Date Due : ……………………………………………………………..
Year 12
80%
A
70%
B
AS Level Chemistry
60%
C
2008 – 2009
50%
D
40%
E
Below
U
Questions on
%
Haloalkanes
2.8
32
1. Chloromethane can be prepared by a reaction between methane and chlorine in the presence of ultraviolet radiation.
(i) Outline the mechanism for this reaction.
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(ii) Name the first step in this mechanism.
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(iii) Suggest, giving a reason, how the reaction would be carried out in order to ensure that chloromethane would be the major organic product.
Suggestion....................................................................................................................
Reason..........................................................................................................................
(Total 7 marks)
2. (a) The compound 1,2-dibromo-1,1,2,2-tetrafluoroethane is used in some fire extinguishers. Draw the structure of this compound.
(1)
(b) Halothane is used as an anaesthetic and has the following structure.
(i) Give the systematic name of halothane.
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(ii) Calculate the Mr of halothane.
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(iii) Calculate the percentage by mass of fluorine in halothane.
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(3)
(Total 4 marks)
3. (a) Give the structural formula of 2-bromo-3-methylbutane.
(1) (b) Write an equation for the reaction between 2-bromo-3-methylbutane and dilute aqueous sodium hydroxide. Name the type of reaction taking place and outline a mechanism.
Equation .....................................................................................................................
.....................................................................................................................................
Type of reaction ..........................................................................................................
Mechanism
(4)
(c) Two isomeric alkenes are formed when 2-bromo-3-methylbutane reacts with ethanolic potassium hydroxide. Name the type of reaction occurring and state the role of the reagent. Give the structural formulae of the two alkenes.
Type of reaction ..........................................................................................................
Role of reagent.............................................................................................................
Structural formula of alkene 1 Structural formula of alkene 2
(4)
(Total 9 marks)
4. (a) Chloromethane can be made by the reaction of chlorine with methane.
(i) Give one essential condition for this reaction.
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(ii) Name the mechanism for this reaction.
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(iii) Further substitution can occur during this reaction. Identify the main organic product when a large excess of chlorine is used in this reaction.
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(3) (b) Ethanenitrile can be made by reacting chloromethane with potassium cyanide.
(i) Write an equation for this reaction.
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(ii) Name the mechanism for this reaction.
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(iii) Explain, in terms of bond enthalpies, why bromomethane reacts faster than chloromethane with potassium cyanide.
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(3)
(c) Chloromethane can react with ammonia to produce a primary amine.
(i) What feature of the chloromethane molecule makes it susceptible to attack by an ammonia molecule?
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(ii) Name the amine produced in this reaction.
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(iii) Outline a mechanism for this reaction.
(6)
(Total 12 marks)
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