Lab Test #1
Chem 24 - Dr Kline
Tuesday, March 22, 2016
Name _______________________________________
This lab test covers the following labs: Oxidation, Reduction, and Grignard and their associated
techniques, including NMR lectures. This lab test is closed notebook.
1. 4 points Diethyl ether is the solvent used in the preparation of the Grignard reagent. • How does diethyl ether help to limit the contact between the Grignard reagent and water?
• Aside from the above, how does the diethyl ether help to ensure that the Grignard reagent survives to
react with the acetophenone?
2. 5 points Complete a splitting tree for Ha in the molecule below. Label each splitting in the tree, e.g. Jab. Use
the following coupling constant values: Jab = 16 Hz and Jac = 4 Hz. Draw the appearance of the signal below
the tree, using the same scale. Then use words, such as “triplet of triplets” to describe the appearance of the
peak.
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description of peak ____________________________________
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3. 3 points Calculate the expected chemical shift for each of the chemically non-equivalent boldfaced
hydrogens. Show work!
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4. 4 points Circle the compound that is expected have NaBH4 attack axially to the larger extent in a reduction
reaction. Justify your choice.
5. 4 points During the isolation of 1,1-diphenylethanol in the Grignard lab, hexane was added to the dried either
solution of the product and then the diethyl ether was evaporated, leaving the hexane (and product) behind.
Would simply evaporating the ether off passively, as was done for both the oxidation and reduction lab
products, have worked as well here? Why or why not?
6. 4 points Which reagent was in excess during the reduction of 4-tert-butylcyclohexanone? How do you know,
based on observations made during the reaction or the isolation of the product?
7. 4 points Define atom economy.
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8. 4 points Suppose a student obtains the following TLC of the reaction mixture at the end of the oxidation
reaction, where A=reference alcohol, B=reference ketone, and C=reaction mixture. When an infrared
spectrum is taken of the isolated product, there is a significant O-H stretch. Can you tell with reasonable
confidence if the O-H is due to the presence of alcohol, water, or both? If so, how can you tell? If you can’t
tell, why not?
9. 4 points What would be an appropriate way to evaporate the diethyl ether as described in question #5 so as
to reduce the change of starting a fire? If a fire were to start in your flask or beaker, what could you do to try
to extinguish it?
10. 4 points Indicate whether each of the following statements is true or false. If false, correct it by replacing one
word, or several words with a new word or words. In other words, don’t correct it simply by adding a “not” or
something similar.
_____
In the reaction between 4-tert-butylcyclohexanone and sodium borohydride, 4-tertbutylcyclohexanone is the oxidizing agent.
_____
In the reaction between 4-tert-butylcyclohexanol and HOCl, the 4-tert-butylcyclohexanol is the
oxidizing agent.
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The KI-starch paper used in the first lab tests for the presence of 4-tert-butylcyclohexanone. _____
The infrared spectrum of 4-tert-butylcyclohexanone was run using NaCl plates.
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