alkanas

Alkanes, also known as alkanas in some languages, are a family of saturated hydrocarbons consisting solely of carbon and hydrogen atoms connected by single bonds. For acyclic alkanes, the general formula is CnH2n+2, where n is the number of carbon atoms.

They include straight-chain alkanes (n-alkanes) and branched alkanes (isoalkanes). The simplest members are methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10). Isomerism increases with chain length; for C4 alone there are two isomers: n-butane and isobutane (2-methylpropane).

Physical properties: Alkanes are generally colorless, odorless liquids or gases at room temperature and are nonpolar, with low solubility in water and good solubility in nonpolar solvents. Boiling points rise with increasing carbon number. Gases predominate for up to about C4; liquids for C5–C16; higher alkanes are waxy solids at room temperature.

Occurrence and production: They are the main components of natural gas and petroleum. They are obtained by fractional distillation and various petrochemical processes such as cracking and reforming. They serve as fuels (gas, gasoline, diesel) and as feedstocks for the production of plastics and other chemicals.

Chemical properties: Alkanes are relatively unreactive; typical reactions include combustion to CO2 and H2O, and substitution reactions with halogens under radical conditions (especially UV light). They can also undergo cracking, isomerization, and other transformations to produce more useful fuels and chemicals.

Safety and environment: They are highly flammable and can form explosive mixtures with air; methane is a potent greenhouse gas with significant environmental impact.