Aromatic Hydrocarbons: Characteristics and the Reactions

Did you know about aromatic hydrocarbons? Aromatic hydrocarbon is one of the compounds found in coal and petroleum. This colorless compound is often used in petrochemical products, such as solvents and plastics.

This article talks about the ins and outs of aromatic hydrocarbons, including the definition and the use. So, read the information below.

What Are Aromatic Hydrocarbons?

Aromatic hydrocarbons are organic aromatic molecules entirely made of hydrogen and carbon. This compound is an unsaturated hydrocarbon having one or more planar rings with six carbons (benzene ring). The hydrogen atom in this compound is bonded to the benzene ring.

Aromatic hydrocarbons are not easily reactive, but when a reaction occurs, this compound substitutes one atom with another atom in other functional groups.

Most aromatic hydrocarbons, or arenes, contain a benzene ring. Benzene is the simplest and most well-known example of an aromatic hydrocarbon and was the first compound to be categorized as an aromatic hydrocarbon. Benzene is volatile at room temperature.

Aromatic hydrocarbons are often used in fuel oil, plastics, dyes, detergents, insecticides, explosives, medicines, and many more.

The Characteristics of Aromatic Hydrocarbons

Despite coming from fossil fuels, like coal and petroleum, aromatic hydrocarbons have several particular characteristics, such as:

It has double bonds spread evenly throughout its ring, making it more stable due to resonance effects.
Made of hydrogen and carbon atoms. Carbon atoms are bonded to each other and form a ring called an aromatic ring.
Sweet odor.
Flammable.
When being combusted, aromatic hydrocarbon emits a strong yellow flame containing soot, water, heat, and carbon dioxide.

Kinds of Aromatic Hydrocarbons

There are several aromatic hydrocarbons you can encounter in daily products, such as:

1. Styrene

Styrene, or styrene monomer, is a yellow or colorless liquid aromatic hydrocarbon. Styrene has a sweet odor and is volatile. Typically, styrene is used to produce Styrofoam, plastic, fiberglass, polystyrene packaging, tires, shoe soles, electronics, and many more.

2. Toluene

Toluene is an aromatic hydrocarbon used to increase the octane of gasoline, as well as a solvent and initial material for organic compound synthesis, such as benzoic acid and benzaldehyde. Toluene is volatile and soluble in water.

3. Aniline

Aniline is an aromatic hydrocarbon used in the synthesis of dyes, resins, drugs, and varnishes, as well as in the manufacture of solvents, perfumes, and vulcanized rubber. Aniline is often used to make textile dyes, one of which is the blue dye in jeans.

4. Phenol

Phenol is a hydrocarbon used as the initial material for synthesizing medicine, resin, and other organic materials and for producing disinfectant. Phenol is typically crystal white and must be handled with care because it can cause chemical burns.

5. Benzoic Acid

Benzoic acid is often used as a food preservative, to dry tobacco, and to synthesize dyes and other organic compounds. In its solid state, benzoic acid tends to be colorless. This compound is soluble in water, alcohol, benzene, and acetone.

6. Nitrobenzene

Nitrobenzene is a compound used to produce shoe polish, soap, cellulose nitrate solvent, and to synthesize aniline. The characteristics of nitrobenzene are that it is yellow-colored, volatile, has an almond-like aroma, and is slightly soluble in water.

7. Bromobenzene

Bromobenzene is a material added to motor oil and solvents, and becomes the initial material for the synthesis of other aromatic compounds. This compound is clear, moveable, has a strong odor, and is insoluble.

In addition, there are also other types of aromatic compounds used to produce manufactured goods, such as trinitrotoluene (TNT) to make explosives; methylbenzene to make model glue solvents; naphthalene to make camphor; and phenanthrene for synthesizing explosives, drugs, dyes, and aryl hydrocarbons.

TNT, methylbenzene, naphthalene, and phenanthrene are polycyclic aromatic hydrocarbons (PAHs), which are hydrocarbons with fused aromatic rings. PAHs are commonly found in oil, coal, tar, and some foods, such as smoked fish and toast.

Reactions Occur to Aromatic Hydrocarbons

In applying aromatic hydrocarbons as the main reactants, many chemical reactions occur. Here are some of the reactions:

1. Coupling Reaction

In this reaction, two fragments that have radical properties will merge. This coupling occurs with the help of a metal catalyst. When aromatic hydrocarbons undergo coupling reactions, there are several bonds formed, including:

Carbon-nitrogen bond. The example is aniline.
Carbon-carbon bond. The examples are alkyl arene, vinyl arene, and others.
Carbon-oxygen bonds that form aryloxy compounds.

2. Substitution Reactions

Substitution reactions replace one substituent on an aromatic hydrocarbon ring with another group of substituent atoms. Usually, the atom that is replaced is hydrogen. There are three common types of substitution reactions, such as:

Electrophilic aromatic substitution: A chemical reaction in which the functional group bound to a compound is replaced with an electrophile. Typically, the functional group replaced is a hydrogen atom.
Substitution nucleophilic aromatics: A chemical reaction in which a nucleophile bonds with the positively charged atom of another substance.
Radical aromatic nucleophilic substitution: A chemical reaction that replaces a group on a molecule or atom with a free radical. Free radicals are species that have unpaired electrons.

3. Hydrogenation Reactions

Hydrogenation reactions use aromatic hydrocarbons to create a saturated ring formation. An example of this reaction is the hydrogenation reaction of resorcinol with the help of sponge nickel and dilute NaOH. This reaction will form an enolate.

That is the information about aromatic hydrocarbons you should know. Aromatics have become one of the materials used to produce various consumer products, such as plastics and tires.

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