Q13-33E - Organic Chemistry (Mcmurry)

Question

Is a nucleus that absorbs at 6.50 $\mathrm{\delta }$ more shielded or less shielded than a nucleus that absorbs at 3.20 $\delta$? Does the nucleus that absorbs at 6.5 $\delta$ require a stronger applied field or a weaker applied field to come into resonance than the one that absorbs at 3.20 $\delta$?

Step-by-Step Solution

Answer

The nucleus that absorbs at 6.50$\mathrm{\delta }$ is less shielded than the nucleus which absorbs at 3.20$\mathrm{\delta }$ thus requires a weaker field to come into resonance.

Step1: Shielding effect

It is defined as the reduction in the effective nuclear charge on an atom due to the difference in the force of attraction on electrons of an atom.

Step 2: Effect of shielding

If the shielding is less than compound is more reactive that is there are more electrons than there are more shells than the distance between each shell is increase so, the attraction between them is less and that’s why they are attracted by the different atoms.

Step 3: Nucleus that requires the weaker field to come into resonance

The nucleus that absorbs at 6.50$\mathrm{\delta }$ is less shielded than the nucleus which absorbs at 3.20$\delta$ thus requires a weaker field to come into resonance.

A shielded nucleus has a small effective field and a stronger field is required to bring it into the resonance.