Heres meta methoxy benzoic acid:
and heres para methoxy benzoic acid:
m-methoxybenzoic acid is a stronger acid than its para substituted analogue. I'm a bit confused about why this is. From what I've read, its because at the meta position, only the methoxy groups inductive withdrawing effects apply whereas at the para position, it also acts as a mesomeric (resonance) donator. Why does the methoxy groups resonance effects only work when its at the para position? Why doesn't it act as a resonance donator when its at the meta position?