丁烷有两种：正丁烷和异丁烷. 正丁烷：CH3-CH2-CH2-CH3 异丁烷：CH3-CH-CH3 I CH3 戊烷有三种：正戊烷、异戊烷和新戊烷. 正戊烷：CH3-CH2-CH2-CH2-CH3 异戊烷：CH3-CH-CH2-CH3 I CH3 新戊烷：CH3 I CH3-C-CH3 I CH3
