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Nuclear Magnetic Resonance (NMR)
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Electronegative substituents remove electron density, unshielding the hydrogens, and shift the signal toward high \delta$ values.

spectrum-bromide-ethyl

In the following table you can see the influence of different atoms on the signal of the methyl hydrogens.

deshielding-table-01

As can be seen in the table, the greater the electronegativity of group X, the greater the chemical shift.

The effect of the electronegative groups is additive, the greater the number of groups the proton is more unshielded and the displacement is greater

deshielding-table-02

The inductive effect propagates along the chains, decreasing its effect with distance, as can be seen in the following table.

deshielding-table-03

In the following spectra, the aforementioned effects on chemical shifts can be observed.

spectrum-diethoxymethane

spectrum-14-oxathian