Organic Chemistry Semester 1 LABORATORY MANUAL - Moravian ...

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Infrared Spectroscopy Appendix C4 Part V. Techniques and Theory Exploration 1. Recognizing that Infrared light absorption results in changes in vibrational states of specific bonds in molecules, we should be able to relate IR absorption frequencies to the bonds present in the absorbing molecules. The most common atoms in organic molecules are C, H, O & N. Below is a list of the commonly observed types of bonds between these atoms found in organic molecules. Comparing the IR absorption frequencies found in the 29 compounds in Figure 1, try to assign approximate absorption frequencies (± 10 cm -1 ) to each of these types of bonds. For each assignment, reference the #’s of the compounds from Figure 1 that you used to determine the assignment and explain the logic used. Note that possible substituents on bonds with no atoms explicitly indicated could be attached to C or H) Carbon-Carbon Bonds Carbon-Oxygen Bonds Bond Frequency Range Bond Frequency Range C C C C O C O C C O C O O C Bond Carbon-Nitrogen Bonds Frequency Range C O C C N O C O C N C O H O O C N C O CH 3 O C N C N
Part V. Techniques and Theory Appendix C5 Infrared Spectroscopy Carbon-Hydrogen Bonds Bond Frequency Range Bond Oxygen-Hydrogen Bonds Frequency Range H C C C O H H H C C C O H O C C H C O H C H Nitrogen-Hydrogen Bonds Bond Frequency Range H C O C C N H N H O C N H 2. Padías groups molecular IR absorption frequencies according to functional groups present. (Table 2-1 p. 70) Although this arrangement can be helpful in identifying peaks expected from the presence of a functional group, often we have a spectral graph, like those in Padías Figures 2-22 – 2-25 (pp. 73 – 74), of an unknown compound and need to use absorptions frequencies to identify likely functional groups present. So it is also useful to divide the IR frequency region into sub-regions and look at the types of bond that absorb in each subregion. Use your frequency assignments in 1. to assign the bond types in 1. to each of the subregions listed below. Region Bond types 1: (3600-3200 cm -1 ) 2: (3100-2500 cm -1 ) 3: (2500-2000 cm -1 ) 4: (1750-1630 cm -1 ) 5: (1350-1000 cm -1 )
Page 1: MORAVIAN COLLEGE CHEMISTRY DEPARTME
Page 4 and 5: Table of Contents (continued) 2 PAR
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Page 8 and 9: I. Introduction 6 Fall 2010 Assignm
Page 10 and 11: Part I. Introduction 8 Fall 2010 La
Page 12 and 13: Part I. Introduction 10 Fall 2010 D
Page 14 and 15: Part II. Lab Rules and Regulations
Page 16 and 17: Part II. Lab Rules and Regulations
Page 18 and 19: III Laboratory Records & Report For
Page 24 and 25: Part V. Experiments 22 Fall 2010 Pa
Page 26 and 27: Part V. Experiments 24 Fall 2010 Ex
Page 28 and 29: Part V. Experiments 26 Fall 2010 H
Page 30 and 31: Part V. Experiments 28 Fall 2010 E.
Page 32 and 33: Part V. Experiments 30 Fall 2010 E.
Page 40 and 41: Part V. Experiments 38 Fall 2010
Page 42 and 43: Part V. Experiments 40 Fall 2010 1
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Page 64 and 65: Nuclear Magnetic Resonance Appendix
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Organic Chemistry Semester 1 LABORATORY MANUAL - Moravian ...

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