1. No category

CHEM 234, Spring 2015
Third Midterm
PRINTED
FIRST NAME
Ian R. Gould
PRINTED
LAST NAME
ASU ID or
Posting ID
Person on your LEFT (or Aisle)
Person on your RIGHT (or Aisle)
1__________/13 .......................
• PRINT YOUR NAME ON EACH PAGE!
2__________/18.........................
• READ THE DIRECTIONS CAREFULLY!
3__________/40.........................
• USE BLANK PAGES AS SCRATCH PAPER
4__________/20.........................
work on blank pages will not be graded...
5__________/20 .........................
•WRITE CLEARLY!
6__________/30.........................
• MOLECULAR MODELS ARE ALLOWED
7__________/20.........................
• DO NOT USE RED INK
8__________/14.........................
• DON'T CHEAT, USE COMMON SENSE!
Total (incl Extra)________/175+5
Extra Credit_____/5
H
He
Li Be
B
N
O
F
Ne
Na Mg
Al Si P
S
Cl
Ar
Ga Ge As Se Br
In Sn Sb Te I
K
Ca
Rb Sr
Cs Ba
Sc Ti V
Y
Cr Mn Fe Co Ni Cu Zn
Zr Nb Mo Tc Ru Rh Pd Ag Cd
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
Tl Pb Bi Po At
H
C
C
N
2850–2960
Rn
Me/Et
1600–1660
11
220 O
10
200
R C OH
~2.7
Approximate Coupling
Constants, J (Hz), for
1H NMR Spectra
H H
H
1680
~7
H
OR
H
~10
C C
1735
CH
~8
H
1600
O
2000
H
O
C CH3
–H2C NR2
7
140
6
120
5
100
R2C
Aromatic
CR2
C CH
4
80
3
60
RC
CR
Alkyl
3Y > 2Y > 1Y
2
40
–OCH2–
R C N
H
~15
C C
1500
–OCH2–
C CH2
8
160
~2
H
NR2
1650
NMR Correlation Charts
H
H
C
1710
~2
C C
O
Aromatic Ar H
mainly 8 - 6.5
O
C
t-Bu/Me
O
C
2500
9
180
~1.1
~2.9
N
–H2C X
(δ, ppm)
~0.95
i-Pr/Me
C C
2200
3000
O
C H
Et/Me
~2.6
C
C
C
amine R NH2 variable and condition
alcohol R OH dependent, ca. 2 - 6 δ
O
R C OH
~1.4
H
C
O
C O H
3500
~0.9
C
broad ~3000
(cm-1)
Me/Me
H
broad with spikes ~3300
broad ~3300
Me/Me
O
2200
O H
H/Me
Xe
C
2720–2820
2 peaks
3000–
3100
N H
Kr
H
C
3300
~1.0
Infrared Correlation Chart
H
Gauche
Eclipsing
H/H
usually
strong
O
C H
Interaction Energies, kcal/mol
1
20
0
0
Alkyl 3Y > 2Y > 1Y
C X
C NR2
-2-
CHM 234, Spring 2015, Midterm #3
NAME
Question 1 (13 pts). Give the IUPAC name for the following compound. Be sure to use
cis/trans, E/Z or R/S where appropriate.
O
OH
Question 2 (18 pts) For the electrocyclic ring-closure reaction shown below
CH3
F3C
heat
H3C
CH3
a) Draw the arrow-pushing to account for the reaction and draw the product
b) How many electrons are involved in this reaction?
c) Is the allowed product formed via a Huckel or a Mobius transition state? Briefly
explain your choice in terms of the concept of aromaticity.
d) Does the allowed reaction proceed via a CONROTATORY or DISROTARORY
ring closure? BRIEFLY explain your choice.
Extra credit question (5 pts). β-carotene is synthesized using which reaction?
Clemmenson
Grignard
Wittig
Aldol
-3 -
CHM 234, Spring 2015, Midterm #3
NAME
Question 3 (40 pts.) Provide the missing major organic products or reagents/conditions as
appropriate, you can IGNORE stereochemistry in these problems
O
SO3/H2SO4
a)
O
O
O
b)
1. PhMgBr
O
2. Zn(Hg)/HCl/H2O
O
Na+ –OCH3
c)
CH3OH
O
d)
Br
Br
H
O
1 Equiv. H2NMe
e)
O
H+ cat.
-4CHEM 234, Spring 2015 MIDTERM #3
NAME
Question 4 (20 pts.) 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.
NO2
CO2H
SO3H
CHM 234, Spring 2015, Midterm #3
-5NAME
Question 5 (20 pts.) Synthesize the (target) molecule on the right from the starting
molecule 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.
O
O
OH
-6-
CHM 234, Spring 2015, Midterm #3
NAME
Question 6 (30 pts.) For the following TWO reactions a) and b):
1) Give a complete arrow-pushing mechanisms
2) Indicate the lewis acid/base for each INTERmolecular step (LB or LA) and whether they
are also Brønsted bases/acids (LB/BB or LA/BA)
3) Show where every proton comes from and goes to (i.e., no +H+ or -H+)
4) DRAW ALL RELEVANT RESONANCE CONTRIBUTORS FOR THE INTERMEDIATES
MeOH (solvent)
a)
heat
Br
Give the number of steps in your mechanism for reaction a) _________
O
b)
H2O
H2SO4 cat.
OH
OH
Give the number of steps in your mechanism for reaction b) _________
-7-
CHM 234, Spring 2015, Midterm #3
NAME
Question 7 (20 pts) Give the curved arrow pushing mechanism for the following reaction, you do
NOT need to indicate the acids/bases at each step, AND you can use the abbreviated +H+/-H+
notation, BUT you MUST include all important resonance contributors for the intermediates
O
N
TsOH (cat.)
H2N
Question 8 (14 pts). Rank the following reactions in order of increasing equilibrium constant for
formation of the acetal and give a BRIEF explanation
O
O
A
HO
OH
O
O
smallest
HCl cat.
O
B
HO
H
OH
O
H
HO
C
O
HCl cat.
O
OH
HCl cat.
<
O
O
O
<
largest