Organic Chemistry II
5 February 1998
Exam I
(8) 1. Provide a complete name for each of these structures:

 

 (12) 2. Identify nucleophilic sites/atoms by circling them. Identify electrophilic sites/atoms by drawing a box around them.

 

 

(16) 3. Give the structure of the major organic product expected in the reaction of the compound below with the reagents listed:

a) CH2I2/Zn

 

b) CH3COCl/AlCl3

 

c) Na/NH3

 

 
d) 1) O3, 2) Zn/HOAc

 

 

 (14) 4. There are three ways to produce alcohols from alkenes. List them below. Then indicate which you would use to make each of the alcohols shown. Give the structure of the alkene you would use.

Method A: _________________________________________________________________________

 

Method B: _________________________________________________________________________

 

Method C: __________________________________________________________________________

 

Method: _____                             _____                                _____                                 _____

Starting alkene:

 

 

(8) 5. Write the mechanism for the synthesis of any of the alcohols in the preceding problem. Show all steps and intermediates. Use arrows. Draw a reaction profile that corresponds to the mechanism.

 

 

 

(12) 6. From the following elimination reactions, choose:

i) the one most likely to give a rearranged product

ii) the one that will react fastest by E1

iii) the one that will react fastest by E2

iv) the one that will give the least elimination product (proportionally)

 

Explain your reasoning.

 

 

 
(26) 7. Complete the following reactions.

 

 

 

 

 

(8) 8. Propose a synthesis for styrene (phenylethylene), starting with benzene and any other needed reagents.

 

 

 
 
Organic Chemistry
13 February 1998
Exam II
(8) 1. Provide names for the following compounds:

 

 
(10) 2. Circle nucleophilic atoms/sites. Draw a box around electrophilic atoms/sites.

 

(12) 3. Tell how you would make each of the following from benzene. Give the reagents used and the order in which they should be used.

(16) 4. Predict the products of reaction of the material shown below with each of the reagents.

a) NaOH/H2O

 
b) Cl2/AlCl3

 

 c) EtO-/EtOH

 
 

d) HBr/Br2

 

 
(16) 5. Tell how each of the following could be made by an aldol condensation, a Claisen condensation, or an acetoacetate or malonate ester synthesis.

a) 

 

 
b) 

 

c) 

 

 d) 

 

 

(8) 6. Predict the products of the following reactions.

 

(8) 7. Give a step by step synthetic sequence for the synthesis of 2-methylpropanoic acid from an alcohol of 3 carbons, plus any inorganic reagents or organic materials with fewer than 2 carbons.

 

 

 

 (4) Now give another sequence following the same groundrules.

 

 

 
(4) Which sequence would be better and why?

 

 

 
(6) 8. One mole of acetone is added to enough water to make 1 liter of solution. The pH is neutral. If the pKa of the enol of acetone is 12, what will be the concentrations of H2O, -OH, H3O+, acetone, the enol of acetone, and the enolate of acetone?

 

 

 

 

 

 (10) 9. Use resonance structures to help explain the regiochemistry and the relative reactivity of nitrobenzene in electrophilic aromatic substitution. Use an electrophile of your choice.

 

 

 

 

 
Organic Chemistry II
20 February 1998
Exam III

 

(10) 1. Identify nucleophilic atoms/sites by circling, electrophilic atoms/sites by drawing a box.

 

(8) 2. Indicate the mechanism and the structure of the polymer resulting from the following reaction.

 

 

 

 
 

(10) 3. Do the same for this reaction. Then indicate what effect it would have to add a small amount of HN(CH2CH2NH2)2.

 

 

 
(10) 4. Is this polymer an addition or condensation polymer? From what monomer and by what mechanism was it likely to have been made?

 
(12) 5. Suggest two different synthetic sequences that will produce 2-pentene in a reasonably efficient way, starting with alcohols of 3 carbons or less, esters of acids of 3 carbons or less, and any inorganic reagents.

