Sp2002 Org II Exam #1 Ch (14-17) (100 points) 1) Provide one reason ...
Sp2002 Org II Exam #1 Ch (14-17)
(100 points)
NAME: To not have your graded script placed outside my office please check this box
1) Provide one reason why Molecular Orbital Theory is so important.
Draw a Lewis structure for a chemical species whose bonding is not accurately described by a Lewis Structure, and draw a more realistic delocalized / hybrid representation of that species. (4pts)
2) Indicate which of the following molecules are aromatic, non-aromatic or anti-aromatic. (Assume all the molecules are planar). (15pts) O
N
N
N
_
O
H B
+
S
3) Which one of the above compounds would you predict to be the least stable of this group, and justify your guess in a sentence. (3pts)
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4) By applying the polygon rule to the below cyclic hydrocarbon:
a) draw out the MO energy level diagram b) label the MO’s using π1….π6* c) circle one pair of degenerate orbitals d) draw in the electrons and explain whether this compound is predicted to be aromatic or antiaromatic. (8pts)
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5) Predict the products in the following reactions (if you believe no reaction will occur, indicate this!), paying attention to regio/stereochemistry where applicable. (21pts) heat
O H Br
H
Br HNO3, H2SO4
CO2H
Excess HI O
O-CH3
H3C
CH3
Heat
NO2 Cl2, AlCl3
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
UV Light
CO2H
OH
heat
1) NaOH 2) CH3CH2Br
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6) The below compound displays 6π Huckel aromaticity. H N
N H
H
H
Choose a nitrogen atom, and describe its hybridization and electron contribution to the aromatic π system.
Which nitrogen would be protonated first in concentrated sulfuric acid?
Which nitrogen is the most basic? (12pts)
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7) Give reagents and conditions to accomplish the following transformations, and draw A where applicable. (18pts)
Cl
A NO2
Cl
Br
A NO2 HO O
Cl
(Ph-CHCl-CH2)2O
O C
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PhCH2Ph
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8) The reaction of 1 equivalent of ethanoyl chloride (with a catalytic amount of AlCl3) with the below bi-aryl compound results in a mixture of products, but one major product in over 90%.
O N C H
H3C
O C
Cl
AlCl3
a) Would the left- or right- hand side aromatic ring be preferentially attacked?
b) Briefly explain your answer.
c) Draw the major product, and briefly state why substitution at the other positions on that ring, are less preferred. (9pts)
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9) Devise synthetic schemes to generate the products from the starting material, bearing in mind more than one step is obviously required. (10pts) Cl a) CH2CH3
CH3
SO3H
b) Cl CO2H
*Bonus question* (up to 2pts) This molecule (dimethylfulvene) is surprisingly acidic for a hydrocarbon. Indicate which hydrogen is most likely to be lost as a proton, and explain why the anion thus formed is strongly stabilized.
Sp02org2ex1
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(100 points)
NAME: To not have your graded script placed outside my office please check this box
1) Provide one reason why Molecular Orbital Theory is so important.
Draw a Lewis structure for a chemical species whose bonding is not accurately described by a Lewis Structure, and draw a more realistic delocalized / hybrid representation of that species. (4pts)
2) Indicate which of the following molecules are aromatic, non-aromatic or anti-aromatic. (Assume all the molecules are planar). (15pts) O
N
N
N
_
O
H B
+
S
3) Which one of the above compounds would you predict to be the least stable of this group, and justify your guess in a sentence. (3pts)
Sp02org2ex1
Page 1
4) By applying the polygon rule to the below cyclic hydrocarbon:
a) draw out the MO energy level diagram b) label the MO’s using π1….π6* c) circle one pair of degenerate orbitals d) draw in the electrons and explain whether this compound is predicted to be aromatic or antiaromatic. (8pts)
Sp02org2ex1
Page 2
5) Predict the products in the following reactions (if you believe no reaction will occur, indicate this!), paying attention to regio/stereochemistry where applicable. (21pts) heat
O H Br
H
Br HNO3, H2SO4
CO2H
Excess HI O
O-CH3
H3C
CH3
Heat
NO2 Cl2, AlCl3
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
UV Light
CO2H
OH
heat
1) NaOH 2) CH3CH2Br
Sp02org2ex1
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6) The below compound displays 6π Huckel aromaticity. H N
N H
H
H
Choose a nitrogen atom, and describe its hybridization and electron contribution to the aromatic π system.
Which nitrogen would be protonated first in concentrated sulfuric acid?
Which nitrogen is the most basic? (12pts)
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7) Give reagents and conditions to accomplish the following transformations, and draw A where applicable. (18pts)
Cl
A NO2
Cl
Br
A NO2 HO O
Cl
(Ph-CHCl-CH2)2O
O C
Sp02org2ex1
PhCH2Ph
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8) The reaction of 1 equivalent of ethanoyl chloride (with a catalytic amount of AlCl3) with the below bi-aryl compound results in a mixture of products, but one major product in over 90%.
O N C H
H3C
O C
Cl
AlCl3
a) Would the left- or right- hand side aromatic ring be preferentially attacked?
b) Briefly explain your answer.
c) Draw the major product, and briefly state why substitution at the other positions on that ring, are less preferred. (9pts)
Sp02org2ex1
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9) Devise synthetic schemes to generate the products from the starting material, bearing in mind more than one step is obviously required. (10pts) Cl a) CH2CH3
CH3
SO3H
b) Cl CO2H
*Bonus question* (up to 2pts) This molecule (dimethylfulvene) is surprisingly acidic for a hydrocarbon. Indicate which hydrogen is most likely to be lost as a proton, and explain why the anion thus formed is strongly stabilized.
Sp02org2ex1
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