Microscale Techniques for the Organic Laboratory

2nd Edition

WEBSITE REFERENCE DISCUSSIONS

Dana W. Mayo

Bowdoin College

Ronald M. Pike

Merrimack College

Peter K. Trumper

University of Southern Maine

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WEBSITE CONTENTS

CHAPTER 3

MICROSCALE LABORATORY EQUIPMENT AND TECHNIQUES

Sand Bath Techniques 8

Metal Heat-Transfer Devices 9

Reflux Apparatus 12

Distillation Apparatus 14

Reduced Pressure Distillation Systems 14

Special Moisture Sensitivity Conditions 16

Collection of Gas Chromatographic Effluents 19

CHAPTER 5

TECHNIQUES 2 AND 3

Simple and Fractional Semimicroscale Distillations

Technique 2: Simple Semimicroscale Distillation. 21

2A. Distillation Theory 21

2B. Steam Distillation 27

Theory 28

Example [2BW]: Illustration of the application of steam distillation

3A. How Spinning Bands Function in Fractional Distillation Columns. 39

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TECHNIQUE 3: Fractional Semimicroscale Distillation

3B. Reduced pressure distillation with microspinning band columns 43

Reduced Distillation Apparatus 43

Example [3BW]: Methylcyclohexane/toluene distillation at 300 Torr

Assembly of the System 45

A standard mixture of 50:50 methylcyclohexane/toluene 46

Vacuum Pumps and Pressure Regulation

TECHNIQUE 5

Crystallization

Two Examples to Practice Recrystallization on a semimicroscale follow:

(This procedure is useful when carrying out scaled-upmicroscale reactions) 61

Example [5AW]: Recrystallization of Benzoin

Example [5BW]: Recrystallization of Naphthalene from a Solvent Pair

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TECHNIQUE 8

Measurement of Specific Rotation

High Performance Polarimeters 64

Optical Rotary Dispersion 65

CHAPTER 6

Spectroscopic Identification of Organic Compounds by Infared Spectroscopy

I. Introduction.

Introduction to Theory 66

A. Molecular Energy 66

B. Molecular Vibrations 67

C. Quantized Vibrational Energy 70

D. Selection Rules 72

1. The Case of HCl 732. The Case of Water 743. The Case of Carbon Dioxide 76

E. Vibrational Coupling 78

1. Coupled Oscillators 782. Second-Order Coupling 79

II. Group Frequencies of the Hydrocarbons

A. Characteristic Group Frequencies of Alkanes 81

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B. Characteristic Group Frequencies of Alkenes 88

1. C=C Stretching 88

2. Alkene C—H 89

3. Out-of-Plane Deformation Modes 91

a. Vinyl Groups 91

b. Vinylidene Groups 91

c. Trans Alkenes 92

d. Cis Alkenes 92

e. Trisubstituted Alkenes 93

f. Tetrasubstituted Alkenes 93

g. Overtones 93

C. Characteristic Group Frequencies of Alkynes 93

1. C≡C Stretching Vibration 93

2. Alkyne C—H Vibrations 94

D. Characteristic Group Frequencies of Arenes 95

1. Group Frequencies of the Phenyl Group 95

a. C—H Stretching Modes 95

b. C=C Stretching Modes 96

c. C—H Bending Vibrations 98

d. Sum Tone Patterns 100

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III. Characteristic Frequencies of HeteroatomFunctional Groups

A. Factors Affecting the Carbonyl Group Frequencies 102

1. Mass Effects 103

2. Geometric Effects 103

3. Electronic Effects (Resonance and Inductive) 104

a. Electronic Effects That Raise the

Carbonyl Frequency 104

b. Electronic Effects That Lower the Carbonyl Frequency 105

c. The Case of Ester Carbonyl Vibrations (CompetingInductive and Resonance Effects) 105

4. Interaction Effects 107

a. Intramolecular Carbonyl Interactions 107

b. Intermolecular Carbonyl Interactions 111

B. Characteristic Frequencies of Functional Groups 112

1. 1-Hexanol 114

2. Hexanal 115

3. 3-Heptanone 117

4. n-Hexyl Acetate 118

5. Hexanoyl Chloride 120

6. Hexanoic Acid 121

7. Hexanoic Anhydride 122

8. Dihexyl Ether 123

9. n-Hexylamine 124

10. Hexanenitrile 126

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11. Hexanamide 127

12. N-Methylhexanamide 128

13. 1-Hexyl Isocyanate 130

14. 1-Hexanethiol 131

15. 1-Chlorohexane 132

16. Chlorobenzene 134

IV. Instrumentation

The Infrared Interferometer 137

WEBSITE DATA FOR CHAPTER 10

Tables of Derivatives

Tables 10.1 – 10.17. pages 143–158