Chapter 14: Q.21558-14-9P. (page 538)
For each compound, first label each different type of proton and then rank the protons in order of increasing chemical shift.
a.

b.

c.

Short Answer
a.

b.

c.

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Chapter 14: Q.21558-14-9P. (page 538)
For each compound, first label each different type of proton and then rank the protons in order of increasing chemical shift.
a.

b.

c.

a.

b.

c.

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What protons in alcohol A give rise to each signal in its 1HNMR spectrum? Explain all splitting patterns observed for absorptions between 0–7 ppm.

Which of the highlighted carbon atoms in each molecule absorbs farther downfield?
a.

b.

c.

d.

Question: Using a 300 MHz NMR instrument:
a. How many Hz downfield from TMS is a signal at 2.5 ppm?
b. If a signal comes at 1200 Hz downfield from TMS, at what ppm does it occur?
c. If two signals are separated by 2 ppm, how many Hz does this correspond to?
Question: Cyclohex-2-enone has two protons on its carbon-carbon double bond (labeled Ha and Hb ) and two protons on the carbon adjacent to the double bond (labeled Hc ). (a) If Jab = 11 Hz and Jbc = 4 Hz, sketch the splitting pattern observed for each proton on the hybridized carbons. (b) Despite the fact that Ha is located adjacent to an electron-withdrawing C=O, its absorption occurs up-field from the signal due to Hb(6.0 vs. 7.0 ppm). Offer an explanation.

Question: 18-Annulene shows two signals in its 1 H NMR spectrum, one at 8.9 (12 H) and one at –1.8 (6 H) ppm. Using a similar argument to that offered for the chemical shift of benzene protons, explain why both shielded and deshielded values are observed for 18-annulene.

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