@ScientistOmega Sorry , was thinking incorrect

By hyper conjugation logic , 2 is more stable as one of double bond is stabilized by 8 alpha H

@YUSUFHASAN in this compound 2 is more stable. Is it due to more ring Strain in 1??

@ScientistOmega one quick way to see is by hyperconjugation like jasmine said. Another way is to draw a chair form of the mooecules,and see that the double bond fixes the trans conformation which is not there in 1

Is there any trick to predict whether a compound is +M<-I or +M >-I in such complicated compounds??

I can do for most of compounds but to predict in some compounds it's really difficult.My teacher told me too just learn these cases as exceptional.

@ScientistOmega How much MO theory do you know?

@YUSUFHASAN jee level only!!

@YUSUFHASAN it's me scientist omega

@111 Ok, well, the thing is, donation depends on effective overlap mostly. The thing is, electronegativity is a bonded phenomenon, it's not applied to O's own lone pairs. You are imagining that since O is more electronegative than Cl, so +M will decrease..But the fact is, electronegativity of O or Cl is not applied on it's own lone pairs, so here it simply depends on the overlap strength , which is weaker in C-Cl than C-O

"Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons."

That's the technicality to look at here

why C-O overlap is more than C-Cl??

Cl size is larger than O.Means more polarisation so a stronger bond.

Am i wrong??

@111 Nope,overlap strength is basically measured in terms of compatibility.. in C-O,overlap is of 2pπ-2pπ type,while in C-Cl it's of 20π-3pπ type

oops**

2pπ-2pπ is better because 3p orbital is much more diffused than 2p

Hence overlap integral is less

Thanku

Consider this reso structures of benzoic acid

As we can see that + charge is at Ortho and Para positions of benzoic acid.

So EWG at Para position must destabilize it.

Hence benzoic acid with ERG at para must make it strongest acid.

BUT it isn't correct.Why?? please explain.

Sir told to consider - charge only on COO- .So EWG will increase stability and acidic strength. But i want to know y i'm wrong??

@111 Your proposed resonance structures have negligible contribution to the resonance hybride of the benzoate anion

This is because,the 3rd structure you have made,has a dianion on the same central atom, a VERY unfavorable intermediate,plus ,your positive charge is on the other end of the molecule,so the charge separation is off the charts here

Hence,what we generally say is that the resonance is within COO- itself,and COO- is essentially an ERG

Hence,if there is an EWG to capture the electrons displaced by COO-,it becomes quite like a "source and sink" flow of electrons,which will be quite stable