Uses of Phenol: Have you ever noticed that in plastic containers, it is sometimes mentioned that the product is BPA? It is Bisphenol A, a common derivative of Phenol. The very popular disinfectant Dettol too is made up of a low concentration of Phenol. Let’s read on to know the uses of Phenol.

What is Phenol?

Phenol is a type of organic compound in which the \(- {\rm{OH}}\) group or the hydroxyl group is attached to an aromatic benzene ring. It is an aromatic organic compound with the chemical formula  \({{\rm{C}}_{\rm{6}}}{{\rm{H}}_{\rm{5}}}{\rm{OH}}\).

Phenol is a mildly acidic toxic white crystalline solid obtained as a byproduct in coal tar distillation. It is highly hygroscopic and volatile. It has a sickly sweet smell and a sharp burning taste. On a large scale, Phenol is obtained from petroleum-derived feedstocks. It is the precursor to the production of many essential commodities such as plastics and antiseptics.

Structural Formula of Phenol

1. All carbon atoms forming the aromatic ring of Phenol are \({\rm{s}}{{\rm{p}}^{\rm{2}}}\) hybridized. Therefore, phenyl has a hexagonal planar structure with all bond angles \({\rm{12}}{{\rm{0}}^{\rm{o}}}\) and delocalized \({\rm{\pi }}\)-electrons distributed over the ring.
2. The hybridization of the \({\rm{C – O}}\) bond is \({\rm{s}}{{\rm{p}}^{\rm{2}}}{\rm{ – s}}{{\rm{p}}^{\rm{3}}},\) respectively, and the \({\rm{O – H}}\) bond is formed from \({\rm{s}}{{\rm{p}}^{\rm{3}}}\) hybrid oxygen and \({\rm{1}}\,{\rm{s}}\) Hydrogen.
3. Two nonbonded electron pairs occupy the other two orbitals of the oxygen atom. It is due to this reason, hydroxyl functional group \({\rm{C – O – H}}\) has a bent shape with a bond angle of \({\rm{109}}{\rm{.}}{{\rm{5}}^{\rm{o}}}\).
4. As oxygen is more electronegative than both carbon and hydrogen atoms, both the \({\rm{C – O}}\) and \({\rm{O – H}}\) bonds are polar.

5. In Phenol, the non-bonded electron pairs of oxygen atoms are in conjugation with the aromatic ring.
6. The delocalization of pi electrons causes partial transfer of negative charge from the oxygen atom to the aromatic ring system.
7. The delocalization of pi electrons strengthens the polarization of the \({\rm{O – H}}\) bond. This results in the acidic character of Phenol.
8. Phenol is a weak acid. This is because it readily loses the hydrogen atom to form a phenoxide ion (phenolate) ion.
9. Both Phenol and its conjugate base are resonance stabilized. Dispersion of the negative charge over the molecule can be illustrated with the resonance structures or as a resonance hybrid as Shown-

Uses of Phenol

Phenol is the precursor to many essential commodities. In addition, pure Phenol finds its use in specific medical procedures and as an active ingredient in numerous treatments and laboratory applications.

1. Preparation of Phenol-Formaldehyde Resin

The largest single use of Phenol is as an intermediate in the production of phenolic resins. Phenol reacts with formaldehyde and polymerizes to form phenol-formaldehyde resins. This resin, also known commercially as bakelite, is used to manufacture switches, cabinets, doors, etc. It can withstand extreme conditions, and hence, this resin is used in various electrical and automobile industries.

The reaction between Phenol and formaldehyde also forms a sun-like compound called Novolac. Novolac has adhesive properties and is used as a binding agent in different industries.

2. Preparation of Phenolphthalein

An important acid-base indicator is phenolphthalein. As its name indicates, phenolphthalein can be synthesized by condensing phthalic anhydride with two equivalents of Phenol under acidic conditions. It turns colorless in acidic solutions and pink in basic solutions. It belongs to the class of dyes known as phthalein dyes.

3. Preparation of Picric Acid

Picric acid is prepared from Phenol by reacting Phenol with concentrated sulphuric acid and concentrated nitric acid. The nitro groups from nitric acid attacks on ortho and para positions which is the best suitable and stable position for the newly formed compound which is picric acid. Picric acid is used in the production of explosives, matches, and electric batteries. It is also used in etching copper and manufacturing colored glass, in the leather industry, and the synthesis of dyes. Picric acid is very unstable and is a flammable/combustible material. It may be ignited by heat, sparks, or flames. Dried-out picric acid may explode if exposed to heat, flame, friction, or shock and should be treated as an explosive.

