3 The first and fourth compounds do not contain
the molecular fragment H-O-C-H. They would not be
oxidized.|
Chemistry 251/253 |
|
Homework 1 |
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0
2. How many of the following alcohols would be oxidized by treatment with CrO3/H2SO4/H2O?
3 The first and fourth compounds do not contain
the molecular fragment H-O-C-H. They would not be
oxidized.
3. Oxidation of an alcohol with aqueous chromic acid produced a
compound that gave the attached 1H-NMR
spectrum. Draw the structure of this alcohol.
CC(O)C(C)c1ccccc1
4. Draw the structure of the product of the following sequence of reactions:
[2H]C(CC)c1ccccc1The first reaction is a free radical bromination. It occurs selectively at the carbon atom adjacent to the phenyl ring. The second reaction generates an organolithium reagent, which is a very strong base. When treated with D20, an acid-base reaction occurs to yield the deuterated product along with a molecule of LiOD.
5. Draw the structure of the product of the following sequence of
reactions:
O=CCCc1ccccc1
6. Draw the structure of the alkene that is best suited for the preparation of (CH3)2CHCH2CHO. (CH3)2CHCH=CH2 CC(C)C=C
7. Draw the structure of the alkene that you should use as a
starting material in the preparation of
.
CC(C)C=Cc1ccccc1
8. Select the species that is most basic:
C
The most basic compound is the conjugate base of the weakest
acid.
9. What is the number of the carbon atom that would be
deprotonated in the following reaction?
4
The protons attached to C-3, C-4, and C-7 all have a pKa of about 19.
The negative charge in the conjugate base produced by deprotonation
of C-4 is stabilized by resonance interactions with the carbonyl
group and the phenyl ring. It is the most stable of the three
conjugate bases.
10. How many of the following compounds would not react
with PCC? 
3
The first and fourth compounds do not meet the structural
requirements for oxidation. The second compound will not react with
PCC, but it would be oxidized by an acidic aqueous solution of
CrO3.
11. How many of the following compounds would not form an
enolate ion when treated with aqueous NaOH?
1
The third compound does not contain any hydrogen atoms on a carbon
that is adjacent to the carbonyl carbon.
12. Draw the structure of the product of the following
reaction:
Assume that all the bonds in the product are covalent.
COc1ccc(C[Mg]Br)cc1
13.The generalized reaction RLi + R'H ==> RH + R'Li is called
transmetallation. What is the equilibrium constant for the
following transmetallation reaction?
Keq
= 10e6 The pKa of butane is approximately 50 if you use methane as
your reference compound, while that of benzene should be about 44 if
you use ethene as your reference compound.
14. Draw the structure of the product of the following
reaction:
CCC(C)(O)O
15. Draw the structure of the major product of the
following reaction:
CCC(C)(C)O
16. Al Keene isolated an unknown compound from a wad of bubble gum he found stuck under the chair in his organic chemistry class. Out of curiosity Al decided to run some tests on the gum to see if he could determine its composition. He observed that a sample of the gum immediately decolorized a solution of Br2 in CCl4. When he treated another portion with aqueous sulfuric acid, Al obtained two new compounds, one of which turned an acidic aqueous solution of CrO3 from orange to green, the olther of which did not. The compound that turned the chromic acid solution green gave the attached 1H-NMR spectrum. Draw the structure of the compound that decolorized the Br2 in CCl4.
CC=C(C)C17. Draw the structure of the carbanion that would be formed by a
kinetically controlled deprotonation of 
.
CC1CC[CH-]C1=O
18. Draw the resonance structure that makes the most
important contribution to the enolate ion that is formed when
is
deprotonated under thermodynamically controlled
conditions.
CC1=C([O-])CCC1
19. Hexadeuteroacetone, a useful solvent for H-NMR work, may be
prepared by treatment of acetone with a strong base in
D2O:
.
Draw the structure of the deuterated product that would be formed
in the following equilibrium:
(You must show deuterium atoms explicitly in JavaGrins.)
[2H]C([2H])([2H])C(=O)C([2H])([2H])C(=O)C([2H])([2H])C
20. What is the equilibrium constant for the following
reaction?
10e34
21. What is the equilibrium constant for the following
reaction?
10e31
22. Draw the structure of the alkene that is best suited for the
preparation of 
by
a reaction sequence involving hydration followed by oxidation.
CCC(=C)C23. Select the best description of the following reaction
sequence:
|
A. The regiochemistry of reaction 1 is incorrect. |
B. The alcohol will be oxidized to a carboxylic acid in reaction 2. |
C. Neither reaction 1 nor reaction 2 will proceed as indicated. |
D. Both reaction 1 and reaction 2 will proceed as indicated. |
24. How many of the following alcohols could you prepare satisfactorily by a hydroboration/oxidation sequence with an appropriate alkene? 1 Only the second compound could be made by this method. Attempts to prepare the other alcohols would either produce a mixture of regioisomers or the wrong regioisomer.
25. The oxidation of 
produced
a compound that gave the attached 1H-NMR
spectrum. Draw the structure of this compound.
CCC#N
This sequence of oxidations is analogous to the oxidation of a
primary alcohol to an aldehyde followed by oxidation of the aldehyde
to a carboxylic acid.
26. Polly Ester performed the following reaction sequence
successfully:
However, she used up all of the 3-phenyl-1-butene when she ran the
reaction. This was unfortunate because Polly's sister Ethyl needed
some of this alkene for her own purposes. So Ethyl ran the following
reaction sequence in order to convert some of Polly's
3-phenyl-2-butanone back to 3-phenyl-1-butene:
,
where [H] is a generic representation for a reduction
reaction. It was also unfortunate because Ethyl did not isolate any
of the desired 3-phenyl-1-butene she needed. Draw the structure of
the material that Ethyl did obtain.
The
dehydration reaction produced the more stable trisubstituted alkene.
CC=C(C)c1ccccc1
27. The reaction
is
A. an oxidation B. a reduction C.
neither an oxidation nor a reduction.
28. Draw the structure of the compound with the lowest MW that has
the empirical formula CHO2 in which the oxidation
level of the carbon(s) is +3. 
OC(=O)C(=O)O
29. An unknown compound, which was a solid at room temperature,
contained 27.3% C. The 13C-NMR spectrum contained one
signal. The compound was completely resistant to oxidation. Draw a
structure that is consistent with this information. Note- carbon
dioxide is not a solid at room temperature.
In
both of these compounds the oxidation level of the carbons is +4,
which is the highest oxidation level possible for carbon. That is why
these compounds are completely resistant to oxidation. O=C1OC(=O)O1
or O=c1oc(=O)oc(=O)o1
30. Draw the structure of the alkene that is best suited to the
preparation of 
by
a reaction sequence involving hydration followed by oxidation.
CC(C)(C)C=Cc1ccccc1