The main reactions that saturated hydrocarbons do undergo are dehydrogenation
and cracking, combustion (with F2
or 02), and halogenation (especially
with Cl and Br).
If the temperature is raised high enough to surmount the activation
barrier, or if catalysts are used to bypass it with an alternative
mechanism, then hydrogen atoms may be removed to form unsaturated
compounds (dehydrogenation),or a long molecule may be broken into
smaller pieces (cracking).
- Dehydrogenation: CH3CH2CH2CH3
- Cracking: CH3CH2CH2CH3
These processes are important in the petroleum industry as a means
of converting oils and kerosenes into the more salable gasolines.
Dehydrogenation and cracking usually are rather nonspecific processes
that lead to a mixture of products.
The selection of the right catalyst (often finely divided metals
or metal oxides) and right temperature and pressure to maximize
the yield of the desired product is one of the black arts of the
Combustion or oxidation by 02 or
F2 is a destructive attack by very
electronegative atoms, which results in the complete fragmentation
of the molecule (see page 15).