Acidity of organic compounds

In this lesson, we consider about acidity of organic compounds and derivatives. Acidity of organic compounds depends on many different factors. Some organic compounds are very acidic and some are less.

As an example,

Carboxylic acid compounds are more acidic than alcohol compounds.

Acidity of phenol derivatives

Acidity depends on polarity of OH bond. When polarity of OH bond increases, acidity also increases.
Electron density of -O-CH3 is high. Therefore it gives electrons to the benzene ring which decreases polarity of OH bond.
Electron density of -NO2 is less. Therefore it attracts electrons from benzene ring. Then OH bond gives electrons to the ring which increases polarity of OH bond. When more NO2 groups connect to the ring, polarity of OH more increases.

Acidity of alcohols, phenol, carbonic acid and carboxylic acid

  • All of those acids react with Na and H2 gas is emitted.
  • Phenol, carbonic acid and carboxylic acids react with NaOH. Only alcohol compounds do not react with NaOH. Therefore alcohols are less acidic than other compound types.
  • Solid Na2CO3 and NaHCO3 react with carboxylic acids and emit CO2.
acidity of ethanol phenol carbonic carboxyic acids

Acidity of alkyne, alkane, alkene

Alkyne with acidic H react with Na and H2 is emitted. But those alkyne don't react with NaOH(aq). Also alkane and alkene don't react with NaOH(aq). However alkyne with acidic H has some acidic properties than alkane and alkene.

acidic H alkyne

Acidity of acid chlorides

When acid chloride is added into the water, acid chloride (ex: CH3COCl ) hydrolyses into strong acid ( HCl ) and carboxylic acid ( CH3COOH ).
Due to exist of strong acid in aqueous acid chloride solution which is more acidic than aqueous carboxylic solution.

acid chloride and water

Last edit: 24 Mar 2018

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