CHEMISTRY 2110
FINAL EXAM
December 10, 2012
Answer Key
*1. (12) For each of the following compounds, state whether or not the benzene rings are activated or
deactivated in comparison with benzene itself. In addition, state whether each compound would be an
ortho / para or meta director. You need not explain your answers.
b)
c)
a)
d)
O
H
F
N
S
N
deactivated
deactivated
deactivated
activated
meta
meta
ortho / para
ortho / para
*2. (2.5) Which of the following carbocations is the most stable?
CH 3 H H
H3 C C C C H
H H
CH 3 H H
H3C C C C H
H H
CH 3 H H
H3C C C C H
H
H
*3. (4) The degree of unsaturation (rings and/or multiple bonds) for the formula C7H4NO2FCl2 is:
a) 4
b) 5
c) 6
d) 7
*4. (2.5) The addition of HBr to 2-methyl-1-butene gives which of the following products?
CH3
BrCH 2 C C CH3
H H2
CH 3
H 3C C C CH 3
H
Br 2
CH 3
H
H3 C C C CH3
H
Br
CH3
H 3C C C CH2Br
H H2
*5. (5) Draw both chair conformations of cis-1,4-dimethylcyclohexane on the templates provided below.
Label each non-hydrogen substituent as axial (a) or equatorial (e).
e
CH3
a
e
H3C
a
CH3
a = axial
e = equatorial
CH3
*6. (3) Which of the following is the best method of preparing the molecule shown from benzene?
A.
B.
C.
D.
SO3H
CH3CH2Cl with AlCl3 then SO3 / H2SO4
CH3COCl with AlCl3 then SO3 / H2SO4 then H2 / Pd
CH3COCl with AlCl3 then H2 / Pd, then SO3 / H2SO4
SO3 / H2SO4 then CH3COCl with AlCl3, then H2 / Pd
*7. (2.5) How many signals are present in the 1H NMR spectrum of the following molecule?
a) 2
b) 3
c) 4
d) 5
*8. (2.5) How many different monochloro derivatives are possible for the molecule shown?
1) two
2) three
3) four
4) five
*9. (2.5) What compound is represented by the Newman projection shown?
a) CH 3CH2 CH3
b) (CH 3 )2 CHCH 2 CH 3
c) CH 3CH(CH3 )2
d) CH 3CH2 CH2 CH(CH 3)2
H
CH3
H
H
CH 3
CH 3
*10. (4) For the 1H NMR spectrum, indicate how many signals there would be and their appearance
(singlet, doublet, etc.) for the molecule shown below.
Cl
2 signals, both singlets
Cl
*11. (2.5) Which is the stronger acid, H-F or H-I?
_H-I_
*12. (2.5) An absorption at 1640 cm-1 in the infrared is characteristic of which functional group?
a) an alkyl CH
b) an amine NH
c) an alcohol –OH
d) a C=C bond
*13. (2.5) Which has the weaker conjugate base, water (H2O, pKa = 15) or HCl (pKa = -7)? _HCl__
*14. (4.5) For each of the following compounds, indicate by yes or no whether or not they contain
conjugated systems.
a)
b)
c)
NH
No
Yes
Yes
*15. (10) From the list below, state whether each species shown is an electrophile or nucleophile.
a)
B(OCH3)3
Electrophile
b) KOCOCH3
Nucleophile
c)
I2
Electrophile
d) CH3COCl / AlCl3
e)
CH3
Electrophile
Nucleophile
*16. (5) For each of the reactions shown below, indicate whether the overall process is a Syn or
Anti addition. Note: you may not have seen the reaction before.
a)
b)
CN
H
HO
Br
Br
OH
H
CH3
Syn
Anti
*17. (6) Circle any of the molecules shown below that can exist as an (E) or (Z) isomer.
