3.2.8 Halogenoalkanes

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  • Created by: Jade
  • Created on: 08-02-13 15:07
What is a halogenoalkane?
are alakanes when one or more hydrogen atoms has been replaced by an atom of a halogen.
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what are the prefixes on the alkanes when a halogen is present?
Fluoro-, Chloro-, Bromo- and Iodo-
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What happens to the nomenclature if there is more than halogen present? Give an example.
Another prefix is added to describe the number. e.g. tetrachloromethane (when 4 cl are present)
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Define Substitution reaction.
These occur when two reactants exchange parts to give two new products.
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Give the general equation for a substitution reaction.
A-B + C-D ----------------------- A-C + B-D
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What are the 3 steps that occur in a radical substitution reaction?
Initiation, propagation and termination.
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Outline what happens in each step of a radical substitution reaction.
Initiation- the production of reactive free radicals. Prop- a reactive halogen radical collides with a alkane molecule and removes a hydrogen atom from it. Term- two radicals may collide to combine & form a stable product,terminating the process.
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What two things can halogenoalkanes do when they react with a nucleophile?
Subsitution of the halogen group by the nucleophile OR elimination of the halogen and 1 hydrogen atom to yield an alkene.
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What are the 3 common nucleophiles halogenoalkanes react with?
The hydroxide ion, Ammonia and the cyanide ion.
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What is the overall nucleophilic substitution reaction between a hydroxide ion and a halogenoalkane?
R-X + OH- ----------------- ROH + X- (R is hydrocarbon chain, X is halogen and ROH is alcohol)
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What is the overall nucleophilic substitution reaction between ammonia and a halogenoalkane?
R-X+ 2NH3-------------------------- RNH2 + NH4X (R is hydrocarbon chain, X is halogen)
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What is the overall nucleophilic substitution reaction between a cyanide ion and a halogenoalkane?
R-X + CN- -------------Nitrile + X-
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What are the 4 factors that determine whether one type of reaction will occur more than the other.
Temperature, Type of halogenoalkane, the concentration of solvent and concentration of hydroxide solution.
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Card 2

Front

what are the prefixes on the alkanes when a halogen is present?

Back

Fluoro-, Chloro-, Bromo- and Iodo-

Card 3

Front

What happens to the nomenclature if there is more than halogen present? Give an example.

Back

Preview of the front of card 3

Card 4

Front

Define Substitution reaction.

Back

Preview of the front of card 4

Card 5

Front

Give the general equation for a substitution reaction.

Back

Preview of the front of card 5
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