Uses of Phenol: Introduction of Phenol, Uses of Phenol, Practice Problems & Frequently Asked Questions(FAQs)

Have you ever noticed that the product is occasionally labelled as BPA-free on plastic containers?

What does BPA represent?

It is a common Phenol derivative called Bisphenol A.

In the plastics sector, where it is employed as a starting material to carry out the polymerization reactions that lead to the manufacturing of various types of plastics, phenol has one of the broadest and most widespread uses.

Without plastics, life in the modern world seems unimaginable.

They play a highly significant role in our daily lives. Everyday, we utilise a huge variety of plastic-based items. Acetone and phenol are made to react, resulting in the creation of bisphenol A.

Additionally, this substance is used to synthesise a variety of polymers, including epoxide resins and polycarbonates, which serve as the fundamental framework for different plastics.

Table of contents:

• Introduction of phenol
• Uses of phenol
• Practice problems
• Frequently asked questions(FAQs)

Introduction of phenol:

A hydroxyl group, often known as a -OH group is joined to an aromatic benzene ring to form the organic compound phenol. It is an organic molecule that is aromatic and has the chemical formula C₆H₅OH or PhOH.

The aromatic ring of phenol has sp₂ hybridised carbon atoms all throughout. Phenyl therefore has a hexagonal planar structure with 120o bond angles and delocalize -electrons distributed across the ring.

Because oxygen is more electronegative than both carbon and hydrogen atoms, both the C-O and O-H bonds are polar.

In phenol, the non-bonded electron pairs of the oxygen atoms are conjugated to the aromatic ring.

The delocalization of -electrons is what causes the partial transfer of negative charge from the oxygen atom to the aromatic ring system.

The delocalization of -electrons enhances the polarisation of the O-H bond. Phenol has an acidic character as a result.

Both alcohols and phenols are acids, however phenols are more acidic than alcohols because of the stability of phenoxide ions. The main element affecting its stability is the delocalization of electrons in the benzene ring. The oxygen's negative charge is delocalized throughout the entire benzene ring, which increases its stability.

Phenols rapidly release protons in the presence of a base because the phenoxide ion is rather stable, increasing the acidity. Here is the example of the resonating structures of phenoxide:

Uses of Phenol:

Phenol has been the most popular disinfectant since the dawn of civilization. It also possesses outstanding antibacterial properties. It was one of the most often used cleaning agents for household items, particularly for cleaning floor tiles and toilets.

Phenol is an effective antibacterial, antifungal, and antiviral substance, as has been demonstrated. To understand the mechanism of action underlying these traits, numerous investigations have been conducted. According to some studies, it stops bacteria from producing RNA and proteins, which kills the bacteria. Furthermore, some studies suggest that it damages the cytoplasmic membranes of the microorganisms.

Even though it is used in very small amounts, phenol is used to make mouthwashes that effectively clean the mouth and get rid of microorganisms.

Additionally, phenol is employed in the mouth as a moderate anaesthetic and analgesic. This is due to the numbing effect that its alcohol's astringent properties produce. However, care should be used while using it orally because the strong solution of phenol can damage mucosal membranes and be toxic to human skin.

Phenol was one of the compounds employed during the Second World War since it is dangerous when used in concentrated volume.

The production of numerous compounds, including picric acid, pharmaceutical medications, explosive substances, and plastic polymers, uses phenol as one of the starting ingredients.

In the colouring industry, phenols are one of the raw chemicals used to make azo dyes.

Phenol is generated as an intermediate in numerous industries, where it is then used to produce or manufacture a variety of compounds in other industries.

Phenol is a preservative that is employed in the wood industry to keep wood from becoming infected by bacteria or fungi.

A variety of skincare and cosmetic goods, including skin-lightening creams and lotions, sunscreens, and solutions for hair colours and dyes, are produced using phenol in the cosmetics and skincare product manufacturing industries.

In order to extract biomolecules for analysis and research, phenol is utilised. Phenol is frequently used in molecular biology labs to extract nucleic acids from DNA structures of tissue samples from a variety of sources for research studies and investigations.

For the formaldehyde polymerization synthesis, phenol is used. The polymer industry uses this reaction in a commercial setting to create phenolic resins. Phenol-formaldehyde resin, popularly known as Bakelite in the commercial world, is the name of the polymeric resin produced in this reaction. This phenol-formaldehyde resin is utilised in switches and other electrical equipment. Additionally, it is used in the auto sector to lubricate a few delicate and small engine components. Due to its remarkable capacity to tolerate extremely harsh circumstances in terms of electrical resistance, heat, or corrosion from other chemical agents, this resin finds application in a wide range of industries.

Novolac is a different intermediate resin-like substance produced by the polymerization of phenol and formaldehyde. Due to its excellent adhesive qualities, this resin is used as a binding substance across numerous sectors. Additionally, it is employed as a protective layer over materials that quickly degrade in the presence of moisture.

Pharmaceutical lotions, ointments, and ear drops used to stop bacterial or fungal infections all contain the active component phenol.

