18. What is the IUPAC name for the compound with the structure shown?
A cis-2-chlorobut-2-ene
B trans-2-chlorobut-2-ene
C E-2-chlorobut-2-ene
D Z-2-chlorobut-2-ene
ANSWER
C E-2-chlorobut-2-ene
Analysis of Option/Explanation
Bylooking on to the structure given, following are the observations:-
i. It has four number of carbon in its long chain, hence it is “but”;
ii. It has C=C double bond, hence it is “ene”;
iii. The structure cannot be named in terms of “cis” and “trans” because the functional group attached to both C=C double are different i.e. not same.
iv. The structure will be named on the basis of “E” and “Z” only. Now for this we have to look for heavy molar mass on both side of the C=C double.
For Carbon at position 2, the heavy functional group is Chlorine. Whereas, for carbon at position 3, the heavy functional group is CH3. So respective heavy functional group are in opposite direction therefore it is “E-2-chlorobut-2-ene”.
Hence, option C is the correct answer.
