Beilsteins classification scheme for organic chemicals

Carbon directly bonded to elements of 3 -l A-groups of periodic table  

In acyclic organic compounds, the carbon atoms are joined together in chains. This arrangement contrasts with the other two structural groups, the isocyclic and heterocyclic compounds in which the carbon atoms are joined together in rings (see Sections 2.2.2 and 2.2.3). As Table 2.3 shows. 

The Cl to C4 hydrocarbons are colomless, odourless gases and all are used as sources of fuel, especially methane where natural gas is supplied for industrial and domestic purposes. Methane is also produced from marshlands and peatlands, and from landfill sites, as a result of vegetation decay. Ethane and propane are employed as refrigerants while butane is used in the manufacture of synthetic rubber. Moreover, many hydrocarbons from crude oil are the basis of the petrochemical industry (see Section 5.4) which provides the starting chemicals for many widely-used synthetic compoimds such as plastics, artificial fibres, soaps, resins and detergents. 

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