Microscale Techniques for the Organic Laboratory

Transcription

1 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

2 2 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

3 3 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-up microscale reactions) 61 Example [5AW]: Recrystallization of Benzoin Example [5BW]: Recrystallization of Naphthalene from a Solvent Pair

4 4 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 The Case of HCl The Case of Water The Case of Carbon Dioxide 76 E. Vibrational Coupling Coupled Oscillators Second-Order Coupling 79 II. Group Frequencies of the Hydrocarbons A. Characteristic Group Frequencies of Alkanes 81

5 5 B. Characteristic Group Frequencies of Alkenes C=C Stretching Alkene C H 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 C C Stretching Vibration Alkyne C H Vibrations 94 D. Characteristic Group Frequencies of Arenes 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

6 6 III. Characteristic Frequencies of Heteroatom Functional Groups A. Factors Affecting the Carbonyl Group Frequencies Mass Effects Geometric Effects 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 (Competing Inductive and Resonance Effects) Interaction Effects 107 a. Intramolecular Carbonyl Interactions 107 b. Intermolecular Carbonyl Interactions 111 B. Characteristic Frequencies of Functional Groups Hexanol Hexanal Heptanone n-hexyl Acetate Hexanoyl Chloride Hexanoic Acid Hexanoic Anhydride Dihexyl Ether n-hexylamine Hexanenitrile 126

7 7 11. Hexanamide N-Methylhexanamide Hexyl Isocyanate Hexanethiol Chlorohexane Chlorobenzene 134 IV. Instrumentation The Infrared Interferometer 137 WEBSITE DATA FOR CHAPTER 10 Tables of Derivatives Tables pages