Oil and gas production handbook An introduction to oil and gas production

Figure 38, Vegetable Oil structure 
 
The glycerol backbone on the left is bound (ester OH binding) to three fatty 
acids, shown here with palmitic acid, oleic acid and alpha-linolenic acid and 
a total carbon number of 55. 
 
This molecule is broken down to individual alkyl esters through a chemical 
process called transesterification, whereby the glycerin is separated from the 
fatty acids. Methanol (CH
3
OH) is added to the lipids and heated. Any strong 
base capable of deprotonating the alcohol, such as NaOH or KOH is used as 
catalyst. 
 

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134 
 
The process leaves behind methyl esters (with a CH
3
 group on the ester 
binding) and glycerin (a valuable byproduct used in soaps, explosives and 
other products).