Question

Draw the structure of the compound C9H10O2 that exhibits the 13C-NMR spectrum below. Impurity peaks are omitted from the peak list. The triplet at 77 ppm is CDCl.

Shift

190.6; 164.0; 131.9; 129.8; 114.7; 63.9; 14.6

Answer 1

First we have to calculate number of index hydrogen deficiency by comparing with saturated hydrocarbon formula ,

C_nH_(2n+2)

_{here n= 9 , number of carbon atoms ,} C₉H₁₀O₂ by comparing ,

C₉H _{(2 x 9 + 2)}

C₉H ₂₀

_{index hydrogen deficiency = (20-10)/2,}

_{here 10 stands for number of hydrogen in molecular formula so index hydrogen deficiency = 5}

_{now it is clear that compound contain aromatic ring and one characterstic peak at 190.6 ppm indicates presence of carbonyl group. So based on chemical shift of CMR , compound would be 4-Methoxyacetophenone,}

PAGE NO. DATE Each Carbon in 4 methoxyacetophenone label as A B C D E F G etc Lets see chanical shift -

A=190.6 ppm

B=164.0 ppn

C=131.9 ppm

D= 129.8 ppm

E=114.7 ppm

F=63.9 ppm

G= 14.6 ppm