Question

Why does aniline shows blue shift in acidic solution?

Answer 1

Answer:

Aniline shows blue shift in acidic medium, it loses conjugation. When absorption intensity (ε) of a compound is increased, it is known as hyperchromic shift. If auxochrome introduces to the compound, the intensity of absorption increases.

Answer 2

Aniline shows a blue shift in acidic solution because of the hypsochromic shift.

• When the spectral band position changes the transmission, absorption, reflectance, or a molecule's spectrum of emission shifts to a higher frequency, then it is known as hypsochromic shift.
• Hypsochromic shift or the blue shift occurs when a compound's absorption maxima (λmax) changes to a short wavelength. This effect is caused when conjugation is removed because of a group or when the solvent is changed.
• Aniline loses conjugation and thus shows a blue shift in acidic solution. "NH2 + H Acidic medium NH3 + Cl - Aniline λmax = 280 nm λmax = 265 nm".