Question

Draw the structure of the compound C3H7Cl that might exhibit the 13C-NMR spectrum below. Impurity peaks are omitted from the peak list. The triplet at 77 ppm is CDCl3

Answer 1

As we are not provided with ¹³C-NMR spectrum therefore, we will answer it for both isomers with a molecular formula C₃H₇Cl. There are only two possible isomers for this chemical formula.

(1) 2-Chloropropane:

If the isomer is 2-Chloropropane then the ¹³C-NMR spectrum will give two peaks. One will lower intensity in downfield will be for the second carbon to which electronegative carbon is attached and the second signal will be at upfield with double integration for the terminal two similar carbons.

(2) 1-Chloropropane:

If the isomer is 1-chloropropane then it will exhibit three signals in ¹³C-NMR spectrum. The most deshielded signal in downfield will be for the carbon directly bonded to chlorine atom, the signal in middle will be for the middle carbon and the most shielded carbon will give the signal in most upfield region.

Below are the isomers with their predicted ¹³C-NMR spectrums.

Note:

We have already omitted the solvent (CDCl₃) peak.