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. contains no sp2 carbons b. reacts with Ag(NH3)2+ (Tollens' reagent) c. forms a salt with NH3 d. very easily oxidized e. is not reduced by LiAlH4 f. incompatible with Grignard reagents g. lowest vapor pressure of the four h. reacts with NaBH4 to form an alcohol i. made in one step from a 2o alcohol j. most basic of the four k. can be formed from oxidation of a 1o alcohol

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) Provide 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 material provided. Please fill in the letter of your choices in the spaces provided on the following page.

There are several correct answers to each synthetic problem.  The syntheses below, though, are
probably the ones that would occur to you first, having been in this class.

5. (16 pts) Explain the following observations.

a. The compound illustrated in the box has the following measurement: [a]25 = +43o. When a tiny amount of anhydrous HCl is added, the +43 number slowly declines, finally settling at 0o.  What does this number represent, and why does this effect occur?

The number is the chiral compound's optical rotation.  When a small amount of acid is added, it catalyzes the formation of the enol tautomer, which is planar and thus achiral.  When the keto form then occurs, the proton can attack either side, giving either enantiomer, so racemization occurs, and there is then no optical rotation.

b. What is the effect of an electron-withdrawing substituent on the basicity of aniline?  Using resonance, illustrate this effect using p-nitroaniline.  Answers without at least two resonance structures will not be graded.
 

Electron-withdrawing groups decrease the basicity of organic bases, by decreasing the electron density of the nitrogen lone electron pair.  This is easily seen with p-nitroaniline, where the electron pair can be delocalized via resonance into the nitro group.  This resonance structure is also an additional one over those for just aniline.

6. (8 pts) Rank the following molecules from most acidic to least acidic, by placing the letters corresponding to each molecule in the appropriate rank supplied below.

Most acidic = 1.    C    2.    G    3.    I    4.    D    5.    F    6.    B    7.    H    8.    E    9.    A    = Least acidic

7. (4 pts) In the box is the acid-catalyzed formation of an acetal from acetone and methanol.  Illustrate the mechanism.

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Bonus(5 pts, no partial credit)
 

A common reaction for sugars is the formation of intramolecular hemiacetals.  Illustrate the product and the mechanism for its formation for 5-hydroxypentanal (depicted in the box).