Interactions Between a Zinc Dialkylphosphorodithioate and Lubricating Oil Dispersants

Publisher Website
Google Scholar
Abstract
Direct infrared spectrophotometric evidence of interactions between lubricating oil dispersants and a zinc dialkylphosphorodithioate (ZDP) is presented. Increasing the concentration of the dispersants polyamino monoalkenylsuccinimide, barium thiophosphonate, and basic barium dinonylbenzene sulfonate in a mineral oil containing 1.2% by weight of a ZDP decreased the intensity of the phosphorus-oxygen-carbon and phosphorus-sulfur infrared bands, and caused the appearance of a new band at 668 cm−1. The dispersants barium dinonylnaphthalene sulfonate, calcium petroleum sulfonate, and alkaline petroleum sulfonate decreased the intensity of the phosphorus-sulfur bands only after the solutions had aged, and independently of dispersant concentration. It is speculated that chemical reactions cause these interactions between the ZDP and the dispersants, and that ionic metal phosphorodithioates are formed. The possibility of association, isomeric, and complexation effects is also explored. Regardless of the exact mechanism involved, these results should be valuable not only to analytical chemists, but also to lubricant technologists and researchers.

This publication has 2 references indexed in Scilit: