CHEM 234, Spring 2011
FINAL EXAM
ANSWER
PRINTED
FIRST NAME
Ian R. Gould
KEY
PRINTED
LAST NAME
ASU ID or
Posting ID
Person on your LEFT (or Aisle)
Person on your RIGHT (or Aisle)
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• DON'T CHEAT, USE COMMON SENSE!
Total (incl Extra)________/375+5
Extra Credit_____/5
H
He
B
N
O
F
Ne
Na Mg
Al Si P
S
Cl
Ar
H/H
~1.0
Me/Me
~0.9
Ga Ge As Se Br
Kr
H/Me
~1.4
Et/Me
~0.95
In Sn Sb Te I
Xe
Me/Me
~2.6
i-Pr/Me
~1.1
Tl Pb Bi Po At
Rn
Me/Et
~2.9
t-Bu/Me
~2.7
K
Ca
Sc Ti V
Cr Mn Fe Co Ni Cu Zn
Rb Sr
Y
Zr Nb Mo Tc Ru Rh Pd Ag Cd
Cs Ba
Lu Hf Ta W
small range
range of values
broad peak
Re Os Ir Pt Au Hg
O H
C N
N H
C O
C
H
C
C
N
2850–2960
H
1680
C
OR
2000
10
200
R C OH
O
C
H
O
C CH3
–H2C NR2
C CH2
8
160
7
140
6
120
5
100
Aromatic
CR2
C CH
4
80
3
60
RC
CR
Alkyl
3Y > 2Y > 1Y
2
40
–OCH2–
R C N
R2C
H
~15
C C
1500
–OCH2–
NMR Correlation Charts
Aromatic Ar H
mainly 8 - 6.5
9
180
~2
H
NR2
1650
2500
H
H
C
1710
3000
11
220 O
~8
~2
C C
O
2200
–H2C X
(δ, ppm)
H
~10
H
1600
O
C
amine R NH2 variable and condition
alcohol R OH dependent, ca. 2 - 6 δ
O
C H
H
C C
1735
CH
broad ~3000
O
R C OH
~7
C C
H
C
O
C O H
3500
H H
O
H
broad with spikes ~3300
broad ~3300
N
C
2200
O H
1600–1660
O
2720–2820
2 peaks
3000–
3100
N H
C
C
H
C
3300
Approximate Coupling
Constants, J (Hz), for
1
H NMR Spectra
Infrared Correlation Chart
H
Gauche
Eclipsing
usually
strong
O
C H
(cm-1)
C
Interaction Energies, kcal/mol
Li Be
1
20
0
0
Alkyl 3Y > 2Y > 1Y
C X
C NR2
CHM 234, Spring 2011, FINAL EXAM
NAME
- 2-
Question 1 (20 pts.) Provide IUPAC names for the following structures, do not forget to use
E/Z and R/S as appropriate.
a)
1
2 CO2H
3
4
(2S)-hydroxy-3-methylbutanoic acid
OH
b)
8
7
6
5
O
Br
4
2
3
(2S)-bromo-6-methyloct-(6E)-en-4-one
1
Question 2 (20 pts.) Serum creatinine levels are used to measure renal function. Creatinin
exists in several tautomeric forms, two are shown below. Write a curved arrow-pushiung
mechanism that shows how the structure on the left is converted into the one on the right.
Show where all protons come from and go to (no +H+/-H+)
Show all resonance contributors to the intermediate structures
Label the Lewis acid/base and and Bronsted acids/bases as appropriate
N
LB/BB
H
N
N
O
O
H
H
H
N
H
N
N
H
N
O
LA/BA
N
H
H
N
O
H
H
N
H
H
N
N
H3O+
O
N
H
N
H
LA/BA
H
N
O
H
H
O
H
LB/BB
CHM 234, Spring 2011, FINAL EXAM
-3 -
NAME
Question 3 (27 pts.) For the following acid/base equilibrium:
a) draw the curved arrows showing bond making/breaking
b) indicate which is the STRONGER and the WEAKER acid and base on each side
c) give a BRIEF explanation for your choice of stronger/weaker that includes the phrase
"energy of the electrons"
H
H
H
H
H
H
slower
N H
N
N
N
H
H
+
+ H
faster
weaker base
weaker acid
stronger acid
stronger base
larger pKa
smaller pKa
equilibrium lies on THIS side
the weaker base has the lower energy electrons, the non-bonding electrons
in A are stabilized by resonance, are this lower in energy
d) Indicate which reaction (left to right or right to left) is faster and which is slower and indicate
on which side the equilibrium lies
e) Draw a PROPERLY labelled reaction energy diagram, indicate the position of the transition
state and include a drawing of the transition state
Energy
H
‡
H
H
‡
N
N
H
H
Reaction Coordinate
Question 4 (10 pts.) Indicate which of the following two structures A and B you would expect to
be the stronger Bronsted BASE, and give a brief explanation that includes the term "energy
of the eletrons". Assume that both structures are completely FLAT.
