Halogenoalkanes

Question 1

Give another word halogenoalkanes

Answer 1

Haloalkanes

Question 2

What are halogenoalkanes

Answer 2

Alkanes with Halogen atoms

Question 3

What type of bond is the Carbon-halogen in halogenoalkanes

Answer 3

Polar

Question 4

How are the bonds between carbon and halogens polar?

Answer 4

Halogens are more electronegative than carbon

Question 5

What is a nucleophile

Answer 5

An electron pair donor

Question 6

Give me examples of nucleophiles

Answer 6

OH-, CN- and NH3

Question 7

What charge is found on carbon

Answer 7

Delta +

Question 8

How is the movement of electron pairs shown?

Answer 8

Using curly arrows

Question 9

What type of reactions do halogenoalkanes undergo?

Answer 9

Nucleophilic substitution reactions

Question 10

How do nucelophilic substitution reactions work?

Answer 10

• The lone pair of electrons in the nucleophile attacks the delta + carbon
• C-X bond breaks
• The halogen leaves taking both electrons with it
• A new bond forms between the carbon and the nucleophile

Question 11

What do halogenoalkanes form when they react with hydroxides?

Answer 11

Alcohols

Question 12

What conditions are required to form alcohols

Answer 12

Warm, aqueous hydroxides and reflux

Question 13

What is formed when halogenoalkanes react with Cyanide

Answer 13

Nitriles

Question 14

How many bonds are found in cyanide

Answer 14

3 bonds

Question 15

What conditions are required to form nitriles

Answer 15

Warm, ethanolic potassium cyanide, reflux, ethanol

Question 16

What is formed when halogenoalkanes react with ammonia

Answer 16

Amines

Question 17

What conditions are required to form amines

Answer 17

• Warm halogenoalkanes, excess ethanolic ammonia

Question 18

The amine group formed can still act as what and why?

Answer 18

• A nucleophile
• Because it still has a lone pair of electrons

Question 19

Which will react the fastest, iodoalkanes or fluoroalkanes?

Answer 19

Iodoalkanes because bond enthalpy esp decrease down the group so they are easier to break and are substituted quickly

Question 20

What other type of reactions do halogenoalkanes undergo?

Answer 20

Elimination reactions

Question 21

What is formed in an elimination reaction?

Answer 21

Alkene

Question 22

What conditions are required for elimination reactions

Answer 22

• Warm halogenoalkanes
• Hydroxides dissolved in ethanol
• Heat the moisture under reflux
• Anhydrous (dry) conditions

Question 23

Which molecule acts as a base in elimination reactions?

Answer 23

OH-, it takes away a proton e.g hydrogen

Question 24

Why does ammonia act as a nucleophile despite not having a negative charge?

Answer 24

It has a lone pair of electrons

Question 25

Where are nucleophiles attracted to?

Answer 25

Electron deficient areas

Question 26

Which will react faster 1-chloropropane or 1-bromopropane and why?

Answer 26

• 1-bromopropane
• C-Br bond is weaker than C-Cl bond

Question 27

Identify the characteristic of a haloalkane that enables it to undergo a Nucleophilic substitution reaction

Answer 27

A polar C-Br bond

Question 28

Explain why the halogenoalkane is attacked by the nucleophile in this reaction

Answer 28

• Bromine is more electronegative than carbon
• C is partially positive / electron deficient
• Lone/electron pair (on the nucleophile) donated to the partially
  positive carbon