Chem 2262, Section 1                           October 4, 2000

Please enter your social security number and your NAME on the scantron answer sheet.            

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Multiple Choice  (4 points each, 28 points total).  Enter your answer on the scantron sheet.

 

A         1.  Which of the following gives the correct relative reactivities of acid derivatives?

 

A. acyl chloride > ester > amide;  B.; ester > amide > carboxylic acid
C. ester > acyl halide > amide, D.  acid anhydride > amide > ester
E. carboxylic acid > acid anhydride > ester

 

D         2.  What base is often used to capture the HCl produced in the formation of amides from acyl chlorides and amines?

 

A.  ammonia;  B.  pyridinium hydrochloride;  C. methylamine; 
D.  pyridine;  E. hydroxide ion

 

D         3.  What is meant by the term "saponification"?

 

A.  Thermal hydrolysis of a fat to form glycerol and neutral fatty acids.

B.  Hydrogen chloride catalyzed hydrolysis of a fat or an oil to form glycerol and neutral fatty acids.

C.  Hydroxide-ion promoted hydrolysis of a fat or an oil to form glycerol and neutral fatty acids.

D.  Hydroxide-ion promoted hydrolysis of a fat or an oil to form glycerol and salts of fatty acids.

E.  Hydroxide-ion promoted hydrolysis of a fat or an oil to form glycol and salts of fatty acids

 

E         4.  Which of the following will result in the formation of a carboxylic acid or carboxylate salt?

 

  1. hydrolysis of an acid anhydride, 

B.  hydrolysis of an acyl halide

C.     hydroxide-ion promoted hydrolysis of a nitrile,

D.  acid-catalyzed hydrolysis of an amide

  1. all of the above

 

B         5.  What happens to the hybridization of the carbonyl carbon upon addition of a nucleophile?

 

A.  It changes from sp3 to sp2 .                   B.  It changes from sp2 to sp3.

C. It changes from sp3 to sp.                  D.  It changes from sp to sp3. 

E.  The hybridization does not change.

 

A         6.  Which of the following statements best explains why protonation increases the rate of ester hydrolysis?

 

A.  The carbonyl carbon is more positive than the carbonyl carbon in the unprotonated ester and therefore more susceptible to nucleophilic attack and the protonated leaving group is a weaker base.

 

B.  The carbonyl carbon is less positive than the carbonyl carbon in the unprotonated ester and therefore more susceptible to electrophilic attack and the protonated leaving group is a stronger base.

 

C.  The carbonyl carbon is less positive than the carbonyl carbon in the unprotonated ester and therefore more susceptible to nucleophilic attack, and the protonated leaving group is a weaker base.

 

D.  The carbonyl carbon is more positive than the carbonyl carbon in the unprotonated ester and therefore more susceptible to electrophilic attack and the protonated leaving group is a weaker base.

 

E.  The carbonyl carbon is more positive than the carbonyl carbon in the unprotonated ester and therefore more susceptible to nucleophilic attack, and the protonated leaving group is a stronger base.

 

C         7.  One step in the Gabriel synthesis involves the reaction of a phthalimide ion with an alkyl halide to produce an N-substituted phthalimide. What type of reaction is this?

 

A.  an SN1 reaction;  B.  an E2 reaction;  C.  an SN2 reaction; 
D.  a nucleophilic addition reaction;  E.  a nucleophilic acyl substitution reaction