CHEMISTRY 2430
Principles of Organic Chemistry I
Exam II - 100 points
Oct. 5, 1998 - Dr. Howard Black
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Name _______________KEY__________________________

Throughout this exam, give answers only in the provided spaces (boxes or lines). Answers not in these spaces will not be graded, even if correct.

1. (12 pts) Give IUPAC names for the following compounds, being sure to address alkene geometry and R/S configuration where appropriate.


 


2.(16 pts) The structures of several pharmacologically important molecules are drawn below. Indicate whether the absolute configuration of each specified carbon atom is R, S, or neither (N).
 


A =__R__ B =__S__ C =__N__ D =__N__ E =__R__ F =__R__ G =__N__ H =__S__


For B, the absolute configuration is derived as follows (groups bonded to the *C, in priority order): N, C-S, COOH, H.

3.(12 pts) Draw all of the carbocations formed by the addition of H+ to each of the following alkenes, and indicate (by circling the appropriate word) which is the more stable (major) , less stable (minor), or if each carbocation is of equivalent (equiv.) stability.


 


4.(18 pts) Consider the reaction coordinate diagram below. Using the letters on the graph, identify each part or feature of the diagram.
A = starting materials

B = activation energy #1

C = transition state #1

D = reactive intermediate

E = activation energy #2

F = transition state #2

G = enthalphy (DH)

Is this reaction exothermic or endothermic? _____exothermic____ What is the sign of DH? __negative___

What is the difference between a transition state and a reactive intermediate?

___TS has only partial bonds; RI has fully formed or broken bonds (both have definite geometry)_____
 

5. (20 pts) Complete the following reactions by supplying either the reagent(s) or product. If more than one product is produced, draw only the major one.

6. (14 pts) For each molecule below, designate with the appropriate letter whether it would most likely function as a Lewis acid (A), Lewis base (B), or neither (N).

7. (8 pts) For these questions, refer to the table to the right. 

Compound  pKa
HCl  -7
HCO2H  3.7
acetaminophen   9.9
CH3CO2H  4.8
NH3  33
aspirin  3.5
CHCl2CO2H  1.3
CH3CH3 48
ibuprofen  5.2
H2O  15.7
a. Of the three common pain-relievers, which is most likely to cause acid indigestion? ____aspirin____

b. Which compound is closest to hydrochloric acid in acidity? ___CHCl2CO2H__

c. Is formic acid (HCO2H) slightly more or less acidic than aspirin? _____less acidic____

d. What compound is in the exact center of the range of acidities for the nine listed? ___thrown out_____

Bonus (5 pts, no partial credit possible)

The reaction in the box is an example of a good method for the preparation of oxygen- containing ring compounds. Its mechanism is very similar to one already known to you. Draw the reaction mechanism below.