CHEM 208 Problems Important Exercises, Spring 2016

1. Multiple Choice Questions. Circle the correct answer, no penalty for a wrong answer. © Which one of the following is a Newman projection of 2,2-dimethylpropane? CH3 CHg CHs See Ser’ CH3 CH3 H i CH3 Hf ~CH3 CHS CH3 CH 1. 2. 3. A. 1 B. 2 cess D. 4 5 e Inwhich two of the following are the methyl group and the chlorine gauche to one another? cl cl H H H H H H ClI-7—H H7—~Ccl H CH H H H CH, H H H CH3 H CH, 1 2 3. 4 What is the IUPAC name of the following compound? Se c——C. 4 oN Cl CHg H3CH2C CH2Br 3(E)-1-Bromo-3-chloro-2-methyl-2-pentene D. (Z)-1-Bromo-3-chloro-2-methyl-2-pentene E. (E)-3-Bromo-1-chloro-1-ethyl-2-methyl-1-propene e Only one of the following compounds is named correctly according to the IUPAC rules. Which one? Structural formula Proposed najné-—~ Ss ssserefdlOsighyp 2,5,6-Trimethyloctane 4-Pentylheptane @ [> CH2CH(CHs)2 tert-Butylcyclopentane e Which pair of structures below is interconvertible by ring-flips? CH CHg H H H CHg HgC H H3C . 1 and 3 2 and 3 . All of them e Identify the allplic halide(s). Br Br CH) CH)Cl cl A. I B. Land II Tand IV only HI E. 1, UL, and IV © Which one of the following reactions does not proceed via a carbocation intermediate? A. Acid-catalyzed hydration of (CH,CH,),C=CHCH, d Addition of hydrogen chloride to (CH,CH,),C-CHCH, q ¥, Alkylation of sodium acetylide with bromoethane D. Dehydration of (CH,CH,),COH with H,SO, > E. E] elimination of (CH,CH,),;CCI . e Which of the following compounds gives a single E2 product on reaction with sodium ethoxide, NaOCH2CH3? H3;C CH; H3C CH; Br Br i Ol A. I B. Land II @ [and Ill D. and Ill © I, Il, and III e Which of the following is the 1,4-addition product of Br, to 1,3-cyclohexadiene? Br A) Br —] SQs vaWw> © The most stable conformation of the compound shown has 0K ‘all methyl groups equatorial. . equatorial methyl groups at C-1 and C-2, axial at C-4. C. equatorial methyl groups at C-1 and C-4, axial at C-2. as, equatorial methyl groups at C-2 and C-4, axial at C-1. 2. Draw clear depictions of two nonequivalent chair conformations of cis-1-Isopropyl-4- methylcyclohexane, indicate which is more stable. Justify your answer. [Ss INSIQ Me vtable, ANE MEMY|C HMONG , IS MACE Over, MG oF Hag CoLutona 3. Draw the structures of all alkenes including stereoisomers that can be formed from the E» elimination of 3-bromo-2,3-dimethylpentane with sodium ethoxide NaOCH,CH; in Ca, Be - COCEC + Moc; = __, CH. Ho Na wilt Bade with He/ Wolo WOR and Ha skudivre Will Fo on ateinoret- alcnono) 4. Determine whether the structures in each of the following pairs represent, Constitutional isomers, different conformations of the same compound, stereoisomers that cannot be interconverted by rotation about a single bond; diastereomers. Answer b) Answer H H and difkat cnily wu Ue tho J cannyoah CH2CH3 sHereo isavar, diccle ceomys Lv mh, Connon Give the stereochemical structure of the major product of each of the following reactions. a) CHs \ Bry CHCl, b) HLO, HySO, CH;C=CH > 8 j HgSO, 2 HCl Chica ———» d) 6. Give a reasonable mechanism for the following reaction. Vague movement of electrons receives no credit. CH; CH3 || sO, H3C- —-C——C CH2CH3 pe | | heat H OH CAs O& | \ | i) 4 on U7 Xs c¥2 \ H en tat chCa © ro /\ H 2H JS 4 any / \ 4 * A2C ch Ws / 2 ro \ Ss 0 KC - se CROs a aa C= co toe the following series of reactions What is the structure of compo nds A Bh k rials NE Lindlar Pd Heese al OX Compound A Compound B Compound C