A
B
In A the electrons are in an aromatic system and are thus stabilized and lower in nergy,
less reactive, and thus a weaker base, in B the electrons are in an antiaromatic system
Extra Credit Question (5 pts). Which kind of molecule was used in the new Two-Electron
Sensitization Process for Photography that Dr. Gould worked on when at Kodak?
amine
ester
amide
aldehyde
-4-
CHM 234, Spring 2011, FINAL EXAM
NAME
Question 5. (38 pts.) Give the mechanisms for formation of the "Normal" and the "Conjugate" addition
products in the following reaction.
Show all resonance structures of the intermediates, show where all protons come from and go
to (no +H+/-H+) and label the Lewis/Bonsted acids/bases as appropriate
O
O
EtO– +Na/EtOH
EtO
H
EtO
O H
+
EtO Conjugate
EtO
Normal
H OEt
EtO H
O
O
EtO
EtO
O
EtO
b) Both products form with the same exothermicity, draw a reaction energy diagram for both reactions
ON THE SAME DIAGRAM, label the activation energy for the rate determining step for each reaction
EtO
O
energy
O
EtO
resonance stabilized,
lower in energy
O
OH
smaller Ea
EtO OH
+ EtO–
EtO
reaction coordinate
c) Under the reaction conditions, the conjugate product will tautomerize back into a ketone, give the
curved arrow-pushing mechanism for this reaction
Show all resonance structures of the intermediates, show where all protons come from and go
to (no +H+/-H+) and label the Lewis/Bonsted acids/bases as appropriate
LA/BA O
H
O
OEt LB/BB
EtO– +Na/EtOH
EtO
EtO
O
EtO
EtO–H
LA/BA
O
EtO LB/BB
-5-
CHM 234, Spring 2011, FINAL EXAM
NAME
Question 6 (64 pts)
Provide the missing products, reagents/conditions or reactants, as required. Do not
forget to include absolute and relative stereochemistry as appropriate unless
otherwise indicated
a)
1. excess CH3I
NH2
2. Ag2O/ H2O
3. heat
1.
HO
O
b)
/ H+ cat.
N
H
HO
O
ignore
stereochemistry
2. CH3Br
3. H3O+
O
H2N
OH
Ph
c)
Cl
1 equivalent
NMe2
Ph
HN
OH
O
NMe2
CO2CH3
CO2CH3
(±)
d)
heat
1 equivalent
O
O
HO
e)
O
O
H+
O
O
O
H
O
f)
O
OH
HCl cat.
heat
H
H
-6-
CHM 234, Spring 2011 FINAL EXAM
NAME
Question 6, Contd...
Provide the missing products, reagents/conditions or reactants, as required. Do not
forget to include stereochemistry as appropriate.
O
O
O
g)
OH
H3O+
heat
O
O
O
OH
H2N CH2 H
H Br
1. NaCN
h)
2. LiAlH4
3. H3O+
Question 7 (8 pts) Give a reactants and reagents/conditions that will give the following
structure in a Claisen reaction
O
O
1. Na+ –OMe/MeOH
OMe
OMe
2. H3O+
O
O
O
ignore
+ MeO
stereochemistry
OMe
excess
Question 8 (12 pts) Give a synthesis of the provided carboxylic acid from malonic ester.
TREAT THIS AS A SYNTHESIS QUESTION. This is a FIVE STEP synthesis, give
reagents/conditions and the intermediate molecules AT EACH STEP.
O
O
O
EtO
OEt
malonic ester
OH
H3O+ / heat
Na+ –OEt/EtOH
O
EtO
O
O
OEt
EtO
EtBr
EtBr
O
EtO
O
Na+ –OEt/EtOH
OEt
EtO
O
O
OEt
O
OEt
-7-
CHEMISTRY 234, Spring 2011 FINAL EXAM
NAME
Question 9 (24 pts.) For the cycloaddition reaction below
a) Draw the curved arrow-pushing that describes the bond-making and breaking processes.
