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exam1%2008Feb17 - 4:122 Exam 1 page 1 of 5 Name 1 For each...

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Unformatted text preview: 4:122 Exam 1 (2/20/08) page 1 of 5 Name_____________________________________ 1) For each structure indicate whether you would expect a peak in the indicated area by filling the box with Y = yes, N = no, or ? = maybe. Use the ? when you don’t have enough information to be sure. [3 pts each structure] structure ↓peaks observed ↓ O‐H, N‐H stretch Csp‐H stretch Csp2‐H stretch Csp3‐H stretch triple bond stretch C=O stretch C6H14O 2) For each structure, fill the box with the requested number or word. [3 pts each structure] structure number of p‐orbitals number of pi electrons aromatic, antiaromatic, neither 4:122 Exam 1 (2/20/08) page 2 of 5 Name_____________________________________ 3) Draw the product(s) of the reactions, indicating stereochemistry when appropriate. No mechanisms, just products. [6 pts each] a) b) 4) Draw a set of resonance structures, each separated by the double headed resonance arrow. Then draw a representation of the resonance hybrid. Circle the latter structure and label it “hybrid” [8 pts] 4:122 Exam 1 (2/20/08) page 3 of 5 Name_____________________________________ 5) For each type of magnetically unique proton in each structure, provide the number of protons and the expected multiplicity. Use as many boxes as appropriate. If you identify more unique protons, write the info into the box next to the structure. Use the whole words singlet, doublet, triplet, quartet, quintet, sextet and septet where appropriate. For multiple couplings, be specific (i.e., doublet of doublet but don’t use multiplet) [20 pts] Ha (number) Ha (multiplicity) Hb (number) Hb (multiplicity) Hc (number) Hc (multiplicity) Hd (number) Hd (multiplicity) He (number) He (multiplicity) 6) List the three compounds in increasing order of acidity of the indicated protons. Place the letters in the proper order below. [4 pts] Order: _______ < _______ < _______ Reasons: 4:122 Exam 1 (2/20/08) page 4 of 5 Name_____________________________________ 7) Read each statement carefully. On the line at the beginning of each statement, indicate whether the statement is true or false by using a capital T or F. If the statement is false, circle the words or short phrases that make it incorrect and write replacements that would make the statement true. Example) __F__ Lecture for this class meets MWF at 8:30 PM. a) ______ The opioid pain receptor senses a substrate via structural features that include hydrogen bonding (OH), a benzene ring (hydrophilic interaction), and an ion (ammonium N+). b) ______ Retinal has several alkenes conjugated with an aldehyde, attaches to a protein in the retina, is supplied to the body as vitamin C (retinol), and triggers the vision process via an axial equatorial conformational change. c) ______ MRI is a diagnostic medical technique that uses NMR signal from NMRactive atoms within tissues; it often involves the use of a metal‐containing contrast agent. d) ______ As the length of a polyene increases, it is capable of absorbing light at a lower energy as the gap between the highest energy occupied orbital and lowest energy (empty) antibonding orbital decreases. e) ______ A sunblock absorbs UV light that might otherwise cause sunburn or suntan; in part, it replaces or supplements the role of the atmosphere that absorbs light > 320 nm. f) ______ Mass spectrometry works by generating a radical cation (i.e., the molecule less one electron); the observed peaks are due to the molecular ion or to the radical fragments of the molecular ion. g) ______ Spin‐spin splitting occurs between adjacent types of magnetically‐unequivalent protons (i.e., four bonds or fewer) and follows the “n+1” rule for observed peaks (due to n equivalent protons). 4:122 Exam 1 (2/20/08) page 5 of 5 Name_____________________________________ 8) All of the data represent a single structure. In the box to the right of each type provide the information that you concluded. Don’t list the data again—give some interpretation. [15 pts.] Mass spec (m/z peak, intensity) 27, 15 39, 70 42, 16 29, 12 40, 12 69, 47 38, 11 41, 100 70, 95 71, 5 Infrared (Formulas, fragments) (Peaks and functional groups) H‐NMR (shift, multiplicity, # hydrogens, partial structure) 13C‐NMR (chemical shift of peak) 1) 194 ppm 2) 154 ppm 3) 135 ppm 4) 19 ppm Overall structure (shift, functional group) Justification ...
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