Skip to content
dronacharya.ai
← JEE Advanced 2022 · Paper 2
ChemistryInteger+3 / -1Question 44 of 54

JEE Advanced 2022 · Paper 2, Chemistry question 8

The total number of chiral molecules formed from one molecule of P\mathbf{P} on complete ozonolysis (OX3,Zn/HX2O)(\ce{O3}, \ce{Zn/H2O}) is ________.

Molecule P: a 19-carbon main chain CH3-CH=C(CH3)-C(OH)(CH3)-C(CH3)=C(CH3)-C(OH)(CH3)-CH=C(CH3)-C(OH)(CH3)-C(CH3)=CH-C(OH)(CH3)-C(CH3)=C(CH3)-C(OH)(CH3)-C(CH3)=CH-CH3, with six trisubstituted/tetrasubstituted C=C bonds (all drawn E in the zigzag) and five tertiary carbinol stereocentres, each drawn with wedge/hash bonds to OH and CH3.
Answer and worked solution

Official answer: 2

Ozonolysis fragments. Ozonolysis cuts all six C=C bonds of P. Reading along the chain, it gives:

  1. CHX3CHO\ce{CH3CHO}.
  2. CHX3CO−C(OH)(CHX3)−COCHX3\ce{CH3CO-C(OH)(CH3)-COCH3}: two identical acetyl groups, so achiral.
  3. CHX3CO−C(OH)(CHX3)−CHO\ce{CH3CO-C(OH)(CH3)-CHO}: four different groups (OH, CHX3\ce{CH3}, COCHX3\ce{COCH3}, CHO), so chiral.
  4. CHX3CO−C(OH)(CHX3)−COCHX3\ce{CH3CO-C(OH)(CH3)-COCH3}: achiral.
  5. OHC−C(OH)(CHX3)−COCHX3\ce{OHC-C(OH)(CH3)-COCH3}: chiral.
  6. CHX3CO−C(OH)(CHX3)−COCHX3\ce{CH3CO-C(OH)(CH3)-COCH3}: achiral.
  7. CHX3CHO\ce{CH3CHO}.

Answer. One molecule of P gives 2 chiral molecules.

Topics:Optical isomerism and chiralityAlkenes
← Previous questionNext question →