Aliphatic hydrocarbons are what?

Aliphatic hydrocarbons are organic compounds, the molecules of which contain only a single bond. These include alkanes and cycloparaffins, their features will be considered in our material.

The general formula of alkanes

Representatives of this class are characterized by the general formula CnH2n + 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 low-active compounds, they have received their name "paraffin". We will clarify some features of the structure of representatives of this class, the nature of the bond in molecules, the field of application.

Brief description of methane

As the simplest representative of this class, we can mention methane. It is he who begins the aliphatic series of hydrocarbons. We reveal its distinctive features.

Methane is, under normal conditions, a gaseous substance that is odorless and colorless. This compound is formed in nature by decomposition without the presence of air oxygen of animals and plant organisms. For example, it is found in natural gas, so at present it is used in large quantities as fuel in production and in everyday life.

What kind of chemical bond do these hydrocarbons have? Aliphatic, limiting organic compounds are covalent polar molecules.

The methane molecule has a tetrahedral form 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 low-active compounds.

Features of Methane Homologues

In addition to methane, other hydrocarbons are contained in natural gas and oil, which have a similar structure. The first four representatives of the homologous series of paraffins are in the gaseous aggregate state, have insignificant solubility in water.

As the value of the relative molecular weight increases, an increase in the boiling and melting points of CxHy is observed. Between the individual representatives of the series there is a certain difference CH2, which is called the homological difference. It is a direct confirmation of the affiliation of the compound to this organic series.

All aliphatic hydrocarbons are substances that are readily soluble in organic solvents.

Isomerism of series

For representatives of a number of paraffins, the isomerism of the carbon skeleton is characteristic. It is explained by the possibility of the spatial rotation of the carbon atom around chemical bonds. For example, to connect the composition of C4H10, you can take a hydrocarbon with a straight carbon skeleton - butane. As the structural isomer will be 2-methylpropane, which has a branched structure.

Among the typical chemical properties characteristic of paraffins, it is necessary to note the substitution reactions. The saturation of the bonds explains the complexity of the reaction, its radical mechanism. In order to obtain halogenated derivatives of 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 content in the carbon molecule, different amounts of heat are released. Irrespective of belonging to the class of organic compounds, all combustion processes are exothermic reactions, used in everyday life and industry.

Dehydrogenation of methane (hydrogen splitting) 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 chlorinated alkanes

Dichloromethane, chloroform, and tetrachloroethane 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 of producing soot, which is necessary for the manufacture of printing ink. Methane is considered to be the main source of the production of gaseous hydrogen in the chemical industry, which goes to the production of ammonia, and also to the synthesis of numerous organic substances.

Unsaturated hydrocarbons

Unsaturated aliphatic hydrocarbons are representatives of a number of ethylene and acetylene. Let us analyze their basic properties and applications. The alkenes are characterized by the presence of a double bond, so the general formula for the series has the form CnH2n.

Given the unsaturated 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 particular feature 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 CnH2n-2. Among the distinctive features of these compounds, one can single out the presence of a triple bond. Its presence explains the course of reactions of the compound with halogens, water, hydrogen halide, hydrogen. If the triple bond in such compounds is located in the first position, then the qualitative substitution reaction with the complex silver salt is characteristic for alkynes. It is this ability that is a qualitative reaction to an alkyne, used to detect it in a mixture with an alkene and an alkane.

Aromatic hydrocarbons are cyclic unsaturated compounds, therefore they are not considered to be aliphatic compounds.

Conclusion

Despite the differences in the quantitative composition of the representatives of the limiting and unsaturated aliphatic compounds, they are similar in quality, contain carbon and hydrogen in the molecules. Differences in the quantitative composition (various general formulas) in the representatives of saturated and unsaturated CCl2 explain the difference in the mechanisms of the reactions of obtaining different 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.