Chem 242 Spring 2008 Problem Set 5 Question 1. Predict the major product of the following reactions. O Me O Me a) Br2, FeBr3 Br OH O Br 1) NaOH, b) 2) H2 (1 atm), Pt catalyst OH Cl c) 1) HNO , H SO 3 2 4 Me Me NO 2) NaOH 2 O O Me Me Me Me d) SO3, H2SO4 SO3H Chem 242 Spring 2008 Question 2. Provide reagents that will accomplish the following transformations. Multiple steps may be needed. 1) acetyl chloride, AlCl a) 3 H3C 2) SO3/H2SO4 SO3H O NH2 NO2 Br Br 1) H2 (1 atm), Pd catalyst b) 2) Br2 (no FeCl3 needed) Br Me Me O Me 1) isobutyryl chloride, AlCl3 c) 2) Cl2, FeCl3 Cl Me Me Me Me OH 1) NaOH, Et–I d) 2) t-butyl chloride, AlCl3 OEt Chem 242 Spring 2008 Question 3. A student wanted to synthesize para-nitroaniline by nitration of aniline as shown below. NH2 NH2 HNO3, H2SO4 + some ortho-product NO2 a) Provide a mechanism for the formation of para-nitroaniline. O O O H2SO4 N N N O OH O OH2 O NH NH NH NH NH2 2 2 2 2 O N O2N H O2N H O2N H O2N H O NH2 HSO4 NO2 b) When the experiment was actually attempted, the reaction was very sluggish and the product mixture contained large amounts of meta-nitroaniline. Briefly explain the sluggish rate and the formation of meta-nitroaniline. + In strong acid, the amine will become protonated. An –NH3 group is stongly deactivating and meta-directing. NH 2 NH3 fast reaction, slow reaction, ortho/para products HNO3, H2SO4 meta-products <.001% >99.999% Chem 242 Spring 2008 Question 4. When styrene is treated with aqueous sulfuric acid, one of the major products is shown below. Provide a mechanism for this dimerization reaction. Me catalytic H+ protonate olefin H+ Me Me 2nd olefin attacks benzene ring attacks carbocation carbocation (Friedel-Crafts rxn) Me HSO4 H elimination Me Chem 242 Spring 2008 Question 5. Provide a complete mechanism for the reaction shown below. Me Me Me Me AlBr3 Me Br AlBr 3 ionization Me & hydride Me Me AlBr shift Me Br 3 H Me electrophilic attack (Friedel- Crafts alkylation) – Br Me Me Me H Me Me Me Chem 242 Spring 2008 Question 6. Non-benzene aromatic compounds frequently show analogous reactivity to benzene. With this in mind, explain why the bromination of furan occurs at the observed position on the five-membered ring. O O O Br2, FeBr3 Br Br furan product not formed O O Only 2 resonance forms, less stable Br H H Br + O " Br " Br H H O H " Br+ " Br O O Br Br Three resonance forms, more stable O Br product.