Aromatic Compounds

Aromatic hydrocarbons are organic compounds having a circular structure that contain sigma bonds as well as delocalized pi electrons. Aromatic hydrocarbons are a class of organic molecules that are derived from petroleum. They are also known as arenes or aryl hydrocarbons in some circles.

Aromatic Hydrocarbons Explanation

Aromatic hydrocarbons are “unsaturated hydrocarbons that contain one or more planar six-carbon rings known as benzene rings, to which hydrogen atoms are connected,” according to the definition. A benzene ring can be found in a large number of aromatic compounds (also referred to as an aromatic ring). Amplification of the benzene ring stabilises it, and the pi electrons are delocalized in the ring structure as a result.

Heteroarenes are aromatic hydrocarbons that do not have a benzene ring and are widely found in natural gas and petroleum. In accordance with Huckel’s rule (total number of pi electrons in a monocyclic ring = 4n + 2 where n is any positive integer or zero), all of these heteroarenes are stable.

In these types of compounds, a minimum of one carbon atom is replaced by either nitrogen, oxygen, or sulphur, with the remainder remaining unchanged. Furan (which contains oxygen) and pyridine are two examples of heteroarenes that are commonly encountered (contains nitrogen).

Aromatic Hydrocarbons Have a Variety of Characteristics

“Benzene was the first substance to be classified as an aromatic hydrocarbon,” according to the American Chemical Society. It is also the most complicated aryl hydrocarbon known to science. For each carbon atom in the benzene ring, there are two carbon-carbon sigma bonds formed, one carbon-hydrogen sigma bond formed, and one double bond formed with a neighbouring carbon in which the pi electron is delocalized.

An inner circle within a hexagon represents the delocalization of pi electrons within the benzene molecule. In this molecule, the bond order of all carbon-carbon bonds is regarded to be 1.5, and the reason for this equivalency may be explained using the resonance structures of benzene.

The following section is a list of some of the general characteristics of aromatic hydrocarbons.

It is important to note that these compounds have aromaticity (extra stability provided by resonance). In addition, the carbon to hydrogen atom ratio is relatively high in these sorts of molecules.

• When burned, aromatic hydrocarbons produce a bright yellow flame that is thick with soot.
• These compounds are subjected to electrophilic substitution processes as well as nucleophilic aromatic substitution reactions in the presence of oxygen.

It should be noted that these compounds might either be monocyclic or polycyclic in nature..

Reactions of Aromatic Hydrocarbons

Aromatic hydrocarbons and their reactions

As a key reactant in many organic chemical reactions, aromatic hydrocarbons are used as an example of molecular structure. Some of these reactions are listed in this subsection, along with a brief description of each of the reactions listed in this paragraph.

Substitution Reactions in Aromatic Compounds

These reactions entail the substitution of one substituent on the ring of an aromatic hydrocarbon, most typically a hydrogen atom, with another substituent group.

The following are examples of aromatic substitution reactions that are commonly encountered:

• Aromatic substitution reactions involving nucleophiles
• Reactions involving electrophilic aromatic substitution
• Nucleophilic aromatic substitution reactions involving radical nucleophiles

An example of an aromatic substitution reaction is the electrophilic substitution found in the nitration reaction of salicylic acid, which is an example of an aromatic substitution reaction.

Coupling Reactions are the second type of reaction.

The coupling of two fragments with a radical nature is accomplished with the assistance of a metal catalyst in these types of reactions. It is possible to produce the following types of bonds when aromatic hydrocarbons undergo coupling processes.

• Carbon-carbon bonds can be produced as a result of the coupling processes of arenes, resulting in the formation of products such as vinyl arenes, alkyl arenes, and so on.
• In these reactions, the creation of carbon-oxygen bonds can occur, resulting in the synthesis of aryloxy molecules.
• Coupling processes can result in the formation of carbon-nitrogen bonds, resulting in the formation of compounds such as aniline.

It is possible to notice an example of an aromatic hydrocarbon coupling reaction in the arylation of perfluorobenzene as depicted in the figure below.

Palladium(II) acetate is utilised as a catalyst in this chemical process. Another thing to keep in mind is that DMA is an abbreviation for Dimethylacetamide.

Reactions Involving Hydrogenation

The development of saturated rings is a common result of the hydrogenation processes involving arenes in general. For instance, the reduction of 1-naphthol into a mixture including distinct isomers of decalin-ol is an example of this type of reaction.

The hydrogenation reaction of resorcinol, which is carried out with the assistance of spongy nickel (also known as Raney nickel) and aqueous NaOH, is another example of this type of reaction. This reaction proceeds by the creation of an enolate, followed by the subsequent alkylation of this enolate (with methyl iodide) to generate 2-methyl-1,3-cyclohexanedione as a result of the enolate formation.

Aromatic hydrocarbons have a variety of applications.

Aromatic hydrocarbons are commonly used in a variety of activities, including biological and synthetic. The following are just a few of the countless applications for aromatic hydrocarbons.

It is known as chlorophyll because it is a green pigment found in plants that is composed of aromatic hydrocarbons and is extremely vital in the process of food generation in plants.

Moreover, these aromatic hydrocarbons can be found in the nucleic acids and amino acids produced by the human body.

It is an aromatic hydrocarbon, and it is used as a solvent in model glues. It is also utilised in the creation of mothballs, and it is a key ingredient in the process.

Aryl hydrocarbons such as Phenanthrene are employed in the production of pharmaceuticals, dyes, and explosives, among other things.

It is a very important aromatic hydrocarbon that is frequently utilised for explosive purposes. The plastics business and the petrochemical industry make substantial use of aromatic hydrocarbons, as do other industries such as the pharmaceutical industry.

Conclusion:

These are the hydrocarbons that contain aromatic rings in a fused state, such as benzene. The presence of these compounds can be found in coal, tar, oil, and various prepared meals such as smoked salmon and burned toast, among other things. Naphthalene is an example of a polycyclic hydrocarbon that is commonly encountered. Pollutants are defined as substances that pollute the environment. Benzene, Naphthalene, phenanthrene, trinitrotoluene, o-dihydroxybenzene, and o-dihydroxybenzene are only a few examples of aromatic hydrocarbons.