Synthesis and characterisation of antioxidant-modified esters of dipentaerythritol as lubricating base oil

ABSTRACT In this paper, five antioxidant‐modified esters were synthesised through two steps of simple esterification. Antioxidant‐modified multi‐hydroxyl compound was synthesised at the first step, and antioxidant‐modified esters were synthesised at the second step. This kind of esters is useful in many fields, such as lubricating oil and cutting compound, because of two important functions (antioxidant and lubricant) in the same compound. The active antioxidant group attached to these esters was 3‐(3,5‐di‐ tert ‐butyl‐4‐hydroxy‐phenyl)‐propionic acid. The esters were characterised with Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis. The analytical results of FTIR demonstrates the changes of alcoholic hydroxyl and carboxyl and suggests that this synthesis was feasible. The TG analysis and rotating pressure vessel method show that this kind of esters has excellent oxidative stability. The physical properties of lubricating base oil, such as viscosity, viscosity index, pour point and flash point, suggested that this kind of esters can be used as lubricating base oil. Copyright © 2012 John Wiley & Sons, Ltd.