Cycloalkanen

Cycloalkanen, commonly called cycloalkanes, are a class of saturated hydrocarbons in which carbon atoms form one or more closed rings. For a ring of n carbon atoms the general formula is CnH2n. The simplest members are cyclopropane (C3H6), cyclobutane (C4H8), cyclopentane (C5H10), and cyclohexane (C6H12). As ring size increases, cycloalkanes become closer to the geometry of unstrained acyclic alkanes; however three- and four-membered rings retain substantial angle strain, while cyclohexane often adopts a low-energy chair conformation with minimal strain.

They are nonpolar, lipophilic, and poorly soluble in water. Physical properties such as boiling points rise with increasing ring size. Cycloalkanes are typically flammable liquids or gases and are used as solvents and as feedstocks in chemical manufacture. Substituted cycloalkanes are common, for example methylcyclohexane and dimethylcyclohexane.

Reactivity of cycloalkanes generally mirrors that of acyclic alkanes, including radical halogenation under photochemical conditions and combustion. Strained rings may open or rearrange under certain conditions. Dehydrogenation can form cycloalkenes, and further reaction can lead to aromatics under strong conditions. Substitution on the ring yields a range of substituted cycloalkanes, which have wide applications in synthesis and materials science.

Industrial relevance is notable: cyclohexane is a major solvent and a precursor in the production of adipic acid and caprolactam, which are used to manufacture nylons. Cyclopentane is employed as a blowing agent for polymer foams and as a solvent in some applications.