10. Organic chemistry - 10.2 Hydrocarbons

Content

I - Alkanes (exemplified by ethane)

II - Alkenes (exemplified by ethene)

III - Arenes (exemplified by benzene and methylbenzene)

IV Hydrocarbons as fuels

Learning outcomes

Candidates should be able to:

(a) be aware of the general unreactivity of alkanes, including towards polar reagents

(b) describe the chemistry of alkanes as exemplified by the following reactions of ethane:

(c) *describe the mechanism of free-radical substitution at methyl groups with particular reference to the initiation, propagation and termination reactions

(d) describe the chemistry of alkenes as exemplified, where relevant, by the following reactions of ethene:

(e) *describe the mechanism of electrophilic addition in alkenes, using bromine/ethene as an example

(f) explain the use of crude oil as a source of both aliphatic and aromatic hydrocarbons

(g) suggest how ‘cracking’ can be used to obtain more useful alkanes and alkenes of lower Mr from larger hydrocarbon molecules

(h) describe and explain how the combustion reactions of alkanes lead to their use as fuels in industry, in the home and in transport

(i) recognise the environmental consequences of:

(j) describe the chemistry of arenes as exemplified by the following reactions of benzene and methylbenzene:

(k) Arenes

(i) *describe the mechanism of electrophilic substitution in arenes, using the mono-nitration of benzene as an example

(ii) describe the effect of the delocalisation of electrons in arenes in such reactions

(l) predict whether halogenation will occur in the side-chain or aromatic nucleus in arenes depending on reaction conditions

(m) apply the knowledge of positions of substitution in the electrophilic substitution of arenas