Question

In this molecules, $\pi$-electron density is more at carbon number X and Y then X + Y is.

Answer 1

5

Answer 2

The oxygen atom in the pyran ring acts as an electron-donating group due to its lone pairs, exhibiting a positive mesomeric (+M) effect. This effect leads to an increase in $\pi$-electron density at specific carbon atoms through resonance. By drawing the resonance structures, it is observed that the negative charge (indicating higher electron density) is primarily developed at carbons C2 and C3. These resonance structures are more stable compared to others where the negative charge might appear on C1 or C4, because the negative charge on C2 and C3 is further separated from the positive charge on the oxygen atom. Thus, C2 and C3 have the highest $\pi$-electron density.