Organic Chemistry Questions

Do the following assignment after you have finished working on Unit 8. When you are satisfied with your answers, send the completed assignment to your tutor for grading using the assignment drop box. 1. Provide a complete IUPAC name for each of the following compounds. Assign stereochemistry (E/Z) where appropriate. a. Me Et Et Me b. ✧ ✧❜ ❜❜❜✧ ✧❜ ❜✧ ✧ ✧ ✧✧ ✧ ✧ ✧ ✧ ✧ c. ✧ ✧❜ ❜ ✧ ✧ ❜ ❜ ✧ ✧❜ ❜ ❜ ❜ ❜ ❜ ✧ ✧❜ ❜✧ ✧ 2. Provide chemical structures for each of the following compounds. a. (2Z,5E)-2,5-octadiene b. 1-(1-propynyl)cyclohexene c. 2,2,3-trimethylpentane 3. Using either 1-hexene or trans-2-hexene as the starting material, describe how you could prepare the following compounds using one or more chemical steps. Make sure you choose the best starting material for each synthesis. a. OH b. Br c. OH Br d. ✧ ✧❜ ❜✧ ✧❜ ❜❜❜ e. O 4. Construct a potential energy diagram for the rotation about the C2 C3 bond of 2,2-dibromobutane (shown below). Be sure to consider the relative energies of all staggered and eclipsed conformations in your analysis. H3C CH3 Br Br 2,2-dibromobutane 5. Devise a multi-step synthesis of butanoic acid and hexanoic acid from bromopentane. Hint: The simplest solution generates both products at the same time in the final step. ✧ ✧❜ ❜✧ ✧ O ❜❜ OH ✧ ✧❜ ❜✧ ✧❜ ❜✧ ✧ O ❜❜ OH ✧ ✧❜ ❜✧ ✧❜ ❜✧✧Br butanoic acid hexanoic acid 1-bromopentane 6. Consider a hypothetical equilibrium that exists between compounds A and B at room temperature (298 K). The
G‡ for the forward reaction (conversion of A to B) is 22 KJ/mol. Likewise,
G‡ for the reverse process has been determined to be 34 KJ/mol. a. Calculate
G◦ for the forward reaction and construct a potential energy diagram for the conversion of A to B. Be sure to place the transition state in accordance with the Hammond Postulate. b. A flask containing a mixture of A and B at equilibrium was discovered, and the concentration of A at room temperature was determined experimentally to be 3.1× 10−2 mol/L. What is the concentration of B? 7. Compound A (C12H18), upon treatment with H2 gas in the presence of Lindlar’s catalyst, furnished compound B (C12H20) as the only product. Compound B was then treated first with ozone and then with zinc dust to yield the two compounds shown below in equal amounts. Provide structures for A and B, being careful to show any relevant stereochemistry. As well, be sure to explain your reasoning. ✧ ✧ O ❜ ❜ H ✧✧ O ❜ ❜✧ ✧ O ❜❜ H 8. Provide synthetic pathways for the following transformations. Be sure to include the structure of any organic intermediates. a. Prepare Pr Pr from ✧ ✧❜ ❜✧ ✧❜❜ ❜❜ Br ✧ ✧❜ ❜✧ ✧ b. Prepare ✧ ✧❜ OH ❜✧ ✧ from ✧ ✧❜ ❜✧ ✧❜❜ OH Do the following assignment after you have finished working on Unit 16. When you are satisfied with your answers, send the completed assignment to your tutor for grading using the assignment drop box. 1. Provide a complete IUPAC name for each of the following compounds. Assign stereochemistry (E/Z) and/or (R/S) where appropriate. a. Cl I Br b. ✧ ✧ ✧✧ Cl ❜ ❜✧ ✧ ✧ ✧ ❜ ❜❜❜✧ ✧ Cl c. I H 2. Starting with butane, show, using chemical equations, how you could prepare: a. 2-bromobutane b. 1-bromobutane Note: For the following targets, you may also choose to begin with either 2-bromobutane or the 1-bromobutane as prepared above without repeatedly showing how you made these two compounds. Be sure to choose the best starting material for each job! c. 1-butene d. ✧ ✧❜ ❜✧✧D e. 3-methylheptane f. 5-methyl-3-heptyne 3. Show, using chemical equations, how you would prepare each of the following compounds from benzene: a. phenol b. o-ethyltoluene c. 3-chloroaniline d. p-nitrobenzoic acid 4. Sketch the expected 1H NMR spectrum for the following compound, doing your best to estimate and represent the chemical shift of each proton, as well as the anticipated integrations and splitting patterns. ✧ ✧❜ ❜❜❜✧✧O❜❜✧ ✧ ✧ ✧ ✧ ✧ ❜ ✧❜ ✧ ✧ ✧✧ ✧ ✧ ✧ p-ethoxyphenylacetylene 5. For each of the following sets of reaction conditions, identify which mechanism or mechanisms you expect to dominate: SNl, SN2, El, or E2. Draw the major product or products you would expect to isolate in each case. a. Ph ✧✧❜ ❜✧✧OTos H2O GGGGGGGGGA b. ❜ ❜✧ ✧❜ ❜✧✧Cl KOH GGGGGGGGGA EtOH c. ✧ ✧❜ ❜❜❜✧ ✧❜ ❜✧✧Br ✧ ✧ ✧ ✧ ❜ ❜ NaSCH3 GGGGGGGGGGGGGA DMF 6. Compound A is a clear, colourless liquid with a molecular formula of C7H10. Upon treatment of A with H2 gas in the presence of Pd on carbon, a single product B (C7H14) is obtained. Compound A has a lmax at 232 nm in its UV spectrum but will not react with any dienophile in a Diels-Alder fashion. Provide a structure for Compound A, and explain how you arrived at your decision. 7. Identify which of the following compounds is most nucleophilic and which is most electrophilic, and provide an explanation for your decisions. ✧✧✧ ✧❜ ❜✭✭✭ ✭ or ❜ ❜✭✭✭✭ ❤❤ ✧❤❤ ✧ 8. For the following pairs of compounds, explain how the listed spectroscopic method or methods could be used to distinguish between the compounds. a. Use mass spectrometry to distinguish between: O and O 2-heptanone 3-heptanone b. Use 1H NMR spectroscopy to distinguish between: O and O H 2-heptanone heptanal c. Use IR spectroscopy and UV spectroscopy to distinguish between: ✧ ✧❜ ❜❜❜✧ O ✧❜ ❜✧ ✧ ✧✧✧ ❜✧ ❜ and ✧ ✧❜ ❜✧ O ✧❜ ❜✧ ✧ ✧ ❜✧ ❜ ethyl phenyl ketone ethyl 5-cyclohexenyl ketone d. Use IR spectroscopy and UV spectroscopy to distinguish between: ✧ ✧❜❜ ❜❜✧ ✧ ✧✧✧❜ ❜✧ ❜ ❜ and ✧ ✧❜❜ ❜❜✧ ✧ ✧❜ ✧✧✧ ✧ ❜✧ o-xylene p-xylene 9. In an effort to identify it, an unknown compound, U, was subjected to extensive spectroscopic analysis. Figure A2.9a, below, shows the IR spectrum for compound U, and Figure A2.9b on page 9 shows the 1H NMR spectrum for compound U. In addition, the mass spectrum of compound U was acquired. A molecular ion peak was observed at m/z = 166, and the molecular formula for compound U was thereby determined to be C9H10O3. A peak at m/z = 121 was by far the most intense peak in the mass spectrum. Determine the structure of compound U. Be sure to include a concise discussion of the reasoning you employed to deduce this structure. As well, construct tables summarizing the IR and 1H NMR data, and assign the peaks in the IR and NMR spectra to the appropriate structural elements in U. Your discussion should also include an explanation for the appearance of the base peak at m/z = 121 in the mass spectrum. Figure A2.9a: IR spectrum for compound U Figure A2.9b: 1H NMR spectrum for compound U