Question

UV absorbance value of Morphine

• A. 266 nm
• B. 276 nm
• C. 256 nm
• D. 286 nm

Hint:

UV absorbance maxima provide valuable information for drug analysis; morphine's peak at 286 nm is a key identifier.

Answer 1

The Correct Option is D

- Morphine is an opiate alkaloid with a characteristic UV absorption spectrum.
- The maximum UV absorbance (\λ max) for morphine is approximately 286 nm due to the conjugated aromatic ring system in its structure.
- This absorbance is used in qualitative and quantitative analysis of morphine in pharmaceutical preparations using UV-visible spectrophotometry.
- Understanding the UV absorbance helps in drug identification and purity analysis in pharmaceutical quality control.

Answer 2

The question asks for the UV absorbance maximum of morphine. Let's weigh each wavelength option against what morphine's chromophore is expected to absorb.

1. 266 nm: This wavelength is closer to the absorbance region of simple unsubstituted aromatic rings without extended conjugation. Morphine's phenolic and diene-conjugated system absorbs at a longer wavelength than this, so 266 nm is too short.
2. 276 nm: This value falls closer to plain phenolic compounds absorbing around 270-280 nm. Morphine's chromophore is more extended than a simple phenol due to its fused ring conjugation, pushing its absorbance further out.
3. 256 nm: This is even shorter than the other distractors and matches simpler, less conjugated aromatic systems. It underestimates the bathochromic shift caused by morphine's conjugated phenanthrene-derived nucleus.
4. 286 nm: Morphine's aromatic ring is conjugated with the adjoining double bond system in its phenanthrene-type core, and this extended conjugation shifts the absorbance maximum out to the longer end of the near-UV range, matching reported values around 286 nm.

Reasoning from the degree of conjugation in morphine's structure points to the longest of the four wavelengths as the correct absorbance maximum.

Therefore, the correct answer is 286 nm.