In meta hydroxy benzaldehyde which position (w.r.t hydroxy group) is more prone to electrophilic attack?

In meta hydroxy benzaldehyde which position (w.r.t hydroxy group) is more prone to electrophilic attack ? 


My approach:I considered hydroxy group as the stronger +M group.So my guess was para position w.r.t hydroxy group.But that's not the correct answer.


The answer is actually given as ortho w.r.t hydroxy and para w.r.t -CHO group!!




This is known as the **ortho effect.** According to it if an **ortho/para** and **meta** directing group are **meta** to each other, then the incoming electrophile prefers to come on **ortho** of **meta** directing group.


See the **reference**.


![enter image description here](https://i.stack.imgur.com/8BMi3.gif)


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