Question

9. Give the major organic product of each intramolecular Aldol reaction. NaOH, H2O heat NaOH, H2O b. H heat NaOH,H,O NaOH, H2O heat 168

Answer 1

for this question we need to know something very important fole, Ring stability puring such intramolecular Aldol Reactions, we prefer sing formation in this order 6 membered ring > 5 membered ting > 7 membered ting and if there are chances for formation of 3 op 4 membered ring, we generally avoid this. NOW, @ We have MC- CH - CH2 - CH-CH2-CH-C- o= from Naon removes to aldehyde carbon &- Hydrogen we know that oth the very next carbon to we get from - Cl - Cha-ch, -ch, C- How and first in this carbation formed, attacks leads to formation of a six the order of our stability) the carbonge capbon membered ring (which is on si "ca- c-H heat -cho ald ol Cl₂ aldehyde alcohol Now, on heating we get an enal. le double bond aldelythe

CH₂ - CH₂ - CH₂ - CH₂ - CH carbanion generation by on to remove de Hydrogen U-C-CM - CH, CM - I carbanion attack on carbonyl carbon to give 5 membered ring Oy Chocno ch сто Caldol) I oh heating we get en-al by removing and on from 5- carbon Hydrogen from 1- carbon си 0 ke have a me ch-ch-CH-CH- ca- & -chals CM- Now, in this case, we have chances of generation too rings 6 membered and membered but accounting our preferential order we will prefer 6-member ring I carbanion generation : in CH- cn - - ench-CH=CH-CH - C- CH₂ - CH – gives 6. membering d) Hz in & -ch, ch, - curent cu ech-cu - gives T-memb. ring we will cand consider the 6 membered product, so we will take ci) carbanion

CH₂ - CH₂ - CH - CH₂ - CH₂ - CH₂ - CH₂ - c-ch-ch, ou uc - H pintas y c - CH₂ - CH₂ hear ċ-CH₂-en, (aldol) CH₂ - Chc - CH₂ - CH₂ -c-n. @ Che-comme-con- en in possibu carbaniory are ci che- ens, & cm. - - - cul CH₂ - CH-C- CH₂ - CH₂-c-n. and (w) CH₂ - CH₂ - C-ch - CH₂ -c-1. Al, we can clearly see that in and cus will gives 3-membered ring but är gives 5 member ring so cu carbanion in prefered, oy 1-0 (aldoe) heat (en-al)

We have considered the products of intramolecular aldol condensation only as mentioned in the question.