3.3 Halogenoalkanes

Question 1

bond between carbon and halogen

Answer 1

polar bond

This is because the halogen is more electronegative than the carbon. It also means that the ∂+ carbon is susceptible to nucleophilic attack which leads to substitution reactions.

Question 2

polar bond

Answer 2

Question 3

nucleophilic attack

Answer 3

Question 4

Answer 4

Question 5

elimination reaction

Answer 5

is one that involves the loss of a small molecule to produce a double bond.

Question 6

halogenoalkanes elimination reactions

Answer 6

Halogenoalkanes can undergo elimination reactions to form alkenes. For example, HBr can be eliminated from 1-bromopropane to form propene.

Question 7

Hydrogen halides - elimination

Answer 7

Hydrogen halides, such as HBr, are acidic and they need to be removed with an alkali, such as sodium hydroxide, NaOH. This must be dissolved in ethanol to avoid a substitution reaction occurring.

Question 8

Answer 8

Question 9

Elimination with unsymmetrical halogenoalkanes

Answer 9

With an unsymmetrical halogenoalkane, more than one alkene can be produced during an elimination reaction.

Question 10

With an unsymmetrical halogenoalkane, more than one alkene can be produced during an elimination reaction.

2-bromobutane

Answer 10

With 2-bromobutane both but-2-ene and but-1-ene can be formed. (You do not need to know which one is more likely to form, just that both are a possibility.)

Question 11

A nucleophile is

Answer 11

a species that has a lone pair of electrons that can be donated to an electron-deficient species. The nucleophile in this reaction is provided by the hydroxide ion, OH-, in aqueous sodium hydroxide, NaOH(aq).