Aliphatic hydrocarbons are organic compounds whose molecules contain only a single bond. These include alkanes and cycloparaffins, their features will be considered in our material.
General formula of alkanes
Representatives of this class are characterized by the general formula SpN2p + 2. Paraffins include all compounds having an open chain, where the atoms are joined together by simple bonds. Due to the fact that under normal conditions, aliphatic hydrocarbons are inactive compounds, they are called paraffins. We will clarify some structural features of representatives of this class, the nature of the bonds in the molecules, and the application industry.
Brief Description of Methane
As the simplest representative of this class, methane can be mentioned. It is he who begins the aliphatic series of hydrocarbons. We will reveal its distinctive features.
Under normal conditions, methane is a gaseous substance, odorless and colorless. This compound is formed in nature when decomposed without the presence of oxygen from the air of animals and plant organisms. For example, it is found in natural gas, which is why it is currently used in large quantities as fuel in production and in everyday life.
What chemical bonding do these hydrocarbons have? Aliphatic, terminal organic compounds are covalent polar molecules.
The methane molecule has the tetrahedral shape of the molecule, the type of hybridization of carbon atoms in it is sp3, which corresponds to a valence angle of 109 degrees 28 minutes. It is for this reason that aliphatic hydrocarbons are chemically inactive compounds.
Features of methane homologues
In addition to methane, natural gas and oil contain other hydrocarbons that have a similar structure to it. The first four representatives of the homologous series of paraffins are in a gaseous state of aggregation, have a slight solubility in water.
As the relative molecular weight increases, an increase in the boiling and melting points of CcNu is observed. Between the individual representatives of the series there is a certain difference in CH2, which is called the homological difference. It is a direct confirmation of the belonging of the compound to this organic series.
All aliphatic hydrocarbons are substances readily soluble in organic solvents.
Row isomerism
Representatives of a number of paraffins are characterized by the isomerism of the carbon skeleton. It is explained by the possibility of spatial rotation of a carbon atom around chemical bonds. For example, for a compound of 410 composition, one can take a hydrocarbon with a direct carbon skeleton - butane. As a structural isomer, 2-methylpropane having a branched structure will act.
Among the typical chemical properties characteristic of paraffins, substitution reactions should be noted . The saturation of bonds explains the complexity of the reaction, its radical mechanism. In order to obtain halogenated aliphatic hydrocarbons, it is necessary to carry out a halogenation reaction proceeding in the presence of UV radiation. The chain nature of this interaction is observed in all representatives of this series. The resulting products are called halogen derivatives. They are widely used in the chemical industry as organic solvents.
In addition, all aliphatic and aromatic hydrocarbons burn in the presence of oxygen, forming water and carbon dioxide. Depending on the percentage in the carbon molecule, a different amount of heat is released. Regardless of belonging to the class of organic compounds, all combustion processes are exothermic reactions that are used in everyday life and industry.
Methane dehydrogenation (hydrogen cleavage) also has practical applications. As a result of this process, acetylene is formed, which is a valuable chemical raw material.
The use of alkanes and chlorine derivatives of alkanes
Dichloromethane, chloroform, tetrachlomethane are liquids that are excellent organic solvents. Chloroform and iodoform are used in modern medicine. The decomposition of methane is one of the industrial methods for producing soot, necessary for the manufacture of printing ink. Methane is considered the main source of hydrogen gas in the chemical industry for ammonia production, as well as for the synthesis of numerous organic substances.
Unsaturated hydrocarbons
Unsaturated aliphatic hydrocarbons are representatives of a number of ethylene and acetylene. Let us analyze their main properties and application. The alkenes are characterized by the presence of a double bond; therefore, the general formula of the series has the form Spn2p.
Given the unsafe nature of these substances, it can be noted that they enter into the reaction of the compound: hydrogenation, halogenation, hydration, hydrohalogenation. In addition, representatives of a number of ethylene are capable of polymerization. It is this feature of them that makes representatives of this class in demand in modern chemical production. Polyethylene and polypropylene are the substances that form the basis of the polymer industry.
Acetylene is the first representative of a series having the general formula SpN2p-2. Among the distinguishing features of these compounds, the presence of a triple bond can be distinguished. Its presence explains the reaction of the compound with halogens, water, hydrogen halide, hydrogen. If the triple bond in such compounds is located in the first position, then the alkynes are characterized by a qualitative substitution reaction with a complex silver salt. It is this ability that is a qualitative reaction to alkine, used to detect it in a mixture with alkene and alkane.
Aromatic hydrocarbons are cyclic unsaturated compounds, therefore, are not considered aliphatic compounds.
Conclusion
Despite the differences in the quantitative composition that exist among representatives of the limiting and unsaturated aliphatic compounds, they are similar in qualitative terms and contain carbon and hydrogen in the molecules. Differences in the quantitative composition (various general formulas) among representatives of saturated and unsaturated CIH explain the difference in the reaction mechanisms of the production of various products.
That is why representatives of all classes of such compounds enter into combustion reactions, forming carbon dioxide, water, releasing a certain amount of thermal energy, which makes them in demand as a fuel in everyday life and industry.