甲醛:CH2O+2NaOH==Na2CO3+2H2;含有R(H)COCH3或R(H)CH(OH)CH3的发生碘仿反应.
乙醛:I2+2NaOH==NaI+NaIO+H2O,CH3-CHO+3NaOI--->CI3-CHO+3NaOH
CI3-CHO+NaOH---->CHI3↓(碘仿)+HCOONa.现象是有黄色沉淀(CHI3).
丙酮:I2+2NaOH==NaI+NaIO+H2O,C2H5-CHO+6NaOI--->2CI3-CHO+6NaOH ,CI3-CHO+NaOH---->CHI3↓(碘仿)+HCOONa