丁烷：分子式C4H10，同分异构体2种，CH3CH2CH2CH3，CH3CH(CH3)2,

戊烷：分子式C5H10，同分异构体3种，CH3CH2CH2CH2CH3，CH3CH(CH3)CH2CH3，C(CH3)4

己烷：分子式C6H14，同分异构体5种，CH3CH2CH2CH2CH2CH3，CH3CH(CH3)CH2CH2CH3，CH3CH2CH(CH3)CH2CH3，CH3C(CH3)2CH2CH3，(CH3)2CHCH(CH3)2

庚烷：分子式C7H16，同分异构体9种，CH3CH2CH2CH2CH2CH2CH3，CH3CH(CH3)CH2CH2CH2CH3，CH3CH2CH(CH3)CH2CH2CH3，CH3C(CH3)2CH2CH2CH3，CH3CH2C(CH3)2CH2CH3，CH3CH(CH3)CH(CH3)CH2CH3，CH3CH(CH3)CH2CH(CH3)CH3，CH3CH2CH(CH2CH3)2，CH3C(CH3)2CH(CH3)2