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Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) W hat is the IUPAC name for the follow ing alkyne?
1)
A) 5-Bromo-2-heptyne
B) 5-Bromo-5,5-dimethylhexyne
C) 5-Bromo-5-methyl-2-hexyne
D) 3-Bromo-5-heptyne
E) 2-Bromo-2-methyl-4-hexyne
Answ er: C
2) How many distinct terminal alkynes exist w ith a molecular for mula of C 5 H8 ?
A) 1
B) 2
C) 3
D) 4
2)
E) 5
Answ er: B
3) How many distinct internal alkynes exist w ith a molecular for mula of C 6 H10 ?
A) 1
B) 2
C) 3
D) 4
3)
E) 5
Answ er: C
4) W hat is the common name for the follow ing alkyne?
4)
A) neohexyne
B) trimethylpropyne
C) trimethylacetylene
D) isopropylacetylene
E) tert-butylacetylene
Answ er: E
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
5) W rite structures and give IUPAC names for all alkynes w ith molecular for mula C5 H8 .
Answ er:
1
5)
6) Give the IUPAC name for (CH3 )2 C(CH2 CH3 )CCCH(CH3 )2 .
6)
Answ er: 2, 5, 5-trimethyl-3-heptyne
7) Give the IUPAC name for HCCCH2 CH2 CH3 .
7)
Answ er: 1-pentyne
8) Give the IUPAC name for BrCH2 CH2 CCCH2 CH3 .
8)
Answ er: 1-bromo-3-hexyne
9)
9) Draw an acceptable structure for acetylene.
Answ er: H
C
C
H
10) Draw an acceptable structure for 3-sec-butyl-1-heptyne.
10)
Answ er:
11)
11) Draw an acceptable structure for 2-hexyne.
Answ er:
12) Provide the systematic name of the compound show n.
12)
Answ er: 5,6,6-trimethyl-1-heptyne
13) Give the systematic name for the alkyne Cl 3 CCH2 CH2 CCCH3 .
13)
Answ er: 6,6,6-trichloro-2-hexyne
14) Provide the structure of all distinct terminal alkynes w ith a molecular for mula of
C6 H10 .
Answ er:
2
14)
15) Give the IUPAC name for the follow ing compound.
15)
A) 2-methyl-1,3-butadiene
B) isobutadiene
C) 3-methyl-1,3-butadiene
D) isoprene
E) 2-methyl-2,3-butadiene
Answ er: A
16) W hat is the IUPAC name for the follow ing compound?
16)
A) 2Z,4Z-2, 4-heptadiene
B) trans, trans-2, 4-heptadiene
C) 2E,4E-2, 4-heptadiene
D) cis, cis-2, 4-heptadiene
E) cis, trans-2, 4-heptadiene
Answ er: E
17) Give the systematic name of the compound show n below .
17)
Answ er: 1, 7-dimethyl-1, 3-cycloheptadiene
18) Give the systematic name of the compound show n below .
Answ er: (S)-5-methyl-5-hexen-2-ol
3
18)
19) Name the follow ing compound:
19)
Answ er: (2E,4Z)-2, 4-hexadiene or trans, cis-2, 4-hexadiene or (2Z,2E)-2, 4-hexadiene or
cis, trans-2, 4-hexadiene
20) Provide the structure of (2E,4E)-2-chloro-2, 4-octadiene.
20)
Answ er:
21) Provide the systematic name of the compound show n.
21)
Answ er: (E)-5-methyl-5-hepten-1-yne
22) W hich of the follow ing improperly describes the physical properties of an alkyne?
22)
A) relatively nonpolar
B) insoluble in most organic solvents
C) less dense than w ater
D) nearly insoluble in w ater
Answ er: B
23) W hat is the hybridization of the carbon atoms numbered 1 and 2 respectively in the follow ing
structure?
A) sp2 , sp
B) sp3 , sp2
C) sp2 , sp2
Answ er: A
4
D) sp, sp
E) sp, sp2
23)
24) W hich of the follow ing statements is not true about propyne, HC
C
CH3 ?
