Chem 334 - Fall 2001
Organic Chemistry I
Dr. Carl C. Wamser

EXAM 2 Answers

1. (20 points) Write complete names for each of the following, including stereochemistry if it is specifically shown:

a)

(E)-3-chloro-2,2,7,7-tetramethyl-5-octen-4-ol

trans is also OK

b)

3,5-cyclooctadienol

c)

trans-4-vinylcyclohexanol

trans-4-ethenylcyclohexanol

d)

(Z)-3-isopropyl-3-penten-1,4-diol

3-(1-methyethyl) is also OK

2. (15 points) Arrange the following sets of compounds in order with respect to the property indicated.
Write "MOST" and "LEAST" under the compounds with the highest and lowest values of the property.

a) stability

LEAST / / MOST / / MIDDLE

b) stability

MIDDLE / / MOST / / LEAST

c) rate of dehydration

MOST / / MIDDLE / / LEAST

d) rate of bromine addition

MOST / / MIDDLE / / LEAST

e) rate of SN2 substitution by HBr

LEAST / / MOST / / MIDDLE

3. (15 points) Complete each of the following reactions by adding the missing part - either the starting compound, the necessary reagents and conditions, or the final major product. Show stereochemistry if it would be specific.

a)

b)

c)

d)

e)

4. (15 points) Heats of combustion for four isomers are indicated below.
Arrange the four compounds in order of stability.

Heats of combustion

cyclobutane 2721 kJ/mol LEAST STABLE
1-butene 2717 kJ/mol
cis-2-butene 2710 kJ/mol
trans-2-butene 2706 kJ/mol MOST STABLE

The heat of hydrogenation for trans-2-butene is 115 kJ/mol. Calculate what the other three values should be.

Heats of hydrogenation

cyclobutane 130 kJ/mol
1-butene 126 kJ/mol
cis-2-butene 119 kJ/mol
trans-2-butene 115 kJ/mol

Using C4H8 to represent any of the four isomers, write the balanced reaction that corresponds to the heat of combustion.

C4H8 + 6 O2 ------> 4 CO2 + 4 H2O

Using C4H8 to represent any of the four isomers, write the balanced reaction that corresponds to the heat of hydrogenation.

C4H8 + H2 ------> C4H10

Heating cyclobutane can lead to a ring opening to form 1-butene.
Calculate the expected delta H for this reaction.
Is it exothermic or endothermic?

delta H = - 4 kJ/mol (exothermic)

5. (10 points) Free radical halogenation of ethylcyclopropane can lead to five possible monochlorination products.
Write structures for all of them.

6. (10 points) Complete the following synthetic sequence by adding the missing parts.

Elimination products may also occur in this reaction. Show the structure of any elimination products expected.