In the transition from inorganic to organic chemistry, one can trace how the classification of organic and inorganic substances differs. The world of organic compounds has a variety and numerous options. The classification of organic substances not only helps to understand this abundance, but also brings a clear scientific basis for their study.
The theory of chemical structure was chosen as the basis for the distribution of organic compounds into classes. The basis of the study of organics is the work with the most numerous class, which is usually called the main for organic substances - hydrocarbons. Other representatives of the world of organics are considered as their derivatives. Indeed, when studying their structure, it is not difficult to notice that the synthesis of these substances occurs by replacing (replacing) in the hydrocarbon structure of one, and sometimes several hydrogen units with atoms of other chemical elements, and sometimes with whole radical branches.
The classification of organic substances was also based on hydrocarbons because of the simplicity of their composition, and the hydrocarbon component is the most significant part of most known organic compounds. Today, of all known chemicals related to the world of organics, compounds built on the basis of carbon-hydrogen bonds have a significant predominance. All other substances are either in the minority, making it possible to classify them as exceptions to the general rule, or are so unstable that their production is difficult even in our time.
Classification of organic substances by dividing into separate groups and classes allows us to distinguish two large organic classes of acyclic and cyclic compounds. Their very name allows us to conclude about the type of molecule construction. In the first case, this is a chain of hydrocarbon units, and in the second, the molecule is a ring.
Acyclic compounds may have branches, or may form a simple chain. Among the names of these substances can be found the expression "fatty or aliphatic hydrocarbons." They can be limiting (ethane, isobutane, ethyl alcohol) or unsaturated (ethylene, acetylene, isoprene), depending on the type of bond of some carbon units.
The classification of organic substances related to cyclic compounds implies their further division into a carbocyclic group and a heterocyclic hydrocarbon group.
Carbocyclic "rings" are composed only of carbon atoms. They can be alicyclic (saturated and unsaturated), as well as aromatic carbocyclic compounds. In alicyclic compounds, the two ends of the carbon chain simply connect, but aromatic compounds in their structure have the so-called benzene ring, which has a significant effect on their properties.
In heterocyclic substances, atoms of other substances can be found, most often nitrogen performs this function.
The next constituent element that affects the properties of organic substances is the presence of a functional group.
For halogenated hydrocarbons, one or even several halogen atoms can act as a functional group. Alcohols get their properties due to the presence of hydroxo groups. For aldehydes, a characteristic feature is the presence of aldehyde groups, for ketones, carbonyl groups. Carboxylic acids are distinguished by the fact that their composition includes carboxyl groups, and amines have an amino group. Nitro compounds are characterized by the presence of a nitro group.
The variety of hydrocarbon species, as well as their properties, is based on a very different type of combination. For example, the composition of one molecule may include two or more identical, and sometimes different functional groups, determining the specific properties of this substance (aminoacetic acid, glycerin).
For clarity, a table will give greater visibility (classification of organic substances), which can be easily compiled on the basis of the information presented in the text of this article.