Hydrogenation of alkenes: Margarine

The catalytic addition of $ H_2 $

$H_2$ is added to an alkene in the presence of platinum catalysts, palladium or nickel/aluminum alloy.

Vegetable oils

Many plants such as sunflower, rapeseed or olive contain so-called "vegetable" oils

These oils are esters of glycerol (propane-1,2,3-triol) with unsaturated fatty acids, for example:


Vegetable oils are viscous liquids, which is an economic disadvantage. To overcome this disadvantage, commonly practice is hydrogenation to turn them into less unsaturated margarines which are spreadable:

"Trans" fats

Following the heating needed to hydrogenation, the typical "cis" configuration of double bonds can turn into "trans" configuration ...

The "trans" fats so obtained are sworn enemies of many dieticians!