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CHM 222: Organic Chemistry III Review 1 (Chapters 14 & 16) 1. Name the following alcohols acording to IUPAC nomenclature. Cl OH (A) Br OH (B) (A) 2-butanol H (C) H3C OH CH 2CH 3 OH OH (D) CH 2CH 2OH (E) (B) 5-bromo-3-hexanol (C) (2S)-1-chloro-2-propanol (D) ethylcyclobutanol (E) (1R, 2R)-2-(2-hydroxyethyl)cyclopentanol 2. Do you expect hyperconjugation to be important in stabilization of alkyloxonium ions? (e.g. ROH 2+ or R2OH+) Explain your answer with respect to the orbitals involved. No. There are no empty orbitals on the oxygen atom. The oxygen is formally positive but has a complete octet of electrons surrounding it. Therefore, the oxygen is not electron deficient. 3. Predict and explain the outcome of the following reactions on mechanistic grounds. Cl Cl Cl OCH2CH3 Cl + (CH3)3CO K PCC, CH2Cl2 HO Cl + CH3CH2OH Br O OH OH SN1 E2 at least sterically hindered site oxidation 4. When 2-ethyl-1-butanol is treated with zinc chloride (ZnCl2) in concentrated hydrochloric acid, a mixture of chloroalkanes forms, including chiefly 2-ethyl-1-chlorobutane, 3-chlorohexane, 2-chlorohexane, and 3-chloro3-methylpentane. When 2-ethyl-1-butanol is treated with thionyl chloride in pyridine, only 1-chloro-2ethylbutane is formed. Write a detailed mechanism which accounts for these observations. OH Cl ZnCl2 Cl HCl 1,2-hydride shift Cl Cl 1,2-hydride shift Cl Cl 1,2-alkyl shift Cl Cl O O OH O S Cl Cl S O H Cl O Cl S Cl H N O Cl Cl O pyridine S Cl 5. Suggest a synthesis for tetrahydrofuran starting from but-3-en-1-ol (could also be named 3-butenol). HINT: it can be done in 2 steps. HBr HO H2O2 Br HO O Na2CO3 6. Suggest separate syntheses for cis- and trans-1,2-cyclopentanediol, starting from cyclopentanol. OH OH + H , OH OsO4 mCPBA OH O OH 1. NaOH 2. H+ 7. Predict the multiplicities of the indicated hydrogens in the 1H-NMR spectrum of the following compounds. triplet Cl doublet of doublets H H Cl Cl H H doublet H H doublet of doublets doublet of doublets 8. Predict the approximate chemical shifts, multiplicities and integrals for the absorptions in the 1H-NMR spectra of the following compounds. O O H3C OH 9. Suggest how the following compounds could be distinguished from each other by 1H-NMR spectroscopy. two singlets for CH2 and CH3 O O and and quartet for CH2 triplet for CH3 Cl Cl O O singlet for one of the methyl groups aldehyde hydrogen Cl O and O complex aromatic region H Cl one singlet for aromatic hydrogens quartet for CH2 triplet for CH3 and singlet for one of the methyl groups 10. Suggest structures for the following four compounds consistent with the spectral information given. First the molecular formula is given. Then the absorptions in the 1H-NMR are listed as chemical shift (multiplicity, integral). Some compounds also have an important IR peak given. C4H9Cl; 3.35 (doublet, 2), 2.0 (multiplet, 1), 1.0 (doublet, 6). Cl C3H6Br2; 3.6 (triplet, 2), 2.4 (quintuplet, 1). Br Br C4H10O; 3.3 (doublet, 2), 2.4 (singlet, 1), 1.7 (multiplet, 1), 0.9 (doublet, 6); 3330 cm -1, broad. OH C5H10O; 2.6 (septet, 1), 2.1 (singlet 3), 1.1 (doublet, 6); 1716 cm -1. O 11. Explain how many absorptions would appear in the 1H-NMR spectrum of the following compound. Cl Cl There will be three absorptions. The two hydrogens on the methylene group will each have a different chemical shift. One will be cis to the chlorines and the other wil be trans.