The autoxidation of alkenyl succinimides - Mimics for polyisobutenyl succinimide dispersants

Jonathan E. Ruffell, Thomas J. Farmer, Duncan J. MacQuarrie, Moray S. Stark*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Short chain alkenyl succinimides (ASIs) were synthesised and used as high purity chemical models to investigate the autoxidative degradation at 170 oC of polyisobutenyl succinimide dispersants (PIBSIs), a significant additive in automotive engine lubricants. Degradation products were characterised by GC-EI-MS and quantified by GC-FID. The rate of autoxidation of ASIs in a model lubricant, squalane, was also investigated. Although this is a complex molecule containing many possible sites of radical attack, all of the autoxidation products identified result from attack at the double bond or the adjacent allylic hydrogen atoms, which indicates the controlling influence of the double bond in the degradation of alkenyl succinimides, and therefore of commercial polyisobutenyl succinimide dispersants. The observed site-selective cleavage of the ASI structure, and by analogy PIBSI dispersants, would yield products that both reduce dispersancy and promote the formation of insoluble products that could have a detrimental effect on lubricant performance.

Original languageEnglish
Pages (from-to)1-12
Number of pages12
JournalIndustrial and Engineering Chemistry Research
Early online date19 Sept 2019
Publication statusE-pub ahead of print - 19 Sept 2019

Bibliographical note

© 2019, The Author(s).


  • autoxidation
  • degradation
  • dispersant
  • lubricant

Cite this