The three groups, (a), (b), and (c) produce spectral features typical of propyl groups. A 3H methyl triplet for (a), split by the neighboring CH2 (b) is straightforward. Likewise, a 2H triplet for (c), also split by (b). The (b) CH2 actually has two different groups of neighbors.
Nonetheless, because rotation within the alkyl group averages all the coupling constants to the typical alkyl 7.5 - 8 Hz, we see a sextet for (b), as if the CH2 and CH3 neighbors were a single CH5 group. Such behavior is quite common is acyclic structures.
Nonetheless, because rotation within the alkyl group averages all the coupling constants to the typical alkyl 7.5 - 8 Hz, we see a sextet for (b), as if the CH2 and CH3 neighbors were a single CH5 group. Such behavior is quite common is acyclic structures.
The other feature of note is that although the benzene ring actually bears three different kinds of H (e, f, and g), the CH2substituent on the ring is not electronegative enough to induce a significant chemical shift difference between the hydrogens near it and those further away.
Thus the five hydrogens accidentally have the same chemical shift in this spectrometer. An instrument with a more powerful magnet would spread out the spectrum still further, and show us the three expected absorptions.
Thus the five hydrogens accidentally have the same chemical shift in this spectrometer. An instrument with a more powerful magnet would spread out the spectrum still further, and show us the three expected absorptions.
DACCA, BANGLADESH
Farmer Harvesting Jute, Tangail,Dhaka, Bangladesh Photographic Print
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