4. Phenol Injection

Muscle spasticity, a condition of muscle tightening, is treated by injecting Phenol into muscles. This happens when there is improper brain nerve coordination.

Muscle spasticity can even affect the ability to walk or talk properly.

Phenol limits the signals sent from the nerves to muscles that cause muscle contractions. A phenol injection helps us to move more easily and feel less discomfort.

5. Chemical Matrixectomy

Surgeries of ingrown toenails include the usage of Phenol. It’s used more on severe ingrown toenails that don’t respond to other treatments. Phenol, in the form of trichloroacetic acid, is used to stop the nail from growing back.

However, nowadays, sodium hydroxide is found to have fewer complications than Phenol as an ingrown toenail treatment.

6. Vaccine Preservative

Phenol is also used as a preservative in certain vaccines. The vaccines are:

1. Pneumovax \(23\) for conditions like pneumonia and meningitis
2. Typhim \({\rm{Vi}}\) for typhoid fever
3. \({\rm{ACAM2000}}\) for smallpox
4. \(2\)-Phenoxyethanol is used in the vaccine Ipol for polio

It helps keep bacteria from growing in and contaminating the vaccine solutions.

7. Sore Throat Spray

Phenols are used in over-the-counter treatments for sore throats (\(1.4\% \) concentration). It can help numb your throat and relieve symptoms caused by a sore throat or irritation in the mouth caused by canker sores. The most common brand of throat spray is Chloraseptic, which contains about \(1.4\) percent phenol.

Phenol spray is safe to use at the recommended dose for a short time. But using too much or giving it to children younger than \(3\)-years old can be unsafe

8. Skin and Phenol

Phenol, if allowed to remain in contact with the skin, destroys the outer layers of the skin. Small amounts of concentrated phenol solutions are sometimes applied to the skin to remove warts and treat other skin blemishes and disorders. Phenol-containing products are used as chemical peels to remove skin lesions and treat severe pain.

9. Oral Analgesics

Many phenol-based products are also used as Oral analgesics and can be bought over-the-counter to cure mouth-related problems.

These products numb tissues in the mouth and lips and help relieve pain or irritation in or around your mouth.

Phenol-based products are also used for temporary relief from pharyngitis, which causes the throat to get inflamed by bacterial infection.

Phenol-based products for mouth and throat pain are widely available and safe to use in small doses. It is always safe to consult a doctor before using any of such products.

10. As a Disinfectant

A \(2 – 5\% \) of aqueous solution phenol is used as an antibacterial and antiviral, and antifungal disinfectant. This can be enough to kill micro bacterium and anthrax spores. They are mainly used as a disinfectant of equipment or organic matter. Phenol can acts as an antiseptic as well as a disinfectant by varying its concentrations. A \(0.2\,\% \) solution of Phenol acts as an antiseptic while its \(1\% \) concentration acts as a disinfectant.

11. Phenol Derivatives

Products	Uses
Bisphenol A	BPA is used to produce epoxy resins for paints coatings and mouldings. It is also used in the manufacture of polycarbonate plastics, familiar in CDs and domestic electrical appliances.
Caprolactam	Caprolactam is used in the manufacture of nylon and polyamide plastics. It includes a wide range of products like carpets, clothing, fishing nets, moulded components and packaging.
Phenylamine (Aniline)	Aniline is used as an antioxidant in the manufacture of rubber and rubber products like balloons, car tyres, gloves. It acts as an intermediate in herbicides and as a dyeing agent in the manufacture of clothes like jeans, etc. It is used for the production of drugs, for example, paracetamol, acetaminophen, and Tylenol. It finds a wide range of uses, from paints and adhesives to expanded foam cushions.
Alkylphenols (\(3\)-methyl Phenol)	Alkylphenols are used in the manufacture of surfactants, detergents and emulsifiers. These are also used in insecticide and plastics production and as a preservative in paints and inks.
Choloro phenols (\(2,4\) – dichlorophenol)	Chlorophenols are used in medical antiseptics and bactericides such as Dettol. These are also for timber preservation and act as additives to inhibit microbial growth in many products; used to manufacture a range of pesticides.
Salicylic acid	Salicylic acid is a drug and is used on the skin to treat common skin and foot (plantar) warts. Salicylic acid helps cause the wart to gradually peel off. This medication is also used to help remove corns and calluses. One of the major uses of salicylic acid is its use in the production of aspirin. Aspirin is an everyday painkiller. It is also used to treat colds and “flu-like” symptoms and to bring down a high temperature. It is also known as acetylsalicylic acid.

