What are Hydrocarbons?
Hydrocarbons are organic compounds whose molecular structure is formed by the union between hydrogen and carbon atoms.
The formula basic of hydrocarbons is the following: CxHy.
These organic compounds can be found in different states of matter: liquid, gaseous (natural gas or condensation) and eventually solid.
He Petroleum (in liquid state) and the natural gas (in the gaseous state) are mixtures of hydrocarbons. Hydrocarbons are the source from which other organic substances, such as fossil fuel, are derived.
Characteristics of hydrocarbons
They are organic compounds formed only by hydrogen and carbon atoms. They are not usually biodegradable. They are hydrophobic, that is, insoluble in water. They are lipophilic, that is, soluble in organic solvents. When combustion is optimal or complete, they produce water and dioxide carbon. When combustion is inadequate or incomplete, they produce water and carbon monoxide or carbon (soot).
Classification of hydrocarbons
There are two main types of hydrocarbons. Let’s look at each one separately.
Aromatic hydrocarbons or arenes
They are organic compounds cyclical characterized by having a common nucleus, known as benzene. It can be of two kinds:
Monocyclic: those in which a hydrogen molecule of the benzene ring is replaced by side chains, that is, by hydrocarbon residues. For example, Methylbenzene or Toluene (C6H5-CH3).
Polycyclic: are those that contain two or more benzene nuclei.
Aliphatic hydrocarbons
They are essentially made up of hydrogen and carbon and have no aromatic character. Their chains are open, and can be both linear and branched. Aliphatic hydrocarbons are subdivided into:
Saturated hydrocarbons or alkanes: are those whose carbon bonds are simple. Alkanes contain carbon-carbon single bonds. The general formula of alkanes is the following: (CnH2n+2) For example, the ethane.
Unsaturated hydrocarbons: are those that contain double or triple carbon-carbon bonds. They are part of this group:
Alkenes or olefins: with carbon-carbon double bonds (CH2=CH2). For example: Limonene (from citrus oils).
Alkynes or acetylenes (with carbon-carbon triple bonds). For example: ethyne (HC≡CH).
Where do hydrocarbons come from?
Hydrocarbons are usually found in deposits, deposits or reservoirs at subsoil level, either on the terrestrial platform or on the marine platform.
The process that results in obtaining hydrocarbons consists of four stages. Let’s get to know them.
1. Sedimentation at great depth
Hydrocarbons are formed from the decomposition and thermal transformation of sediments of organic matter (algae, remains of plants, animals) deposited at great depth, which are contained in the so-called bedrockthat is, at the rocky base of the soil.
2. Heating and pressure
The concentration of temperature and pressure exerted on organic matter over the centuries causes it to transform into liquid (oil) or gas. The transformation of organic matter depends on the presence of the parent rock.
3. Migration of hydrocarbons from the source rock to the storage rock
Once transformed, the hydrocarbons migrate towards the pores of the so-called warehouse rocks, that is, sands and fragmented rocks that can absorb and expel fluids. Reservoir rocks have two characteristics: porosity and permeability. It is not, therefore, a concave tank as is usually imagined.
4. Retention by oil trap or impermeable rocks
Is called oil trap to the geometric shape of a storage rock where the fluid is trapped. The trap is covered by a rock seal which prevents the hydrocarbon in question from being expelled to the surface.
See also: Petroleum and Organic Compounds.
Use and importance of hydrocarbons
Other important substances are formed from hydrocarbons, without which modern, industrial life as we know it would not be possible.
Hydrocarbons have, in fact, many uses both at the industrial level and in everyday life, since from them we obtain:
Energetic resources: refers to fuels from hydrocarbons that allow the mobilization of industry, transportation, agriculture and electricity for domestic consumption. This is equivalent to almost 80% of the world’s electricity generation.
Raw Materials: useful in the manufacture of products such as plastic, inks, rubber, synthetic fibers for textiles, detergents, pencils, insecticides and chemicals in general.
Special products: These include asphalt, greases for equipment and engines, lubricants, paraffins, etc.
Substituted hydrocarbons
It refers to those compounds that, although they share the same basic structure of a hydrocarbon, also contain atoms of other chemical elements. That section of the molecule with these characteristics is called a functional group.
For example:
Halogenated compounds such as those included in pesticides, repellents, solvents or refrigerants.