5. Biofuels

Biofuels and related molecules are distinguished from fossil hydrocarbons by the presence of one or more oxygen atoms in their structure. The presence of this heteroatom locally impacts the energies of C-H bonds, preferentially orienting the attacks of chain carriers on these positions. What's more, the presence of non-bonding doublets on the oxygen atom opens up the possibility of molecular rearrangements as early as the initiation stage.