Phenol is also used in varicose vein sclerotherapy as a sclerosing agent. Its alcohol content creates an irritating solution that, when injected into blood vessels, causes inflammation in the blood vessel's inner lining, which causes the blood vessels to collapse. The blood clots in that area when the opposing walls of the blood arteries meet and become caught there. In order to force blood to flow via the healthy veins instead of the damaged veins, this is done. It is a very harmful type of treatment, and it is typically not advised unless all other effective options, including sodium tetradecyl sulphate solution, polidocanol, hypertonic saline solution, or chromated glycerin solution, cannot be employed.

Phenol is also a component of the chemical face peeling masks created by the dermatological sector due to its astringent qualities. For individuals with severe skin burns on their hands, feet, or face, it is a harsh remedy, but it is thought to be beneficial. In addition, the rough wrinkle lines, scars, and in some cases even premature tumour outgrowths can be treated with the phenol chemical peel-off masks. However, because it is not suitable for all skin types and might severely injure specific skin areas, you should only use this phenol peel mask under your dermatologist's supervision. It can also cause extreme swelling, redness, and itching in some people.

Phenol can also be used to chemically sterilise hospital rooms and medical equipment occasionally.

Patients with Parkinson's disease, brain damage, or cerebral palsy can receive an injection of phenol to cure their muscle spasms. The same principles that were previously discussed for the treatment of varicose veins or persistent nerve pain apply here. It interferes with all impulses travelling from the brain to nerves, muscles, or blood vessels, including those conveying pain or spasms.

Some throat sprays contain phenol, which can help numb your throat and reduce sore throat symptoms as well as oral discomfort brought on by canker sores.

Antioxidants are known to exist in phenol-containing plant-based substances. This indicates that they have the ability to halt the interaction of free radicals with other molecules in your body, avoiding both DNA damage and long-term negative consequences on your health.

Many vaccines, including Pneumovax 23 (used to prevent pneumonia and meningitis), Typhim Vi (used to prevent typhoid fever), ACAM2000 (used to prevent smallpox), and Ipol (used for the prevention of Polio), contain phenol as a preservative.

Practice problems:

Q.1. Phenol is also known as

(A) Carbolic acid
(B) Salicylic acid
(C) Benzoic acid
(D) None of the above

Answer: (A)
When used as a disinfectant, phenol is commonly referred to as Carbolic.

It has an acidic character and an -OH group on the aromatic ring. As a result, it is known as carbolic acid.

Q.2. Which of the following is least acidic?

(A) o-fluorophenol
(B) o-chlorophenol
(C) o-bromophenol
(D) o-iodophenol

Answer: (A)
The order is o-chlorophenol > o-bromophenol > o-iodophenol > o-fluorophenol.

This is so because fluorine in o-fluorophenol forms an intramolecular hydrogen bond with the -OH group's H atom due to fluorine's strong electronegative properties. The acidity of this -OH is therefore at its lowest.

Since the electronegativity in the other three cases is not as great as it is for F, we should now search for the halogens -I effect.

-I effect follows the order Cl >Br>I.

Q.3. Phenol is

(A) Polar
(B) Non polar
(C) Both A and B
(D) None of the above

Answer: (A)
A functional group -OH is present in the phenol. The hydrocarbon (C₆H₅) has a hydroxyl group in place of one of its hydrogens. The hydroxyl group is polar in nature because oxygen attracts hydrogen toward itself because it has a higher electronegativity than hydrogen, giving hydrogen a partial positive charge and oxygen a partial negative charge.

Q.4. In phenol, a carbon atom bound to a -OH group possess

(A) sp³ hybridisation
(B) sp² hybridisation|
(C) sp hybridisation
(D) No hybridisation

Answer: (B)
The carbon atom connected to the -OH group in phenol is bonded with three sigma () bonds and one pi () bond. As a result, the hybridisation will be sp2.

Frequently asked questions(FAQs):

1. What causes phenol to be more reactive than alcohol?
Answer: Because it rapidly loses H+ and creates resonance-stabilised phenoxide ions, phenol is highly reactive. The alkoxide ion RO-, on the other hand, is unstable due to the + I effect of the R group and increases the electron density on the oxygen atom.

2. Is the use of phenols safe?
Answer: Exposure to phenol can cause irritation of the eyes, nose, skin, throat, and nervous system. The effects of phenol exposure include weakness, weariness, muscle aches, and discomfort. Skin burns, tremors, convulsions, twitching, and liver and kidney damage can all arise from extreme exposure.

3. What makes phenol soluble in water?
Answer: The number of hydroxyl groups determines how phenol is soluble in water. Intermolecular hydrogen bonds are made by the hydroxyl groups in phenol. Water and phenol molecules interact to produce hydrogen bonds that make phenol soluble in water. The aryl group that is joined to the hydroxyl group, however, has a hydrophobic character. As a result, phenol's solubility diminishes as the size of the aryl group increases.

4. Do people still use phenol as a disinfectant?
Answer: Aqueous solution with a concentration of 2-5 percent Phenol is used as an antiviral, antibacterial and antifungal disinfectant. This is sufficient to kill mycobacterium and anthrax spores. They are mostly used to disinfect equipment or organic matter. By altering its concentrations, phenol can serve as both an antiseptic and a disinfectant. A 0.2 % solution of Phenol functions as an antiseptic, whereas a 1 % concentration acts as a disinfectant.

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