Suggestion for a general method to determine a chemical structure based on the provided molecular formula, IR, 'H-NMR and 13C-NMR spectroscopy data: 1. Determine the degrees of unsaturation (understand what constitutes a degree of unsaturation and how to calculate it for molecules composed of C, H, O, S, N, Cl, Br, F, I). 2. Identify possible/likely functional groups based on the data (especially IR and 'H-NMR spectra). 3. Identify evidence of symmetry in the molecule (many equivalent carbons or protons is a good indicator of symmetry in the molecule) 4. Construct a molecule that is consistent with ALL pieces of the provided data. After constructing a molecule, re-check it, and make modifications as necessary. It is possible, although extremely rare, that more than one structure is considered consistent with the provided data and would receive full credit. Notes on determining a chemical structure based on provided spectroscopy data. 1. The same tables as used during the Spectroscopy Experiment (from the Jones textbook) should be consulted for this assignment and will be provided on the Final Laboratory Exam. However, do not interpret the values in these tables as absolutes. Think about why something shows up where it does in the spectrum. For example, the table values assume only one factor (e.g. a nearby halogen), but if multiple compounding factors exist (e.g. nearby halogen and aromatic ring), then the influence (downfield shift to higher ppm) may be greater (maybe 1ppm higher) than the table indicates. 2. There are NO solvent, water, or other impurities displayed in these spectra. 3. It may be difficult to distinguish every signal in the 13C-NMR spectrum due to overlapping signals but it is still possible to assess the types of environments that exist. Further, the exact number of unique carbon signals (non-equivalent carbons) is provided above each 13C-NMR spectrum. 4. If signals are labeled as "overlapped," they are not equivalent; they are unique signals that occupy overlapping space in the spectrum. 5. For all structures (including aromatic rings) assume no long-range coupling/splitting effects (i.e. only consider coupling/splitting between protons that are 3 bonds or fewer away from each other). 6. Remember, equivalent protons do not couple (split) with each other (even if they are separated by three bonds). Protons are equivalent if they are in exactly equivalent electronic environments (i.e. they experience the rest of the molecule in exactly the same way). Note that it is possible for protons attached to different carbon atoms to be equivalent to each other. 7. Remember that single bonds rotate, so symmetry can be disguised. Re-check PART 1 to be sure symmetry is not overlooked. 8. The H-NMR spectra will be labeled with the splitting pattern. As you have seen, the designations are: s=singlet, d=doublet, t-triplet, q=quartet, m=multiplet, dd-doublet of doublets (if a proton is split by more than two non-equivalent protons, it will be termed multiplet for the simplification purpose of this assignment). 1) Using the information below, provide (a) the degrees of unsaturation and (b) a single chemical structure that is consistent with all of the data on this page. Molecular Formula: C5H10O3 (a) How many degrees of unsaturation exist in this molecule? → 1H-NMR spectrum: t, 6H q, 4H 15 पु 13C-NMR spectrum (total of 3 unique signals in the 13C-NMR spectrum): 200 160 149 100 IR spectrum: LOD HAYENULICI.l (b) In the space below, draw a single chemical structure that is consistent with the molecular formula, mass, 13C and 1H-NMR spectra, and IR spectrum above. If you draw more than one structure below, you must CIRCLE the answer you want to be graded.

Suggestion for a general method to determine a chemical structure based on the provided molecular formula, IR, 'H-NMR and 13C-NMR spectroscopy data: 1. Determine the degrees of unsaturation (understand what constitutes a degree of unsaturation and how to calculate it for molecules composed of C, H, O, S, N, Cl, Br, F, I). 2. Identify possible/likely functional groups based on the data (especially IR and 'H-NMR spectra). 3. Identify evidence of symmetry in the molecule (many equivalent carbons or protons is a good indicator of symmetry in the molecule) 4. Construct a molecule that is consistent with ALL pieces of the provided data. After constructing a molecule, re-check it, and make modifications as necessary. It is possible, although extremely rare, that more than one structure is considered consistent with the provided data and would receive full credit. Notes on determining a chemical structure based on provided spectroscopy data. 1. The same tables as used during the Spectroscopy Experiment (from the Jones textbook) should be consulted for this assignment and will be provided on the Final Laboratory Exam. However, do not interpret the values in these tables as absolutes. Think about why something shows up where it does in the spectrum. For example, the table values assume only one factor (e.g. a nearby halogen), but if multiple compounding factors exist (e.g. nearby halogen and aromatic ring), then the influence (downfield shift to higher ppm) may be greater (maybe 1ppm higher) than the table indicates. 2. There are NO solvent, water, or other impurities displayed in these spectra. 3. It may be difficult to distinguish every signal in the 13C-NMR spectrum due to overlapping signals but it is still possible to assess the types of environments that exist. Further, the exact number of unique carbon signals (non-equivalent carbons) is provided above each 13C-NMR spectrum. 4. If signals are labeled as "overlapped," they are not equivalent; they are unique signals that occupy overlapping space in the spectrum. 5. For all structures (including aromatic rings) assume no long-range coupling/splitting effects (i.e. only consider coupling/splitting between protons that are 3 bonds or fewer away from each other). 6. Remember, equivalent protons do not couple (split) with each other (even if they are separated by three bonds). Protons are equivalent if they are in exactly equivalent electronic environments (i.e. they experience the rest of the molecule in exactly the same way). Note that it is possible for protons attached to different carbon atoms to be equivalent to each other. 7. Remember that single bonds rotate, so symmetry can be disguised. Re-check PART 1 to be sure symmetry is not overlooked. 8. The H-NMR spectra will be labeled with the splitting pattern. As you have seen, the designations are: s=singlet, d=doublet, t-triplet, q=quartet, m=multiplet, dd-doublet of doublets (if a proton is split by more than two non-equivalent protons, it will be termed multiplet for the simplification purpose of this assignment). 1) Using the information below, provide (a) the degrees of unsaturation and (b) a single chemical structure that is consistent with all of the data on this page. Molecular Formula: C5H10O3 (a) How many degrees of unsaturation exist in this molecule? → 1H-NMR spectrum: t, 6H q, 4H 15 पु 13C-NMR spectrum (total of 3 unique signals in the 13C-NMR spectrum): 200 160 149 100 IR spectrum: LOD HAYENULICI.l (b) In the space below, draw a single chemical structure that is consistent with the molecular formula, mass, 13C and 1H-NMR spectra, and IR spectrum above. If you draw more than one structure below, you must CIRCLE the answer you want to be graded.

Organic Chemistry

9th Edition

ISBN:9781305080485

Author:John E. McMurry

Publisher:John E. McMurry

Chapter13: Structure Determination: Nuclear Magnetic Resonance Spectroscopy

Section13.SE: Something Extra

Problem 56GP: Long-range coupling between protons more than two carbon atoms apart is sometimes observed when ...

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