Halogenoalkanes Flashcards
Physical properties of halogenoalkanes (2)
1) They have higher mpt/bpt as compared to alkanes of similar mr due to the presence of permanent dipole attraction as the molecules are polar
2) They are insoluble in water. They are not polar enough and do not exhibit H-bonding. They are soluble in organic solvents
Nucleophile
A nucleophile is a species that is attracted to electron-deficient part of the molecule
Reaction with NaOH(aq)
Reagents: NaOH
Condition: aqueous, heat
Type of reaction: nucleophilic substitution
An alcohol is produced
Which mechanism do primary alcohols undergo during nucleophilic substitution?
SN2
A 1 step reaction
Which mechanism do tertiary alcohols undergo?
SN1
A 2 step reaction
Reactions with KCN/NaCN
Reagents: KCN/NaCN
Conditions: ethanol (solvent), heat under reflux
Type of reaction: nucleophilic substitution
A nitrile is formed
What does a nitrile become when it is reduced?
An amine
What does a nitrile become when it undergoes hydrolysis?
A carboxylic acid
Reaction with NH3
Reagents: NH3 in excess
Conditions: ethanol (solvent), heat under pressure
Type of reaction: nucleophilic substitution
An amine is produced
Why does NH3 need to be in excess?
To prevent the formation of other products
Elimination reaction
Reagent: NaOH
Conditions: ethanol (solvent), heat
An alkene is produced
Which reactions produce halogenoalkanes?
1) Free radical substitution of alkanes
2) Electrophilic addition of alkenes with HX
3) Nucleophilic substitution of an alcohol with HX(g)
