● reaction with hydrogen:
○ alkene + hydrogen → alkane
○ E.g. Ethene + hydrogen → ethane
Adding Hydrogen to the double bond
We will work with ethene but the same reaction occurs with any alkene.
Ethene reacts with hydrogen using a nickel catalyst at around 150°C.
The product of this reaction is ethane.
Ni/150° to 200°
CH2=CH2 + H2
CH3CH3
For this reaction or similar you should remember
- what saturated means
- conditions of the reaction (temperature and pressure if specified)
- catalyst
This reaction is used to hydrogenate vegetable oil to produce margarine.
Not all margarines are made by hydrogenation of the double bonds in fat acids. When an oil is hydrogenated and loses all the double bonds, it is SATURATED. It cannot accept more hydrogens in the molecule. If the molecule has one double bond is MONOUNSATURATED, and if it has several double bonds is called POLYUNSATURATED.