Notes On Alcohols And Phenols: Chemical Reactions - CBSE Class 12 Chemistry

Alcohols are a versatile class of compounds.

Alcohols can act as both nucleophiles and electrophiles. Protonated alcohols act as electrophiles. Electrophiles will react with electron-rich species such as nucleophiles.

Alcohols and phenols react with active metals to form alkoxides (or) phenoxides, while phenols can react with aqueous sodium hydroxide to form phenoxides.

Phenols react with aqueous sodium hydroxide to form sodium phenoxides. Water is a by-product of the reaction.

Alcohols and phenols are weakly acidic. Phenols are stronger acids than alcohols.

The presence of alkyl groups in alcohols increase the electron density around oxygen by the inductive effect. As alkyl groups donate electron density to the oxygen, the oxygen-hydrogen bond becomes less polar. It then becomes difficult to remove an H+ from the alcohol.

Alcohols and phenols can react with carboxylic acids, acid chlorides and carboxylic acid anhydrides to form esters.

Alcohols react with hydrogen halides to form alkyl halides and with phosphorus tribromide to form alkyl bromides.

Acid-catalysed dehydration of tertiary alcohols produces alkenes.

Primary and secondary alcohols can be oxidised to a variety of carbonyl-containing compounds depending on the oxidising agent.

Passing vapours of primary or secondary alcohols over heated copper forms aldehydes (or) ketones but tertiary alcohols under these conditions form alkenes.

Summary

Alcohols are a versatile class of compounds.

Alcohols can act as both nucleophiles and electrophiles. Protonated alcohols act as electrophiles. Electrophiles will react with electron-rich species such as nucleophiles.

Alcohols and phenols react with active metals to form alkoxides (or) phenoxides, while phenols can react with aqueous sodium hydroxide to form phenoxides.

Phenols react with aqueous sodium hydroxide to form sodium phenoxides. Water is a by-product of the reaction.

Alcohols and phenols are weakly acidic. Phenols are stronger acids than alcohols.

The presence of alkyl groups in alcohols increase the electron density around oxygen by the inductive effect. As alkyl groups donate electron density to the oxygen, the oxygen-hydrogen bond becomes less polar. It then becomes difficult to remove an H+ from the alcohol.

Alcohols and phenols can react with carboxylic acids, acid chlorides and carboxylic acid anhydrides to form esters.

Alcohols react with hydrogen halides to form alkyl halides and with phosphorus tribromide to form alkyl bromides.

Acid-catalysed dehydration of tertiary alcohols produces alkenes.

Primary and secondary alcohols can be oxidised to a variety of carbonyl-containing compounds depending on the oxidising agent.

Passing vapours of primary or secondary alcohols over heated copper forms aldehydes (or) ketones but tertiary alcohols under these conditions form alkenes.

Videos

References

Previous
Next