Overview of Alkanes

  • Alkanes are a form of hydrocarbon where all the hydrocarbons are single bonded.
  • They are the simplest form of hydrocarbons, and are also considered saturated hydrocarbons due to the presence of single bonds only.
  • Their general formula is CnH2n+2 where ‘n’ is the number of carbon atoms.

Properties of Alkanes

  • Alkanes are generally non-polar due to the similar electronegativity of hydrogen and carbon.
  • They are insoluble in water but soluble in organic solvents.
  • Alkanes have relatively low reactivity because of the stability of their single bonds and lack of polarity.
  • As the length of the carbon chain increases, boiling points of alkanes also increase.

Nomenclature and Isomerism

  • Alkanes are named by counting the number of carbon atoms in the longest chain. Prefixes are used to denote the number of carbons (e.g., ‘meth-’ for 1, ‘eth-’ for 2, ‘prop-’ for 3, and so forth).
  • The prefixes are followed by the suffix ‘-ane’ to show it’s an alkane.
  • When alkanes have four or more carbon atoms, they can exist in different structural forms, known as isomers. This is because of the flexibility of the C-C single bonds.

Reactions of Alkanes

  • Alkanes undergo various types of reactions, including combustion (burning in air or oxygen), substitution reactions, particularly halogenation (replacement of a hydrogen atom by a halogen atom).
  • Combustion of alkanes is a highly exothermic reaction releasing a large amount of energy, which is why alkanes are often used as fuel.
  • Alkanes tend to react with halogens in the presence of UV light or high temperature, a type of reaction known as radical substitution.