Using the NMR 1H 13C Cosy identify peaks for both the starti

Using the NMR (1H, 13C, Cosy) identify peaks for both the starting material 2-aminobenzoic acid and the product (2-iodobenzoic acid)

Explain the differences in the chemical shifts (ie. Product has two doublets then two triplets moving upfield, product has doublet two triplets followed by doublet.

180 160 140 120 100 80 60 1.0 1.0 1.0 8.0 7.8 7.6 7.4 (ppm)

Solution

For 2-aminobenzoic acid

1H -NMR shows doublet for H beside acidic group , multiplet for ortho -H to acidic group , multiplet for para -H to acidic group and doublet for -H beside -NH₂ group.

For  2-iodobenzoic acid

1H -NMR shows doublet for H beside acidic group , doublet for -H beside -I group , multiplet for ortho -H to acidic group , multiplet for para -H to acidic group .

These splitting is written according to the chemical shift from upfield to downfield.

Everything is same in both 1H NMR expect the doublet coming because of -I and -NH₂ group. Since -I is more electronegative group than -NH₂ , thus the H beside it is more deshielded and shifted upfield. All rest peaks are same.