Organic Chemistry - Mechanisms

Question 1

What is the essential condition in free radical substitution?

Answer 1

Presence of UV light which causes homolytic fission

Question 2

What were chlorofluorocarbons used for and why were they banned?

Answer 2

Used as refrigerants as well as ion aerosol sprays. They were banned due to the C-Cl bond being broken by UV light creating a free radical which catalyses depletion of the ozone layer.

Question 3

What is a free radical?

Answer 3

An atom with a single unpaired electron, making them highly reactive.

Question 4

What is a nucleophile?

Answer 4

A molecule that is attracted to a nucleus and donates a lone pair of electrons. They tend to be bases.

Question 5

What is the reagent, nucleophile and essential condition for nucleophilic substitution of a halogenoalkane to form a alcohol?

Answer 5

Reagent: NaOH/KOH (Sodium/Potassium hydroxide)
Nucleophile: OH⁻
Essential condition: Dissolved in aqueous solution

Question 6

What is the reagent, nucleophile and essential condition for nucleophilic substitution of a halogenoalkane to form a nitrile?

Answer 6

Reagent: KCN (Potassium Cyanide)
Nucleophile: CN⁻
Essential condition: Dissolve in hot concentrated ethanol and under reflux

Question 7

What is the reagent, nucleophile and essential condition for nucleophilic substitution of a halogenoalkane to form an amine?

Answer 7

Reagent: NH₃ (Ammonia)
Nucleophile: NH₃
Essential condition: Excess NH₃ in a sealed tube under pressure

Question 8

What is the reagent and essential condition for elimination of a halogenoalkane to form an alkene?

Answer 8

Reagent: KOH
Essential condition: Dissolved in hot concentrated ethanol and under reflux