ORGANIC CHEMISTRY
ORGANIC CHEMISTRY
5th Edition
ISBN: 9781259977596
Author: SMITH
Publisher: MCG
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Chapter 21, Problem 21.74P

Use the 1 H NMR and IR data to determine the structure of each compound.

Compound A Molecular formula: C 5 H 10 O

IR absorptions at 1728 , 2791 , and 2700 cm 1

1 H NMR data: 1 .08 ( singlet, 9 H ) and 9 .48 ( singlet, 1 H ) ppm

Compound B Molecular formula: C 5 H 10 O

IR absorptions at 1718 cm 1

1 H NMR data: 1 .10 ( doublet, 6 H ) , 2 .14 ( singlet, 3 H ) , and 2 .58 ( septet, 1 H ) ppm

Compound C Molecular formula: C 10 H 12 O

IR absorptions at 1686 cm 1

1 H NMR data: 1 .21 ( triplet, 3 H ) , 2 .39 ( singlet, 3 H ) , 2 .95 ( quartet, 2 H ) , 7 .24 ( doublet, 2 H ) , and 7 .85 ( doublet, 2 H ) ppm

Compound D Molecular formula: C 10 H 12 O

IR absorptions at 1719 cm 1

1 H NMR data: 1 .02 ( triplet, 3 H ) , 2 .45 ( quartet, 2 H ) , 3 .67 ( singlet, 2 H ) , and 7 .06-7 .48 ( multiplet, 5 H ) ppm

Expert Solution & Answer
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Interpretation Introduction

Interpretation: The structure of each compound from the given IR, and 1HNMR data is to be stated.

Concept introduction: Spectroscopy method is used to identify the structure of the molecule. It is based on the interactions between matter and electromagnetic radiations. Proton NMR spectroscopy identifies the number of hydrogen atoms present in a molecule and the nature of the functional group. The value of chemical peaks depends upon the chemical environment around the hydrogen atom.

Answer to Problem 21.74P

The structure of A compound from the given data of IR, and 1HNMR is shown below:

ORGANIC CHEMISTRY, Chapter 21, Problem 21.74P , additional homework tip  1

The structure of B compound from the given data of IR, and 1HNMR is shown below:

ORGANIC CHEMISTRY, Chapter 21, Problem 21.74P , additional homework tip  2

The structure of C compound from the given data of IR, and 1HNMR is shown below:

ORGANIC CHEMISTRY, Chapter 21, Problem 21.74P , additional homework tip  3

The structure of D compound from the given data of IR, and 1HNMR is shown below:

ORGANIC CHEMISTRY, Chapter 21, Problem 21.74P , additional homework tip  4

Explanation of Solution

Structure determination of Compound A:

The molecular formula of the Compound A is C5H10O.

Information from IR spectrum:

The IR absorption at 1728cm1 suggests the presence of C=O bond, carbonyl group.

The IR absorption at 2791,and2700cm1 suggests the presence of CHO group.

Information from 1HNMR spectrum:

The observed chemical shift value at 1.08(singlet,9H)ppm suggests the presence of three methyl groups, bonded to carbon that has no hydrogen atoms.

The observed chemical shift value at 9.48(singlet,1H)ppm suggests the presence of CHO group.

Thus, the structure of Compound A from the given IR, and 1HNMR data is,

ORGANIC CHEMISTRY, Chapter 21, Problem 21.74P , additional homework tip  5

Figure 1

Structure determination of Compound B:

The molecular formula of the Compound B is C5H10O.

Information from IR spectrum:

The IR absorption at 1718cm1 suggests the presence of C=O bond, carbonyl group.

Information from 1HNMR spectrum:

The observed chemical shift value at 1.10(doublet,6H)ppm suggests the presence of two methyl groups, bonded to carbon that has 1H.

The observed chemical shift value at 2.14(singlet,3H)ppm suggests the presence of one methyl group, bonded to carbon that has no hydrogen atoms.

The observed chemical shift value at 2.58(septet,1H)ppm suggests the presence of CH group bonded to two methyl groups, and carbon that has no hydrogen atoms.

Thus, the structure of Compound B from the given IR, and 1HNMR data is,

ORGANIC CHEMISTRY, Chapter 21, Problem 21.74P , additional homework tip  6

Figure 2

Structure determination of Compound C:

The molecular formula of the Compound C is C10H12O.

Information from IR spectrum:

The IR absorption at 1686cm1 suggests the presence of C=O bond, carbonyl group.

Information from 1HNMR spectrum:

The observed chemical shift value at 1.21(triplet,3H)ppm suggests the presence of methyl group, bonded to carbon that has 2H's.

The observed chemical shift value at 2.39(singlet,3H)ppm suggests the presence of one methyl group, bonded to carbon that has no hydrogen atoms.

The observed chemical shift value at 2.95(quartet,2H)ppm suggests the presence of CH2 group bonded to carbon that has 3H's. The slightly downfield absorption indicates that some electron withdrawing group, (C=O) is also bonded to it.

The observed chemical shift values at 7.24(doublet,2H)ppm, and 7.85(doublet,2H)ppm suggest the presence of benzene ring on which substituents are present at para position to each other.

Thus, the structure of Compound C from the given IR, and 1HNMR data is,

ORGANIC CHEMISTRY, Chapter 21, Problem 21.74P , additional homework tip  7

Figure 3

Structure determination of Compound D:

The molecular formula of the Compound D is C10H12O.

