants in the lubricant. Although these compounds are commonly called detergents, their function appears to be the dispersing of particulate matter rather than cleaning up existing dirt and debris. Therefore, it is more appropriate to categorize them as dispersants. The molecular structure and a brief outline of the preparation methods for some representative types of metallic dispersants are discussed below. Sulfonates Sulfonates are the products of the neutralization of a sulfonic acid with a metallic base.
R represents the organic radical that acts as an oil solubilizing group.
The molecular weight of the hydrocarbon must be on the order of 350 or more, and the presence of the organic radical in the molecule is considered necessary for the oil solubility of the sulfonate. Currently, with the high demand for detergent oils, sulfonates rather than white oils have become the principal product. The structure of the organic portion of petroleum sulfonates is not completely known. Depending on the crude oil source, the structure can have varying proportions of aliphatic, naphthenic, and aromatic hydrocarbon groups. Synthetic sulfonates are metal salts of acids produced from the sulfonation of alkylated aromatics by reaction with sulfur trioxide.