24)
A) It contains six sigma bonds.
B) The C
C
C bond angle is 180°.
C) The H
C
H bond angle is about 109.5°.
D) It contains three pi bonds.
E) The pi bond is w eaker than the sigma bond.
Answ er: D
25) The carbon-carbon triple bond of an alkyne is composed of __________.
A) three
bonds
B) one
C) three
bonds
D) tw o
25)
bond and tw o
bonds
bonds and one
bond
Answ er: B
26) W hat are the hybridizations of the carbon atoms numbered 1 and 2 in the structure below ?
1
H3 C-CH
CH-C
26)
2
C-H
A) sp2 , sp2
B) sp3 , sp2
D) sp2 , sp
C) sp, sp
Answ er: C
27) W hat tw o atomic or bitals or hybrid atomic or bitals overlap to form the carbon -carbon
bond
27)
in ethyne?
A) sp3
sp3
B) s
s
C) sp
sp
D) sp2
sp2
E) p
p
Answ er: C
28) W hich of the follow ing statements cor rectly describes the general reactivity of alkynes?
28)
A) Alkynes are generally mor e reactive than alkenes.
B) Alkynes reacts as electrophiles, w hereas alkenes reacts as nucleophiles.
C) The
bonds of alkynes ar e higher in energy than the
bonds and are thus mor e reactive.
D) Unlike alkenes, alkynes fail to undergo electrophilic addition reactions.
E) An alkyne is an electron-rich molecule and therefor e reacts as a nucleophile.
Answ er: E
29) Although you might expect 1-propyne to b e mor e reactive than 1-propene in
electrophilic addition reactions, the reverse is true. Explain this using your know ledge
of the mechanism of electrophilic additions to b oth alkynes and alkenes.
Answ er: W hen HCl is added to an alkene, a secondary carbocation intermediate is
formed, CH3CHCH3. W hen HCl is added to an alkyne, a vinylic cation is for med
as an intermediate, CH3 C
CH2 . Alkynes are less stable than alkenes but vinylic
carbocations are less stable than secondary carbocations. Thus, alkenes are mor e
reactive than alkynes since the difference in stabilities betw een the carbocations
is greater than the difference in stabilities betw een the alkene and alkyne.
5
29)
30) W hat is the maj or product of the follow ing reaction?
30)
HCl
CH3 C
CH
excess
A) CH3 CH
CH
Cl
B)
C)
D)
E)
Answ er: D
31) W hich of the follow ing is the best synthesis of 2, 2-dibromopropane
Br 2
A) CH3 CH
CH2
light
2 HBr
B) CH3 C
CH
CH3 CH
peroxide
CH2
C)
Br 2
H2 O
D) CH3 C
CH
CH3 CH
E)
2 HBr
CH2
Br 2
CCl4
Answ er: D
6
31)
32) In the addition of hydrogen bromide to alkynes in the absence of peroxides, w hich of the
32)
follow ing species is believed to b e an intermediate?
A) bromonium ion
B) vinyl anion
C) vinyl cation
D) car bene
E) vinyl radical
Answ er: C
33) __________ is produced w hen 1 equivalent of HBr is added to 1-hexyne in the presence of
33)
peroxides.
A) E-1-bromo-1-hexene
B) E-2-bromo-2-hexene
C) 2-bromo-1-hexene
D) a mixture of E and Z isomers of 1-bromo-1-hexene
E) Z-1-bromo-1-hexene
Answ er: D
34) W hich of the follow ing compounds is the maj or product w hen 1 -hexyne is treated w ith excess
HBr?
A) 1,2-dibromohexene
B) 1,1-dibromohexane
C) 2,2-dibromohexane
D) 1,2-dibromohexane
E) 1,1-dibromohexene
Answ er: C
35) Provide the structure of the maj or or ganic product(s) in the reaction below .
Answ er:
7
35)
34)
36) Provide the structure of the maj or or ganic product of the follow ing reaction.
