As others answers have pointed out, the main pathways for reducing carbohidrates to hydrocarbons involves the dehydration elimination of the alcohol groups. This reaction is catalized by acidic conditions and can be carried out with linear alcohols (i.e. like ethanol, resulting in an olefin) in laboratory conditions, at temperatures higher than 160 °C and atmospheric pressure. The products are unsaturated compounds and water.

Even if the geochemical conditions don't allow a strongly acidic medium, the pressures and temperatures attained should be enough to pyrolitically dehydrate sugars and cellulosic material which makes up most of the cell walls of vegetal biomass. Nevertheless, pyrolitic conversion of mainly-cellulosic biomass in sedimentary basins ussually doesn't produce aliphatic hydrocarbons. Instead, the carbon skeletons are further dehydrogenated and compressed forming coal deposits containing minor aromatic derivatives like phenols and aniline.

The main source of hydrocarbon deposits are the pyrolitic decarboxylation of fatty acids, in turn produced by the hydrolisis of lipids. Those lipids mostly come from microphytes (microalgae) which comprise most of the phytoplancton in the seas, and which have been accumulated at the bottom of ancient oceans. For example, the rich sedimentary basin of modern Middle East was once the Tethys Ocean seabed.

So, in essence, both in the dehydration of carbohidrates and in the decarboxylation of fatty acids, the oxygen goes away in the form of water or carbon dioxide.

As others answers have pointed out, the main pathways for reducing carbohidrates to hydrocarbons involves the dehydration elimination of the alcohol groups. This reaction is catalized by acidic conditions and can be carried out with linear alcohols (i.e. like ethanol, resulting in an olefin) in laboratory conditions, at temperatures higher than 160 °C and atmospheric pressure. The products are unsaturated compounds and water.

Even if the geochemical conditions don't allow a strongly acidic medium, the pressures and temperatures attained should be enough to pyrolitically dehydrate sugars and cellulosic material which makes up most of the cell walls of vegetal biomass. Nevertheless, pyrolitic conversion of mainly-cellulosic biomass in sedimentary basins ussually doesn't produce aliphatic hydrocarbons. Instead, the carbon skeletons are further dehydrogenated and compressed forming coal deposits containing minor aromatic derivatives like phenols and aniline.

The main source of hydrocarbon deposits is the pyrolitic decarboxylation of fatty acids, in turn produced by the hydrolisis of lipids. Those lipids mostly come from microphytes (microalgae) which comprise most of the phytoplancton in the seas, and which have been accumulated at the bottom of ancient oceans. For example, the rich sedimentary basin of modern Middle East was once the Tethys Ocean seabed.

So, in essence, both in the dehydration of carbohidrates and in the decarboxylation of fatty acids, the oxygen goes away in the form of water or carbon dioxide.

As others answers have pointed out, the main pathways for reducing carbohidrates to hydrocarbons involves the dehydration elimination of the alcohol groups. This reaction is catalized by acidic conditions and can be carried out with linear alcohols (i.e. like ethanol, resulting in an olefin) in laboratory conditions, at temperatures higher than 160 °C and atmospheric pressure. The products are unsaturated compounds and water.

Even if the geochemical conditions don't allow a strongly acidic medium, the pressures and temperatures attained should be enough to pyrolitically dehydrate sugars and cellulosic material which makes up most of the cell walls of vegetal biomass. Nevertheless, pyrolitic conversion of mainly-cellulosic biomass in sedimentary basins ussually doesn't produce aliphatic hydrocarbons. Instead, the carbon skeletons are further dehydrogenated and compressed forming coal deposits containing minor aromatic derivatives like phenols and aniline.

The main source of hydrocarbon deposits are the pyrolitic decarboxylation of fatty acids, in turn produced by the hydrolisis of lipids. Those lipids mostly come from microphytes (microalgae) which comprise most of the phytoplancton in the seas, and which have been accumulated at the bottom of ancient oceans. For example, the rich sedimentary basin of modern Middle East was once the Tethys Ocean seabed.

As others answers have pointed out, the main pathways for reducing carbohidrates to hydrocarbons involves the dehydration elimination of the alcohol groups. This reaction is catalized by acidic conditions and can be carried out with linear alcohols (i.e. like ethanol, resulting in an olefin) in laboratory conditions, at temperatures higher than 160 °C and atmospheric pressure. The products are unsaturated compounds and water.

Even if the geochemical conditions don't allow a strongly acidic medium, the pressures and temperatures attained should be enough to pyrolitically dehydrate sugars and cellulosic material which makes up most of the cell walls of vegetal biomass. Nevertheless, pyrolitic conversion of mainly-cellulosic biomass in sedimentary basins ussually doesn't produce aliphatic hydrocarbons. Instead, the carbon skeletons are further dehydrogenated and compressed forming coal deposits containing minor aromatic derivatives like phenols and aniline.

The main source of hydrocarbon deposits are the pyrolitic decarboxylation of fatty acids, in turn produced by the hydrolisis of lipids. Those lipids mostly come from microphytes (microalgae) which comprise most of the phytoplancton in the seas, and which have been accumulated at the bottom of ancient oceans. For example, the rich sedimentary basin of modern Middle East was once the Tethys Ocean seabed.

So, in essence, both in the dehydration of carbohidrates and in the decarboxylation of fatty acids, the oxygen goes away in the form of water or carbon dioxide.