name (this is an open brain exam, those who brought their...
TRANSCRIPT
Final Exam for Organic I 200pts (graded as 300pts) Name (This is an "open brain" exam, those who brought their brain, are encouraged to keep it open during the examination). 1) Explain in a simple sentence what is meant in a chemical sense by the
following arrows. (7.5 pts)
(c)
(d)
(b)
(a)
(e)
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2) Name the classes of compound that the following molecules belong to
(E.g. alkane, amide, etc). (13.5pts)
R-C C-R
R O-H
R O-R
O
RR
O
HR
O
O-HR
O
O-RR
O
ClR
R NH2
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3) Classify each of the following reactions as either an Elimination,
Addition or Substitution. (7.5pts)
(c)
(d)
(b)
(a)
(e)
HH3CBr H
HH3C
I
H3CH
Br
Br
HCH3 CH3H3C
H3CH
Br
Br
HCH3
H CH3
HH3C
C C:-Ph + CH3-Br C C CH3Ph
4) Draw Lewis structures (sticks for bonds, and dots for lone pairs) for the
below two molecules. (6.5pts)
CH CH OH CH CO H3 2 3 2
5) For the above two molecules, label the hybridization of all the carbons
and oxygens. (5pts)
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6) Explain why ethanoic acid is a much stronger acid than ethanol. (10pts) 7) On the below energy level diagram, label (a) the axes (b) the reactants
and products (c) any transitions states (d) ΔHo for the overall reaction (e) is this reaction exothermic or endothermic (f) is this reaction more likely to proceed by an E1 or E2 mechanism? (10pts)
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8) Explain why CH3
+ (methyl cation) has a different three dimensional geometry to CH3
- (methyl anion). (12pts) 9) Briefly explain which of the two above geometries best describes CH3•
(methyl radical)? (3pts)
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10) Name the following molecules in IUPAC form. (16pts)
(c)
(d)
(b)
(a)
(e)
F
OH
Br
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11) Asterix any chiral atoms in these molecules, and assign R or S to each
chiral center. (15pts)
(c)
(d)
(b)
(a)
F
F
F
F
F
F
F
F
H
CH3FCl
CH3
CF3
CH2FClHClH
CH2F
12) Which of the above molecules are achiral, and in a sentence explain
why they are achiral. (4pts)
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13) Circle the more stable member of each pair, and in a sentence explain your choice. (15pts)
(a)
(b)
(c) CH2
(d) CH2
(e)
++
CH2
++
14) Name two of the geometrical conformations a cyclohexane molecule
can adopt. (2pts) 15) Name the two different positions that the hydrogens of cyclohexane
can be located in the more stable geometrical conformation. (2pts)
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16) Even in its most stable geometry, Bromo-cyclohexane can exist as
two conformers. Draw these two conformers, and label which is the more stable, and in a sentence explain why one is more stable. (10pts)
17) Name the two allowed geometries for any elimination reaction to
proceed. (3pts)
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18) Which conformation of bromocyclohexane in (16) undergoes reaction with potassium tbutoxide, and explain in a sentence your choice. (4pts)
19) Provide a mechanistic explanation for the observed mixture of
products in the following SN1 reaction. (10pts)
D2CC
CH2-Br
HCH3OH
SN1D2C
HC
CH2
OCH3H2C
HC
CD2
OCH3
20) What would you expect the approximate ratio of these products to be?
(2pts)
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21) Give the products of 5 of the 6 following reactions. (15pts)
(c)
(d)
(b)
(a)
(e)
HH3C
I
HH3C
1) NaNH2
2) CH3CH2Br
1) Mg, Ether
2) D2O
HBr, Peroxides
H CH3
CH3H
1) BH3.THF
2) H2O2, NaOHH CH3
CH3H
1) Hg(OAc)2,H2O
2) NaBH4
(f) HH3C1) Na, NH3
21b) Write the mechanism for one of the above anti-Markovnikov additions. (6pts)
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22) Give reagents to perform 5 of the 6 following transformations. (15pts)
(c)
(d)
(b)
(a)
(e)
OH
HH3C
(f) HH3C
NH2
OH O CO
CH3
H
O
O O
O
OH O
O
HCl
H OH
Br
Br
22b) Write the mechanism for either of the above alkyne reactions. (6pts)
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