Fri October 05, 2012 By: Achyut Goel

places of ortho, meta and para.

Expert Reply
Fri October 05, 2012
In the ortho-substitution, two substituents occupy positions next to each other, which may be numbered 1 and 2. In the diagram, these positions are marked R and ortho.
In meta-substitution the substituents occupy positions 1 and 3 (corresponding to R and meta in the diagram).
In para-substitution, the substituents occupy the opposite ends (positions 1 and 4, corresponding to R and para in the diagram). The toluidinesserve as an example for these three types of substitution.
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