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Organic Chemistry 1

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$^{1}$HNMR of [18]Annulene: Two Chemical Shifts

ORGO1-UVAPRK

A $^{1}$HNMR spectrum of [18]annulene (solvent: tetrahydrofuran-d8, vacuum-sealed) show two multiplets at 9.25 ppm and −2.9 ppm, respectively, at −60 $^{o}$C. The structure of [18]annulene is shown below.

Which of the following statements is TRUE?

Structure of [18]Annulene. Created for Albert.io. Copyright 2016. All rights reserved.

A

The two multiplets at 9.25 ppm and −2.9 ppm belong to the 12 $H$'s outside the ring and the 6 $H$'s inside the ring, respectively.

B

The two multiplets at 9.25 ppm and −2.9 ppm belong to the 12 $H$'s inside the ring and the 6 $H$'s outside the ring, respectively.

C

The two multiplets at 9.25 ppm and −2.9 ppm belong to the 9 $H$'s in the top half of the ring and the 9 $H$'s in the top half of the ring, respectively.

D

The two multiplets at 9.25 ppm and −2.9 ppm belong to the 9 $H$'s in the left half of the ring and the 9 $H$'s in the right half of the ring, respectively.