It is known as alkenes to hydrocarbons type unsaturated molecules have at the least one double carbon-carbon bond. These compounds are alkanes that, when losing a pair of hydrogen atoms, come to have a double bond formed by two carbons.
It is important to mention that the notion of alkenes is not included in the dictionary. Instead, the concept of alkanes does appear.
Alkenes used to be known as olefins, since the simplest compounds generate oils by establishing a reaction with a halogen. Alkenes, on the other hand, have different physical characteristics compared to alkanes because the carbon double bond changes the properties linked to acidity and polarity, for example.
Through different chemical reactions, alkenes are transformed into different organic compounds. These reactions can be pericyclic mechanisms, the action of free radicals or electrophilic additions. Let’s look at these concepts in more detail:
* chemical reaction: it is a phenomenon that is also known as chemical change and it consists of a thermodynamic process (certain quantities undergo an evolution) in which one substance or more undergo a transformation that changes its bonds and structure molecular to give rise to new substances, which are called products. Iron oxide, for example, is formed through a chemical reaction between iron and oxygen in the air;
* pericyclic reaction: it is a concept belonging to organic chemistry, and it serves to define a reaction in which a cyclical geometry is seen in the transition state. It is possible to classify this type of reactions as electrocyclic, sigmatropic, cycloaddition, kelotropic or group transfer. It is known that they are usually in chemical equilibrium, that is, there are no net changes in concentrations and activities over time, although a displacement of equilibrium in one direction can occur if the energy content of the product is considerably reduced;
* free radical: this chemical species, whose action can collaborate with the transformation of alkenes into other compounds, can be organic or inorganic and is currently simply called radical. It is characterized by having a minimum of one unpaired electron (also called an unpaired electron, it is one in which there is no compensation for its spin by another electron that has it opposite). Radical formation takes place when a molecule undergoes a homolytic breakdown in the middle of a chemical reaction and is usually very unstable, which is why it lives only a few milliseconds but is considerably reactive;
* electrophilic addition: a reaction of this type is characterized by the loss of a pi bond that undergoes a chemical compound, thanks to which two new sigma bonds are formed. It is framed in organic chemistry, more precisely in reaction mechanisms. The substrates that usually appear in an electrophilic addition have carbon-carbon double or triple bonds. This type of reaction is generally biomolecular or second-order.
Among the alkenes, we can mention ethylene, which is found in plants. When water is added to ethylene, it is possible to obtain ethanol. On the other hand, through a metallic catalyst, a reaction can be carried out between ethylene and molecular hydrogen to achieve ethane.
The isobutylene is another alkene used in the field of industry. Branched in structure, isobutylene is a colorless gas that is flammable under normal temperature and pressure conditions.