Why is c12 Not NMR active?

There is no NMR spin capability with 12C (6 protons and 6 neutrons). There must be an odd number of a) protons, b) neutrons, or c) both in order for there to be spin activity and thus NMR detectability. [1] What is NMR?

Why does NMR focus on the 13C isotope and not 12C?

C-13 NMR relies on the magnetic properties of the C-13 nuclei. The effect of this is that a C-13 nucleus can behave as a little magnet. C-12 nuclei don’t have this property. If you have a compass needle, it normally lines up with the Earth’s magnetic field with the north-seeking end pointing north.

Why do nuclei such as 12C 16O which do not possess nuclear spin do not show NMR spectra?

8 Nuclei such as 12C, 16O, and 32S, which have even mass and atomic numbers, have no magnetic properties and do not give nuclear magnetic resonance signals. For various reasons, routine use of NMR spectra in organic chemistry is confined to 1H, 19F, 13C, and 31P.

Why is c13 used in NMR?

C-13 NMR relies on the magnetic properties of the C-13 nuclei. Because a C-13 nucleus behaves like a little magnet, it means that it can also be aligned with an external magnetic field or opposed to it. Again, the alignment where it is opposed to the field is less stable (at a higher energy).

Why is c13 not sensitive?

Many of the molecules studied by NMR contain carbon. Unfortunately, the carbon-12 nucleus does not have a nuclear spin, but the carbon-13 (C-13) nucleus does due to the presence of an unpaired neutron. Therefore, carbon-13 NMR spectroscopy will be less sensitive (have a poorer SNR) than hydrogen NMR spectroscopy.

Why is 13C not quantitative?

With conventional acquisition parameters, 13C NMR spectra of liquids are rarely quantitative and usually not integrated. In the middle spectrum, the NOE is greatly reduced by decoupling only during the acquisition time (decoupling duty cycle = 10 \%), however the long T1’s prevent the spectrum from being quantitative.

When might you choose to do c13 NMR instead of H NMR?

There are two common types of NMR: 1H NMR and 13C NMR. The main difference between 1H NMR and 13C NMR is that 1H NMR is used to determine the types and number of hydrogen atoms present in a molecule whereas 13C NMR is used to determine the type and number of carbon atoms in a molecule.

Is CL NMR active?

(Cl) Chlorine has two useful NMR active nuclei 35Cl and 37Cl. Both yield relatively broad signals but have a broad chemical shift range. Either nucleus can be used to detect and quantify the presence of ionic chlorides.

Which of the following nuclei is not active for NMR spectroscopy?

Nuclei that possess an even number of both neutrons and protons have no spin (spin quantum number = 0) and are not NMR-active, for example 2He, 12C, 16O, 32S.

Why does c13 have spin?

Many of the molecules studied by NMR contain carbon. Unfortunately, the carbon-12 nucleus does not have a nuclear spin, but the carbon-13 (C-13) nucleus does due to the presence of an unpaired neutron. The sensitivity of an NMR spectrometer is a measure of the minimum number of spins detectable by the spectrometer.