Carboxylic acid chloride preparing, reactions, physical properties

When a chlorine atom is connected instead of -OH bond in carboxylic acid it's called carboxylic acid chloride. In this tutorial we study about preparing, reactions and physical properties of carboxylic acid chloride compounds.

Acid Chlorides | Acyl Chlorides | Carboxylic Acid Chlorides

Different names are used to name this organc compound type. -COCl group is connected to a carbon atom as the active group of the acyl chloride.

Examples of acid chloride

Acid chlorides (Acyl Chlorides) can be aliphatic or aromatic compounds.

Here, we see some aliphatic acid chlorides. Their IUPAC name should be finished as "oyl chloride".

example of acid chloride

Chemical properties of Carboxylic acid chloride

Carboxylic acid chloride show different types of reactions such as an acid and to extend the carbon chain. But reactions of carboxylic acid chloride differ from carboxylic acids. The carbon atom which is linked with Cl atom is positively charged. Therefore carboxylic acid chloride mostly show Nucleophilic substitution reactions.

Hydrolysis with water

Carboxylic acid chloride hydrolysis easily and in the water and give carboxylic acid and HCl as products. We know carboxylic acid is a weak acid and HCl is a strong acid.

Due to formation of strong acid and a weak acid, pH value of aqueous solution become a below than 7.

Carboxylic acid chloride and water

Carboxylic acid chloride aqueous solution

Aqueous acid chloride solution contain HCl and carboxylic acid. So aqueous solution can reacts with following reagents and can show different characteristics.

  • Emit carbon dioxide gas when sodium carbonate is added
  • Add dilute nitric acid and then silver nitrate solution, silver chloride (white precipitate) forms.

Strong aqueous bases and Carboxylic acid chloride reaction

Some strong bases are NaOH and KOH. This reaction gives, salt of carboxylic acid, salt of strong base and water. This reaction release a large heat.
First, carboxylic acid chloride reacts with water and produce two acids, CH3COOH and HCl.This is the hydrolysis of carboxylic acid chloride. Next, these two acids react with NaOH and form salts of two acids (NaCl, CH3COO-Na+).

NaOH and acid chloride reaction

Carboxylic acid chloride and ammonia or amine

Carboxylic acid chloride reacts with ammonia or amine and give amides. According to the amine types (primary, secondary or tertiary), type of amide is changed.

Ammonia behave as a nucleophile iwhen it reacts with acid chlorides.

Reaction of carboxylic acid chloride and amine also similar to the reaction of ammonia and carboxylic acid chloride. Amines also behave as nucleophiles.

With ammonia

Carboxylic acid chloride and ammonia react and give amide. Ammonia behave as a nucleophile and it attacks the acidic carbon. Then chlorine atom is eliminated to give amide.

With primary amine

Carboxylic acid chloride and primary amine react and give substituted amide.

With secondary amine

Acid halide and secondary amine react and give substituted amide.

ammonia, primary amine and secondary amine with acid chloride

With tertiary amine

Carboxylic acid chloride and tertiary amine do not react with each other.

With grignard reagent reaction

Carboxylic acid chloride reacts with excess grignard reagent and give tertiary alcohols. Two grignard molecules are added to the carbon atom which is in carboxylic acid chloride group. Water should be added after grignard applying. In this reaction, grignard acts as nucleophile.

Alkyl part of grignard attacks the carbon atom which is in carboxylic acid chloride group

acid halide and grignard reaction

Questions of carboxylic acid chlorides

How to identify ethanoyl chloride and benzoyl chloride?

Ethanoyl chloride and benzoyl chloride are added to water separately. A white precipitate forms in one solution. The precipitate is benzoic acid. In other solution, ethanoic acid is given.

Ethanoyl chloride and water reaction

Ethanoyl chloride hydrolysis to ethanoic acid and hyrochloric acid (HCl). Ethanoyl chloride is water soluble and form an acidic aqueous solution with HCl.

ethanoyl chloride and water reaction

Benzoyl chloride and water reaction

Benzoyl chloride hydrolysis to benzoic acid and hyrochloric acid. Benzoic acid is not soluble in water and form a white precipitate.

benzoyl chloride and water reaction

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