10.8 When 3,3-dichloropentane is treated with excess sodium amide in liquid ammonia, the initial product is 2-pentyne. HH CIH H H-C-C-C-C-C-H xs NaNH2 NH3 (1) HH CIH H HH H H H-C-C-CEC-C-H I I HH However, under these conditions, this internal alkyne quickly isomerizes to form a terminal alkyne that is subsequently deprotonated to form an alkynide ion. HICH HH H-C-C-CEC-C-H HH xs NaNH2 NH3 (1) HHH H-C-C-C-CEC-H HHH xs NaNH, NH3 (1) HHH III H-C-C-C-CEC: III HHH The isomerization process is believed to occur via a mechanism with the following six steps: (1) deprotonation, (2) resonance, (3) protonation, (4) deprotonation, (5) resonance, (6) protonation. Using these six steps as a guide, try to draw the mechanism for isomerization. Explain why the equilibrium favors the terminal alkyne.
10.8 When 3,3-dichloropentane is treated with excess sodium amide in liquid ammonia, the initial product is 2-pentyne. HH CIH H H-C-C-C-C-C-H xs NaNH2 NH3 (1) HH CIH H HH H H H-C-C-CEC-C-H I I HH However, under these conditions, this internal alkyne quickly isomerizes to form a terminal alkyne that is subsequently deprotonated to form an alkynide ion. HICH HH H-C-C-CEC-C-H HH xs NaNH2 NH3 (1) HHH H-C-C-C-CEC-H HHH xs NaNH, NH3 (1) HHH III H-C-C-C-CEC: III HHH The isomerization process is believed to occur via a mechanism with the following six steps: (1) deprotonation, (2) resonance, (3) protonation, (4) deprotonation, (5) resonance, (6) protonation. Using these six steps as a guide, try to draw the mechanism for isomerization. Explain why the equilibrium favors the terminal alkyne.
Chapter11: Reactions Of Alkyl Halides: Nucleophilic Substitutions And Eliminations
Section11.SE: Something Extra
Problem 72AP: Treatment of 1-bromo-2-deuterio-2-phenylethane with strong base leads to a mixture of deuterated and...
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Transcribed Image Text:10.8 When 3,3-dichloropentane is treated with excess sodium amide in liquid ammonia,
the initial product is 2-pentyne.
HH CIH H
H-C-C-C-C-C-H
xs NaNH2
NH3 (1)
HH CIH H
HH
H
H
H-C-C-CEC-C-H
I I
HH
However, under these conditions, this internal alkyne quickly isomerizes to form a terminal alkyne
that is subsequently deprotonated to form an alkynide ion.
HICH
HH
H-C-C-CEC-C-H
HH
xs NaNH2
NH3 (1)
HHH
H-C-C-C-CEC-H
HHH
xs NaNH,
NH3 (1)
HHH
III
H-C-C-C-CEC:
III
HHH
The isomerization process is believed to occur via a mechanism with the following six steps:
(1) deprotonation, (2) resonance, (3) protonation, (4) deprotonation, (5) resonance, (6) protonation.
Using these six steps as a guide, try to draw the mechanism for isomerization. Explain why the
equilibrium favors the terminal alkyne.
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