91Ó°ÊÓ

Label each \(\mathrm{C}-\mathrm{C}\) double bond as \(\mathrm{E}\) or \(\mathrm{Z}\). Kavain is a naturally occurring relaxant isolated from kava root. CC=CC1C=C(C)CC(=O)C1 a. b. CCC(C)=C(C)CC c.

Addition of HBr to which of the following alkenes will lead to a rearrangement? a. \(\mathrm{CH}_{2}=\mathrm{C}\left(\mathrm{CH}_{3}\right) \mathrm{CH}_{2} \mathrm{CH}_{3}\) b. \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{2} \mathrm{CH}_{3}\) c. \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}\left(\mathrm{CH}_{3}\right)_{2}\)

Each of the following names is incorrect. Explain why it is incorrect and give the correct IUPAC name. a. 2 -butyl-3-methyl-1-pentene d. 5 -methylcyclohexene g. 1 -cyclohexen- 4 -ol b. \((Z)-2\) -methyl-2-hexene e. 4 -isobutyl-2-methylcyclohexene h. 3 -ethyl-3-octen- 5 -ol c. (E)-1-isopropyl-1-butene f. 1 -sec-butyl-2-cyclopentene

Draw an energy diagram for the two-step mechanism for the addition of \(\mathrm{Br}_{2}\) to \(\mathrm{CH}_{2}=\mathrm{CH}_{2}\) to form 1,2 -dibromoethane. Draw the structure of the transition state for each step.

Explain each of the following differences in alkene reactivity in electrophilic addition reactions. a. \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}=\mathrm{CHC}_{6} \mathrm{H}_{5}\) reacts with HBr faster than \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{3}\), even though both compounds are 1,2 -disubstituted alkenes. b. When treated with \(\mathrm{H}_{2} \mathrm{O}\) in the presence of acid, \(\mathrm{CH}_{2}=\mathrm{C}\left(\mathrm{CH}_{3}\right) \mathrm{CH}_{2} \mathrm{OCH}_{3}\) reacts more slowly than \(\mathrm{CH}_{2}=\mathrm{C}\left(\mathrm{CH}_{3}\right)_{2}\).