The compounds of elemental carbon are characterised by their exceptional diversity and specific properties. Their acquisition, testing of properties and practical application are the interests of organic chemistry. It is a field of science that has intensively developed, particularly in the recent years. The scientific achievements of organic chemistry are used by such disciplines as pharmacy, medicine or genetics.
The key issues that organic chemistry deals with include the synthesis, isolation and testing of the properties of organic compounds. It was initially thought that these substances can only be formed in the human body. That theory was refuted upon the synthesis of urea in laboratory conditions. The first organic compounds were examined and characterised already back in the 12th century. With time, further compounds were discovered along with their properties. Important events which affected the development of organic chemistry include the following:
The elemental composition of organic compounds mainly includes elements such as carbon, hydrogen, oxygen, sulphur, nitrogen and chlorine. Their presence can be proved by observing their heating processes. A vast majority of organic compounds are not thermally stable, and thus they break down. The products of such a disintegration are simple inorganic compounds such as carbon dioxide, water, ammonia, or sulphur dioxide. Additionally, we can often find pure elements (carbon, hydrogen or nitrogen). The incineration of organic compounds in the presence of oxygen or air, as well as their oxidation, generates certain products. The formation of carbon dioxide (CO2) proves that the organic substance contains carbon, the formation of water (H2O) – hydrogen, the formation of cyanogen ions (CN–) – nitrogen, the formation of chloride ions (Cl–) – chlorine, etc.
If we know the elemental composition of the organic compound and the percentage content of each component, we can note down its molecular formula.
Organic compounds, which are the subject of organic chemistry, have a range of features and properties that clearly differentiate them from inorganic compounds. These properties substantially differ based on the group to which the substance belongs (e.g. alcohols, alkanes, ethers, etc.) and the structure of the molecule (the length of its chain or the number of substituents). Carbon is the principal element that builds these compounds. Only few of them have a single atom of carbon. Others contain tens or even hundreds of carbon atoms. This indicates an extreme diversity of compounds in organic chemistry.
Atoms existing in the molecules of organic compounds are usually interlinked with (polarised or non-polarised) covalent bonds. For this reason, in water solutions they do not disintegrate into ions nor conduct electric current. The valence of carbon in organic compounds equals 4. Carbon forms single, double or triple bonds with other chemical elements. The presence of multiple bonds increases the degree of unsaturation of the organic compound. Due to the capacity of elemental carbon to form stable links between atoms, organic substances often contain rings and chains of different lengths and shapes.
Organic substances show relatively large sensitivity to high temperatures and oxidation. In certain conditions, it is easy to destroy their structure. Then they disintegrate or undergo other transformations. Most of them decompose, melt or sublimate at a temperature exceeding 300ᵒC.
The solubility of organic compounds largely depends on the molecular structure, the type and number of substituents, and on the solvent. Individual atoms in the molecules of organic compounds are linked with polarised or non-polarised covalent bonds (the common pair of electrons is shifted towards the atoms with a higher electronegativity). Therefore, these compounds can be divided into polar and non-polar ones. According to the “like dissolves like” rule, polar substances will eagerly dissolve in solvents such as water or methanol. These substances mainly include short-chain compounds, which contain one or several hydroxyl, carboxyl or ester groups. Similarly, non-polar compounds (having long carbon chains and normally no substituents) are freely soluble in non-polar substituents such as benzene, toluene or hexane.
Organic chemistry is a highly organised field of science. Organic compounds, which are analysed within that field, undergo reactions that operate according to specified mechanisms. Principal reactions characteristic of organic chemistry include:
The synthesis of organic compounds on an industrial scale is closely linked with the processes applied by inorganic technology. The installations used to obtain organic and inorganic products are often built within a single production plant. This is due to the use or production of both organic and inorganic compounds in one process.
Today’s organic synthesis industry includes mainly:
Industrial synthesis in organic chemistry deals with high-volume processes of producing organic compounds with a relatively simple structure. They are used as solvents or reactants. In a large part, they are also applied as raw materials in other technological processes, such as the production of plastics, drugs, dyes, surfactants or synthetic resins. Besides the production of synthesis gas and hydrocarbons, organic technology focuses on the industrial production of alcohols (methanol, ethanol, propanol, etc.), acetic aldehyde, formaldehyde, carboxylic acids, phenol, and chloro-organic compounds.
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