Phenols are a class of aromatic compounds characterized by the presence of one or more hydroxyl (-OH) groups directly attached to a benzene ring. The simplest and most well-known phenol is phenol itself (C6H5OH), also referred to as carbolic acid, which was first isolated from coal tar. Phenols exhibit unique chemical properties due to the resonance stabilization of the aromatic ring, making them more acidic than aliphatic alcohols. They are widely used in various industrial applications, including the production of plastics, resins, and pharmaceuticals, and serve as important intermediates in organic synthesis. Additionally, phenols possess antiseptic properties and are utilized in disinfectants and preservatives.
What are phenols?
Phenols are aromatic compounds that contain one or more hydroxyl (-OH) groups directly attached to a benzene ring. The simplest example is phenol (C6H5OH).
How are phenols classified?
Phenols can be classified into two main categories: simple phenols, which have a single hydroxyl group attached to a benzene ring, and polyphenols, which contain multiple hydroxyl groups or multiple benzene rings.
What is the acidity of phenols compared to alcohols?
Phenols are more acidic than aliphatic alcohols due to the resonance stabilization of the phenoxide ion formed when phenols lose a proton. However, they are less acidic than carboxylic acids.
What is the common method for preparing phenol?
One common method for preparing phenol is the Dow process, where chlorobenzene is treated with sodium hydroxide at high temperature and pressure, resulting in the formation of sodium phenoxide, which is then acidified to yield phenol.
What are some common reactions of phenols?
Phenols undergo various reactions, including electrophilic aromatic substitution (such as halogenation), oxidation, and reactions with formaldehyde to form resins like Bakelite.
Which of the following statements is true about phenols?
a) They are less acidic than alcohols.
b) They contain a hydroxyl group attached to an alkane.
c) They are more acidic than carboxylic acids.
d) They contain a hydroxyl group attached to a benzene ring.
Answer: d) They contain a hydroxyl group attached to a benzene ring.
What is the primary method for preparing phenol from chlorobenzene?
a) Hydrolysis
b) Dow's process
c) Oxidation
d) Reduction
Answer: b) Dow's process
Which of the following reactions can phenol undergo?
a) Nucleophilic substitution
b) Electrophilic aromatic substitution
c) Addition reaction
d) Elimination reaction
Answer: b) Electrophilic aromatic substitution
What is Bakelite?
a) A type of alcohol
b) A type of phenolic resin
c) A simple phenol
d) A natural product
Answer: b) A type of phenolic resin
Which of the following is a property of phenols?
a) They are completely insoluble in water.
b) They are strong acids.
c) They can form hydrogen bonds with water.
d) They do not react with bases.
Answer: c) They can form hydrogen bonds with water.