Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub

All four are active-methylene compounds; enol content grows with the stability of the enol. (III) trifluoroacetylacetone : the $\mathrm{C}{\mathrm{F}}_3$ group is powerfully electron-withdrawing, making the chelated enol the most stable - the largest content. (I) pentane-2,4-dione : H-bonded enol conjugated with the second carbonyl - next. (II) ethyl acetoacetate : one ketone and one ester; the ester carbonyl stabilises the enol less than a ketone does. (IV) diethyl malonate : two ester groups, the least stabilising, so the least enol. Hence III $>$ I $>$ II $>$ IV.