Et
Et
Δ
Me
+
Pr
Me
Me
Pr
Et
Et
Me
b) Draw the HOMO and LUMO of the reactants as requested, ON TOP of the structures that
are redrawn below
Et
Pr
anti-bonding
Me
bonding
HOMO
Me
Et
LUMO
c) Is the cycloaddition reaction shown above allowed or forbidden. Give a BRIEF
explanation that includes the words suprafacial and/or antarafacial as appropriate
this is antarafacial on the cation and suprafacial on the alkene, which is forbidden based on
FMO theory since there is a bonding and an anti-bonding interaction interaction between the
pairs of atoms involved in making the two new sigma bonds
Question 10 (20 pts) Give the mechanism for the following reaction
• AS APROPRIATE, SHOW WHERE ALL PROTONS COMES FROM AND GO TO (no +H+/-H+)
• DRAW ALL RESONANCE CONTRIBUTORS for the intermediates as approriate
• At each INTERMOLECULAR step, INDICATE THE Lewis acid and base (LA or LB) and whether
they are also Bronsted acids and bases (BA or BB) as appropriate
O
O
O
O
OH
+
O
LA
+
OH
LB
O
O
O
O
H
O
LB/BA
O
O
O
O
H
O
LA/BA
O
CHEMISTRY 234, Spring 2011 FINAL EXAM
NAME
-8-
Question 11 (24 pts.) Give a curved arrow-pushing mechanism for the following reactionShow
where all protons come from and go to (no +H+/-H+)
Show all resonance contributors to the intermediate structures
Label the Lewis acid/base and and Bronsted acids/bases as appropriate
OH
O
LB/BB
O
H3O+
H
H O+ LA/BA
H
O
OH
O
O+ H
O
LA/BA
O H
LB/BB
H
O
O H
H
H
OH
O H
O
O H
O H
O H
LA/BA
LB/BB
H
O+ H
H
LA/BA
O
H
LB/BB
-9-
CHM 234, Spring 2011, Final Exam
NAME
Question 12 (24 pts) Provided are spectra for a compound with molecular formula C6H12O2
a) Give the degrees of unsaturation
1
degree of unsaturation
________________
b) On the infrared spectrum, indicate the peaks that identify the functional groups in the
molecule (including C(sp3)-H). Indicate BOTH the functional group, and where
appropriate, the specific BOND in the functional group that corresponds to the peak.
3401
H C
2879
1463
sp3
1089
1450
1199
2939
1372
O
O
1739
c) draw the structure and clearly indicate which hydrogens correspond to which
signals in the proton nmr spectrum (only)
2 peaks here
e
3H
d
2H
O
d
b
CH2 e
a CH2 c C
O
H3C
CH3
CH2
c
2H
b
2H
a
3H
CHM 234, Spring 2011 FINAL EXAM
- 10 -
NAME
Question 13 (24 pts.) Show how you would make the target componds on the right from the
starting compounds on the left. Show reagents and conditions where appropriate, and the
structures of important intermediate compounds. Do not show any (arrow pushing)
mechanisms. If necessary, you must indicate steps that require separation of isomers
NO2
separate
isomers
O
Cl
AlCl3
Cl
HNO3/H2SO4
O
O
Cl2/AlCl3
Zn/Hg/HCl/H2O
Cl
Cl
Question 14 (28 pts) Show how you would make the target componds on the right from the
starting compounds on the left. Show reagents and conditions where appropriate, and the
structures of important intermediate compounds. Do not show any (arrow pushing) mechanisms.
These 2 questions use only reactions from the basic sets that were provided on the class website
ignore
stereochemistry
a)
PCC
NBS, hν
Na+ –OH
Br
O
1. BH3.THF
2. –OH/H2O2
OH
OH
b)
Ph
Br
K+ –O-t-Bu
1. BH3.THF
2. –OH/H2O2
OH
PCC
O
H
1. PhMgBr
2. H3O+
CHM 234, Spring 2011 FINAL EXAM
NAME
- 11 -
Question 15 (32 pts.) In each case, synthesize the (target) molecules on the right from the
starting molecules the left. this can not be done in one reaction. Give reagents and
conditions and the intermediate molecules at each step. Do not show any mechanisms or
transient intermediates.
a)
N
HNMe2/H+
H2/Pd/C
HBr, ROOR
O
Br
MgBr 1.
Mg.THF
H
O
OH
PCC
2. H3O+
H
b)
Br
N
O
O
O
O
HO
OH
H+
Cl
Br
NH2
O
O
Na+ –CN
O
CN
O
O
1. LiAlH4
2. H3O+