Problem_Set_3 - antiaromatic character? H H...

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Chem 358 Spring 2007 Problem Set #3 Chapter 16 : 16 .11, 15, 19, 23, 24, 29, 38(a) and (c), 40, 44, 47, 48, 49, 54, 55, 57 Additional problems 1. Propose a mechanism using the curved arrow formalism for the reaction shown below. H + 2. [From 2006 Prelim I) Cations A-D initially form during electrophilic aromatic substitutions with Br 2 /FeBr 3 . After considering other important resonance structures rank the cations in order of increasing stability. Br Br CH 3 O Br O 2 N Br NO 2 A B C D 3. [From 2006 Prelim I] Propose a synthesis of the following compounds from benzene by filling in the reagents needed as well as the isolable intermediate product along the way. You can disregard the possible formation of minor isomers. SO 3 H NO 2 4. The compound shown below, called 1,6-methano[10]annulene, exhibits two sets of signals in the 1 H NMR spectrum at δ = 7.10 (8 H) and -0.50 (2 H) ppm. Is this a result of aromatic character or
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Unformatted text preview: antiaromatic character? H H 1,6-methanoannulene[10] 5. The 1 H NMR spectrum of the most stable isomer of [14]annulene shows two signals at = -0.61 (4 H) and 7.88 (10 H) ppm. Two possible structures (A and B) for [14]annulene are shown below. Which one corresponds to the NMR spectrum described? Give reasons for your answers. A B 6. Rank the following in order of decreasing reactivity in electrophilic aromatic substitution. CF 3 CH 3 CH 3 CF 3 CH 3 CH 3 A B C D 7. Propose a reasonable synthesis for the following compounds from benzene. O NO 2 Cl (a) (b) 8. (From 1999 Final Exam) Complete the following reactions by drawing the major product that would be formed. NO 2 NO 2 NO 2 NO 2 NO 2 Br NH 2 NO 2 Cl 2 AlCl 3 Br 2 FeBr 3 HNO 3 H 2 SO 4 Cl 2 AlCl 3...
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Problem_Set_3 - antiaromatic character? H H...

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