Question

9. Rank the labeled hydrogen atoms (a-c) from least to most acidic. Briefly explain 10. Give the curved arrow mechanism for each reaction. dlack 11. In the previous problem, explain why the ketone in problem a) halogenates only once, while the ketone in problem b) overhalogenates. 12. The "Haloform reaction reacts a methyl ketone with 1, in basic conditions, and produces a yellow precipitate, CHI (s). Draw the mechanism for this reaction. + CHIZ () NaOH

Answer 1

lectronegativity, The most acidic proton is cas os after removing Ht, negative charge appears on orggen atom which is stable due to its high electronectors Then, herser acidic proton is (b) as of when it is removed, Carbanion in resenance resent stabilised on both Carbonyl centres, and the leasts acidic proton is c' as after removing Ho carbanion in resenance Atabdised over one Carbonyl group. Order of Acidic strength (c) < Hydrogen b <ias least acidic - most acidic. lo. (Acid Catalysed enolisation (a) 0:0 Bry & U CVDH Haloguration) L-HBY lence, (enal) (b) Naoh Eacidic Hydrogen 0 more acidic.

. 11. In acid reatulysed Halogenation of Katune, only one x- hydrogen is replaced by te atom because each successive halogenation becomes slower & Halogen decreases the basicity of Lone pair on ouygen atom of Carbonyl group re), thus making proteination less favourable while en Bare - catalysed Halogenation of Ketua Both X- hydrogen atoms were replaced by te', this succesive hologenation is more rapid due to - effect ( Electron withdrawing tendency) by halogen, making the second alpha-hydrogen more acidic, clarity 04 (Bere will entracts Proton) Acidir 47 - /more landic feting Hydnegen) / Ya 477 Lits Les gode muligen) leven more acidic to good Leaniny Hydrogen ) Soorep trötches on O +CHI (6) the one yources Auld-Base reen - + Cr,