A systematic nomenclature allows you to name representatives of different classes of organic compounds. Depending on the belonging to a certain group of substances, there are certain nuances in the names that should be mentioned. Let's talk about how a systematic nomenclature is applied to hydrocarbons of various structures, as well as to oxygen-containing compounds.
Classification of Organic Compounds
According to the type of carbon chain, it is customary to subdivide organic substances into cyclic and acyclic; saturated and unsaturated, heterocyclic and carbocyclic. Acyclic is a substance that does not have cycles in its structure. The carbon atoms in such compounds are arranged sequentially, forming straight or branched open chains.
Limit hydrocarbons that have single carbon bonds, as well as compounds with multiple (double, triple) bonds, are isolated.
Nomenclature of alkanes
A systematic nomenclature implies the use of a certain algorithm of actions. Compliance with the rules allows error-free naming of saturated hydrocarbons. If you need an assignment: “Name the proposed hydrocarbon according to a systematic nomenclature,” you must first make sure that it belongs to the class of alkanes. Next, you need to find the longest chain in the structure.
When numbering carbon atoms, the proximity of the radicals to the beginning of the chain, their number, and the name are taken into account. A systematic nomenclature involves the use of additional prefixes that specify the number of identical radicals. Their position is indicated by numbers, they determine the quantity, then they are called radicals. At the final stage, a long carbon chain is named, adding the suffix –an. For example, the hydrocarbon CH3-CH2-CH (CH) -CH2-CH3 has a systematic nomenclature called 3-methylpentane.
Nomenclature Alkenes
According to a systematic nomenclature, these substances are called with the obligatory indication of the position of a multiple (double) bond. In organic chemistry, there is a certain algorithm of actions that helps give names to alkenes. To begin with, the longest fragment comprising a double bond is determined in the proposed carbon chain. The numbering of carbons in the chain is carried out from the side where a multiple bond is located closer to the beginning. If the task is offered: “Name the substances according to the systematic nomenclature”, you need to determine the presence of hydrocarbon radicals in the proposed structure.
If they are absent, they call the chain itself, adding the suffix –en, indicating the position of the double bond with a number. For representatives of unsaturated alkenes, in which radicals are present, it is necessary to indicate their position in numbers, add the number of prefixes specifying, and only then proceed with the name of the hydrocarbon chain itself.
As an example, we give the name of the compound of the following structure: CH2 = CH-CH (CH3) -CH2-CH3. Given that the molecule has a double bond, a hydrocarbon radical, its name will be as follows: 3-methylpunten-1.
Diene hydrocarbons
The nomenclature of this class of unsaturated hydrocarbons is characterized by some features. The molecules of diene compounds are characterized by the presence of two double bonds; therefore, the position of each of them is indicated in the name. We give an example of a compound belonging to this class, give its name.
CH2 = CH-CH = CH2 (butadiene -1.3).
If radicals (active particles) are present in the molecule, then their position is numbered by numbering the atoms in the main chain from the side closest to its beginning. If there are several hydrocarbon atoms in a molecule at once, the prefixes di-, tri-, tetra- are used in the enumeration.
Conclusion
Using a systematic nomenclature, you can give a name to representatives of any classes of organic compounds. A general algorithm of actions has been developed that allows naming samples of saturated and unsaturated hydrocarbons. For carboxylic acids, in which a carboxyl functional group is present, the numbering of the main chain is carried out precisely from it.