Question

Give simple chemical test to distinguish between the following pairs of compounds.
i. Propanal and Propanone
ii. Acetophenone and Benzophenone
iii. Phenol and Benzioc acid
iv. Benzoic acid and Ethyl benzoate
v. Pentan-2-one and Pentan-3-one
vi. Benzaldehyde and Acetophenone
vii. Ethanal and Propanal

Answer 1

(i) Propanal and Propanone can be distinguished by iodoform test.
`CH_(3)COCH_(3)+3NaOlrarrunderset("(Yellow ppt.)")underset("lodoform")(CH_(3)I)darr+CH_(3)COONa+2NaOH`
This test is given by aldehydes containing `-COCH_(3)` group. Propanal does not have `-COCH_(3)` group thus it does not give iodoform test
(ii) Acetophenone and Benzophenone can be distinguished by iodoform test.
`C_(6)H_(5)COCH_(3)+3NaOIrarrC_(6)H_(5)COONa+underset("(Yellow ppt.)")underset ("Iodoform")(CH_(3)I)darr+2NaOHrarr C_(6)H_(5)COC_(6)H_(5)overset(NaOI)rarr"No yellow ppt."`
This test is given by aldehydes and ketones containing `-COCH_(3)` group
(iii) Phenol and Benzoic acid can be distinguised by `FeCl_(3)` test