What are alcohols, phenols, and ethers?

Alcohols contain an –OH group attached to an aliphatic carbon. Phenols have an –OH group attached to an aromatic ring. Ethers consist of two alkyl or aryl groups connected by an oxygen atom (–O–).

How are alcohols classified?

Alcohols are classified as primary (1°), secondary (2°), or tertiary (3°) based on the carbon atom to which the –OH group is attached.

What is the general formula for alcohols?

The general formula for alcohols is C_nH_2n+1OH.

How are alcohols named according to IUPAC rules?

The longest carbon chain containing the –OH group is selected, and the suffix "-ol" replaces the "-e" of the parent alkane. Example: Ethanol (C₂H₅OH).

What is the IUPAC name of CH₃CH(OH)CH₃?

Propan-2-ol (Isopropanol).

How are ethers named?

Ethers are named as alkoxyalkanes, where the smaller group is treated as an alkoxy (–OR) substituent. Example: Methoxyethane (CH₃OCH₂CH₃).

 How are alcohols prepared from alkenes?

Alcohols are synthesized using:

1. Acid-catalyzed hydration (follows Markovnikov’s rule).

2. Hydroboration-oxidation (anti-Markovnikov addition).

How are alcohols prepared from aldehydes and ketones?

Alcohols can be obtained by reduction of aldehydes and ketones using NaBH₄ or LiAlH₄.

What reaction produces alcohols from carboxylic acids?

Carboxylic acids are reduced to primary alcohols using LiAlH₄.

What happens when alcohols react with active metals like Na or K?

Alcohols react to form alkoxides and hydrogen gas:

2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂

What is esterification?

Alcohols react with carboxylic acids to form esters and water in the presence of concentrated H₂SO₄.

What is Lucas test, and how does it differentiate alcohols?

Lucas test uses ZnCl₂ and HCl to distinguish alcohols based on reaction time:

• Tertiary alcohols react immediately (cloudy solution).
• Secondary alcohols react in a few minutes.
• Primary alcohols show no reaction at room temperature.

How does phenol differ from alcohols?

In phenols, the –OH group is attached to an aromatic ring, making it more acidic than alcohols.

How is phenol prepared from benzene diazonium chloride?

By hydrolysis: C₆H₅N₂⁺Cl⁻ + H₂O → C₆H₅OH + N₂ + HCl

Why is phenol more acidic than ethanol?

Due to resonance stabilization of the phenoxide ion.

What is the Reimer-Tiemann reaction?

Phenol reacts with chloroform (CHCl₃) and NaOH to form salicylaldehyde.

What happens when phenol reacts with bromine water?

Phenol forms 2,4,6-tribromophenol, which appears as a white precipitate.

What is Kolbe’s reaction?

Phenol reacts with NaOH and CO₂ to produce salicylic acid.

How are ethers prepared by Williamson’s synthesis?

By reacting alkyl halides with sodium alkoxides:

R–O⁻ + R'–X → R–O–R' + X⁻

What is the difference between symmetrical and unsymmetrical ethers?

Symmetrical ethers have identical alkyl/aryl groups (e.g., Diethyl ether, C₂H₅–O–C₂H₅), whereas unsymmetrical ethers have different groups (e.g., Ethyl methyl ether, C₂H₅–O–CH₃).

Why do ethers have lower boiling points than alcohols?

Ethers lack hydrogen bonding, leading to lower boiling points compared to alcohols of similar molecular weight.

How do ethers react with HI or HBr?

Ethers undergo cleavage to form alkyl halides:

R–O–R' + HI → R–I + R'–OH

What happens when anisole (methoxybenzene) reacts with HI?

Anisole undergoes cleavage, forming phenol and methyl iodide.

How does an ether undergo electrophilic substitution?

The –OR group activates the benzene ring, leading to ortho and para substitution in aromatic ethers like anisole.

Explain the mechanism of alcohol dehydration.

Alcohols undergo elimination (E1 mechanism) in the presence of acid (H₂SO₄), forming alkenes.

How does the oxidation of primary alcohols proceed?

Primary alcohols → Aldehydes → Carboxylic acids (with strong oxidizers like KMnO₄).

What is the mechanism of acid-catalyzed hydration of alkenes?

• Protonation of alkene to form a carbocation.
• Nucleophilic attack by water.
• Deprotonation to form alcohol.