Fall 2013- Chem 2311 Homework Problems- Chapter 9 1) In each of the following problems you are given the IR, NMR, and molecular formula. Using this information, draw the structure of the compound. A suggested approach for spectroscopy problems: (a) Calculate the degree of unsaturation to limit the number of possible structures. (b) Primarily analyze the IR absorption bands > 1500 cm-1 to determine what functional groups are likely to be found in the compound. It is important to remember that these functional groups must be consistent with the degree of unsaturation. (c) Analyze the NMR to determine the connectivity of the compound. Be sure to include chemical shifts and absorption multiplicity in your analysis. The relative area under each of the absorptions is indicated. (d) Draw some possible structures and see if they "work" with the IR, NMR, and unsaturation.(a) C5H10O, MW = 86(b) C4H10O, MW = 74(c) C4H8O2, MW = 88(d) C8H8O, MW = 120(e) C11H14O2, MW = 178(f) C4H9Br, MW = 1372) Compound A has the formula C6H14O. It reacts with sodium metal to produce H2 gas. It reacts with H2SO4 to produce compound B. Compound A is formed by the reaction compound B with BH3/THF followed by reaction with H2O2/NaOH. Compound A: 3) Compound B has the formula C6H12. Using this information and the IR and MS below identify compounds A and B.Compound B:4) Listed here are the 1H NMR absorption peaks for several compounds. The chemical shifts and the number of protons associated with each absorption are given. Propose a structure that is consistent with each set of data. (a) C4H8O 1H NMR spectrum Triplet 1.05 (3H) Singlet 2.13 (3H) Quartet 2.47 (2H) IR Spectrum Strong peak near 1720 cm-1 (b) C15H14O 1H NMR spectrum Singlet 2.20 (3H) Singlet 5.08 (1H) Multiplet 7.25 (10H) IR Spectrum Strong peak near 1720 cm-1 5) You have three unlabeled vials each containing a trichlorobenzene isomer. In order to correctly identify each compound and properly label its container you have taken their 13C nmr spectra. Match the spectrum characteristics given below with a compound from the following group: 1,2,3-trichlorobenzene 1,2,4-trichlorobenzene 1,3,5-trichlorobenzene (1) 13C NMR: (i) Two peaks between δ125 and 140 ppm a. 1,2,3-trichlorobenzene b. 1,2,4-trichlorobenzene c. 1,3,5-trichlorobenzene (2) (ii) Six peaks between δ125 and 140 ppm a. 1,2,3-trichlorobenzene b. 1,2,4-trichlorobenzene c. 1,3,5-trichlorobenzene (3) (iii) Four peaks between δ125 and 140 ppm a. 1,2,3-trichlorobenzene b. 1,2,4-trichlorobenzene c.
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