How can we distinguish between
a) CH3OH and CH3CH2OH
b) 1-propanol and 2-propanol
(a)Ethanol contains the group CH3CHOH, therefore it gives a positive iodoform test, whereas methanol doesnot give iodoform test.
The reaction is as follows:
CH3CH2OH + 4I2+ 6 NaOH → CHI3 + HCOONa + 5 NaI + 5 H2O
Yellow ppt.
CH3OH + I2 + NaOH → no reaction
(b) 2-propanol contains CH3CHOH unit, so it will give positive iodoform test whereas 1-propanol will not give this test.The reaction is as follows:
CH3CH(OH)CH3 + 4I2+ 6 NaOH → CHI3 + CH3COONa + 5 NaI + 5 H2O
2-propanol Yellow ppt.
CH3CH2CH2OH + I2 + NaOH → no reaction
1- propanol