CHEMISTRY 2430
Principles of Organic Chemistry I
Exam II - 100 points
February 18, 2000 - Dr. Howard Black

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).


 

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) In the box below, draw a reaction coordinate diagram for a reaction that is two-step, exothermic, and for which the first step is rate-determining. Using the letters on the left to label your diagram, identify each requested part or feature of the diagram. Label both axes!
 
A = starting materials

B = products

C = reactive intermediate(s)

D = enthalpy (DH)

E = rate-determining Eact

F = other Eact

G = transition state(s)

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

     Transition states contain partial bonds (partially broken and/or partially formed), while reactive intermediates have fully formed or broken bonds.

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. (12 pts) For each terpene below, indicate the isoprene units by clearly circling each unit in each molecule. Alternatively, you may indicate which bonds would be broken between isoprene units by drawing a wavy line through each bond (this is the recommended method). Whichever method you choose, be certain that it is clear.
 

 

7. (10 pts) Outline the mechanism for the addition of H2O (with proton catalysis) to 1-methylcyclohexene, showing any reactive intermediate(s) and using correct arrows to show electron movement.
 


 

Bonus (5 pts, no partial credit possible)

The addition of HBr also occurs with alkynes. Draw the reaction of 1-butyne with two moles of HBr.