McMurry (Kap. 2,4)

Question 1

In the acetate ion, one carbon is bounded to 2 oxygens. One oxygen it is double bounded to, and another it is singly bounded to.

But how do we know which oxygen is which, because they both are the same.

Therefore, how do we solve this problem?

Answer 1

With a resonance hybrid, which is the structure that acetate is found in. In that structure, the C is both partially “double bonded” to both Oxygens, and the negative charge is shared equally by both oxygens.

The individual resonance forms for the acetate ions can also be drawn (one structure showing C double bonded to one of the Oxygens, and another one showing carbon double bonded to the other oxygen, but in real life, the hybrid form is exciting). A double headed arrow is placed between the different resonance structures (NOT the hybrid resonance structure tho).

Question 2

Is benzene a resonance structure?

Answer 2

Yes, because each C is double bonded to another C atom alternating (BUT which C atom is it?) Therefore a resonance hybrid is drawn to illustrate that whether it is that carbon or the other, it is the same, and the charge between the atoms and bond length are the same (not alternating).