PROBLEMS FOR 13.1
1
Use systematic nomenclature to name the following halogenoalkanes.
a CHCl3
b CH3CHClCH3
c CF3CCl3
2
Draw skeletal formulae for
compounds d and e in
problem 1.
(Use the table rignt as a
guide.)
3
When 1-chloropropane is heated under reflux with aqueous sodium hydroxide a
nucleophilic substitution reaction occurs, forming propan-1-ol.
a Write a balanced equation to show the overall reaction.
b Explain why this is classed as a substitution reaction.
c Write down the structure of the attacking nucleophile, showing the charge and any
lone pairs of electrons.
4
Draw a full structural formula for each of the following:
a 1,1,1-trichloroethane
c 4-bromo-1,1-dichloropentane.
b 1,1,2,2-tetrafluoropropane
5
Look at the following compounds.
a Which compound reacts most rapidly with alkali?
b When hydrolysis is carried out by water in the presence of silver nitrate, which
compound(s) produce a cream precipitate?
c Which compound has the lowest boiling point? (It will help to look at the table
below.)
Compound
State at 298 K
Boiling
point/K
CH3F
g
195
CH3Cl
g
249
CH3Br
g
277
CH3I
l
316
CH2Cl2
l
313
CHCl3
l
335
CCl4
l
350
C6H5Cl
l
405
d Which compound is the least volatile?
e Draw the structure of the product when compound E is hydrolysed. Name the
product.
6
The following table shows the structure of
common nucleophiles.
Write a balanced equation to show the
nucleophilic substitution reaction which takes
place between each of the following pairs of
compounds.
Your equations should show the structures of
the reactants and products clearly.
Example: bromomethane and CN- (cyanide) ions
a
b
c
d
e
f
g
iodoethane and OH- ions
bromoethane and CN- ions
chlorocyclopentane and OH- ions
2-chloro-2-methylpropane and H2O
1,2-dibromoethane and OH- ions
bromomethane and C2H5O- (ethoxide) ions
2-chloropropane and CH3COO- (ethanoate) ions.
7
1-bromoethane reacts with concentrated ammonia solution when heated in a sealed
tube.
a Write an overall equation for the nucleophilic substitution reaction that takes place.
b Using the reaction of halogenoalkanes with water as a guide (page 302 Chemical
Ideas), draw out the mechanism for this reaction.
c Write a few sentences to explain this mechanism to a fellow student.
d Give definitions of all the terms in your mechanism.
8
Suggest the starting halogenoalkane, reagents and the conditions you would use to
prepare a sample of each of the following compounds:
9
Chloromethane has a lifetime in the troposphere of about 1 year, which allows enough
time for some of it to be transported into the stratosphere where it helps to destroy
ozone.
In contrast, iodomethane has a tropospheric lifetime of about 8 days and much less
reaches the statosphere. This is because iodomethane is rapidly broken down by light
in the troposphere. This is called photolysis.
a Write equations for the photolysis of iodomethane and chloromethane.
b Explain why iodomethane is photolysed in the troposphere whereas chloromethane
is only photolysed when it reaches the stratosphere.