Question

When comparing the spectra for the starting material and the product – where do you observe the biggest change(s)?
2-hydroxy-3-methoxybenzoic acid HN MR (600 MHz, DMSO-do) -251DMS0-d6 -13.96 1139 ;2.38 7:21 7.20 L89- 6.85 17.36 .6.84 380 он он ܢ0-Hac 0.98- ܓ104 107z 3.00- 14.5 14.0 13.5 13.0_12.5 12.0 115 11. 010.5_10.0 9. 5 _8.0 7. 5 7 . 0 6.5 _6. 0 5 . 5 5 .0 4. 5 4 .0 _3.5 _3.0 _2.5 9.0 _8.5 f1 (ppm)

Answer 1

Carboxylic acid hydrogens occur as broad or very broad singlets due to chemical exchange. Their exact chemical shift depends on concentration, temperature, and solvent but usually you will found the peaks beyond 10 around 14 or 15 ppm( not fixed.)

So the two peaks beyond 10 one is of OH of carboxylic acid and another is of Alcoholic OH.

When you convert carboxylic acid to aldehyde you will find an additional peak in between 9.5 to 10.5 for aldehydic Hydrogen ( fixed) Maximum time you will fijd at around 9.8 ppm.

Here also if you say the only major change is at 9.8 fir aldehydic Hydrogen and absence of peak at 14.

Other things remaining same.

Thanks for asking the question.