12. Food and Cosmetic Preservatives

Butylated hydroxytoluene \(\left( {{\rm{BHT}}} \right)\), which is a phenol derivative, is used as a preservative in food as well as in cosmetics. It’s safe to consume in small amounts.

13. Phenol Liquid

In molecular biology, Phenol liquid is often used with trichloromethane and chloroform to separate RNA, DNA, or proteins and isolate them in their pure form.

This process is known as liquid-liquid extraction, which is carried out by adding an equal amount of Phenol and chloroform to a solution of cells or tissues.

The phenol-chloroform mixture separates molecules based on the extent of the solubility of tissues. The pH level of Phenol helps separate the DNA and RNA.

14. Antioxidants

Plant-based phenolic compounds are known to act as antioxidants. Antioxidants stop the reaction of free radicals, which cause damage to our DNA as well as affect our health in the long term.

radicals are unstable molecules that damage molecules like DNA. radicals sometimes initiate more radicals.

Antioxidant molecules are like a barrier between radicals and healthy molecules. Antioxidants replace the missing electron and render it harmless.

Some notable phenolic antioxidants with proven health effects include:

1. bioflavonoids, found in wines, teas, fruits, and vegetables
2. tocopherols, including vitamin \({\rm{E}}\), found in many fruits, nuts, and vegetables
3. resveratrol, found in fruits, nuts, and red wine
4. oregano oil, composed of many beneficial phenols like carvacrol, cymene, terpinene, and thymol

Safety Precautions While Using Phenol

Phenol may have its share of uses and health benefits, but it can also be toxic or cause long-term health effects if you’re exposed to it in high amounts. Here are few tips to avoid exposure:

1. Avoid exposure. Be careful in places that may contain high levels of Phenol, such as industrial facilities.
2. Don’t eat anything that might contain Phenol. Consuming Phenol in its pure form can be fatal. Its pure form can damage internal organs like the oesophagus, stomach, intestines, and other digestive organs.
3. Don’t put it on your skin. Pure Phenol can cause burns and blisters if it comes in direct contact with the skin.
4. Don’t inhale it. Inhaling Phenol causes serious damage to the respiratory tract.
5. Don’t drink it. Consuming water containing a lot of Phenol can make muscles spasm and affect your ability to walk. Too much can be fatal.

Summary

Phenol is a widely used chemical solvent used in numerous places, including chemistry, biology, and medical laboratories to household products. However, its toxicity cannot be neglected. Phenol should be handled with proper care as even a slight mishandling can cause death.

FAQs on Uses of Phenol

Q.1. How is Phenol used in medicine?
Ans: Phenol acts as a precursor to a wide range of drugs in the pharmaceutical industry. It is used to disinfect skin and relieve itching. Phenol is also used as an oral analgesic or anaesthetic in products such as Chloraseptic to treat pharyngitis. Additionally, Phenol and its related compounds are used in surgical ingrown toenail treatment, a process termed penalization.

Q.2. Is Phenol a poison?
Ans: Phenol is highly toxic to humans if consumed orally and in more than permissible amounts.

Q.3. What products use Phenol?
Ans: Phenols are widely used in household products and as intermediates for industrial synthesis. For example, Phenol itself is used (in low concentrations) as a disinfectant in household cleaners and mouthwash. Phenol may have been the first surgical antiseptic.

Q.4. What is one important use of Phenol in forensic chemistry?
Ans: The phenol-chloroform mixture separates molecules based on the extent of the solubility of tissues. The \({\rm{pH}}\) level of Phenol helps separate the DNA and RNA.

We hope this article has helped you understand various uses of phenols in our day to day life. If you have any questions related to this article in general, reach out to us through the comment box below and we will get back to you as soon as possible.