Stereochemistry Problem Set

CH 201

Name ______________________________

1. Label the following as chiral or achiral.

Br

CH3

CH3

H

H3C

H

CH3
Achir al

C

C

H

H

I

Br

Br
I

CH3

CH3

CH3

Br

H

H

Br

CH3

Achir al

Achir al

Achir al

Achir al

2. Circle or supply the correct answer.

a. Which of the following is expected to rotate the plane of polarized light?

a meso compounda racemic mixtureCH2FBr

D-glyceraldehyde

b. The (-)-isomer of any compound MUST be levorotatory?

True

False

c. Which of the following tells you NOTHING (in the absence of additional information) about
the molecule's absolute configuration?

+

R

S

d. Cis-transisomers are correctly described as--

diastereomers

enantiomers

different conformations

racemic

e. For a molecule containing five chiral (stereogenic) centers, the maximum number of
stereoisomers is--

5

10

20

25

32

1

3. Give the stereochemical relationship between Compound A below and the five compounds B-F by
writing "enantiomer," "diastereomer," "identical," or "structural isomer" in the appropriate blanks.
IGNORE DIFFERENCES IN CONFORMATION.

A

COOH

H

OH

H

OH

COOH

COOH

OH

H

H

OH

COOH

COOH

OH

H

OH

H

COOH

B ______________

C ______________

COOH

H

COOH

H

OH

OH

D ______________

COOH

OH

H

COOH

OH

H

E ______________

C

C

H

H

OH

OH

COOH

COOH

F ______________

diastereomer

identical

identical

identical

structural isomer

2

4. Using the Fischer Projections below for the question below.

CH2CH3

H

Br

Br

H

CH3

CH2CH3

H

Br

H

Br

CH3

CH2CH3

Br

H

H

Br

CH3

CH2CH3

Br

H

Br

H

CH3

A

B

C

D

Using the letters below the frameworks to designate the structures that fit the following definitions. If no
example exists, write "none" in the blank. NOTE: Points will be deducted for extraanswers, even if
correct.

a. onepair of enantiomers _A&CorB&D_________

b. onepair of diastereomers __A&BorA&DorB&CorC&D_________

c. onemeso compound __NONE________

d. onecompound with the R configuration at carbon 2 (the lower "rung" on the framework)B or C

e. onecompound that, by itself, is optically inactive __NONE________

3