CH3COOH\mathrm{CH}_{3} \mathrm{COOH}CH3COOH
CF3COOH\mathrm{CF}_{3} \mathrm{COOH}CF3COOH
CCl2COOH\mathrm{CCl}_{2} \mathrm{COOH}CCl2COOH
CBr3COOH\mathrm{CBr}_{3} \mathrm{COOH}CBr3COOH