CH3COOCH3\mathrm{CH}_{3} \mathrm{COOCH}_{3}CH3COOCH3
CH3COOCH2CH3\mathrm{CH}_{3} \mathrm{COOCH}_{2} \mathrm{CH}_{3}CH3COOCH2CH3
HCOOCH3\mathrm{HCOOCH}_{3}HCOOCH3
CH3CH2COOCH3\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOCH}_{3}CH3CH2COOCH3