In the article, we will consider the preparation of cycloalkanes and the features of their structure. Let us try to explain the characteristic properties of these substances, based on the features of their structure.
Structure
First, let us analyze the structure of this class of organic hydrocarbons. All cyclic compounds are divided into heterocyclic and carbocyclic species.
The second group has three carbon atoms inside a closed cycle. Heterocyclic compounds, in addition to carbon, also contain sulfur, oxygen, phosphorus, and nitrogen atoms in their molecules.
There is a division of carbocyclic compounds into aromatic and alicyclic substances.
Alicyclic substances
These include cycloalkanes. The chemical properties and the preparation of these substances are determined precisely by the closed structure of this class of hydrocarbons.
Alicyclics are those substances that have one or more cycles of a non-aromatic nature. The preparation and use of cycloalkanes is considered in terms of their relationship to alicyclic compounds.
Classification
The simplest representative of this class of hydrocarbons is cyclopropane. In its structure there are only three carbon atoms. Representatives of this homologous series are also called paraffins. By their chemical and physical properties they are similar to saturated hydrocarbons. The molecules contain single bonds formed by hybrid orbitals. In cycloalkanes, the sp3 hybridization type.
The general composition of the class is expressed by the formula SnH2n. The named compounds are interclass isomers of ethylene hydrocarbons.
According to the modern international substitution nomenclature, when the representatives of this class are named, the prefix “cyclo” is added to the hydrocarbon corresponding to the number of atoms. Thus, for example, receive cyclohexane, cyclopentane. The rational nomenclature provides names by the number of closed methylene groups of CH2. Due to this, cyclopropane will be called trimethylene, and cyclobutane - tetramethylene.
This class of organic substances is characterized by structural isomerism regarding the number of carbon atoms in the cycle, as well as optical isomerism.
Education Options
Now we will consider how receiving occurs. Cycloalkanes can be obtained in several ways, depending on which starting material is chosen for the chemical transformation. We will analyze the main options for the synthesis of paraffins.
So what is their receipt? Cycloalkanes are formed by cyclization of dihalogenated saturated hydrocarbons. In a similar chemical way, four- and three-membered rings are formed. For example, cyclopropane. Let us consider its preparation in more detail - cycloalkanes, which are the first representatives of this homologous series, are formed upon the action of metallic magnesium or zinc on the dihalogen derivative of the corresponding alkane.
And how can five-membered and six-membered cyclic compounds be formed? How are they prepared? It is quite difficult to create cycloalkanes with so many carbon atoms in the structure, because there will be a problem with the cyclization of the molecule due to conformation. A similar phenomenon is explained by free rotation on the CC bond, which significantly reduces the likelihood of a cyclic compound. For the formation of these representatives of cycloalkanes, 1,2- or 1,3-dihalo derivatives of the corresponding alkane act as starting materials.
Among the methods for the synthesis of paraffins, we also single out the process of decarboxylation of dicarboxylic acids and salts. Five- and six-membered cycloalkanes are obtained by intermolecular condensation.
And among the special methods of their formation, we note the reaction between alkenes and carbenes, the reduction of oxygen-containing derivatives of cyclo compounds.
Chemical properties
All possible methods for producing cycloalkanes and their interactions are determined by the features of the chemical structure. Given the presence of a cyclic structure, among the basic chemical properties of cycloalkanes, we single out the reactions of hydrogen addition (hydrogenation), its cleavage (dehydrogenation).
For carrying out the reactions, a catalyst is used, in the role of which platinum, palladium can act. Interact at an elevated temperature, its value depends on the size of the cycle. When a cyclic hydrocarbon molecule is exposed to UV radiation, a chlorination reaction (chlorine addition) can be carried out.
Like all representatives of organic compounds, cycloalkane is able to enter into a combustion reaction, forming after the interaction of carbon dioxide, water vapor. This reaction refers to exothermic processes, as it is accompanied by the release of a sufficient amount of heat.
Conclusion
Paraffins are closed hydrocarbon compounds formed from dihalogenated alkanes or other organic compounds. Features of their structure determine the basic chemical properties of cycloalkanes, their application areas. They are mainly used in organic synthesis to produce oxygen-containing organic substances.