Chapter 13 - Halogenoalkanes

Question 1

What reagents can substitue the polar C - X bond?

Answer 1

nucleophiles (positive loving groups), namely OH-, CN- and NH3

Question 2

Outline the mechanism for nucleophilic subsititution

Answer 2

The C - X bond will break homolytically as the lone pair of the nucelophile will interact with the carbon bonded to the halogen, replacing it

Question 3

Which reagent can act as both a base and a nucleophile to halogenoalkanes

Answer 3

Hydroxide ions

Question 4

What is elimination

Answer 4

It is the creation of an unsaturated organic molecule from a saturated one

Question 5

What is the mechanism between a halogenoalkane and potassium hydroxide?

Answer 5

The OH- group will react with a hydrogen on the carbon next to the halogenocarbon, and the electrons held in the C - H bond will go to the C - C with the halogen, and the halogen will take the electrons in its bond to become a halide ion

Question 6

In what conditions will hydroxide ions act as a base and when will they act as a nucelophile

Answer 6

Substitution - solution + cold
Elimination - ethanolic + hot

Question 7

What danger do CFCs (chloroflurocarbons) pose?

Answer 7

The C - Cl bond can be broken by U.V radiation in the atmosphere, at the same altitude where ozone is found. The Cl free radicals are able to catalyse the depletion of ozone, which prevents U.V from reaching the Earth. This is why the use of CFCs as a refigerant has been banned