Question

Propose reagents and experimental conditions for the conversion of butadiene to adipic acid.

Short answer

Answer: To convert butadiene to adipic acid, follow these steps: 1. Perform a Diels-Alder reaction with maleic anhydride (C4H2O3) at 100-150°C to form a cyclic intermediate. 2. Perform hydrolysis of the cyclic intermediate using water (H2O) and a catalyst such as hydrochloric acid (HCl). 3. Perform oxidation of the alkene using an oxidizing agent like potassium permanganate (KMnO4) or osmium tetroxide (OsO4), followed by a reduction step using sodium bisulfite (NaHSO3) or sodium periodate (NaIO4) to obtain a diol. 4. Perform oxidative cleavage of the diol using an oxidizing agent like sodium periodate (NaIO4) or lead tetraacetate (Pb(OAc)4) at room temperature, with water as a solvent to obtain adipic acid.

Step-by-step solution

Diels-Alder Reaction of Butadiene

Perform the Diels-Alder reaction with maleic anhydride (C4H2O3) to form the cyclic intermediate. This reaction involves the addition of the diene (butadiene) with maleic anhydride to form a six-membered ring by the formation of two new sigma bonds and the loss of pi electrons from the diene and dienophile. The Diels-Alder reaction is performed at moderate to high temperature (100-150°C) and no catalyst is needed.

Hydrolysis of the Cyclic Intermediate

Perform hydrolysis of the cyclic anhydride obtained in step 1 using water (H2O) and a catalyst. This step involves the cleavage of the anhydride to form two carboxylic acid groups. The cleavage is performed by reaction with water and the rate of the reaction can be improved by adding a suitable catalyst such as an inorganic acid (e.g. hydrochloric acid, HCl).

Oxidation of the Alkene

Perform an oxidation reaction to convert the alkene in the cyclic intermediate to a diol. This can be achieved using an oxidizing agent like potassium permanganate (KMnO4) or osmium tetroxide (OsO4) in a suitable solvent, followed by a reduction step, such as sodium bisulfite (NaHSO3) or sodium periodate (NaIO4), to obtain a diol.

Oxidative Cleavage of the Diol

Perform an oxidative cleavage of the newly formed diol to convert it into a dicarboxylic acid. This can be achieved using an oxidizing agent like sodium periodate (NaIO4) or lead tetraacetate (Pb(OAc)4). The reaction usually takes place at room temperature, and water is added as a solvent to facilitate the reaction. The final result is adipic acid. Both the reagents and experimental conditions have been presented for all the required steps to convert butadiene into adipic acid.