Question

Why malonate is less acidic than diketone？

CH3-H 15 9 CH20-H NH-H CH2CH20-H 16 (CH3)NH-H 10. 7 Ph-H PhCH2-H (CH3)3N-H 9.8 (CH3),CO-H 19 CH2-H 41 10 PhO-H 9.2 NC-H H-CEC-H H 25 16 mostly T dth CHACH-H 30 CHO CH₂O CH,O CH-H 24-25 H 11,2 H 13.5 0 CN NC-CH2-H 25 chocha - CN + NHA CH3OH H 11.2 9 CH CH₂-H 20 Ph CH2-H 16 CHE Y CH O2NCH-H 10.2 e complete, Generation & Alkylation Ph NAUPko :33

Answer 1

Answer:

0 0 Base RR - R XR RR RY In diketone case, the conjugate base stibilization is as shown above. The Carbonyl C is enough electrophilic and just little Electron donating inductive effect lowers its electrophilicity. Hence H of active methylene group (CH2) are enough acidic. 0 0 Base ROOR ROOR ROOR ROOR In Dialkyl malonate, the conjugate base is stabilized through the resonance as shown above. But this resonance is interrupted to some extend by the resonance in Dialkyl malonate itself as shown below, These Carbonyl Carbons are hence little less electrophilic due to electron donting resonance effect than in diketone case. Hence Malonates are less acidic (Higher pka) than Diketone Smaller pka)

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