ABSTRACT
Hydrocarbons (HCs) are composed of carbon and hydrogen molecules whose carbon–carbon (C–C) bonds are composed of either all single (saturated) bonds or combinations of single and multiple (unsaturated) bonds. Aliphatic HCs, the term usually pertaining to fats or oils, applies to straight, open chains of carbon atoms, rather than ring structures, the simplest of which are the saturated HCs (alkanes). In addition, alkanes exist as unbranched straight chains or branched (for butane or longer chains), depending on the structural isomerism. Multiple C–C bonds result when hydrogens are removed from the alkanes, yielding unsaturated HCs such as alkenes (double C–C bond) and alkynes (triple C–C bonds). Alicyclic HCs are saturated, ring structures consisting of three or more carbon atoms. Unlike the aromatic chemicals (below), cyclopropane, cyclobutane, cyclopentane and cyclohexane, for example, have three-, four-, Þve-, and six-membered rings, respectively, but do not exhibit double bonds within the rings.