Cl
a)
b)
H3C CH2
C CHCH3
H3C CH2
c)
CH3CH=CHCH3
d)
*18. (2.5) What is the relationship between the 2 structures shown?
a) constitutional isomers
b) same compound
c) stereoisomers
d) gauche conformers
H3C
H3C
Cl
H
C
H3C
CH
CH3
CH3
CH CH
H3C
Cl
*19. (3) A compound of molecular formula C10H14 undergoes catalytic hydrogenation but absorbs only 2 molar
equivalents of hydrogen. How many rings are present?
a) none
b) one
c) two
d) three
*20. (2.5) What is the IUPAC name of (CH3)2CHCH=CH2?
a) 3,3-dimethylpropene
b) 2-methyl-3-butene
c) 3-methyl-1-butene
d) 1-pentene
*21. (3) What are the hybridizations of the carbon atoms numbered 1 and 2 in the structure below?
a)
b)
c)
d)
sp3, sp2
sp2, sp
sp2, sp3
sp, sp2
2
1
*22. (3) Circle the choice to the right which provides the correct configuration for the following:
H3C
H
H3C
H
H
a)
b)
c)
d)
(2E, 4E)
(2Z, 4Z)
(2Z, 4E)
(2E, 4Z)
*23. (3) Circle the reaction conditions below which would convert 2-pentyne to trans-2-pentene?
a) Pd and H2
b) Lindlar's catalyst and H2
c) Na in liquid NH3 then water
d) NaNH2
*24. (3) Circle the reagent below, which would convert a primary alcohol to a bromo product.
a) SOCl2
b) PBr3
c) HBr
d) HCl
e) Cl2
*25. (5) Circle any statement in the box to the right of each reaction which is an appropriate description.
• addition
• Markovnikov
• non-Markovnikov
• reaction with Br2
• reaction with HBr
Br
Br
*26. (6) A compound, “Y” of molecular formula C8H8 undergoes catalytic hydrogenation (with
H2 / Pd) and absorbs 2 molar equivalents of hydrogen. Separately, “A” reacts with H2 / Lindlar’s
catalyst and absorbs only 1 molar equivalent of hydrogen.
a) How many degrees of unsaturation are present in “A”? 5°
b) How many triple bonds are present? 1
c) How many double bonds are present? 0
d) How many rings are present?
3
*27. (8) By assigning priorities to the groups attached, designate either E or Z or R or S (as appropriate)
to the molecules shown. You must show all the priorities (#1 = highest) to receive full credit.
a)
H3C O
H3C
4
1
b)
CN 3
NCH3
2
Cl
Cl
O
3
2
H 4
1
N
H
NH2
S
E
*28. (3) How many signals are present in the 13C NMR spectrum of the following molecule?
a) 2
b) 3
c) 4
d) 5
*29. (2.5) True or False? The rate of reaction for an SN1 reaction is determined by the concentration of
only the species containing the leaving group.
*30. (2.5) True or False? For leaving group ability, assuming atom size stays roughly the same, the
general trend is, the weaker the basicity, the better the leaving group.
*31. (3) True or False? A stereoisomer with 4 chiral centers of configuration R,R,R,R could not be
meso.
*32. (7.5) True or False? (Circle your choice).
a) A successful SN2 reaction must convert an (S) configuration to and (R)
b) An SN2 reaction of 2-bromobutane with NaCN could not occur because
of steric hindrance
c) A successful SN2 reaction will always invert configuration
T or F
T or F
T or F
*33. (12) For the molecule shown below, answer the questions to its right.
CHO
H
OH
H
OH
H
OH
1.
2.
3.
4.
OH
enantiomer
3
How many chiral centers? Mark them with an *
How many stereoisomers possible? 23 = 8
Draw a Fischer projection of the enantiomer
Draw a Fischer projection of any diastereomer
CHO
H
OH
HO
H
H
OH
CHO
HO
H
HO
H
HO
H
diastereomer
OH
OH
*34. (7) Show the reaction scheme you would use to convert ethyne to 4-methyl-1-pentene
1. 1 eq. NaNH2
H
H
2.
Br
H2 , Lindlar's
H
OR
1. Li / NH3
2. H2O