Question

Write the chemical test to distinguish between the following pair of compounds.

Ethanol and propan-1-al

Answer 1

A methyl group (-CH₃) that is directly joined to a carbonyl or hydroxyl group (OH) can be found using the iodoform test. Since ethanol includes the -CH₃CH(OH)- group, which reacts with iodine and NaOH to generate a yellow precipitate of iodoform (CHI₃), it yields a positive iodoform test. However, because Propan-1-ol does not contain the -CH₃CH(OH)- group, it yields a negative result.

\[\ce{CH3CH2OH + 4I2 + 6NaOH ->[\Delta] \underset{(Iodoform)}{\underset{Yellow ppt}{CHI3}} + HCOONa + 5NaI + 5H2O}\]

\[\ce{CH3 - CH2 - CH2OH -> No Reaction}\]