A cycloalkane is a saturated hydrocarbon whose carbon atoms form a closed ring. It matters because ring closure removes two hydrogens compared with the open-chain alkane and can introduce ring strain that affects stability and reactivity. A cycloalkane has the general formula CnH2n, two hydrogens fewer than the corresponding acyclic alkane of formula CnH2n+2.

环烷烃是碳原子构成闭合环的饱和烃。它之所以重要,是因为成环使其比开链烷烃少两个氢,并可能引入影响稳定性和反应活性的环张力。环烷烃的通式为 CnH2n,比对应的开链烷烃(通式 CnH2n+2)少两个氢。