Question

An organic compound (a) of molecular formula C4H6O3 Produces two organic compounds (b) and (c) in reaction with methanol. (c) on refluxing with methanol in the presence of catalytic amount of H2SO4 gives (b). When (a) is allowed to react with excess conc. NH4OH it furnishes (d) and (e). Write down the structures of (a) (b) (c) (d) and (e) and explain the reactions???