Question

NMR SPECTROSCOPY NMR stands for nuclear magnetic resonance. PMR or "HNMR stands for proton magnetic resonance, which is the type of magnetic resonance that will be specifically discussed. PMR is a spectroscopic technique that allows the detection of hydrogen atoms in molecules. Different kinds of hydrogens as well as the relative numbers of each kind of hydrogen can be detected. PMR is a powerful tool for determining the structures of organic molecules. Exercises These exercises are to be done in the style of a lab report. The PMR spectrum is your data. The exercises below are the interpretation of the data. You will be given the spectra of four compounds. On each spectrum will also be listed the molecular formula of the compound. The goal will be to determine the structure of each compound to the extent that is possible from the information given. For each compound answer all 5 questions below. Answer the questions one compound at a time, that is, answer all 5 questions for the first compound, then all 5 questions for the second compound, and so on. Organize your lab report as follows: 1. title page 2. spectra in increasing number 3. analysis of spectra in increasing number 1) determine the index of hydrogen deficiency (IHD) 2) draw the possible structures based on the IHD 3) for each structure, indicate how many different kinds of hydrogens are present based on the structure 4) determine the one structure that is consistent with the PMR spectrum with regard to the different of kinds of hydrogens, the relative numbers of each kind of hydrogen, and the splitting patterns 5) identify which hydrogens correspond to which peaks in the PMR spectrum by labeling both the hydrogens and the peaks a, b, c, etc., as was done in the discussion

Answer 1

1) Given M.F: C₃H₄Cl₂

IHD = [2C + 2 + N - H - X] / 2 = [(2 x 3) + 2 - 4 - ( 2 x 1)] / 2 = 1

IHD = 1, one unsaturation

2) possible structures

H HC ل ت عی 3

3) , 4), & 5)

doublet Hp | | ܝ Re- HC singlet doublet CI } } _3 _H,

- THE doublet - . . Ho 37 C₃ Hy Cl Ho LHC singlet doublet CI doublet I doublet, singlet

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