feb_12 - What would be the predominant form of nicotine...

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Unformatted text preview: 2/13/2010 What would be the predominant form of nicotine present at the physiological pH = 7.2? What would be the predominant form of nicotine present at the physiological pH = 7.2? sp3 N pKa = 8.02 pKa = 3.12 N N CH3 nicotine pKa = 8.02 pKa = 3.12 N CH3 nicotine sp2 When the pKa = pH the [base] = [conjugate acid]. A B C D Which of the following nitrogen atoms in imidazole would you predict to be more basic? The imidazole ring is present in the amino acid histidine and the biogenic amine histamine. A pKa = 6.99 pK pKa = ??? B imidazole histidine pKa = 6.99 A B histamine 1. Draw the two cations that are formed by protonating each nitrogen atom. 2. Circle the more acidic cation. cation. 3. Circle the more basic nitrogen atom. Which atom would you predict to be more basic on histamine? Why? The imidazole ring is present in the amino acid histidine and the biogenic amine histamine. Phenol is a stronger acid than cyclohexanol. O O O O phenol pKa = 9.95 imidazole histidine pKa = 6.99 pKa = 5.8 pKa = 9.4 9.4 histamine cyclohexanol pKa = 16 What would be the predominant species present at the physiological pH = 7.2? A. Very sure this is true A B C D C. Maybe this is true D. Maybe this is false F. Very sure this is false B. Somewhat sure this is true E. Somewhat sure this is false 1 2/13/2010 Aniline is a stronger base than cyclohexylamine. NH3 + H Aniline is a stronger base than cyclohexylamine. NH2 NH2 + H NH3 aniline pKa = 4.63 aniline pKa = 4.63 cyclohexylamine pKa = 9.82 cyclohexylamine A. Very sure this is true C. Maybe this is true D. Maybe this is false F. Very sure this is false A. Very sure this is true C. Maybe this is true D. Maybe this is false F. Very sure this is false B. Somewhat sure this is true E. Somewhat sure this is false B. Somewhat sure this is true E. Somewhat sure this is false H3C Br As of today, the reading assignment for Exam 1 is Chapter 13, 14 and 15.1 through 15.11. 3 HNO H3C O4 H 2S NO2 There will be a TA run review in ESS 001 at 6:50 PM on Tuesday, February 16. 3 -C l 3 SO CH 4 SO H2 Al Cl 3 CH3 HO3S Propose a mechanism for the following reaction. Choose the structure that would be a first intermediate in your mechanism. H D Cl H D H D D = 2H D Cl D D Cl H D Cl D base acid A B C D E 2 2/13/2010 Predict the major product of the following reaction. Predict the major product of the following reaction. H D CH3 -H D CH3 D D CH3 D CH3 CH3 D more stable intermediate major product CH3 -H D minor product A B C A B C Why does benzene give substitution rather than addition products when it reacts with bromine? What is the mechanism of bromine substitution? Br Br H Br H Br Br Br + Br Br Br + Br Br or Br + HBr + HBr Choose the true statement about the following intermediates. A. The bromine atom of compound (b) does not have an octet. B. All of the carbon atoms of compound (a) have an octets. C. Compound (a) has more stability due to electron delocalization. D. Compound (a) has more strain energy. E. Compound (a) is aromatic. H Br H C. Compound (a) has more stability due to electron delocalization. Br Br Br Br Br Br Br + Br Br Br Br + Br Br or (a) (b) + HBr Br + HBr 3 2/13/2010 How can bromine be made more reactive? Br + Br Br H + Br Br What is the role of the lewis acid? Br Fe Br Br Br + HBr + Br Br + Br + HBr H Br energy progress of reaction Which of the two products would you predict to predominate in the following bromination? bromination? O O Br Which of the two intermediates would you predict to be more stable? O O Br H Br H O Br O O O (A) O Br2, FeBr3 O Br (A) O Br2, FeBr3 O Br (B) O O Br O H Br O O (B) O O H Br Br O Besides the bromonium ion are there other electrophiles that react with benzene to give electrophilic substitution? Br Br Fe Br Br Br + Br + Br + HBr H Br Besides the bromonium ion are there other electrophiles that react with benzene to give electrophilic substitution? Br Br Fe Br Br + Br Br Br + Br Fe Br Cl Cl Fe Cl Cl + Cl Cl Cl + Cl Fe Cl Cl Br energy progress of reaction 4 2/13/2010 Would the carbocation be (A) more or (B) less reactive than the chloronium ion? Choose the reactants that would give carbocations? carbocations? slow Cl Cl Fe Cl Cl + Cl Cl Cl + Cl Fe Cl Cl Cl Cl Fe Cl Cl + Cl Cl Cl + Cl Fe Cl H Cl C H H H HO C H H Cl Electronegativities I KMnO4 A B AlCl3 H Cl C H H OH H HO C H H C D 5 ...
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This note was uploaded on 04/06/2010 for the course CHE 326 taught by Professor Fowler during the Spring '08 term at SUNY Stony Brook.

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