Saturated hydrocarbons are defined as chemical compounds that are made up exclusively of carbon and hydrogen atoms. These compounds arise from fractional distillation, from oil or natural gas. Aliphatic hydrocarbons whose carbon atoms are linked together by single bonds are saturated. When joined by double or triple bonds they are unsaturated hydrocarbons.
Aliphatic hydrocarbons, according to theory, are those that lack an aromatic ring. They can be saturated or unsaturated. The saturated ones are the alkanes (group in which all carbons have two pairs of single bonds), while the unsaturated ones (also known as the unsaturated ones) are the alkenes (which, at least, have one double bond) and the alkynes (with triple links).
Saturated hydrocarbons are named according to the number of carbon atoms in the chain that forms the molecule, adding the ending -ano.
Examples:
Methane → CH3
Ethane → CH3-CH3
Propane → CH3-CH2-CH3
Butane → CH3-CH2-CH2-CH3
Pentane → CH3-CH2-CH2-CH2-CH3
The example above shows a homologous series, because although each molecule is made up of a different number of carbon atoms, they all have the same functional group in common.
When a hydrocarbon undergoes the loss of hydrogen, what is called a radical is formed. The radicals are named after the hydrocarbon from which they come, but changing the final year, by -ilo, in the case that we name the radical in isolation, or with the ending -il, in the case of naming the entire compound.
Examples:
Methyl → CH3
Ethyl → CH3CH2
Propyl → CH3CH2CH2
Saturated hydrocarbons are obtained from oil or natural gas. They can also be synthesized in the laboratory. One of the methods used is the addition of hydrogen to the double bonds of alkenes and alkynes (see t28). This relationship arises with the presence of platinum, nickel or palladium catalysts, to form alkanes with the same carbon skeleton.
CH3 - CH = CH2 + H2® CH3 - CH2 - CH3
When the right conditions are found, the following types of reactions can occur:
1. Combustion: the combustion reaction is the most important in saturated hydrocarbons, since these hydrocarbons are used as fuels, since they are capable of releasing a large amount of energy. In combustion, CO2 and water are always released.
Example: butane combustion reaction:
2 C4H10 + 13 O2 → 8 CO2 + 10 H2O + 2640 KJ / mol
2. Cracking: it is when the saturated hydrocarbons are separated from those that contain less carbon, that is, smaller hydrocarbons. When this reaction occurs with heat, it is called thermal cracking, when it is carried out by catalysts, it is called catalytic cracking. Cracking is used to obtain gasoline from oil fractions that have a greater weight.
3. Halogenation: in this type of reaction, a hydrocarbon hydrogen is replaced by a halogen element.
