ORGANIC CHEMISTRY 301

EXAMINATION TWO-OCT. 30, 1996

I. (Five points each) Synthesize the following:

a. 1,2-dibromo-1,2-dimethylcyclohexane from 3-bromo-1,1-dimethylcyclohexane

b. 1,2-hexadiene from 1-hexene

c. 1-bromopentane from materials of two carbons or less

II. (Three points each) Complete the following reactions, include stereochemistry, where applicable.

a. 1-methylcyclohexene + HBr ®

b. 1-methylcyclohexene + O₃/H₂O₂ ®

c. 1-methylcyclohexene + HBr/peroxide ®

d. 1-methylcyclohexene + H₂/cat ®

e. 2-hexyne + Na/lig NH₃ ®

f. 3,3-dimethyl-1-butene + HOBr ®

g. 1-hexyne + H₂O ®

h. 1,3-cyclohexadiene + Br₂/CCl₄ ®

i. 1,3-cyclohexadiene + O₃/Zn,H⁺ ®

j. acetylene + O3/Zn, H⁺ ®

k. 1,4-heptadiene + H₂SO₄ ®

l. cyclopentene + ? ® 1,2-dihydroxycyclopentane

III. (Fifteen points) Consider the following compound:

Compound A (C₈H₁₂)

A + Br₂/CCl₄ ® colorless

A + KMnO₄ ® brown ppt.

A + H₂/cat ® B + C (both C₈H₁₄)

major

A + excess H₂/cat ® D (C₈H₁₆)

B + HBr ® E

B + HBr/peroxide ® E

E + alc-KOH ® B + C + F

major minor

A + O₃/Zn,H⁺ ® G + 2H

B + O₃/Zn,H⁺ ® I

B + O₃/H₂O₂ ® I

C + O₃/Zn,H⁺ ® J + H

C + HBr ® E

C + HBr/peroxide ® K

Identify A through K

IV. (Four points each)

a. Would the following compound show a preference of 1,2 versus 1,4 addition to the diene system? Explain.

b. For the hydrogenation of cyclohexene to cyclohexane would it matter what type of catalyst was used in the process? Explain.

c. Explain why the addition of HCl to the following compound would be fairly complex.

d. Why is the E,Z system of alkene nomenclature better than the cis,trans system?

e. Why does the allylic halogenation of alkenes leave the pi bond intact?