Chemistry 234 Chapter 16 Problem Set. 3) Predict the product and draw the active electrophile for each reaction shown below.

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Nathan Jesse Norman
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1 Chemistry 234 Chapter 16 Problem Set Electrophilic Aromatic Substitution 1) Predict the product and draw the mechanism for electrophile generation for each of the following reactions. (a) 2 Fe 3 (b) HN 3 H 2 S 4 (c) S 3 H 2 S 4 2) Explain why reaction of benzene with 2/Fe3 results in the product bromobenzne instead of 5,6-dibromo-1,3-cyclohexadiene. 3) Predict the product and draw the active electrophile for each reaction shown below. (a) Al 3 (b) Al 3 (c) Al 3 Page 1 of 13

2 4) Explain why each of the following substrates do not undergo Freidel-Crafts reactions. N 2 N(CH 3 ) 3 NH 5) Arrange the following benzene substituents in order of reactivity in electrophilic aromatic substitution reactions. Ph Ph Ph Ph N Ph H N Ph H N Ph S Ph 6) Predict the major products when the following benzene derivatives are treated to nitration conditions (HN3/H2S4). N 2 7) Write the full electron pushing mechanism for the nitration of toluene. Page 2 of 13

3 8) Predict the product(s) when each of the following benzene derivatives is treated to chloroethane and Al3. H H e. N 2 f. g. S 3 H Page 3 of 13

4 9) Predict the product(s) when the following benzene derivatives are subjected to electrophilic chlorination conditions (2, Fe3). Chem. 234 Chapter 16 Problem Set N 2 H H N 2 S 3 H 10) Predict the product(s) for each of the following reactions. H 3 C CH 3 2 Fe 3 HN 3 CH 3 H 2 S 4 S 3 H 2 S 4 H N 2 S 3 H 2 S 4 Page 4 of 13

5 11) Predict the product for each benzene side-chain modification reaction shown below. KMn 4 H 2 Cr 4 NBS light N 2 H 2 Pd/C e. N 2 Sn H f. Zn(Hg) H g. N 2 H 2 H - 12) Propose a synthesis for each of the following compounds starting with benzene. CH N 2 CH Page 5 of 13

6 N 2 N 2 e. CH N 2 Page 6 of 13

7 f. N 2 g. 2 N Diazonium Ion Reactions 13) Write out the synthetic sequence to prepare phenol and acetanilide (Ph-NHCCH3) from benzene. Page 7 of 13

8 14) Provide syntheses for each of the following compounds, free of other isomers. Your starting material should be benzene in each case. H I F Page 8 of 13

9 NC Nucleophilic Aromatic Substitution 15) For each reaction shown below, determine if the reaction is (a) electrophilic aromatic substitution, (b) Nucleophilic Aromatic Substitution: Addition-Elimination, or (c) Nucleophilic Aromatic Substitution: Benzyne Mechanism. NaH 350 C Na NH 3 H 3 C Na NH 3 NaH N 2 e. HN 3 H 2 S 4 f. N 2 NaCH3 N 2 Page 9 of 13

10 16) Show the full electron pushing mechanism for reaction 15 Chem. 234 Chapter 16 Problem Set 17) Show the full electron pushing mechanism for reaction 15 18) Explain why the reaction shown below does not occur. H NaH Heat 2 N N 2 2 N N 2 19) Consider the reaction shown below. Theoretically, there are three possible products. Draw each of these products. In reality only one of these products is forme Which one is the observed product? CH 3 N 2 Page 10 of 13

11 20) Show two methods to synthesize the molecule shown below starting with benzene. ne route should use diazonium ion chemistry while the other route should not. N 2 H 21) Show the reaction of phenol with NaH. 22) Show the reaction of benzoic acid with NaH. 23) Is phenol or benzoic acid a stronger acid? Explain. 24) Show the reaction of aniline with H. Page 11 of 13

12 25) Rank the compounds in each set below in order of increasing acidity. Chem. 234 Chapter 16 Problem Set (a) H H H (b) H N 2 H H H 2 N 26) Rank the aniline derivatives below in order of increasing basicity. 2 N Challenge Problems 27) Write a mechanism for the following reaction. H H H Page 12 of 13

13 28) Predict the major product for the reaction of pyrrole with 2, Fe3. Hint: use resonance analysis of the intermediate to determine the preferred regioselectivity of the reaction. H N 2 Fe 3 29) Show the electron pushing mechanism for the reaction shown below. H S 2 N 2 NaH N 2 S 2 30) Substituted pyridines are known to undergo nucleophilic aromatic substitution via an addition elimination mechanism. Predict the product and show the mechanism for the reaction shown below. H N Page 13 of 13

C h a p t e r N i n e t e e n Aromatics II: Reactions of Benzene & Its Derivatives

C h a p t e r N i n e t e e n Aromatics II: Reactions of Benzene & Its Derivatives Arenium ion from addition of tert-butyl cation to benzene (blue is δ+and red δ-) Note: Problems with italicized numbers