the-methyl-h-highlighted-in-the-isopentane-structure-appears-at-0-87-ppm-while-t

Question

The methyl-H highlighted in the isopentane structure appears at 0.87 ppm, while that of 2-methylbut-2-ene appears at 1.56 ppm. Rationalize this observation.

H NMR table comparing methyl-H shifts in isopentane (0.87 ppm) and 2-methylbut-2-ene (1.56 ppm).

Accepted Answer

The presence of an sp²-carbon creates magnetic anisotropy, which de-shields the nearby proton and shifts the NMR signal downfield.

Answer

The presence of an sp²-carbon creates magnetic anisotropy, which shields the nearby proton and shifts the NMR signal downfield.

Answer

The presence of an sp²-carbon creates magnetic anisotropy, which shields the nearby proton and shifts the NMR signal upfield.

Answer

The presence of an sp²-carbon creates magnetic anisotropy, which de-shields the nearby proton and shifts the NMR signal upfield.