w_aroma_2_all (2) - Exam Name_ SHORT ANSWER. Write the word...

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Exam Name___________________________________ SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question 1) Provide the major resonance structures of the intermediate sigma complex in the reaction of benzene with the generic electrophile E + . 1) ESSAY. Write your answer in the space provided or on a separate sheet of paper. 2) In the bromination of benzene using Br 2 and FeBr 3 , is the intermediate carbocation aromatic? Explain. 3) Which step in an electrophilic aromatic substitution reaction is typically rate determining, formation of the sigma complex or loss of H + by the sigma complex to form the product? Explain. 4) Provide a detailed, stepwise mechanism for the reaction of benzene with Br 2 and FeBr 3 . Make sure to include the activating reaction between Br 2 and FeBr 3 in your mechanism. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 5) Under what reaction conditions does the electrophilic chlorination of aromatic compounds usually occur? A) NaCl, CH 3 OH B) Cl 2 , AlCl 3 C) Cl 2 , CCl 4 D) NaCl, H 2 O E) Cl 2 , H 2 O 5) 6) Which of the following species is attacked by benzene in the electrophilic nitration reaction? A) HNO 3 B) NO 2 + C) NO 2 D) N 3 - E) NO + 6) SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question 7) Name the major organic product which results when 3 - ethylbenzenesulfonic acid is heated in aqueous acid. 7) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 8) In electrophilic aromatic substitution reactions the hydroxyl group is an o,p - director because: A) it donates electron density to the ring by resonance and stabilizes the ortho and para sigma complexes. B) it donates electron density to the ring by induction and stabilizes the ortho and para sigma complexes. C) it donates electron density to the ring by resonance and destabilizes the meta sigma complex. D) it withdraws electron density from the ring by induction and destabilizes the meta sigma complex. E) it donates electron density to the ring by induction and destabilizes the meta sigma complex. 8) 1
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9) In electrophilic aromatic substitution reactions the nitro group is: A) an o,p - director since it stabilizes the ortho, para sigma complex less than the meta. B) a m - director since it destabilizes the meta sigma complex less than the ortho, para. C) an o,p - director since it stabilizes the ortho, para sigma complex more than the meta. D) a m - director since it destabilizes the meta sigma complex more than the ortho, para. E) none of the above. 9) 10) The nitration of anisole: A) proceeds at the same rate as the nitration of benzene and yields predominantly the meta product. B) proceeds more rapidly than the nitration of benzene and yields predominantly the ortho, para products.
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This note was uploaded on 04/07/2010 for the course ERRE 2324 taught by Professor Dsfdsf during the Spring '10 term at University of South Africa.

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w_aroma_2_all (2) - Exam Name_ SHORT ANSWER. Write the word...

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