[dnbwise]

when you have an intramoleclular aldol reaction leading to a ring structure, where a 5 or 6 membered ring is possible, will the 5 membered ring be product? and why?

ie CH3CHOCH2CH2CH2CH2CHOCH3 --------> ? 5 OR 6 membered ring structure
                                                   OH-

[swati]

  hello

1.)  Sorry , but you have written incorrect formula of the compound .
     CH3CHOCH2CH2CH2CH2CHOCH3  (see C-2 & C-7 , you have shown 5 valencies of carbon)

2.)  If you want to ask about interamolecular aldol condensation in CH₃COCH₂CH₂CH₂CH₂COCH₃  , it can form either 5 or 7 membered ring structure (not 6) . According to Baeyer strain theory 5 & 6 membered rings are more stable than other ring structures , since 5 & 6 membered rings have bond angles close to that of tetrahedral bond angle , thus less strain & so more stable.

3.)  Any dicarbonyl compound can form the product as 3 or 5 ring structure ; 4 or 6 ring structure ;5 or 7 ring structure i.e as n & n+2 ring structure . So there will never be competition between 5 & 6 ring structure.

[dnbwise]

sorry about the mistake, I should have looked at that more closely before posting, but thanks for the response.

[swati]

   welcome