Question

Compound (X) $C_4{H}_{8}O,$ which reacts with 2, 4-DNP derivative and gives negative haloform test. The compound is:

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

2,4-Dinitrophenylhydrazine can be used for the qualitative identification of ketone or aldehyde functional group carbonyl functionality. So, to show DNP test the compound must be ketone or aldehyde. .
Compound (a) shows positive iodoform test since it has methyl group attached to carbonyl group. Also (d) shows positive iodoform test because $NaOH+I_2$ being a mild oxidising
agent and can easily oxidise alcohol group to carbonyl and since the compound has $-C{H}_3$ attached to carbonyl it can show positive iodoform test.
Compound in option (b) does not show positive iodoform test since it is an aldehyde and only aldehyde that shows positive iodoform test is $C{H}_{3}CHO$
Option (b) is correct