Halogenoalkanes

What is the formula of halogenoalkanes?
CnH2n+1X
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What halogens make halogenoalkanes?
Fluoride, chloride, bromide, iodide
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How is a polar bond created in halogenoalkanes?
Halogens are more electronegative than carbon
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Why do halogenoalkanes have higher melting points than alkanes?
Higher melting points than alkanes due to high molecular mass and polar bonds
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Why are halogenoalkanes reactive?
Partial positive charges in polar bond are attacked by nucleophiles
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What conditions are needed for nucleophilic substitution with hydroxide?
Warm and ethanolic
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What is formed during nucleophilic substitution with hydroxide?
An alcohol
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What is this reaction called?
Hydrolysis
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What conditions are needed for nucleophilic substitution with cyanide?
Warm and ethanolic
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What is formed during nucleophilic substitution with cyanide?
Nitrile and halogen
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What conditions are needed for nucleophilic substitution with excess ammonia?
Sealed, ethanolic and under high pressure
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What is formed during nucleophilic substitution with excess ammonia?
Amine, ammonium and halogen
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What are the main features of a nucleophile?
Negatively charged and has a lone pair of electrons
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What do curly arrows represent in mechanisms?
Movement of electrons
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What happens during elimination reactions?
Hydroxide act as a base to remove H+ ion to form an alkene
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What conditions are needed for an elimination reaction?
Hydroxide dissolved in ethanol and hot
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How can we show an alkene has been formed?
Adding bromine water which will be decolourised
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What is produced from an elimination reaction?
Alkene, water and halogen
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What are primary halogenoalkanes?
Halogen is at the end of the chain
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What are secondary halogenoalkanes?
Halogen is in the body of the chain
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What are tertiary halogenoalkanes?
Halogen is in the branch of the chain
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What are chlorofluorocarbons?
Short chains used for fridges and aerosols, long chains used as cleaning agents
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Why are chlorofluorocarbons bad for the environment?
They decompose in the atmosphere and form chlorine free radicals which breakdown the ozone layer
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What are the 3 stages of free radical substitution?
Initiation, propagation and termination
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What happens during initiation?
UV light breaks bond homolytically to create 2 free radicals
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What happens during propagation?
Radicals react with alkane to form other free radicals - this creates chain reaction
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What happens during termination?
2 free radicals react to form a stable compound, therefore ending chain reaction
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How is the ozone layer broken down?
Chlorine free radical acts as a catalyst to breakdown O3 to O2
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What is hydrogen halide addition?
Polar bond between hydrogen halide attacks electron dense area in an alkene to form a carbocation which then forms an alkane
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How is a polar bond created on a halogen for addition?
Double bond from alkene induces a dipole
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Other cards in this set

Card 2

Front

What halogens make halogenoalkanes?

Back

Fluoride, chloride, bromide, iodide

Card 3

Front

How is a polar bond created in halogenoalkanes?

Back

Preview of the front of card 3

Card 4

Front

Why do halogenoalkanes have higher melting points than alkanes?

Back

Preview of the front of card 4

Card 5

Front

Why are halogenoalkanes reactive?

Back

Preview of the front of card 5
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