Hydrocarbon

Name:
Hydrocarbon
Detailed information:
An organic compound consisting exclusively of the elements carbon and hydrogen. Derived principally from petroleum, coal tar, and plant sources. Following is a resume of the principal types.

1. Aliphatic (straight-chain)
   1. Paraffins (alkanes): generic formula C_nH_2n+2. Saturated, single bonds only.
   2. Olefins: generic formula C_nH_2n.
      1. alkenes: unsaturated (one double bond).
      2. alkadienes: unsaturated (two double bonds) (butadiene).
   3. Acetylenes: generic formula C_nH_2n-². Unsaturated (triple bond).
   4. Acyclic terpenes. Unsaturated (polymers of isoprene, C₅H₈).Note: Some aliphatic compounds have branched chains in which the subchain also contains carbon atoms (isobutane); both chains are essentially straight.
2. Cyclic (closed ring)
   1. Alicyclic: three or more carbon atoms in a ring structure with properties similar to those of aliphatics.
      1. Cycloparaffins (naphthenes): saturated compounds often having a boat or chair structure, e.g., cyclohexane, cyclopentane.
      2. Cycloolefins: unsaturated, two or more double bonds, e.g., cyclopentadiene (2), cyclooctatetraene (4).
      3. Cycloacetylenes (cyclynes): unsaturated (triple bond).
   2. Aromatic: unsaturated, hexagonal ring structure (three double bonds), single rings and double or triple fused rings.
      1. benzene group (1 ring).
      2. naphthalene group (2 rings).
      3. anthracene group (3 rings).
   3. Cyclic terpenes: monocyclic (dipentene); dicyclic (pinene).Note: Olefinic (isoprenoid) hydrocarbons are produced by a number of plants, notably Hevea braziliensis (rubber), guayule, and various members of the Euphorbiaceae family. Current research on the latter group indicates that they could be used as a source of liquid fuels and chemical feedstocks by genetic modification of the plants and control of their molecular constitution. It is estimated that oil obtained by large-scale cultivation of such plants, which grow well in semi-arid environments, could become economically competitive with petroleum within a few years.

See Guayule; Biomass; Copaiba Oil.