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Basics of Organic Chemistry question

2008 · Shift 0 · Q4
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Basics of Organic Chemistry question

2008 · Shift 0 · Q4

JEE MainChemistryBasics of Organic ChemistryMCQ+4 / −1
The correct decreasing order of priority for the functional groups of organic compounds in the IUPAC system of nomenclature is
  1. A
    −COOHCOOHCOOH, −SO3HSO_3HSO3​H, −CONH2CONH_2CONH2​, −CHOCHOCHO
  2. B
    −SO3HSO_3HSO3​H, −COOHCOOHCOOH, −CONH2CONH_2CONH2​, −CHOCHOCHO
  3. C
    −CHOCHOCHO, −COOHCOOHCOOH, −SO3HSO_3HSO3​H, −CONH2CONH_2CONH2​
  4. D
    −CONH2CONH_2CONH2​, −CHOCHOCHO, −SO3HSO_3HSO3​H, −COOHCOOHCOOH
View written solutionFree

Correct answer: A

  1. In IUPAC nomenclature, when multiple functional groups are present, the principal functional group is chosen according to a fixed priority order.

  2. Among the given groups, the relevant priority order is:

−COOH>−SO3H>−CONH2>−CHO-COOH > -SO_3H > -CONH_2 > -CHO−COOH>−SO3​H>−CONH2​>−CHO

This means:

  • Carboxylic acid (−COOH)(-COOH)(−COOH) has highest priority among these.
  • Sulphonic acid (−SO3H)(-SO_3H)(−SO3​H) comes next.
  • Amide (−CONH2)(-CONH_2)(−CONH2​) follows.
  • Aldehyde (−CHO)(-CHO)(−CHO) has the lowest priority among these four.
  1. Now compare with the options:
  • A: −COOH,−SO3H,−CONH2,−CHO-COOH, -SO_3H, -CONH_2, -CHO−COOH,−SO3​H,−CONH2​,−CHO ✅
  • B: −SO3H,−COOH,−CONH2,−CHO-SO_3H, -COOH, -CONH_2, -CHO−SO3​H,−COOH,−CONH2​,−CHO ❌
  • C: −CHO,−COOH,−SO3H,−CONH2-CHO, -COOH, -SO_3H, -CONH_2−CHO,−COOH,−SO3​H,−CONH2​ ❌
  • D: −CONH2,−CHO,−SO3H,−COOH-CONH_2, -CHO, -SO_3H, -COOH−CONH2​,−CHO,−SO3​H,−COOH ❌
  1. Therefore, the correct decreasing order of priority is:
−COOH>−SO3H>−CONH2>−CHO-COOH > -SO_3H > -CONH_2 > -CHO−COOH>−SO3​H>−CONH2​>−CHO

Hence, Option A is correct.

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