CHEMISTRY 2430 - Principles of Organic Chemistry I - Exam III
March 12, 1999 - Dr. Howard Black

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 acceptable names for the following compounds, being sure to address alkene geometry and R/S configuration where appropriate.

2. (14 pts) For each of the following four molecules, list the properties from the list on the right which best describe it. Each item on the list can be used as often as necessary, or not at all. DON'T GUESS!!
 
a. forms the least stable carbocation upon loss of bromide ion
b. SN1 reaction very facile
c. contains no sp3 carbon atoms
d.capable of E1 reaction to form an alkene
e. whether SN1 or SN2 mechanism is solvent-controlled
f. incapable of an elimination reaction
g. completely planar (all atoms)
h.  SN2 reaction is essentially impossible
i. SN2 reaction is very facile
j. reacts with bromine (uncatalyzed)
k. capable of E2 reaction to form an alkene

3. (30 pts) Complete the following reactions (provide either the starting molecule, the reagent(s), or product(s). If more than one product is produced, draw them all. If one product predominates, circle it.

4. (16 pts) Indicate a synthesis of any TWO (2) of the following four molecules from the indicated starting materials. You may use any inorganic reagents you like, but all carbon atoms must come from the starting materials provided. Please fill in the letter of your choices in the spaces provided.




5. (16 pts) Explain the following observations.

a. Phenol is about a million times more acidic than methanol (pKa of about 10 vs. about 16, respectively). You must use resonance structures in your answer.

b. (R)-2-bromohexane, when treated with sodium bromide in polar or nonpolar solvents, yields racemic 2-bromohexane as the product. Your answer must address both solvent types.


6. (8 pts) Outline the mechanism of the reaction (diagrammed in the box) of 1-bromo-1-methylcyclopentane and ethanol to form the ether 1-ethoxy-1-methylcyclopentane, with the alkene 1-methylcyclopentene as a by-product. Your mechanism must account for both products.


 


 

7. (4 pts) Circle the aromatic molecules or ions in the following selection:
 


 
 
Bonus(5 pts, no partial credit)

The reaction diagrammed in the box is called bromolactonization, and is a valuable method for fusing one ring onto another. Provide a mechanism which details this transformation.