CH3CHO\mathrm{CH}_{3} \mathrm{CHO}CH3CHO
CH3COCOCH3\mathrm{CH}_{3} \mathrm{COCOCH}_{3}CH3COCOCH3
CH3COCH2CH3\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{3}CH3COCH2CH3
CH3COOH\mathrm{CH}_{3} \mathrm{COOH}CH3COOH