CHEMISTRY 2311-EXAMINATION III
NOVEMBER 21, 1997
DR. MARK A. FORMAN
NAME:
QUESTION
POINTS
SCORE
1
3
_______
2
6
_______
3
5
_______
4
15
_______
5
4
_______
6
4
_______
7
12
_______
8
12
_______
9
12
_______
10
9
_______
11
6
_______
12
6
_______
13
6
_______
TOTAL
_______
1.
Assign an (R) or (S) configuration to the stereocenter in norepinephrine (3 points).
OH
C
HO
H
CH2NH2
__________
HO
2.
Answer the following questions about tartaric acid.
H
H
COOH
OH
OH
COOH
a.) What is (R)/(S) designation of the indicated stereocenter? (3 points)
b.) Is this stereoisomer of tartaric acid optically active? Why or why not? (3 points)
3.
a.) Place an asterisk at all stereogenic centers in guaiol (3 points).
H 3C
H 3C
C
H 3C
CH3
OH
b.) How many stereoisomers are possible for guaiol? Show how you arrived at this conclusion (2 points).
4.
Identify the relationship between the following pairs of molecules by describing them as enantiomers,
diastereomers, constitutional isomers, or two molecules of the same compound. (15 points)
a.)
b.)
COOH
HO
CH3
H
H
HOOC
c.)
CH3
CH3
OH
Cl C H
Br
___________________
CH3
Br
C
H
H
Cl
Cl
___________________
d.)
e.)
CH3
CH3CH2
H
C CH
3
Cl
CH3CH2
CH3
Cl
________________________
5.
CH3
H
CH3
CH3
______________________
Provide an IUPAC name for the following molecule (4 points).
CH2CH2CH2CH3
H C
H3C Br
6.
____________________________
What is a Grignard reagent? Give an example (4 points).
CH3
H
Cl
CH3
H
Cl
CH3
Cl
H
CH3
____________________
7.
Match each of the following definitions to a term from the list below. Place the letter of the term in the
blank to the left of the definition (12 points).
A. Racemic Mixture
D. Resolution
B. Enantiomers
E. Diastereomers
C. Stereogenic Center
F. Meso Compounds
________ Stereoisomers that are non-superimposable mirror images.
________ The process of separating a racemic mixture into pure enantiomers.
________ Molecules which contain stereogenic centers but are achiral.
________ A 50:50 mixture of enantiomers.
________ Stereoisomers that are not mirror images.
________ An atom connected to 4 different groups.
8.
Provide reagents which will carry-out the following transformations (12 points).
a.)
b.)
CH3
HO C CH3
CH3
Br
CH3
Br C CH3
CH3
c.)
CH3Li
9.
(CH3)2CuLi
CH3CH2CH2CH2CH3
Which product (or products) would you expect to obtain from each of the following reactions? In each
case, give the mechanism (S N1, SN2, E1, E2) by which each product is formed and predict the relative
amount of each (i.e. the only product, the major product, a minor product etc.?) (12 points)
a.)
CH3
Br C CH3
CH3
CH3CH2O Na
dimethylsulfoxide
(DMSO)
b.)
H3C Br
CH3OH
25 oC
10.
Draw all resonance structures for each of the following (9 points).
a.)
b.)
11.
Consider the following reaction.
NaOH
CH3CH2CH2I
dimethylsulfoxide
(DMSO)
CH3CH2CH2OH
a.) What affect would you expect on the rate of the reaction if the concentration of sodium hydroxide is
doubled? Explain (3 points).
b.) What affect would you expect on the rate of the reaction if the solvent was changed from DMSO
(dimethylsulfoxide) to water? Explain (3 points).
12.
Consider the following reaction.
CH3
Br C CH3
CH3
H2O
CH3
HO C CH3
CH3
a.) What affect would you expect on the rate of the reaction if leaving group was changed to iodide?
Explain (3 points).
b.) What affect would you expect on the rate of the reaction if the concentration of water is tripled?
Explain (3 points).
13.
a.) Which substrate will react faster in an SN2 reaction with hydroxide (3 points)?
CH3 I or (CH3 )3 CI
a.) Which substrate will react faster in an SN1 reaction with methanol (CH3 OH) (3 points)?
CH3 F or CH3 CHBrCH3