Question

Why is ${}^{13}\mathrm{C}-{}^{13}\mathrm{C}$spin-spin splitting not observed in ordinary organic compounds?

Short answer

The ${}^{13}\mathrm{C}-{}^{13}\mathrm{C}$spin-spin splitting is not observed in ordinary organic compounds because the natural abundance of ${}^{13}\mathrm{C}$ is very less.

Step-by-step solution

Step 1. Given information 

Explain the reason for the non-occurrence of ${}^{13}\mathrm{C}-{}^{13}\mathrm{C}$ spin-spin splitting in an ordinary organic compound.

Step 2. The reason for the non-occurrence of C13- C13 spin-spin splitting in an ordinary organic compound

The abundance of ${}^{13}\mathrm{C}$is $1.1\%$that is very less. The ${}^{13}\mathrm{C}-{}^{13}\mathrm{C}$spin-spin splitting is observed when the two nuclei of ${}^{13}\mathrm{C}$are adjacent to each other in a compound, but it is impossible because the natural abundance of ${}^{13}\mathrm{C}$is very low. The spin quantum number of ${}^{13}\mathrm{C}$is zero. Hence, the coupling will be observed as zero. Therefore, it will not undergo homonuclear coupling with ${}^{13}\mathrm{C}$.

Therefore, the ${}^{13}\mathrm{C}-{}^{13}\mathrm{C}$spin-spin splitting is not observed in ordinary organic compounds.