Question

PART 3 For each set of data on pages 5-9, calculate and record the degree of unsaturation. Then use your problem solving skills to determine the chemical structure that is consistent with ALL of the data on each page. You are not required to label the spectra (but feel free to do so). This entire assignment is to be completed independently Suggestion for a general method to determine a chemical structure based on the provided molecular formula, IR, H-NMR and C-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, CI, 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 (c.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 ppm 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 C-NMR spectrum due to overlapping signals but i 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 C-NMR spectrum. 4. If signals are labeled as "overlapped," they are not equivalent; they are unique signals that occupy . For all structures (including aromatic rings) assume no long-range coupling/splitting effects (i.e. 6. Remember, equivalent protons do not couple (split) with each other (even if they are separated by overlapping space in the spectrum only consider coupling/splitting between protons that are 3 bonds or fewer away from each other). 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 patter. As you have seen, the designations are: s-singlet, d doublet, t-triplet, qquartet, m-multiplet, dd-doublet of doublets (if a proton is split by more than two non-equivalent protons, will be termed multiplet for the simplification purpose of this assignment). The following questions are NOT in order of difficulty. If you get stuck, try the next one.

Answer 1