Question

3) Identify the first mechanistic step in the reaction shown below. H2O OH Lilia ci H-Ö: H-02 4) Rank the following from least reactive to most reactive towards nucleophilic acyl substitution. NH2 ОСН3 III IV a) II <I< IV < III b)I<IV < II < III c) III <IV <I<II d) I< II <IV < III

Answer 1

(8.1) The acyl chlorides are most reactive towards electrophillic substitution Reaction and therefore the protonation step of carbonyl oxygen is not required as the carbon is very electrophillic Means: usually for y=0 groups, to se electrophilicity the Reaction is done in acidic medis 0-1 ice- chlorides this step is NOT But for acyl - required. Therefore: - - :. ANSWER. ©

ORDER OF REACTIVITY TOWARDS NuⓇ SUBSTITUTION : aloos Rhoma celor cada Explanation : The reactivity of the carbonyl group in all these carboxylic acid derivatives can be evaluated on. the basis of the degree of partial positive charge present on carbonyl carbon. & this depends on the groups directly attached to carbonyl carbon. If x = Electron donating group then it lowers the partial positive charge on carbonyl carbon and uses electrophilicity of c : reactivity towards attack of Nuo Ises. If x= e- with drawing group then it ises the to charge on = 0 and ises electrophilicity of carbonyl carbon : les repartir &=0 towards nucheophile

are most reactive towards nucleophilic Acyl hallides substitution : e loce - ce is electron with drawing in nature takes e from carbonyl carbon & makes it more electrophillic Un Ro-R 03 er NR₂ R - electron donation by -o-R and also e-withdrawing naturore of o both factors operating → e-doration by Ä is more as compared to oxygen e En of - N is less than oxygen & anides are less reactive than esters. This is Leat least reactive towards electrophed nucleo phillic substitution as it have equal contributing resonance structures : This makes earbenyl carbon least" electrophillic Joo llos R-6=0 / R-C-00 . ANSWER: 0 0 <@ < < <©