In Section 19-10B, we saw that pyridine undergoes electrophilic aromatic substitution reluctantly, requiring strong conditions and giving

Question:

In Section 19-10B, we saw that pyridine undergoes electrophilic aromatic substitution reluctantly, requiring strong conditions and giving disappointing yields. In contrast, pyridine N-oxide undergoes EAS under moderate conditions, giving good yields of substitution on C2 and C4. Explain this surprising difference.