Chemistry - STEREO ISOMERISM Question with Solution | TestHub
Which of the following E, Z designations are correct, and which are incorrect ?
(a) 
(b) 
(E)
(c) 
(Z)
(d) 
(E)
(e) 
(Z)
(f) 
(E)
Options:
Answer:
Solution:
(a) On the ring carbon the path through C-2 (towards the CH₃-bearing C-3) outranks the path through C-6, and this higher path and CO₂H are on the same side.
Ans. Z
(b) Correct. Right carbon : CH₂CH=CH₂ CH₂CH(CH₃)₂ (the allyl group extends to (C, C, H) then (C, H, H), beating the isobutyl group); left carbon : CH₃ H. The higher groups are on opposite sides, so the designation E is correct.
(c) Incorrect. Left carbon : Br H; right carbon : CH₂NHCH₃ CH₂NH₂ (at nitrogen (C, H) beats (H, H)). The higher groups are on opposite sides, so the structure is E, not Z.
(d) Correct. Left carbon : CN CH₂N(CH₃)₂ ((N, N, N) beats (N, H, H)); right carbon : C₂H₅ CH₃. The higher groups (CN and C₂H₅) are on opposite sides, so the designation E is correct.
(e) Incorrect. The right-hand carbon is part of an unsubstituted cyclopentane ring, so its two ring paths are identical and no E/Z designation exists for this double bond at all.
(f) Correct. Left carbon : CH₂OCH₃ CH₂OH (at the ether oxygen (C) beats (H)); right carbon : CO₂H COCH₃ ((O, O, O) beats (O, O, C)). The higher groups are on opposite sides, so the designation E is correct.
