Source of organic compounds:
The major commercial sources of alkanes are coal, natural gas, petroleum, and living organisms.
coal:
Coal is a source of many organic compounds. When coal is heated in the absence of air at high temperature, it is converted into coal gas, coal tar and coke. This process is called destructive distillation. Coal is also used as solid fuel.
Natural gas:
Natural gas is a mixture of low boiling hydrocarbons. Natural gas is mostly methane. It also contain smaller amount of ethane, propane and butane.
Petroleum:
Petroleum contain a wide variety of alkanes including those having very long chains. On fractional distillation petroleum separates into various hydrocarbon components,known as fraction. Each faration is not a pure compound but a mixture of different compounds that boil in a certain range of temperature.
Living organisms:
Many important organic compounds such as proteins, fats, carbohydrates, vitamins, drug and medicines are obtained from plant and animals.