Information from IR spectrum:

The IR absorption at 1719cm1 suggests the presence of C=O bond, carbonyl group.

Information from 1HNMR spectrum:

The observed chemical shift value at 1.02(triplet,3H)ppm suggests the presence of methyl group, bonded to carbon that has 2H's.

The observed chemical shift value at 2.45(quartet,2H)ppm suggests the presence of CH2 group bonded to carbon that has 3H's. The slightly downfield absorption indicates that some electron withdrawing group, (C=O) is also bonded to it.

The observed chemical shift value at 3.67(singlet,2H)ppm suggests the presence of CH2 group bonded to carbon that has no hydrogen atoms. The slightly downfield absorption indicates that some electron withdrawing group, (C=O) is also bonded to it.

The observed chemical shift value at 7.06-7.48(multiplet,5H)ppm suggests the presence of monosubstituted benzene ring.

Thus, the structure of Compound D from the given IR, and 1HNMR data is,

ORGANIC CHEMISTRY, Chapter 21, Problem 21.74P , additional homework tip  8

Figure 4

Conclusion

The structures of A, B, C, and D compounds from the given data of IR, and 1HNMR are shown in Figure 1, Figure 2, Figure 3, and Figure 4 respectively.

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Chapter 21 Solutions

ORGANIC CHEMISTRY

Ch. 21 - Prob. 21.11PCh. 21 - Prob. 21.12PCh. 21 - Prob. 21.13PCh. 21 - Prob. 21.14PCh. 21 - Problem 21.15 Draw the product of each...Ch. 21 - Prob. 21.16PCh. 21 - Problem 21.17 Draw the products of the following...Ch. 21 - Problem 21.18 Outline a synthesis of each Wittig...Ch. 21 - Problem 21.19 Draw the products (including...Ch. 21 - Problem 21.20 What starting materials are needed...Ch. 21 - Prob. 21.21PCh. 21 - Problem 21.22 The product formed when reacts with...Ch. 21 - Prob. 21.23PCh. 21 - Prob. 21.24PCh. 21 - Prob. 21.25PCh. 21 - Prob. 21.26PCh. 21 - Prob. 21.27PCh. 21 - Problem 21.28 Draw a stepwise mechanism for the...Ch. 21 - Problem 21.29 Draw the products of each...Ch. 21 - Problem 21.30 Label each compound as an acetal, a...Ch. 21 - Problem 21.31 Draw a stepwise mechanism for the...Ch. 21 - Problem 21.32 Draw the products of each...Ch. 21 - Problem 21.33 Safrole is a naturally occurring...Ch. 21 - Prob. 21.34PCh. 21 - Problem 21.35 How would you use a protecting group...Ch. 21 - Prob. 21.36PCh. 21 - Problem 21.37 Two naturally occurring compounds...Ch. 21 - Problem 21.38 Draw the products of each...Ch. 21 - Prob. 21.39PCh. 21 - Problem 21.40 (a) Give the IUPAC name for A and B....Ch. 21 - 21.41 Rank the following compounds in order of...Ch. 21 - Prob. 21.42PCh. 21 - 21.43 Give the IUPAC name for each compound. a....Ch. 21 - 21.44 Give the structure corresponding to each...Ch. 21 - Prob. 21.45PCh. 21 - 21.46 Draw the products of each reaction. a. e....Ch. 21 - Prob. 21.47PCh. 21 - 21.48 Draw all stereoisomers formed in each...Ch. 21 - Prob. 21.49PCh. 21 - What products are formed when each acetal is...Ch. 21 - Prob. 21.51PCh. 21 - Prob. 21.52PCh. 21 - Which compound forms the higher concentration of...Ch. 21 - Prob. 21.54PCh. 21 - Prob. 21.55PCh. 21 - Prob. 21.56PCh. 21 - Prob. 21.57PCh. 21 - Devise a synthesis of each alkene using a Wittig...Ch. 21 - Devise a synthesis of each compound from...Ch. 21 - Prob. 21.60PCh. 21 - Devise a synthesis of each compound from ethanol...Ch. 21 - Prob. 21.62PCh. 21 - Prob. 21.63PCh. 21 - 21.64 Draw a stepwise mechanism for the following...Ch. 21 - 21.65 Draw a stepwise mechanism f or the following...Ch. 21 - Prob. 21.66PCh. 21 - 21.67 Draw a stepwise mechanism for each...Ch. 21 - 21.68 Draw a stepwise mechanism for the following...Ch. 21 - Prob. 21.69PCh. 21 - Prob. 21.70PCh. 21 - Prob. 21.71PCh. 21 - Prob. 21.72PCh. 21 - 21.73 Although the carbonyl absorption of cyclic...Ch. 21 - 21.74 Use the and data to determine the...Ch. 21 - 21.75 A solution of acetone in ethanol in the...Ch. 21 - Compounds A and B have molecular formula ....Ch. 21 - 21.77 An unknown compound C of molecular formula ...Ch. 21 - 21.78 An unknown compound D exhibits a strong...Ch. 21 - Prob. 21.79PCh. 21 - -D-Glucose, a hemiacetal, can be converted to a...Ch. 21 - 21.81 Draw a stepwise mechanism for the following...Ch. 21 - Prob. 21.82PCh. 21 - 21.83 Draw a stepwise mechanism f or the...Ch. 21 - Prob. 21.84PCh. 21 - Prob. 21.85PCh. 21 - 21.86 Draw stepwise mechanism for the following...
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