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Name: Whittier College
Organic Chemistry: CHEM 231A
Test # 3
120 Points Total November 4, 2002
- Answer the following questions: (24 points – 6 pts each)
1a. What is a solvent? How might it affect a reaction? Explain briefly.
1b. What is an enantiomer? Provide two structures that demonstrate what an enantiomer is. Explain briefly.
1c. What makes a nucleophile a good nucleophile? Explain briefly.
1d. What is a leaving group and what kind of reactions need one? What determines how good a leaving group is? Explain briefly.
- Consider the following reactions. Predict the product in the absence of a product and explain thoroughly your rationale OR discuss whether the product will be formed as drawn and explain thoroughly: ( points – 7 points for each)
Br
H 2 N
Br CH 3 OH
Cl
H (^) Br (^) H (^) OH
NH (^2) O
2a.
2b.
2c.
2d.
2e.
CH 3 OH / Heat
NaCN / Ethyl Acetate
pH 11 H 2 O
NaOCH 3 / Et 2 O
3d. What is the optical purity of the product? What is the optical rotation of the product? Briefly explain (3 points)
3e. If the water solution of sodium sulfide is acidified, the reaction does not occur unless heated. Explain these results (3 points)
3f. What is the mechanism and product for the acidified reaction? 4 points
3g. What is the optical purity of this reaction? What is the optical rotation for this reaction? Briefly explain. (2 points)
- Our bodies use glycogen as way to store glucose, the main source of energy in our bodies. When glycogen is placed in phosphoric acid and water, glycogen will break apart to form glucose and a smaller glycogen molecule as is depicted in the reaction below. Consider and explain thoroughly the following questions about this reaction: (17 points)
O
HO
OH
HO
OH
O
O
HO HO
OH
O
O
HO HO
OH
O (Etc.)
O
HO
OH
HO
OH
OH O
HO HO
OH
O
O
HO HO
OH OH O^ (Etc.)
H 3 PO 4 / H 2 O
Glycogen (^) Glucose Glycogen - 1 glucose unit
A B^ C (^) A B C
4a. Circle the atoms and/or molecules that have changed in the above reaction? (1 points) 4b. What are the nucleophiles, electrophiles, acids and/or bases that may be involved in this reaction? ( points)
4c. What kind of reaction is this? Explain. (3 points)
4d. Why is phosphoric acid required in this reaction? (2 pts)
4e. Draw the mechanism for this reaction (5 pts)
4f. Why does the molecule fragment the way that it does? (Hint: Is there an alternative way that it could fragment; pay attention to the stereochemistry of the products to see this) (5 points)
