Indietro
Bruice 8th EditionCh. 19 - More About Amines • Reactions of Heterocyclic CompoundsProblema 31
A tertiary amine reacts with hydrogen peroxide to form a tertiary amine oxide.
Tertiary amine oxides undergo a reaction similar to the Hofmann elimination reaction (Section 10.10), called a Cope elimination. In this reaction, a tertiary amine oxide, rather than a quaternary ammonium ion, undergoes elimination. A strong base is not needed for a Cope elimination because the amine oxide acts as its own base.
Does the Cope elimination have an alkene-like transition state or a carbanion-like transition state?
Problema 32a,b
What products are obtained when the following tertiary amines react with hydrogen peroxide followed by heat?
a.
b.
Problema 32c
What products are obtained when the following tertiary amines react with hydrogen peroxide followed by heat?
c.
Problema 32d
What products are obtained when the following tertiary amines react with hydrogen peroxide followed by heat?
d.
Problema 33a
a. Draw resonance contributors to show why pyridine-N-oxide is more reactive than pyridine toward electrophilic aromatic substitution.
Problema 33b
b. At what position does pyridine-N-oxide undergo electrophilic aromatic substitution?
Problema 34
The chemical shifts of the C-2 hydrogen in the spectra of pyrrole, pyridine, and pyrrolidine are 2.82 ppm, 6.42 ppm, and 8.50 ppm. Match each heterocycle with its chemical shift.
Problema 36
Explain why pyrrole (pKa ~ 17) is a much stronger acid than ammonia (pKa = 36).
Problema 37
Propose a mechanism for the following reaction:
Problema 39a
Propose a mechanism for the following reactions:
a.
Problema 39b
Propose a mechanism for the following reactions:
b.
Problema 40a
What is the major product of the following reactions?
a.
Problema 40b
What is the major product of the following reactions?
b.
Problema 40c
What is the major product of the following reactions?
c.
Problema 40d
What is the major product of the following reactions?
d.
Problema 40f
What is the major product of the following reactions?
f.
Problema 42c
What starting materials are required to synthesize the following compounds, using the Fischer indole synthesis?
c.
Problema 44a
Show how the following compounds can be prepared from the given starting material.
a.
Problema 44b
Show how the following compounds can be prepared from the given starting material.
b.
