Question 13.3: Draw structures for both the cis and trans isomers of hex-2-...
Draw structures for both the cis and trans isomers of hex-2-ene.
ANALYSIS First, draw a condensed structure of hex-2-ene to see which groups are attached to the double-bond carbons.
\overset{1}{C} —\overset{2}{C}=\overset{3}{C}—\overset{4}{C}—\overset{5}{C}—\overset{6}{C} Hex-2-ene
Next, begin to draw the two isomers. Choose one end of the double bond, and attach its groups in the same way to generate two identical partial structures.
Finally, attach groups to the other end in the two possible different ways.
Trace the longest chain in each structure. In the structure on the left, the longest chain comes in on one side of the double bond and exits on the same side; thus, the two hydrogens are on the same side of the double bond and this is the cis isomer. The structure on the left is the trans isomer because the longest chain comes in on one side of the double bond and exits on the opposite side, and the two hydrogens are on opposite sides of the double bond. It is common in line structures to show the hydrogens attached to the double bond, but not necessary.