15 Haloalkanes

Question 1

What is a haloalkane? (1 mark)

Answer 1

Saturated hydrocarbons
Contain one or more halogen atoms

Question 2

What is a primary haloalkane? (1 mark)

Answer 2

The halogen is attached to a carbon atom which is bonded to one other carbon atom.

Question 3

What is a secondary haloalkane? (1 mark)

Answer 3

The halogen is attached to a carbon atom which is bonded to two other carbon atoms.

Question 4

What is a tertiary haloalkane (1 mark)

Answer 4

The halogen is attached to a carbon atom which is bonded to three other carbon atoms.

Question 5

Why is a C-halogen bond polar? (2 marks)

Answer 5

Halogens are more electronegative than carbon.
Therefore, the pair of electrons is closer to the halogen in the bond.
This makes it a polar bond.

Question 6

What is a nucleophile? (3 marks)

Answer 6

A species containing one or more lone pairs of electrons
Which can donate to an electron deficient atom
To form a covalent bond

Question 7

What is the trend in boiling point in haloalkanes, why? (3 marks)

Answer 7

Boiling point increases as halogen in it goes down group.
As the size of the halogen increases
The IDD forces of attraction increase
Increasing the boiling point.

Question 8

What is the trend in polarity of the haloalkanes? (1 mark)

Answer 8

Get less polar as go down group.

Question 9

What is nucleophilic substitution? (1 mark)

Answer 9

When one nucleophile replaces another in a molecule.

Question 10

What is formed when an OH- nucleophile reacts with a haloalkane? (1 mark)

Answer 10

Alcohol

Question 11

What is formed when a CN- nucleophile reacts with a haloalkane? (1 mark)

Answer 11

Nitrile

Question 12

What is formed when a 2NH3 reacts with a haloalkane? (1 mark)

Answer 12

Amine

Question 13

What conditions must there be to form an alcohol from a haloalkane and OH- nucleophile? (2 marks)

Answer 13

Aqueous NaOH
Reflux

Question 14

What conditions must there be to form a nitrile from a haloalkane and CN- nucleophile? (2 marks)

Answer 14

KCN in ethanol
Reflux

Question 15

What conditions must there be to form an amine from a haloalkane and NH3? (2 marks)

Answer 15

Concentrated NH3 in ethanol
Reflux

Question 16

Amines act as nucleophiles, what can this lead to? (1 mark)

Answer 16

Secondary and tertiary amines forming.

Question 17

To ensure only the primary amine is formed from the haloalkane, what is used? (1 mark)

Answer 17

Concentrated ammonia

Question 18

What is the trend in reactivity of the haloalkanes, why? (1 mark)

Answer 18

More reactive as go down the halogens, these bonds are weaker, easier to break, higher reactivity.