Synthesis- Haloalkanes

Question 1

What are haloalkanes?

Answer 1

Substituted alkanes in which one or
more of the hydrogen atoms is replaced with a halogen atom

Question 2

What is a monohaloalkane?

Answer 2

Contains only 1 halogen atom

Question 3

What types of reactions will haloalkanes take part in?

Answer 3

Elimination reactions and nucleophilic substitution reactions

Question 4

Describe an elimination reaction involving a haloalkane.

Answer 4

Forms alkenes using a strong
base such as potassium or sodium hydroxide in ethanol

Question 5

Describe the nucleophilic substitution reactions possible using a haloalkane.

Answer 5

React with…
* aqueous alkalis to form alcohols
* alcoholic alkoxides to form ethers
* ethanolic cyanide to form nitriles (chain length increased by
one carbon atom) that can be hydrolysed to carboxylic acids

Question 6

What is an SN1 reaction?

Answer 6

A nucleophilic substitution reaction with one species in the rate
determining step and occurs in a minimum of two steps via a trigonal
planar carbocation intermediate

Question 7

What is an SN2 reaction?

Answer 7

A nucleophilic substitution reaction with two species in the rate
determining step and occurs in a single step via a single five-centred,
trigonal bipyramidal transition state

Question 8

What can be used to explain what will be the preferred reaction mechanism (in terms of SN1 and SN2) for a given haloalkane?

Answer 8

Steric hindrance and the inductive
stabilisation of the carbocation intermediate