Question

Aniline absorbs at 280 nm. However, in an acidic solution, the main absorption band is seen at:

• A. 280 nm
• B. 260 nm
• C. 205 nm
• D. 225 nm

Hint:

Protonation of the NH2 group removes conjugation, so the ring absorbs like benzene.

Answer 1

The Correct Option is C

Step 1: Aniline's NH2 lone pair conjugates with ring, giving 280nm band.

Step 2: Protonation forms anilinium, NH3+, removing conjugation.

Step 3: Ring now behaves like benzene, absorbing near 205nm.

\[\boxed{205 \text{ nm}}\]