Autoxidation of Chemical Models of Ester Lubricants

J.R. Lindsay Smith,^a D.J. Waddington,^a M.S. Stark,^a P.W. Smith^b, E.D. Pritchard*^a

a Department of Chemistry, University of York, York YO10 5DD, UK

b Castrol lnternational Technology Centre, Reading, RGB 7QR, UK

Polyol esters are already used as base fluids in a wide range of lubricants, in automotive, industrial and aviation applications, but have potential for much wider use.¹ If this potential is to be realised, the oxidation of these esters under industrial application conditions needs to be better understood.

Neopentyl esters (1) and neopentyl glycol esters (2), although of little use as lubricants themselves, can be considered as models for heavier esters of polyols such as trimethylolpropane (TMP) (3) and pentaerythritol (PE) (4). The autoxidation of 1 and 2 under conditions of high temperature and pressure has been investigated, and the compositions of the oxidised samples determined by gas chromatography. The physical characteristics of the oxidised ester have also been probed by other techniques such as viscometry, FTIR spectroscopy and gel permeation chromatography (GPC). The formation of the oxidation products can be explained by conventional autoxidation chemistry followed by the further reaction of oxidation products. The oxidation behaviour of the monoesters, also investigated in previous work at York,² shows some significant differences from that of the diesters. The poster will suggest mechanisms for the formation of some oxidation products and draw conclusions about the important pathways in ester autoxidation.

References

1. P.M. Morse, Article, Chemical & Engineering News, Sept. 1998

2. J.R. Lindsay Smith, E. Nagatomi, D.J. Waddington, J. Chem. Soc, Perkin Trans. 2, 2000, 2248-2258