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)
Loading flashcards...
1

Which elements are we looking at?

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

2

What are dihalogenoalkanes?

compounds where atleast one hydrogen in the alkane chain has been replaced by a halgen

3

Primary, secondary and tertiary?

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

Fact about the carbon-halogen bond?

it's polar as the halogen is always more electronegative

5

What is a nucleophile?

Electron donating, electron rich

6

What is an electrophile?

Electron pair acceptor, electron defficient

7

What does the nucleophile do?

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

8

What happens during the hydrolysis of halogenoalkanes?

The halogen atom is replaced by the hydroxide ion

9

What is nucleophillic attack?

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

10

How does the carbon- halogen bond break?

Heterolytic fission?

11

Substitution reactions, with water?

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

12

Substitution reactions, with aqueous potassium hydroxide?

Another way to produce alcohols - very quick
Halide is replaced with OH group

13

Substitution reactions, with potassium cyanide?

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

Substitution reactions, with ammonia?

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

15

Elimination reactions, with ethanolic potassium hydroxide?

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

16

Carbo-cations?

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

Are halogenalkanes soluble in water?

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

18

do halogenalkanes have a polar bond? why?

Yes, as the halogen has a higher electronegativity than carbon

19

When do their boiling points increase?

Further down group 7
When the carbon chain length increases

20

which halogen bond is most polar?

C-F bond, as fluorine is most electronegative

21

which halogen has the lowest bond enthalpy?

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

22

Examples of nucleophiles?

OH-, CN-

23

What is nucleophilic substitution?

a reaction where a nucleophile donates a lone pair of electrons

24

what is formed in the elimination reactions of halogenalkanes?

an alkene, water and halogen ion