**3.3 Elimination reactions**

Ester based lubricants have been observed to decompose One possible reaction of esters is an elimination reaction in which an alkene and a carboxylic acid are the products. The mechanism for this reaction involves the loss of a proton on the β carbon atom leading to the formation of a double bond and the elimination of the carboxylate anion. The mechanism for the β elimination reaction is shown in **Figure 6**.

The use of alcohols without hydrogen atoms at the β carbon atom eliminates this mechanism, but under operating conditions of turbine engines, high temperature and metal catalyzed elimination reactions are possible. For this reason, modern ester based lubricants are based on neopentyl polyols, where elimination is blocked due to the lack of hydrogen atoms at the β position. Significant work has been conducted on optimizing the properties of the lubricant for use in turbine engines [13, 14].
