2 1. Circle the correct answer: (40 pts) (1) Benzyl bromide can undergo: a. SN1 reaction more easily than SN2 reaction. b. SN2 reaction more easily than SN1 reaction. c. either SN1 or SN2 reaction depending on the reaction condition. d. neither SN1 nor SN2 reaction under any conditions. (2) A Diels-Alder reaction leads to the formation of a. one new σ bond. b. two new σ bonds c. three new σ bond. d. four new σ bonds (3) In a Lewis structure, two double bonds or triple bonds are said to be in conjugation when they are separated by a. no other bonds. b. a single bond. c. a double bond. d. a triple bond. (4) The electrophilic addition of H-X to a conjugated diene involves an intermediate that is a. a secondary carbocation. b. a tertiary carbocation c. a resonance stabilized allylic cation. d. a radical. (5) Which of the following is an INCORRECT description of benzene? a. All the bond angles are equal to 120o. b. The molecule is always planar. c. The molecule is a 6-membered ring containing alternating single and double carbon-carbon bonds. d. The molecule is aromatic3 (6) Aromatic molecules contain at least π electrons. a. 0 b. 1 c. 2 d. 3 e. 4 (7) The -NO2 group deactivates the benzene ring of nitrobenzene toward electrophilic aromatic substitution by a. changing the distribution of π electrons. b. polarizing the benzene ring. c. only activating the meta positions. d. deactivating all positions on the ring. (8) In an electrophilic aromatic substitution reaction, the sigma complex is stabilized when a is attached to the aromatic ring. a. a hydrogen atom A. a nitrogen atom c. an electron-donating group d. an electron-withdrawing group (9) Halogens direct electrophiles to the ortho and para positions of a halobenzene because of a. donation of nonbonding electrons to the ring through resonance. b. removal of ring electrons through resonance. c. removal of ring electrons because of halogen’s electronegativity. d. inductive effect. (10) In Friedel-Crafts alkylation, the resultant alkylbenzene product is a. less reactive than benzene. b. more reactive than benzene. c. as reactive as benzene. d. completely deactivated.4 2. Provide the structure of the major (or only) product in each of the reactions shown below.(12 pts. 3pts/each) + CH3CH2CH2ClAlCl3(a)(b)CH3HNO3(c)NH2H2SO4HBrCC+(d)CO2CH3CO2CH3!BrOCH31,2-additionOCH3OCH3CH(CH3)2orCH3NH3+NO2CH3NH2NO2orBrBrCO2CH3CO2CH3 3. What dienes and denophiles would react to give the products below? (12 pts) OOCH3OOO(a)(b)(c)(d)Structure of diene!! Structure of dienophileOCO2CH3OO5 4. Propose the mechanism for the following nitration reaction: (12 pts) OCH3HNO3H2SO4OCH3NO2 OCH3NO2++OCH3HO2NOCH3HNO2OCH3HNO2OCH3HNO2OCH3NO2+++++•••• ••++H O NO2O SO3HH O NO2HHHSO4-+••••••••••••+H OHO=N=O(or NO2+)HSO4-(1) Formation of the nitronium ion(2) Formation of the ! complex and abstraction of proton3 pts for showing the nitronium ion4 pts for showing the ! complex2 pts for showing abstraction of proton1 pt for showing at least one addition resonance form of the ! complex:(1 pt for showing at least one correct curved arrow)1 pt for showing at least one correct curved arrow6 5. One of the following compounds is much more stable than the other two. Classify each as aromatic, antiaromatic, or nonaromatic. (10 pts) OAB C A: non-aromatic (3 pts); B: aromatic (4 pts); C: anti-aromatic (3 pts) 6. Please draw the major product(s) of the following nitration and bromination reactions (assuming mono-nitration or mono-bromination in each case). (10 pts) N CH3OHH2NHNO3H2SO4Br2H2O NaHCO3N CH3OHH3N+O2NN CH3OHH3N+NO2and(or H2N-)(or H2N-)N CH3OHH2NBr(3 pts)(3 pts)(4 pts) 7. When 3-bromo-1-methylcyclohexene undergoes solvolysis in hot methanol, two products are formed. Please draw the structures of the corresponding carbocation intermediates that lead to these two products. (10 pts) CH3BrCH3OH!CH3OCH3CH3CH3O+AB CH3CH3Carbocation intermediate for product A:Carbocation intermediate for product B:7 8. Devise a synthesis of p-n-butylacetophenone from benzene. (12 pts) CH2CH2CH2CH3CH3Op-n-butylacetophenone CH2CH2CH2CH3CH3OOClCCH2CH2CH3+AlCl3C CH2CH2CH3OZn(Hg)/HCl(or H2/Pd-C)CH2CH2CH2CH3OClCCH3AlCl3(2 pts)(2 pts)(2 pts)(2 pts)(1 pt)(1 pt)(1 pt) 9. When treated with magnesium in THF Compounds A and B. One compound reacted easily, leading to the desired product; the other showed no sign of any reaction in spite of repeated efforts under a variety of conditions. Please indicate which compound reacted, which did not. For each compound, Briefly state the reason(s) for its reactivity or inactivity. (12 pts) BrBrA B The compound that reacted easily: A (4 pts) The transition state and product of this reaction are stabilized by the appearance of a non-bonded pair of electrons on the C atom connected to Br, leading to an aromatic system (w/ 6 π electrons). (2 pts) The compound that failed to react: B (4 pts) The transition state and product of this reaction are destabilized stabilized by the appearance of a non-bonded pair of electrons on the C atom connected to Br, leading to an anti-aromatic system (w/ 8 π electrons). (2 pts)8 10. When warmed in dilute sulfuric acid, compound A undergoes dehydration and rearrangement to give one of two possible products, B or C. Please indicate which product is formed and propose a mechanism for its formation. (10 pts) OHOHHOOorAB CH2SO4 The product that is formed: B (5 pts) Mechanism for forming that product: OHOHAH++OH2OHOHOH+ H2OH2OHOB(1 pt)(2 pt)(1 pt)1 pt for at least one correct curved