Q. The IUPAC name of the compound ClC(CH₃)=C(I)CH₂CH₃, in which Cl and I lie on opposite sides of the double bond, is
A) trans-3-iodo-4-chloro-3-pentene
B) cis-3-chloro-3-iodo-2-pentene
C) trans-2-chloro-3-iodo-2-pentene
D) cis-3-iodo-4-chloro-3-pentene
Explanation
[Solution from source] The longest chain containing the double bond has five carbons, numbered from the end nearer the double bond: C2 carries Cl and C3 carries I, giving 2-chloro-3-iodopent-2-ene. Cl and I, the heavier substituents on each alkene carbon, are on opposite sides, so it is trans. Names like 3-iodo-4-chloro-3-pentene number from the wrong end. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.