What is the correct IUPAC name for the molecule shown below?
E)-4-isopropyloct-3-en-5-yne
Z)-4-isopropyloct-3-en-5-yne
E)-5-isopropyloct-5-en-3-yne
Z)-5-isopropyloct-5-en-3-yne
E)-4-(2-methylethyl)oct-3-en-5-yne

Question

What is the correct IUPAC name for the molecule shown below? 
E)-4-isopropyloct-3-en-5-yne 
Z)-4-isopropyloct-3-en-5-yne 
E)-5-isopropyloct-5-en-3-yne 
Z)-5-isopropyloct-5-en-3-yne 
E)-4-(2-methylethyl)oct-3-en-5-yne

Quizplus · Accepted Answer

The longest continuous carbon chain in the molecule is eight carbons long and contains a triple bond and a double bond. The triple bond is given the highest priority for naming purposes, so the chain is numbered from the end closest to the triple bond, giving a locant of 3 for the triple bond and a locant of 5 for the double bond. The substituent on carbon 4 is isopropyl, and since the double bond creates a cis configuration between carbons 3 and 4, the configuration is Z. Therefore, the correct name is (Z)-4-isopropyloct-3-en-5-yne.

What Is the Correct IUPAC Name for the Molecule Shown