6.3 - Halogenoalkanes And Alcohols Flashcards Preview

Edexcel A Level Chemistry > 6.3 - Halogenoalkanes And Alcohols > Flashcards

Flashcards in 6.3 - Halogenoalkanes And Alcohols Deck (24)
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1
Q

Which elements are we looking at?

A

Halogens , Group 7 elements… F, Cl, Br, I, At

2
Q

What are dihalogenoalkanes?

A

compounds where atleast one hydrogen in the alkane chain has been replaced by a halgen

3
Q

Primary, secondary and tertiary?

A

You work out the stability of the compound; primary is week as it only has one methyl group, tertiary is strong as it has 3 methyl groups.

4
Q

Fact about the carbon-halogen bond?

A

it’s polar as the halogen is always more electronegative

5
Q

What is a nucleophile?

A

Electron donating, electron rich

6
Q

What is an electrophile?

A

Electron pair acceptor, electron defficient

7
Q

What does the nucleophile do?

A

Replaces the halogen atom in the halogenoalkane, forming a compound with a different functional group

8
Q

What happens during the hydrolysis of halogenoalkanes?

A

The halogen atom is replaced by the hydroxide ion

9
Q

What is nucleophillic attack?

A

Hydroxide ion attacks the electron defficient carbon with its lone pair of electrons

10
Q

How does the carbon- halogen bond break?

A

Heterolytic fission?

11
Q

Substitution reactions, with water?

A

Halide is replaced with OH group, producing an alcohol, this is a hydrolysis reaction.

12
Q

Substitution reactions, with aqueous potassium hydroxide?

A

Another way to produce alcohols - very quick

Halide is replaced with OH group

13
Q

Substitution reactions, with potassium cyanide?

A

Halide is replaced with CN group, which increases the carbon chain length and forms a nitrile
This is carried out under reflux with potassium cyanide in ethanol

14
Q

Substitution reactions, with ammonia?

A

Halide is replaced with NH2 group, producing an amine
Ethanol is used
Ammonium salt is also produced

15
Q

Elimination reactions, with ethanolic potassium hydroxide?

A

Produces an alkene
Heated under reflux
hydroxide ion acts as a base

16
Q

Carbo-cations?

A

the stability of the carbocation formed, effects the products of a reaction! primary (1 methyl group- very weak) quaternary ( 4 methyl groups- very strong)

17
Q

Are halogenalkanes soluble in water?

A

No, as C-H bonds are non polar they need to dissolve in ethanol which is also non polar

18
Q

do halogenalkanes have a polar bond? why?

A

Yes, as the halogen has a higher electronegativity than carbon

19
Q

When do their boiling points increase?

A

Further down group 7

When the carbon chain length increases

20
Q

which halogen bond is most polar?

A

C-F bond, as fluorine is most electronegative

21
Q

which halogen has the lowest bond enthalpy?

A

Iodine, therefore the C-I bond is the most reactive

22
Q

Examples of nucleophiles?

A

OH-, CN-

23
Q

What is nucleophilic substitution?

A

a reaction where a nucleophile donates a lone pair of electrons

24
Q

what is formed in the elimination reactions of halogenalkanes?

A

an alkene, water and halogen ion