Halogenalkanes

Question 1

Uses of Halogenalkanes

Answer 1

Refrigerants, solvents and pharmaceuticals
CFCs restrict the use

Question 2

Reactivity of Halogenalkanes

Answer 2

More reactive than Alkanes due to Polar Bonds
Reactivity increases going down the Halogens , as the bond enthalpy and polarity decreases

Question 3

Solubility of Halogenalkanes

Answer 3

Insoluble as chain length increases

Question 4

Nuclophile

Answer 4

Electron pair donor
OH-
CN-
NH3

Question 5

What are the two mechanisms Halogenalkanes can go under?

Answer 5

Nucleophilic Substitution
Elimination

Question 6

What does the OH- nucelophile act as in Nucleophilic Substitution?

Answer 6

Nucelophile

Question 7

What does the OH- act as in Elimination?

Answer 7

Base

Question 8

Nucleophilic Substitution

Answer 8

Conditions KOH / NaOH (aq)
OH- acts as Nucleophile
Lone pair on O- attacks Cδ+
Products: Alcohol

Question 9

Elimination Reaction

Answer 9

KOH / NaOH dissolved in Warm Ethanol
OH- acts as Base
H+ removed from nucleophile
Prodcuts: Alkenes

Question 10

How do Primary Halogenalkanes tend to react?

Answer 10

By Substitution

Question 11

How do Tertiary Halogenalkanes tend to react?

Answer 11

By elimination

Question 12

How do Secondary Halogenalkanes tend to react

Answer 12

Both elimination and substitution

Question 13

Ozone Depletion

Answer 13

Ozone is formed naturally in the upper atmosphere since it absorbs UV radiation
Chlorine free radicals are found in the upper atmosphere when UV causes Cl-Cl bonds in CFCs to break
Chlorine atoms catalyse the decomposition of the ozone layer and contribute to hole in ozone layer, scientific community has banned CFCs as solvents and refrigerants

Question 14

How can you show that one of the products is an Alkene?

Answer 14

Decolourisation of solution of Bromine