36)
Answ er:
37)
Answ er:
38) Provide the maj or or ganic product in the reaction below .
Answ er:
8
38)
39)
Answ er:
40)
Answ er:
41)
Answ er:
Answ er:
9
42)
43) W hich of the follow ing are enol for ms of 2-butanone,
A)
B)
C)
D)
E)
Answ er: E
10
43)
44) W hich of the follow ing is the final and maj or product of this reaction?
A) I
B) II
C) III
D) IV
44)
E) V
Answ er: A
45)
Answ er:
46) For the reaction below indicate w hether the equilibrium constant w ill be greater than 1
46)
or less than 1.
CH3 CH2 CHO
CH3 CH
CHOH
Answ er: < 1
47) Provide the structure of the intermediate w hich for ms in the first step of the reaction of
1-butyne w ith w ater in the presence of H2 SO4 /HgSO4 .
Answ er:
11
47)
48)
Answ er:
Answ er:
12
49)
50) W hich of the follow ing is the final and maj or product of this reaction?
A) I
B) II
C) III
D) IV
50)
E) V
Answ er: C
51) W hich of the alkyne addition reactions below involves an enol intermediate?
51)
A) hydr oboration/oxidation
B) treatment w ith HgSO4 in dilute H2 SO4
C) hydr ogenation
D) both A and B
E) both A and C
Answ er: D
Answ er:
13
52)
53) Complete the follow ing reaction.
53)
Answ er: ethynylcyclobutane
54)
Answ er:
55)
Answ er:
56) The reagent needed to convert 2-butyne to cis-2-butene is:
56)
A) Li/NH3
B) H+ /Zinc dust
C) Na/NH3
D) H2 /Lindlar 's catalyst
E) H2 /Pt
Answ er: D
57) The reagent needed to convert 2-butyne to trans-2-butene is:
A) H2 /Pt
B) H2 /Lindlar 's catalyst
C) Li/NH3
D) Na/NH3
E) C or D
Answ er: E
14
57)
58) A mixture of 1-heptyne, 2-heptyne, and 3-heptyne w as hydrogenated in the presence of a
58)
platinum catalyst until hydrogen uptake ceased. If one assumes that the hydrogenation w ent to
completion, how many distinct seven-carbon hydrocarbons w ere produced?
A) 1
B) 8
C) 3
D) 6
E) 2
Answ er: A
59) In the reduction of alkynes using sodium in liquid ammonia, w hich of the species below is not
believed to b e an intermediate in the commonly accepted mechanism?
A) vinyl anion
B) vinyl cation
C) vinyl radical
D) radical anion
Answ er: B
60)
Answ er:
61) An optically active compound (A), C6 H10 , reacts w ith H2 /Ni to produce compound (B),
61)
C6 H14 . (B) is optically inactive. Deduce the structures of (A) and (B).
Answ er:
Answ er:
15
62)
59)
CH3 CH2
C
C
CH3
63)
Na, NH3
Answ er:
64) Complete the follow ing reaction.
3-hexyne
64)
Na, NH3
Answ er: trans-3-heptene
65)
Answ er:
Answ er:
16
66)
67)
Answ er:
68) W hich is the cor rect or der of decreasing acidity in the follow ing compounds?
H2 O
CH3 CH3
A
NH3
B
C
CH2
CH2
HC
D
68)
CH
E
A) E > A > C > B > D
B) A > C > E > D > B
C) E > D > B > A > C
D) A > E > D > B > C
E) A > E > C > D > B
Answ er: E
69) W hat are the products of the follow ing reaction,
CH3 OH + CH3 C
A) CH3 OC
C- Na +
69)
?
CH + NaCH3
B) CH3 C
CH + CH3 O- Na +
C) CH3 C
COCH3 + NaOH
D) CH3 C
CCH3 + NaOH
E) no reaction
Answ er: B
70) W hich of the species below is less basic than acetylide?
70)
A) CH3 Li
B) CH3 ONa
C) NaOH
D) both B and C
E) all of the above
Answ er: D
71) Among the compounds w ater, 1-butyne, 2-butyne, and ethane, w hich are stronger acids than
ammonia?
