Q15-14E - Organic Chemistry (Mcmurry)

Question

All-cis cyclodecapentaene is a stable molecule that shows a single absorption in its NMR spectrum at $\mathbf{5}\mathbf{.}\mathbf{67}\mathit{\delta }$. Tell whether it is aromatic, and explain its NMR spectrum.

Step-by-Step Solution

Answer

Cyclodecapentaene is not aromatic in nature as well as it is a non-planer molecule due to ${\text{sp}}^3$carbon present so that shows a peak at 5.67 instead of 6.5 -8$\delta$.

Step 1: H NMR 1

Nuclear magnetic resonance is the technique that is used to identify the hydrogen in the compound and produce the corresponding peaks for its detection.

Step 2: H NMR 1 for aromatic compounds

Aromatic compounds which are planer in shape and follow Huckel’s rule and the aromatic compounded due to its plane nature show peaks at 6.5 -8$\delta$.

Step 3: H NMR 1 for non-aromatic compounds

Cyclodecapentaene is a non-aromatic compound due to the presence of the hybridized carbon and that disturbs the planarity of the molecule which makes the molecule out of the plane and that’s why its absorption is shifted to 5.67 instead of 6.5 -8$\delta$.