ORGANIC CHEMISTRY MASTERINGCHEM ACCESS
9th Edition
ISBN: 9780137249442
Author: Wade
Publisher: INTER PEAR
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Textbook Question
Chapter 16.9C, Problem 16.18P
The proton NMR spectrum of 2-pyridone gives the chemical shifts shown.
- a. Is 2-pyridone aromatic?
- b. Use resonance forms to explain your answer to (a). Also explain why the protons at δ7.31 and δ7.26 are more deshielded than the other two (δ6.15 and δ6.57).
- c. Thymine is one of the heterocyclic bases found in DNA. Do you expect thymine to be aromatic? Explain.
- d. The structure of 5-fluorouracil is shown in the box at the side of the page. Is 5-fluorouracil aromatic? Explain.
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Students have asked these similar questions
1. Why does H2 not give an IR spectrum?
2. Explain why primary amines and unsubstituted amides have two NH stretching absorptions.
3. Why do anhydrides show two carbonyl peaks?
4. HCl is known to give addition reactions to carbon-carbon double bonds. Why is this behavior not observed in this reaction?
5. Predict the structure of the product expected from addition of molecular bromine to maleic acid.
Step 1: Brief Description
The given compound is 4-aminobenzoic acid. The IR and NMR spectrum of this compound also given.
Determine the spectrum.
Step 2: Determination of IR data
The peaks are identified as following:
Two bands at 3300 & 3230 cm. This is due to asymmetrical and symmetrical N-H stretching of NH₂ group.
A broad stretching between $200-2500 cm** - This broad stretching is due to O-H in carboxylic acid group.
Band at 1680-1700 cm¹. C=O Stretching
1600 cm C-C-C (aromatic carbon)
Step 3: Determination of PMR spectrum
Splitting patterns: It should be noted that spin-spin splitting is observed only between nonequivalent
neighboring protons. Equivalent protons do spin-spin couple with one another but splitting is not
observed.
Chemical shift: A highly shielded proton has a low chemical shift and a highly deshielded proton has a high
value of chemical shift.
The given peaks are of following:
Proton Level
Chemical shift (ppm)
Relative integration
Multiplicity
ABC
-11.9
7.8
8.3…
Aniline (conjugate acid pKa 4.63) is a considerably stronger base than diphenylamine (pKa 0.79). Account for these marked differences.
Chapter 16 Solutions
ORGANIC CHEMISTRY MASTERINGCHEM ACCESS
Ch. 16.2 - Prob. 16.1PCh. 16.2 - Prob. 16.2PCh. 16.2 - a. Draw the resonance forms of benzene,...Ch. 16.2 - Show the product of the Diels-Alder dimerization...Ch. 16.4 - Prob. 16.5PCh. 16.6 - Make a model of cyclooctatetraene in the tub...Ch. 16.6 - Prob. 16.7PCh. 16.6 - Prob. 16.8PCh. 16.7 - Prob. 16.9PCh. 16.8A - a. Draw the molecular orbitals for the...
Ch. 16.8A - Repeat Problem16-10 for the cyclopentadienyl ions....Ch. 16.8C - Explain why each compound or ion should be...Ch. 16.8C - The following hydrocarbon has an unusually large...Ch. 16.8C - Prob. 16.14PCh. 16.8C - Prob. 16.15PCh. 16.9B - Prob. 16.16PCh. 16.9C - Show which of the nitrogen atoms in purine are...Ch. 16.9C - The proton NMR spectrum of 2-pyridone gives the...Ch. 16.9D - Prob. 16.19PCh. 16.9D - Prob. 16.20PCh. 16.10 - Prob. 16.21PCh. 16.12 - Ciprofloxacin is a member of the fluoroquinolone...Ch. 16.13 - Draw and name all the chlorinated benzenes having...Ch. 16.13 - Name the following compounds:Ch. 16.15 - The UV spectrum of 1-phenylprop-2-en-1-ol shows an...Ch. 16 - Prob. 16.26SPCh. 16 - Name the following compounds:Ch. 16 - Draw and name all the methyl, dimethyl, and...Ch. 16 - Four pairs of compounds are shown. In each pair,...Ch. 16 - One of the following hydrocarbons is much more...Ch. 16 - In Kekuls time cyclohexane was unknown, and there...Ch. 16 - Prob. 16.32SPCh. 16 - Azulene is a deep-blue hydrocarbon with resonance...Ch. 16 - Prob. 16.34SPCh. 16 - Prob. 16.35SPCh. 16 - Prob. 16.36SPCh. 16 - Prob. 16.37SPCh. 16 - Prob. 16.38SPCh. 16 - Prob. 16.39SPCh. 16 - Biphenyl has the following structure. a. Is...Ch. 16 - Anions of hydrocarbons are rare, and dianions of...Ch. 16 - How would you convert the following compounds to...Ch. 16 - Prob. 16.43SPCh. 16 - Prob. 16.44SPCh. 16 - A student found an old bottle labeled thymol on...Ch. 16 - Prob. 16.46SPCh. 16 - Prob. 16.47SPCh. 16 - Prob. 16.48SPCh. 16 - The proton NMR chemical shifts of the hydrogens in...Ch. 16 - Prob. 16.50SPCh. 16 - NMR has been used to probe many molecular...
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- 4. The pk, of vanillin is about 9, which is much more acidic than a normal alcohol. Draw a reaction showing the deprotonation of vanillin with NaOH, and then draw six resonance structures of the conjugate base. Draw the hybrid structure and clearly indicate how the negative charge is distributed in the compound.arrow_forwardThe two following molecules are very common reagents for organic synthesis. They botn have a basic nitrogen, but their pka's are very different (see values given in question 1). The goal of this problem is to understand why. N-H A 1) Please draw below the conjugated acid of A and B respectively: H base conjugated acid base conjugated acid pka of this acid/base pair: - 5 pka of this acid/base pair: ~ 0 2) Both molecules exhibit resonance forms (see below). Draw curved arrows to go from one resonance structure to the next (molecule A: 1->2; molecule B 1->2->3–>4->5). A 1 1 2 4 5arrow_forwardHow does the pKe of the conjugate acid of benzylamine (C3H5CH,NH2) compare to the pK,'s of the conjugate acids of cyclohexanamine (10.7) and aniline (4.6)? Explain your choice.arrow_forward
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- 4-Cyanophenol has a pKa = 8.0, whereas phenol has a pKa= 10.0. Resonance form that best illustrates why 4-cyanophenol is more acidic isarrow_forward4-Methylphenol is more acidic than ethanol (pKa 10.36 vs 16.0) , even though both contain an OH group and a methyl group. Draw the structures of the anions formed from loss of the alcoholic protons from both compounds. Use resonance to explain the difference in their respective acidities.arrow_forwardAnalyse the high resolution proton NMR spectrum of a compound with a molecular formula of C8H16O2 and and write its name. Options: A. 2-ethylhexanoic acid B. 1,4-cyclohexanedimethanol C. ethyl hexanoate D. butyl butyrate E. ethyl 2,2-dimethylpropanoatearrow_forward
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