Alkadienes are typical representatives of unsaturated hydrocarbons

Alkanes, alkenes, alkynes, alkadienes, whose formulas differ in the number of hydrogen atoms, refer to hydrocarbons. Consider the distinguishing features of each class, the type of hybridization, the characteristic properties.

Paraffins

The limiting hydrocarbons have the general formula C _n H _{2n + 2} . In them, all the bonds between the hydrogen and carbon atoms are single. If a single hydrogen is detached in the reaction, the alkane is converted to an active particle - a radical. The first representatives of this series are gaseous substances that are slightly soluble in water.

As the number of carbons in the main chain increases, solubility decreases, and hydrocarbons enter a solid aggregate state under normal conditions.

Among the basic chemical properties inherent in the representatives of this class, we select substitution. In connection with the fact that all bonds are saturated, the addition for alkanes is uncharacteristic. Like all other organic substances, alkanes react with oxygen (combustion), as a result of which energy is released. This process is endothermic, used in production for heating residential and industrial premises.

Cycloalkanes

The peculiarity of this class is the presence of a closed structure of molecules. The general formula for such hydrocarbons is C _n H _2n . Taking into account the peculiarities of the structure of this class, they are characterized by substitution reactions in the side chain, as well as the addition of hydrogen, which is accompanied by the destruction of the cycle.

Alkenes

In the homologous series of ethylene, the general formula has the form C _n H _{2n + 2} . Among the distinguishing features of hydrocarbons (naphthenes), we distinguish the presence of a double bond between carbon atoms. A p-bond is formed due to overlapping of two non-hybrid p-orbitals from neighboring carbon atoms.

Its presence determines not only the type of carbon hybridization in alkenes, but also the characteristic chemical properties of all representatives of this class of organic compounds. A qualitative reaction to the unsaturated (double) bond will be the decolorization of bromine water.

As a result of the interaction, a double bond is cleaved, the halogen molecule is attached to the alkene. In addition, the decoloring of potassium permanganate also applies to specific reactions characteristic of a given homologous series.

Among the properties of ethylene and its homologues, it is necessary to identify other types of addition reactions. When hydrogenating (interaction with hydrogen), the corresponding alkane forms. Hydration (with water) and hydrohalogenation (with a hydrogen halide molecule) proceed in unsaturated alkenes according to the Markovnikov rule.

Its essence lies in the fact that the double bond is split when an asymmetric alkene (bond position 1) of water or hydrogen halide molecules is attached. Hydrogen is attached by reacting to a more hydrogenated (hydrogen saturated) carbon atom, and the hydroxo group or halogen is attached to the less hydrogenated H.

In addition to addition, polymerization reactions are characteristic for ethylene and its homologues. A large polymer molecule consisting of identical structural units is formed from a small initial monomer. Polymerization is widely used in the chemical industry to create modern plastics.

Alkadiene

To begin with, we note that the alkadienes are unsaturated hydrocarbons having the general formula C _n H _{2n + 2} . There is a certain similarity between the representatives of a given homologous series and alkenes. Since alkadienes are unsaturated hydrocarbons, they are also characterized by addition reactions.

The difference is that there are two unsaturated double bonds in the dienes, therefore, to complete the connection, excess bromine water, hydrogen, water, hydrogen halide will be required.

Representatives of a number of propadien also enter the polymerization reaction. The products obtained during this reaction are used for the production of synthetic rubbers, the production of rubber. Since alkadienes are unsaturated substances, a qualitative reaction to their determination will be the decolorization of potassium permanganate and bromine water. Alkadiene, whose homologous series begins with propadiene, are liquids or solids.

Among the spheres of application of representatives of this class, we will distinguish the production of polymer materials.

Alkyny

In the homologous series of acetylene, the general formula has the form C _n H _2n-2 . If alkadienes are substances in which there are two double bonds, then for alkynes one triple bond is characteristic. A qualitative reaction to a triple bond for unsymmetrical alkynes is the interaction of representatives of this class with a complex compound - silver amine hydroxide (1). As a result of the interaction, a salt-silver acetylide is formed.

Representatives of this homologous series are interclass isomers for alkadienes. Similarly to alkenes, alkadienes, all alkynes enter the addition reactions with halogens, hydrogen, hydrogen halide, water. When an insufficient amount of hydrogen is added to the acetylene molecule, ethylene is formed. In the case of interaction with excess hydrogen from acetylene, ethane (the ultimate hydrocarbon) is formed.

Conclusion

Alkines, alkenes, alkadienes, alkadienes, whose chemical properties were discussed above, clearly demonstrate the main similarities and differences between different classes of substances. All hydrocarbons in their composition have carbon and hydrogen atoms, so they are an excellent fuel.