Compound A of molecular formula \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{~N}_{2} \mathrm{O}_{2}\) reacts with aqueous nitrous acid to give compound \(B\) of formula \(\mathrm{C}_{6} \mathrm{H}_{10} \mathrm{O}_{4}\). Compound B readily loses water on heating to give \(\mathrm{C}, \mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{3}\). Compound A can also react with a solution of bromine and sodium hydroxide in water to give \(\mathrm{D}, \mathrm{C}_{4} \mathrm{H}_{12} \mathrm{~N}_{2}\), which on treatment with nitrous acid and perchloric acid gives methyl ethyl ketone. Write structures of all compounds and the equations involved.

Compound A is a dipeptide Gly-Ala with the molecular formula \(\mathrm{C}_6\mathrm{H}_{12}\mathrm{N}_2\mathrm{O}_2\), and its structure is: \(\mathrm{H}_{2}\mathrm{N}-\mathrm{CH}_{2}\mathrm{CO}-\mathrm{NH}-\mathrm{CH}_{3}-\mathrm{COOH}\). A reacts with aqueous nitrous acid to form B, losing two hydrogen atoms and gaining two oxygen atoms: \(\mathrm{H}_{2}\mathrm{N}-\mathrm{CH}_{2}\mathrm{CO}-\mathrm{NO}-\mathrm{CH}_{3}-\mathrm{COOH}\). B loses water upon heating to form C: \(\mathrm{H}_{2}\mathrm{N}-\mathrm{CH}_{2}\mathrm{CO}-\mathrm{NO}-\mathrm{CH}_{3}-\mathrm{CO}\). A reacts with bromine and sodium hydroxide to form D: \(\mathrm{H}_{2}\mathrm{N}-\mathrm{CH}_{2}\mathrm{NH}_{2}\) and \(\mathrm{H}_{2}\mathrm{N}-\mathrm{CH}_{3}\). D reacts with nitrous and perchloric acids to produce methyl ethyl ketone: \(\mathrm{CH}_{3}\mathrm{COCH}_{2}\mathrm{CH}_{3}\).