Problems for Chapter 7
PROBLEM 1
Are these molecules conjugated? Explain your answer in any reasonable way.
PROBLEM 2
How extensive is the conjugated system(s) in these compounds?
PROBLEM 3
Draw diagrams to represent the conjugation in these molecules. Draw two
types of diagram:
(a) Show curly arrows linking at least two different ways of representing the
molecule
(b) Indicate with dotted lines and partial charges (where necessary) the partial
double bond (and charge) distribution.
PROBLEM 4
Draw curly arrows linking alternative structures to show the delocalization in
(a) diazomethane CH2N2
(b) nitrous oxide, N2O
(c) dinitrogen tetroxide, N2O4
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Problems to accompany Organic Chemistry
PROBLEM 5
Which (parts) of these compounds are aromatic? Justify your answer with some
electron counting. You may treat rings separately or together as you wish. You
may notice that two of them are compounds we met in problem 2 of this
chapter.
PROBLEM 6
The following compounds are considered to be aromatic. Account for this by
identifying the appropriate number of delocalized electrons.
Problems for Chapter 7 – Delocalization and conjugation
PROBLEM 7
Cyclooctatetraene (see p. 158 of the textbook) reacts readily with potassium
metal to form a salt, K2[cyclooctatetraene]. What shape do you expect the
ring to have in this compound?
A similar reaction of
hexa(trimethylsilyl)benzene with lithium also gives a salt. What shape do
you expect this ring to have?
PROBLEM 8
How would you expect the hydrocarbon below to react with bromine, Br2?
PROBLEM 9
In aqueous solution, acetaldehyde (ethanal) is about 50% hydrated. Draw
the structure of the hydrate of acetaldehyde. Under the same conditions,
the hydrate of N,N-dimethylformamide is undetectable.
Why the
difference?
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