Alcohols and Phenols Overview

Alcohols and Phenols

• Alcohols are important compounds containing a hydroxyl group (-OH) bonded to a carbon atom.
• Alcohols are classified as primary, secondary, or tertiary based on the number of carbon atoms bonded to the carbon atom bearing the hydroxyl group.
• Primary alcohols have the -OH group attached to a carbon atom bonded to only one other carbon atom.
• Secondary alcohols have the -OH group attached to a carbon atom bonded to two other carbon atoms.
• Tertiary alcohols have the -OH group attached to a carbon atom bonded to three other carbon atoms.
• Phenols have the hydroxyl group directly bonded to an aromatic ring.
• Phenols differ from alcohols in acidity; phenols are significantly more acidic than alcohols.
• Sufficient aqueous sodium hydroxide will deprotonate the -OH group in phenols, but not in alcohols.

Properties of Alcohols

• The solubility of alcohols in water depends on their size.
• Smaller alcohols are generally soluble due to hydrogen bonding with water molecules.
• Larger alcohols are less soluble as the non-polar alkyl chains disrupt hydrogen bonding in water.
• Phenols also exhibit varying water solubility, decreasing with increasing nonpolar groups attached to the ring.

Ritter Test

• Used to distinguish primary and secondary alcohols from tertiary
• Potassium permanganate (KMnO4) is used as the oxidizing agent.
• Primary alcohols are oxidized to aldehydes and then to carboxylic acids.
• Secondary alcohols are oxidized to ketones.
• Tertiary alcohols do not react or get oxidized as there are no hydrogen atoms to be lost.
• KMnO4 changes color from purple to brown as it is reduced.
• Primary and secondary alcohols change the colour to brown because they are oxidized.