Dicarbonyl compounds, such as benzil, can be characterized by reaction with o-phenylenediamine to form a substituted quinoxaline.
a. Write the structure for the quinoxaline derivative obtained when benzil is the reactant? Do you think this compound would be colored? If so, why?
b. Suggest a suitable mechanism for the formation of the quinoxaline compounds based on the reaction scheme.
c. What reagent would you react with o-phenylenediamine to prepare the unsubstituted compound quinoxaline? Show a reaction scheme giving the structure of reactants and products.