i.            1,2-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 shown above.

(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.