1. More on halogenoalkanes
Friday, 21 September 2018

2. More on halogenoalkanes
Objective: To know about some more reactions of halogenoalkanes
Outcomes:
To know the reaction with potassium cyanide to produce nitriles
To know the reaction with ammonia to produce primary amines, including knowing the mechanism
To know the reaction with ethanolic potassium hydroxide to produce alkenes

3. Reflux Reflux video

4. Making Nitriles
Nitriles contain – C ≡ N
Halogenoalkanes react under reflux with potassium cyanide, KCN, dissolved in ethanol to produce nitriles
E.g. CH3CH2Br + CN-  CH3CH2CN + Br-
What happens to the length of the carbon chain?
It increases by one, this is a useful way to increase the length of the carbon chain

5. Making Nitriles These reactions proceed by a nucleophilic substitution mechanism. The CN- ion acts as a nucleophile. It is similar to that with :OH-, but :CN- is the nucleophile They are named according to the number of carbon atoms in the longest chain containing the nitrile group. CH3CH2CN is propanenitrile not ethanenitrile

6. More on halogenoalkanes
Objective: To know about some more reactions of halogenoalkanes
Outcomes:
To know the reaction with potassium cyanide to produce nitriles
To know the reaction with ammonia to produce primary amines, including knowing the mechanism
To know the reaction with ethanolic potassium hydroxide to produce alkenes

7. Making Amines Amines contain the amino group –NH2 They are based on NH3 but one or more of the hydrogen atoms are replaced by alkyl groups Primary halogenoalkanes react with ammonia to make primary amines. The halogenoalkane is warmed with excess ethanolic ammonia (ammonia dissolved in ethanol) The ammonia swaps places with the halogen to form a primary amine. E.g. CH3CH2Br + 2NH3  CH3CH2NH2 + NH4Br Can you suggest a mechanism?

8. Making Amines Mechanism (nucleophilic substitution)
Pg 93 CGP, 59 Edexcel

9. Examples Of Amines CH3NH2 Methylamine or Aminomethane or Methanamine CH3CH2NH2 Ethylamine or aminoethane or ethanamine

10. More on halogenoalkanes
Objective: To know about some more reactions of halogenoalkanes
Outcomes:
To know the reaction with potassium cyanide to produce nitriles
To know the reaction with ammonia to produce primary amines, including knowing the mechanism
To know the reaction with ethanolic potassium hydroxide to produce alkenes

11. Halogenoalkanes reacting with ethanolic potassium hydroxide When halogenoalkanes are reacted with a warm alkali dissolved in ethanol you get an alkene. The reaction is heated under reflux. E.g. What sort of reaction is this? Elimination reaction, the hydroxide ions are acting as a base to remove an H+ ion from the halogenoalkane
Pg 93 CGP

12. More on halogenoalkanes
Objective: To know about some more reactions of halogenoalkanes
Outcomes:
To know the reaction with potassium cyanide to produce nitriles
To know the reaction with ammonia to produce primary amines, including knowing the mechanism
To know the reaction with ethanolic potassium hydroxide to produce alkenes

13. Questions page 59 workbook Revision guide CGP pg 93 Edexcel pg 59

14. More on halogenoalkanes
Objective: To know about some more reactions of halogenoalkanes
Outcomes:
To know the reaction with potassium cyanide to produce nitriles
To know the reaction with ammonia to produce primary amines, including knowing the mechanism
To know the reaction with ethanolic potassium hydroxide to produce alkenes