6D: Halogenoalkanes

Question 1

What is meant by the term nucleophile?

Answer 1

A lone pair donor

Question 2

Reaction of halogenoalkanes with aqueous potassium hydroxide:
Condition,
Product,
Nucleophile.

Answer 2

Heat under reflux,
Alcohols,
Hydroxide ion.

Question 3

Reaction of halogenoalkanes with aqueous silver nitrate:
Condition,
Product,
Nucleophile.

Answer 3

In ethanol,
Alcohols,
Water.

Question 4

Describe the reactions
Halogenoalkane -> alcohol

Answer 4

React with aqueous potassium hydroxide,
Heat under reflux.

or

React with aqueous silver nitrate,
in ethanol.

Question 5

Reaction of halogenoalkanes with potassium cyanide:
Condition,
Product,
Nucleophile.

Answer 5

Dissolve in ethanol and heat under reflux,
Nitriles,
Cyanide ion.

Question 6

Describe the reaction
Halogenoalkane -> Nitrile

Answer 6

React with potassium cyanide,
Dissolve in ethanol and heat under reflux.

Question 7

Reaction of halogenoalkanes with ammonia:
Condition,
Product,
Nucleophile.

Answer 7

Concentrated ammonia dissolved in ethanol + heat in a sealed tube.
Amines,
Ammonia.

Question 8

Describe the reaction
Halogenoalkane -> Amine

Answer 8

React with concentrated ammonia,
Dissolved in ethanol.

Question 9

Reaction of halogenoalkanes with ethanolic potassium hyrdoxide:
Condition,
Product,
Base.

Answer 9

Heat under reflux,
Alkenes,
Hydroxide ion.

Question 10

Describe the reaction
Halogenoalkane -> Alkene

Answer 10

React with ethanolic potassium hydroxide,
Heat under reflux.

Question 11

What reagent is used to compare the rates of hydrolysis of halogenoalkanes?

Answer 11

Aqueous silver nitrate in ethanol

Question 12

What is the trend in reactivity of primary, secondary and tertiary halogenoalkanes?

Answer 12

Tertiary = most reactive
Primary = least reactive

Question 13

Explain the trend in reactivity of chloro-, bromo-, and iodoalkanes.

Answer 13

The C-Cl bond has the highest bond enthalpy,
So the bond is stronger and takes more energy to break,
So reactivity increases down the group.