Reactions of alkanes, including combustion and halogenation
Alkanes and cycloalkanes are relatively inert compounds due to their strong carbon-carbon and carbon-hydrogen bonds. However, they can undergo some important reactions, such as combustion and halogenation. In this article, we will explore these reactions and their mechanisms.
Combustion of Alkanes:
Alkanes are highly flammable and can undergo combustion when exposed to oxygen. The general equation for the combustion of alkanes is:
alkane + oxygen → carbon dioxide + water
For example, the combustion of methane (CH4) can be represented by the following equation:
CH4 + 2O2 → CO2 + 2H2O
This reaction is highly exothermic and releases a large amount of energy. It is commonly used as a source of heat and energy in various applications, such as cooking and heating.
Halogenation of Alkanes:
Alkanes can react with halogens (such as chlorine and bromine) to form alkyl halides. The reaction is known as halogenation, and it requires light or heat as a source of energy. The general equation for halogenation of alkanes is:
alkane + halogen → alkyl halide + hydrogen halide
For example, the halogenation of methane with chlorine gas can be represented by the following equation:
CH4 + Cl2 → CH3Cl + HCl
This reaction proceeds through a radical mechanism, where the halogen molecule is broken down into two halogen atoms in the presence of light or heat. The halogen atoms then react with the alkane molecule to form an alkyl radical and a hydrogen halide molecule. The alkyl radical can then react with another halogen molecule to form the alkyl halide product.
Cycloalkanes can also undergo halogenation, but the reaction is usually slower and less selective than with alkanes due to the limited accessibility of the ring carbons.
For a complete list of alkane reactions used in Organic Chemistry 1, check out our Reaction Library!
In this lesson, we explored the reactions of alkanes and cycloalkanes, focusing on combustion and halogenation. Alkanes are highly flammable and can undergo combustion to produce carbon dioxide and water. Halogenation of alkanes involves the reaction of halogens with alkanes to form alkyl halides and hydrogen halides. The reaction proceeds through a radical mechanism, and requires light or heat as a source of energy.
Test Your Knowledge:
What is the general equation for the combustion of alkanes?
What is the general equation for the halogenation of alkanes?