Download CHM 222: Organic Chemistry III

CHM 222: Organic Chemistry III
Review 1 (Chapters 14 & 16)
1. Name the following alcohols acording to IUPAC nomenclature.
Cl
OH
(A)
Br
OH
(B)
(A) 2-butanol
H
(C) H3C
OH
CH 2CH 3
OH
OH
(D)
CH 2CH 2OH
(E)
(B) 5-bromo-3-hexanol (C) (2S)-1-chloro-2-propanol
(D) ethylcyclobutanol
(E) (1R, 2R)-2-(2-hydroxyethyl)cyclopentanol
2. Do you expect hyperconjugation to be important in stabilization of alkyloxonium ions? (e.g. ROH 2+ or R2OH+)
Explain your answer with respect to the orbitals involved.
No. There are no empty orbitals on the oxygen atom. The oxygen is formally positive but has a
complete octet of electrons surrounding it. Therefore, the oxygen is not electron deficient.
3. Predict and explain the outcome of the following reactions on mechanistic grounds.
Cl
Cl
Cl
OCH2CH3
Cl
+ (CH3)3CO K
PCC, CH2Cl2
HO
Cl
+ CH3CH2OH
Br
O
OH
OH
SN1
E2 at least
sterically hindered
site
oxidation
4. When 2-ethyl-1-butanol is treated with zinc chloride (ZnCl2) in concentrated hydrochloric acid, a mixture of
chloroalkanes forms, including chiefly 2-ethyl-1-chlorobutane, 3-chlorohexane, 2-chlorohexane, and 3-chloro3-methylpentane. When 2-ethyl-1-butanol is treated with thionyl chloride in pyridine, only 1-chloro-2ethylbutane is formed. Write a detailed mechanism which accounts for these observations.
OH
Cl
ZnCl2
Cl
HCl
1,2-hydride
shift
Cl
Cl
1,2-hydride
shift
Cl
Cl
1,2-alkyl
shift
Cl
Cl
O
O
OH
O
S Cl
Cl
S
O
H
Cl
O
Cl
S Cl
H
N
O
Cl
Cl
O
pyridine
S Cl
5. Suggest a synthesis for tetrahydrofuran starting from but-3-en-1-ol (could also be named 3-butenol). HINT: it
can be done in 2 steps.
HBr
HO
H2O2
Br
HO
O
Na2CO3
6. Suggest separate syntheses for cis- and trans-1,2-cyclopentanediol, starting from cyclopentanol.
OH
OH
+
H ,
OH
OsO4
mCPBA
OH
O
OH
1. NaOH
2. H+
7. Predict the multiplicities of the indicated hydrogens in the 1H-NMR spectrum of the following compounds.
triplet
Cl
doublet of doublets
H
H
Cl
Cl
H H
doublet
H
H
doublet of doublets
doublet of doublets
8. Predict the approximate chemical shifts, multiplicities and integrals for the absorptions in the 1H-NMR spectra
of the following compounds.
O
O
H3C
OH
9. Suggest how the following compounds could be distinguished from each other by 1H-NMR spectroscopy.
two singlets for
CH2 and CH3
O
O
and
and
quartet for CH2
triplet for CH3
Cl
Cl
O
O
singlet for one
of the methyl
groups
aldehyde
hydrogen
Cl
O
and
O
complex
aromatic
region
H
Cl one singlet
for aromatic
hydrogens
quartet for CH2
triplet for CH3
and
singlet for one
of the methyl
groups
10. Suggest structures for the following four compounds consistent with the spectral information given. First the
molecular formula is given. Then the absorptions in the 1H-NMR are listed as chemical shift (multiplicity,
integral). Some compounds also have an important IR peak given.
C4H9Cl; 3.35  (doublet, 2), 2.0  (multiplet, 1), 1.0  (doublet, 6).
Cl
C3H6Br2; 3.6  (triplet, 2), 2.4  (quintuplet, 1).
Br
Br
C4H10O; 3.3  (doublet, 2), 2.4  (singlet, 1), 1.7  (multiplet, 1), 0.9  (doublet, 6); 3330 cm -1, broad.
OH
C5H10O; 2.6  (septet, 1), 2.1  (singlet 3), 1.1  (doublet, 6); 1716 cm -1.
O
11. Explain how many absorptions would appear in the 1H-NMR spectrum of the following compound.
Cl
Cl
There will be three absorptions. The two hydrogens on the methylene group will each have a
different chemical shift. One will be cis to the chlorines and the other wil be trans.