A) w ater and 1-butyne
B) 1-butyne and 2-butyne
C) 1-butyne and ethane
D) w ater and ethane
Answ er: A
17
71)
72) W hat type of organic product results w hen 1-butyne is treated w ith 6M aqueous NaOH?
72)
A) an alcohol
B) a sodium acetylide
C) an aldehyde
D) an enol
E) Not much reaction; most of the alkyne remains unchanged.
Answ er: E
73) Explain w hy HC
N is a stronger acid than HC
CH.
73)
Answ er: Because nitrogen is mor e electronegative than carbon.
74) W hich hydrogens are mor e acidic, those of benzene or those of cyclohexane? W hy?
74)
Answ er: Benzene. The carbon hybridization of benzene is sp 2 w hile that of cyclohexane is
sp3 . The mor e s character in benzene causes its hydrogens to b e mor e acidic than
those of cyclohexane.
75) W hy ar e terminal alkynes more acidic than other hydrocar bons?
75)
Answ er: The car banion w hich results upon deprotonation of a terminal alkyne has the
lone pair of electrons in an sp hybrid or bital. The greater % s character of this
orbital gives the orbital a significantly low er energy.
76)
or less than 1.
CH3 Li + CH3 C
CH
CH4 + CH3 C
CLi
Answ er: >1
Answ er:
18
77)
78)
or less than 1.
KOH + CH3 C
CH
H2 O + CH3 C
CK
Answ er: <1
79) W hat is/are the maj or or ganic product(s) of the follow ing reaction,
A) HC
CBr
B) CH3 C
CCH3
C) CH3 CH2 C
D) HC
79)
CH
CCH2 CH2 Br
E) CH2
CH2 + HC
CH
Answ er: C
CH3 CH2
CH
80)
1. NaNH2
2. PhCH2 Br
Answ er: CH3 CH2 C
CCH2 Ph
Answ er:
19
81)
82) Suggest a plausible scheme for the follow ing synthesis
82)
Answ er:
83) Describe a sequence of r eactions by w hich 3-heptyne can be straightforw ar dly
83)
prepared from acetylene.
Answ er: 1)
NaNH2
2)
CH3 CH2 Br
3)
NaNH2
4)
CH3 CH2 CH2 Br
84) Describe a sequence of r eactions by w hich meso-2, 3-dibromobutane can be
84)
straightforw ardly prepared from propyne.
Answ er: 1)
NaNH2
2)
CH3 Br
3)
Na, NH3
4)
Br 2 , CCl4
85) Describe a sequence of r eactions by w hich butylbenzene can be straightforw ardly
85)
prepared from phenylacetylene.
Answ er: 1)
NaNH2
2)
CH3 CH2 Br
3)
H2 , Pt
86) Describe a sequence of r eactions by w hich CH3 CH2 CH2 COCH2 CH3 can be
straightforw ardly prepared from 1-butyne.
Answ er: 1)
NaNH2
2)
CH3 CH2 Br
3)
HgSO4 , H2 O, H2 SO4
20
86)
87) Describe a sequence of r eactions by w hich trans-2-pentene can be straightforw ardly
87)
prepared from propyne.
Answ er: 1)
NaNH2
2)
CH3 CH2 Br
3)
Na, NH3
88) Describe a sequence of r eactions by w hich the aldehyde CH3 CH2 CH2 CH2 CHO could be
88)
prepared from acetylene.
Answ er: 1)
NaNH2
2)
CH3 CH2 CH2 Br
3)
disiamylborane
4)
H2 O2 , - OH
89) Describe a sequence of r eactions by w hich cis-2-pentene could be prepared from
acetylene.
Answ er: 1)
NaNH2
2)
CH3 CH2 Br
3)
NaNH2
4)
CH3 Br
5)
H2 , Lindlar 's catalyst
21
89)
90) Complete the follow ing tree of r eactions by giving the maj or products.
Answ er:
22
90)

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