 

 
 

 

(24) 6. The synthesis of metoprolol, a b 1-adrenergic blocker lacking intrinsic sympathomimetic activity, from phenol, is shown below. For each reaction in the sequence, describe the type of reaction shown and indicate likely reagents to effect the transformation. (Hint: you might need OsO4 for one of these)

1)

 
2)
 

3)
 

4)

 

5)

 

6)

 

7)

 

8)

 
 

 

(12) 7. D-Xylose, an aldopentose, upon treatment with NaBH4 yields a meso product, xylitol. Oxidation of xylose by Br2, followed by oxidative chain shortening, produces an aldotetrose, which, when treated with nitric acid produces an optically active diacid. On the other hand, the Kiliani synthesis on xylose produces two sugars whose diacids are both optically active. What is the structure of xylose? Explain.

 

 

 

 (14) 8. Give the numbers of the structures that satisfy the following:

  
hemiacetal ______ undergoes mutarotation ______
acetal ______ a pair of epimers __________
b -glycoside ______ a pair of anomers __________
a -aldohexose ______ a pair of stuctural isomers __________
hemiketal ______ a pair of enantiomers __________
 
 
Organic Chemistry II
24 February 1998
Final Exam
(10) 1. Identify nucleophilic sites/atoms by circling; electrophilic ones by drawing a box around each.

 

(12) 2. Consider the following alkyl halides. Which one will

undergo the fastest E1 reaction? _______

be most likely to undergo rearrangement? _______

be more likely to substitute than eliminate with hydroxide? _______

be least likely to give a single product on treatment with a base such as KOC(CH2CH3)3? _______

Explain your reasoning. Show the structure of the major product(s) in each case.
 

 

(10) 3. Tell how 2-butene can be converted into 2-butyne. Then give two ways to convert 2-butyne back into 2-butene.

 

 

(12) 4. The following compound reacts with HBr to give the addition product. However, a different product is obtained in ether solvents than in solvents like methylene chloride. What are the two products obtained? Explain on the basis of the mechanisms of the reactions why two different products are obtained.

 
(16) 5. The structure of D-xylose is shown below. Next to it draw furanose and pyranose hemiacetal forms of xylose. Then predict the product(s) of reaction of xylose under each of the reaction conditions shown.

a) acid/CH3OH

 
b) Br2

 
c) NaCN, pH=9

 
d) 1) base/(CH3)2SO4; 2) H3O+

 
 

(6) 6. Draw the structure of the only L-aldopentose that yields an optically inactive product on treatment with hot HNO3.

 (6) 7. Draw the structure of a D-aldohexose which, on treatment with NaBH4, yields a polyacohol which cannot be produced from any other aldohexose.

 
 

(12) 8. Suggest two reasonably efficient syntheses for pentanoic acid starting from aliphatic structures of 3 carbons or less.

 

 
(18) 9. The final steps in the synthesis of a component of sun-cured Greek tobacco are shown below. For each step, tell what type of reaction is taking place and suggest reagents that may be used to effect the transformation.

Some possible reagents might be: a) LiAlH4, b) ethylene glycol at low pH, c) Ph3P=CH2, d) CH3I, e) excess CH3Li.

1)

 2)

3)

4)

5)

6)

 

(12) 10. Aspartame (Nutrasweet) is a methyl ester of the peptide shown below. Estimate the pKa for each boxed proton. Circle the side chains and tell what type of side chain each is. Identify the most acidic proton not boxed and estimate its pKa. Draw the form of the peptide that will dominate at pH 7.

 

Major form at pH 7 (indicate the state of the ionizable groups):

 

(20) 11. Predict the major products of the following reactions:

 

 

 

 

(10) 12. Predict the relative reactivity and regioselectivity of anisole in electrophilic aromatic substitution. Explain your reasoning.
 
  (6) 13. A mole of acetic acid is dissolved in enough water to make a liter of solution and the pH is fixed at 2. Give the concentrations of water, hydronium ion, hydroxide ion, acetic acid, acetate and the conjugate acid of acetic acid (pKa = -5).