Question

Explain why NMR spectrum of benzen observed at a lower field where that the acetylene observed at a higher field strength .​

Answer 1

Answer:

In an applied magnetic field the valence electrons of the protons are caused to circulate. This circulation, called a local diamagnetic current, generates a counter magnetic field which opposes the applied magnetic filed.. This effect is called diamagnetic Shielding or diamagnetic anisotropy.

Answer 2

Because of the anisotropic effect produced by the circulation of - electrons, the NMR spectra of acetylene is observed at a greater field strength than that of benzene.

NMR Spectrum:

• A plot of the applied radio frequency vs the absorption is used to depict the NMR spectrum.
• Since the applied frequency rises from left to right, the plot's left and right sides correspond to the low field and upfield, respectively, and the protected side corresponds to the right field.
• We'll go about shielding in more detail later.
• The precise strength of the magnetic field that a certain nucleus experiences will depend on the structural characteristics of the molecule.
• As a result, H atoms in various chemical environments will exhibit various chemical changes.
• This is what makes NMR such a valuable tool for determining structure in organic chemistry.
• Three primary characteristics—electronegativity, the magnetic anisotropy of systems, and hydrogen bonding—will have an impact on the nucleus' shielding.

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