High School

A Grignard's reagent R-Mg-X reacts with CO₂ to give a carboxylic acid X with the molecular formula [tex]C_3H_6O_2[/tex]. X has less acidic strength than acetic acid and on decarboxylation gives ethane.

Identify X and the Grignard's reagent. Write the chemical reactions involved.

Answer :

The carboxylic acid produced by reacting a Grignard reagent with CO2, which has a molecular formula of C3H6O2 and yields ethane upon decarboxylation, is propanoic acid. The Grignard reagent used here is ethylmagnesium bromide.

The student is asking about the reaction of a Grignard reagent with carbon dioxide to form a carboxylic acid with the molecular formula C3H6O2, which upon decarboxylation yields ethane.

From this information, we can deduce that the Grignard reagent must be ethylmagnesium halide (EtMgX), where 'X' is a halogen such as Br or Cl.

The carboxylic acid formed will be propanoic acid (CH3CH2COOH), which is less acidic than acetic acid (CH3COOH) and gives ethane on decarboxylation.

The chemical reactions involved are as follows:

  1. Formation of Grignard Reagent: EtBr + Mg Rightarrow EtMgBr
  2. Reaction with CO2: EtMgBr + CO2 Rightarrow EtCO2MgBr
  3. Hydrolysis: EtCO2MgBr + H2O Rightarrow CH3CH2COOH + Mg(OH)Br

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