CHEM 234, Spring 2010 Third Midterm Ian R. Gould · CHM 234, Spring 2010, Midterm #3 - 2 - NAME...
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Transcript of CHEM 234, Spring 2010 Third Midterm Ian R. Gould · CHM 234, Spring 2010, Midterm #3 - 2 - NAME...
Third Midterm Ian R. Gould
PRINTED FIRST NAME
Person on your LEFT (or Aisle)
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
CHEM 234, Spring 2010
PRINTED LAST NAME
H/H ~1.0
Eclipsing
H/Me ~1.4
Me/Me ~2.6
Me/Me ~0.9
Et/Me ~0.95
i-Pr/Me ~1.1
t-Bu/Me ~2.7
Gauche
Me/Et ~2.9
Interaction Energies, kcal/mol
ASU ID or Posting ID
Person on your RIGHT (or Aisle)
• PRINT YOUR NAME ON EACH PAGE!
• READ THE DIRECTIONS CAREFULLY!
• USE BLANK PAGES AS SCRATCH PAPER
work on blank pages will not be graded...
•WRITE CLEARLY!
• MOLECULAR MODELS ARE ALLOWED
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1__________/18 .......................2__________/32.........................3__________/40.........................4__________/20.........................5__________/40 .........................6__________/25.........................
Extra Credit_____/5 Total (incl Extra)________/175+5
C NR2
RC CRR2C CR2
Aromatic
CR OHO
C X
R NH2R OH
aminealcohol
3Y > 2Y > 1Y
020406080100120140160180200220
–H2C X
–H2C NR2
–OCH2–
01234567891011
C CHC HO
CR OHO
Aromatic Ar HAlkylmainly 8 - 6.5
C CH2
C CH3
O
3Y > 2Y > 1YAlkyl–OCH2–
CO
(δ, ppm)
variable and condition dependent, ca. 2 - 6 δ
R C N
O H C N
CN
CC
H
C ON H
C H
C N
O
HCO
CH
C CH
COR
ON H
C H
CO
O H
C O HO
CNR2
O
3000–3100
2850–2960
3300
broad ~3300
broad with spikes ~3300
2200
broad ~30001710
2200
1650
2720–28202 peaks
1735
1600–1660
1680
range of valuesbroad peak
small range usuallystrong
1600
CH
CH
C CHH
CH
CH
CH
CH
H
H
H
H
Approximate Coupling Constants, J (Hz), for
1H NMR Spectra
~7
~10
~2
~15~2
~8
Infrared Correlation Chart
NMR Correlation Charts
3000 200025003500 1500(cm-1)
EASreactions
retro 1retro 2mxn 1
spect
ANSWER KEY
CHM 234, Spring 2010, Midterm #3 - 2 - NAME
Extra credit question (5 pts). β-carotene is synthesized using which reaction?
Clemmenson Grignard Wittig Aldol
from weekly work #12
Question 1 (18 pts). Rank the following reactions in order of increasing rate. Give a BRIEF explanation that includes discussions of Lewis acidity/basicity, nucleophilicity/ electrophilicity, substitution, addition, elimination or rearrangement as appropriate.
slowest fastest< <D B C
These are all electrophilic aromatic substitution, reaction at any position on a ring with a withdrawing group is slow because the W-group is deactivating, so reaction A is slower than both reactions B and C. Reaction B, meta with respect to the string donating group is slower than C (ortho-) because the positive charge in the intermediate in C is directly stabilized by the strong donating group whereas it is not in B.
NH2
O2NCl2
AlCl3NH2
O2N
Cl
A
NH2
O2NCl2
AlCl3NH2
O2NB
Cl
NH2
O2NCl2
AlCl3NH2
O2NC Cl
Question 2 (32 pts.) Provide the missing major organic products, you can IGNORE stereochemistry EXCEPT WHERE EXPLICITELY INCLUDED IN THE STARTING STRUCTURE, and you do NOT need to state what kinds of reactions these are or whether a solution of the product would be opticaly active.
CHM 234, Spring 2010, Midterm #3 - 3 - NAME
a)
c)
d)
b)
1. PhMgBr
2. Zn(Hg)/HCl/H2O
O
O
OOH
N
NH2
OHCl (cat.)
H
OO
KOH/heat
OBr HON2H4
O
HO
CO/HCl
AlCl3
O
HOCHO
Question 3 (40 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)
b)
CHEM 234, Spring 2010 MIDTERM #3- 4 -
NAME
O
Br
OH
O
H
N
H
NBS/hν
K+ –O-t-Bu
1. BH3.THF
2. –OH/H2O2
PCC
H2NMe/H+ (cat.)
Br
OO
OO OO
MgBr
OH
O
OH
OH
HO OH/ H+ cat. (not H3O+)
HBr/ROORMg.THF 1.
O
2. H3O+
NaBH4/EtOH
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.
CHM 234, Spring 2010, Midterm #3- 5 -
NAME
NO2
NO2
Br
NH2
Br
NH2
Br
HNO3H2SO4
Br2/FeBr3
H2/Pd/C
AlCl3separateisomers
NH2
Br
HO3S
O
O
Cl
O
SO3H2SO4
CHM 234, Spring 2010, Midterm #3 - 6 - NAME
Question 6 (20 pts.) Give a complete arrow-pushing mechanisms for the following reactions.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)a) DRAW ALL RELEVANT RESONANCE CONTRIBUTORS OF THE INTERMEDIATES
H
O
HOO OCH3
CH3OH
HCl (cat.)
ClH:
H
OH
HO:
O
OH
HCl
O
OH..
ClH
O
OH2
:
O
O
H
CH3:
O
O+
CH3
H
:
::
::
::
: :LB/BB
LA/BA
:
:
::
::: ::
..
.... :
:
:
:O: :
: :
: Cl
:: ::
LA/BA
LB/BB
LB/BB
LA/BA
LA/BALB/BB
LA LA LB
LB
TsOH (cat.)
OH2
OH
H
OTs
:: H-OTs
: :::
LB/BB LA/BA
LALB
LA/BA
LB/BB
b) DO NOT draw resonance contributors for the intermediates
CHM 234, Spring 2010, Midterm #3 - 7 - NAME
a) Give the degrees of unsaturation ________________0 degrees of unsaturation
Question 6 (25pts) Provided are spectra for a compound with molecular formula C6H14O
b) On the infrared spectrum, indicate which peaks correspond to which functional groups
3321
2981
2903
2846 1436
13561189
958
877
OH
Hsp3
3Htriplet
6Hsinglet
2Htriplet
1Hsinglet
2Hsextet
c) draw the structure and clearly indicate which hydrogens correspond to which signals in the proton nmr spectrum (only)
CH3CH2
CH2OH
CH3
H3Cc
a
a
b
b
cd
d
e
e