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.