Oleochemistry

As the price of crude oil rose in the late 1970s, manufacturers switched from petrochemicals to oleochemicals because plant-based lauric oils processed from palm kernel oil were cheaper. Since then, palm kernel oil is predominantly used in the production of laundry detergent and personal care items like toothpaste, soap bars, shower cream and shampoo.

Processes

Important process in oleochemical manufacturing include hydrolysis and transesterification, among others.

Hydrolysis

The splitting (or hydrolysis) of the triglycerides produces fatty acids and glycerol follows this equation:

RCO₂CH₂–CHO₂CR–CH₂O₂CR + 3 H₂O → 3 RCOOH + HOCH₂–CHOH–CH₂OH

To this end, hydrolysis is conducted in water at 250 °C. The cleavage of triglycerides with base proceeds more quickly than hydrolysis, the process being saponification. Saponification however produces soap, whereas the desired product of hydrolysis are the fatty acids.

Transesterification

Fats react with alcohols (R'OH) instead of with water in hydrolysis in a process called transesterification. Glycerol is produced together with the fatty acid esters. Most typically, the reaction entails the use of methanol (MeOH) to give fatty acid methyl esters:

RCO₂CH₂–CHO₂CR–CH₂O₂CR + 3 MeOH → 3 RCO₂Me + HOCH₂–CHOH–CH₂OH

FAMEs are less viscous than the precursor fats and can be purified to give the individual fatty acid esters, e.g. methyl oleate vs methyl palmitate.

Hydrogenation

The fatty acid or fatty esters are susceptible to hydrogenation converts unsaturated fatty acids into saturated fatty acids. The acids or esters can also be reduced to the fatty alcohols. For some applications, fatty acids are converted to fatty nitriles. Hydrogenated of these nitriles gives fatty amines, which have a variety of applications.

Gelation

Liquid oil can also be immobilized in a 3D-network provided by various molecules called oleogelators.