How are alkanes obtained from alkenes?

Alkanes are obtained from alkenes through a process known as hydrogenation.

Hydrogenation is a chemical reaction that involves the addition of hydrogen (H2) to a substance. In the context of obtaining alkanes from alkenes, hydrogenation involves the addition of hydrogen to an alkene in the presence of a catalyst. This process converts the double bonds of the alkene into single bonds, resulting in an alkane.

The general reaction can be represented as follows:

RCH=CH2 + H2 → RCH2-CH3

Where RCH=CH2 represents an alkene and RCH2-CH3 represents an alkane. The reaction is typically carried out at room temperature and pressure, with a metal catalyst such as nickel, platinum or palladium.

The hydrogenation of alkenes is an example of an addition reaction, which is a type of reaction where atoms or groups of atoms are added to a molecule. In this case, hydrogen atoms are added to the carbon atoms of the alkene, breaking the double bond and forming a single bond, thus creating an alkane.

This process is widely used in the industrial production of alkanes, particularly in the petroleum industry where it is used to convert unsaturated hydrocarbons (like alkenes) into saturated hydrocarbons (like alkanes). This is important because saturated hydrocarbons are generally more stable and less reactive than unsaturated hydrocarbons, making them safer and easier to handle and store.

In addition to its industrial applications, the hydrogenation of alkenes is also a key concept in organic chemistry. Understanding this process can help you understand the properties and behaviours of different types of hydrocarbons, and how they can be manipulated through chemical reactions.