Phenol is one of a group of organic compounds identified by a group of hydroxyl (-OH) bound to a carbon atom that forms part of an aromatic ring. . The word phenol is also the specific name for its simplest member, mono hydroxybenzene (C6H5OH), as benzenol, or carbolic acid. Alcohols are similar to phenols, but stronger bonds of hydrogen are formed.
They are also more water-soluble than alcohols and have higher boiling points. At room temperature, phenols appear either as colourless liquids or white solids and can be extremely poisonous and caustic. Phenol was initially extracted from coal tar but is now produced from petroleum feedstocks on a wide scale.
As a precursor to many products and valuable compounds, it is a major manufacturing product. It is mostly in use to synthesize plastics and products associated with it. For the manufacture of polycarbonate, epoxy, Bakelite, nylon, detergents, herbicides such as phenoxy herbicides, and various prescription drugs, phenol, and its chemical derivatives are important.
Properties of Phenol
- Acidity – Phenol is a weak acid. In an aqueous solution within the pH spectrum of approx. 8 – 12 is in equilibrium with the C6H5O-phenolate anion (also referred to as phenoxide). Resonance stabilization of the phenoxide anion by the aromatic ring is one reason why phenol is more acidic than aliphatic compounds containing a -OH group. In this way, by the pi mechanism, the negative charge on oxygen is delocalized to the ortho and para carbon atoms.
- Hydrogen Bonding – Phenol hydrogen bonds with a large variety of Lewis bases, such as pyridine, diethyl ether, and diethyl sulphide, in carbon tetrachloride and alkane solvents. The adduct formation enthalpies and the-OH IR frequency changes that follow adduct formation have been studied. Phenol is a strong acid that is consistent with the ECW model’s C/E ratio with EA = 2.27 and CA = 1.07
- Oxidation – Phenols undergo oxidation, like other alcohols, but have distinct forms of properties than those seen in aliphatic alcohols. For starters, most phenols are oxidized by chromic acid into conjugated 1,4-diketones called quinones. Many phenols steadily oxidize in the presence of oxygen in the air to provide dark mixtures containing quinones.
- Tautomerism – In its unstable keto tautomer cyclohexanone, Phenol experiences keto-enol tautomerism, but as the keto form, only a tiny fraction of phenol remains. The equilibrium constant for enolization is roughly 10-13, indicating that at every moment there is only one in every ten trillion molecules in the keto form. The minimal amount of stabilization is achieved by replacing a C=C bond for a C=O bond is more than balanced by the significant loss of aromaticity resulting in destabilization. Therefore, phenol occurs practically solely in the form of enol.
In various areas, including chemistry, biology, and medical labs, phenol is commonly in use as an organic solvent. It is especially toxic to live cells. Consumers of phenol must understand its properties and know the right procedures for treating them. In consumer products and as intermediates for industrial synthesis, phenols are commonly useful. Uses include:
- In over-the-counter remedies for sore throats, phenols are useful in (1.4 per cent concentration).
- In various consumer goods that we eat or add to different areas of the body, phenol is present. That includes ointments, drops in the ear and nose, cold sore lotions, mouthwashes, gargles, drops in toothache, analgesic rubs, lozenges in the throat, and antiseptic lotions.
- Until conducting any operation, phenol was traditionally useful for sterilization in surgical regions.
- To minimize discomfort associated with some nerve conditions, small doses of phenol in water are injected into nerve tissue.
- When allow staying in contact with the blood, Phenol removes the outer layers of the skin. To extract warts and cure other skin blemishes and conditions, small doses of refined phenol solutions are often added to the skin. To eliminate skin lesions and relieve extreme discomfort, phenol-containing materials are useful as chemical peels.
- Phenol is a component of the extraction procedure of liquid-liquid phenol-chloroform which is useful in molecular biology to derive nucleic acids from tissues or cell culture samples. Either DNA or RNA may remove, depending on the pH of the solution.
- Non-ionic detergents are manufacture by phenol alkylation to provide alkylphenols, such as nonylphenol, which are subsequently subject to ethoxylation.
- It is also useful in the manufacture of caprolactam (useful to produce nylon 6 and other synthetic fibres) and bisphenol A. (which is useful in the manufacture of epoxy and other resins).
The pupils, the ears, and the respiratory tract are corrosive to Phenol and its vapours. Its corrosive effect is due to a protein-degenerating effect on the skin and mucous membranes. Dermatitis or even second and third-degree burns may be caused by frequent or extended skin contact with phenol. Phenol vapour inhalation can cause lung oedema. The kidneys can also be damaged. There can be adverse effects on the liver and kidneys from long-term or regular exposure to the drug. No proof exists that phenol promotes cancer in humans.
In addition to its hydrophobic effects, the formation of phenoxyl radicals can be another cause of the toxicity of phenols. As phenol absorption is relatively easily through the skin, in addition to the local caustic burns, systemic poisoning may occur. Also, with just a small area of skin, vascular poisoning by a significant volume of phenol will occur, quickly leading to central nervous system paralysis and a drastic drop in body temperature. For oral toxicity, the LD50 for dogs, rabbits, or mice is less than 500 mg/kg; the mean lethal human dosage was 140 mg/kg. Toxic Substances and Disease Registration Agency (ATSDR), U.S(, the Department of Health and Human Services reports). The lethal dosage for phenol consumption is 1 to 32 g.
By cleaning with polyethene glycol, isopropyl alcohol, or even massive quantities of water, chemical burns from skin contact may be thoroughly clean. As well as urgent emergency care for major splashes, removal of dirty clothing is needed. If the phenol is paired with chloroform, this is especially important (a commonly used mixture in molecular biology for DNA and RNA purification). Phenol is also a reproductive poison that induces raise abortion risk and low birth weight, suggesting delayed utero growth.
FAQs about Phenol
Q.1 Is Phenol acidic or basic?
Ans. Phenol is a poor acid. In aqueous solutions within the pH range of 8-12, it is in equilibrium with the phenolate anion C6H5O- (also phenoxide). Phenol is more acidic than aliphatic compounds as it contains an OH group. The phenoxide anion is stabilized by the aromatic ring resonance.
Q.2 Explain the solubility of phenol in the water?
Ans. Phenol is a substantially soluble organic compound in water, dissolving about 84.2 g in 1000 mL of water (to form a 0.895 M solution). At phenol to water mass ratios of ~2.6 and higher, homogenous phenol-water mixtures are possible. The sodium phenol salt, sodium phenoxide, is even more water-soluble.
Q.3 Define Kolbe’s reaction?
Ans. The phenoxide ion is derivative of sodium hydroxide phenol treatment is far more reactive to electrophilic aromatic replacement than phenol. It then undergoes electrophilic substitution with a weak electrophile, carbon dioxide. As a key reaction product, ortho hydroxybenzoic acid is formed.