11-30 - 12/1/2009 pKa data clearly show OH is a better...

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Unformatted text preview: 12/1/2009 pKa data clearly show OH is a better leaving group than H2O H in substitution reactions. C O H C O H pKa data clearly show OH is a better leaving group than H2O H in substitution reactions. C O H Nu C Nu + O C Nu C O H Nu H + O H H pKa pKa A. A. Very sure this is true B. B. Somewhat sure this is true C. Maybe this is true D. Maybe this is false E. Somewhat sure this is false F. Very sure this is false A. A. Very sure this is true B. B. Somewhat sure this is true C. Maybe this is true D. Maybe this is false E. Somewhat sure this is false F. Very sure this is false pKa data clearly show OH is a better leaving group than H2O H in substitution reactions. C O H Nu C Nu + O C Nu C O H Nu H + O H All alcohols react by a SN2 reaction mechanism. H C O H +H Br C O H + Br C Br H + O H H pKa H Br + C O H SN2 H Br C O H A. A. Very sure this is true B. B. Somewhat sure this is true C. Maybe this is true D. Maybe this is false E. Somewhat sure this is false F. Very sure this is false What other mechanism can occur in this reaction? H C O H +H Br C O H + Br C Br H Which mechanism will 2-methylpropan-2-ol be predicted to follow when it reacts with H-Br? H H Br C O H Br C O H H Br H C O H + O H Br H Br + C O H C O H H Br C (A) (B) SN2 Br C and? C Br + O C H Br Br C SN1 C 3° CH3 H3C C OH CH3 H Br CH3 H3C C CH3 H3C CH3 C Br CH3 SN 1 1 12/1/2009 Which mechanism will butanol be predicted to follow when it reacts with H-Br? H Br Br C O H H Br H C O H Br C O H Order of alcohol reactivity with HBr: 1° < 2° < 3° increasing reactivity O H Br Br H C O H C O H (A) (B) C Br C + C Br C H H Br (A) (B) Br C + C Br Br C 3° CH3 H3C C OH CH3 H Br fast H Br CH3 H3C C CH3 H3C CH3 C Br CH3 SN 1 3° CH3 H3C C OH CH3 H Br fast H Br CH3 H3C C CH3 H3C CH3 C Br CH3 SN 1 CH3 CH2 CH2 CH2 OH CH3 CH2 CH2 Br C HH OH3 slow CH3 CH2 CH2 CH2 Br CH3 CH2 CH2 CH2 OH CH3 CH2 CH2 Br C HH OH3 slow CH3 CH2 CH2 CH2 Br 1° SN 2 1° SN 2 Use the curved arrow formalism to show the bond making and bond breaking in the following transformation. O Cl S Cl Choose a reasonable intermediate structure in the reaction mechanism. O Cl S Cl O O S A Cl O O H Cl S Cl Cl O H Cl O S Cl Cl O H H R3N R3N B O Cl Cl O O S H C S Cl Cl D O Which of the following reactions would you predict to occur at a faster rate? pKa of the conjugate acid O O S CH3 O N3 O N3 + O S CH3 O What reactant might be used to prepare sulfonate esters? O O O S Cl Cl S Cl O H O A -1.9 O S CH3 O Cl O S Cl Cl O S CH3 Cl O S CH3 ? O O S CF3 O N3 O N3 + O S CF3 O A H Cl O S Cl O B O HO S O CH3 O C B -15 O D E 2 12/1/2009 How can these sulfonate esters be prepared from the alcohol? Use the curved arrow formalism to show the bond making and bond breaking in the following transformation. In the first step benzyl alcohol is behaving as an acid. A. A. Very sure this is true D. Maybe this is false E. Somewhat sure this is false F. Very sure this is false O O S CH3 O Cl O Cl S O Et3N CH3 O O H S O S O CH3 O CH3 B. B. Somewhat sure this is true C. Maybe this is true O H O H H O Ethers can be prepared by the treatment of alcohols with H+. Use the curved arrow formalism to show the bond making and bond breaking in this following transformation. Predict the product(s) of the following reaction. A. HO O H H O H 3C O CH3 -H2O H B. -H O CH3 H O H H O O H + HO CH3 C. H O D. All of the above. Predict the product(s) of the following reaction. H H O + CH3 HO Predict the product(s) of the following reaction. -H2O A. H 3C O CH3 A. CH3 O H 3C O CH3 O H H HO CH3 B. O B. O CH3 H O H + HO CH3 C. H O O H C. 1. Na :H 2. CH3 Br O D. All of the above. D. All of the above. 3 12/1/2009 Predict the major products of the following reaction. H H H C H C O H C H H H H Br H H Propose a synthesis of methyl t-butyl ether (MTBE) from compounds containing four carbon atoms or less. H C H C H O H + Br H3C O (one equivalent) C H H H CH3 C CH3 CH3 ? ? A. H H H C H H C H C Br + H HO CH3 C O H H + Br CH3 B. H H Propose a synthesis of methyl t-butyl ether (MTBE) from compounds containing four carbon atoms or less. Williamson ether synthesis C O R OR C Br CH3 H3C O C CH3 CH3 What is wrong about the following reaction sequence? A. The hydride base (pKa H2 = 35) is not able to remove the acetylenic hydrogen (pKa = 25). B. The alkyl bromide does not undergo SN2 reactions. C. The acetylide does not undergo SN2 reactions. D. The acetylide will react more rapidly with the acidic The alcohol (pKa = 16). C Nu SN2 Nu= N3, OR, CN, etc. C Br ? ? CH3 H3C O C CH3 CH3 CH3 Br CH3 O CH3 C CH3 CH3 Na H CH3 HO C CH3 CH3 A H Na :H Br OH OH H3C C H3C CH2 Br C CH3 CH3 O CH3 Na H HO CH3 B What is wrong about the following reaction sequence? What strategy could be successful for accomplishing the following transformation? Br O H Na :H O-R + Br O R H Na :H Br O H OH H Na :H Br O H OH 4 12/1/2009 What strategy could be successful for accomplishing the following transformation? Epoxides are very reactive ethers. Propose a synthesis of styrene oxide from styrene. C Nu SN2 Nu= N3, OR, CN, etc. C Br H Na :H H3C OTMS Si CH3 CH 3 H N + Br O Williamson ether synthesis F C H3 H3C Si Cl = TMS-Cl CH3 C O O R OR C Br N imazole H Na :H Br O H + TMS-F OH styrene oxide styrene Choose reactants and reagents that could be used to prepare styrene oxide. A. i D. D. iv B. ii E. E. i+iv C. iii Na :H OH F. F. ii + iii i OR Br Williamson ether synthesis C O Br O R OR C Br ii ii OR iii styrene oxide styrene Na :H Br iv OH 5 ...
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