Organic Chemistry : Help with Aldehyde and Ketone Synthesis

Study concepts, example questions & explanations for Organic Chemistry

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Example Questions

Example Question #1 : Carbonyl Products

What reagents are required to undergo Swern oxidation?

Possible Answers:

COCl2, triethylamine, and DMSO

SOCl2, pyridine, and triethylamine

Diethyl ether, organometallic compound, and H3O+

Dichloromethane, trimethylamine, and DMS

Pyridine, DMSO, and HCOOH 

Correct answer:

COCl2, triethylamine, and DMSO

Explanation:

Swern oxidation requires COCl2, triethylamine, and DMSO. The same reaction can be accomplished using PCC and dichloromethane. This reaction oxidizes an alcohol to a carbonyl, but only works with primary and secondary alcohols. 

 

Example Question #2 : Carbonyl Products

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Which of the following reactions will result in the given product?

Possible Answers:

E

C

A

D

B

Correct answer:

C

Explanation:

The starting material first needs to be brominated, which occur at the tertiary carbon. Then, an elimination reaction needs to take place to form an alkene intermediate, which will transpire through the E2 pathway with the tertbutoxide ion in tertbutanol. After this, an alcohol needs to be formed through hydroboration because we need the carbonyl group on the less subsituted carbon. After an alcohol is formed, the PCC reaction can oxidize the alcohol to make it a carbonyl. All these reactions are shown in choice C. 

Example Question #3 : Carbonyl Products

A compound, , is reacted with sodium ethoxide to give the single elimination product . This product then reacts with ozone, zinc, and water to give the product shown below.

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What is the original compound?

Possible Answers:

2-chloro-1,1-dimethylcyclopentane

1-chloro-1,2-dimethylcyclopentane

4-chloro-1,2-dimethylcyclopentane

2-chloro-1,3-dimethylcylopentane

None of the other answers

Correct answer:

2-chloro-1,3-dimethylcylopentane

Explanation:

In the first step of the reaction, a chlorine is abstracted and a double bond is formed. In the ozonolysis step, the molecule is broken at the double bond and each carbon at that bond gets double bonded to an oxygen. The presence of zinc keeps it from becoming a carboxylic acid.

Working backwards, you must remove the oxygens from the final product and redraw the molecule at the double bond. This intermediate is 1,3-dimethylcyclopentene. Next, the chlorine must be added to one of the carbons on the double bond. The only possible choice is 2-chloro-1,3-dimethylcyclopentane.

Example Question #4 : Carbonyl Products

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Which of the following reagents is required to produce the ketone product?

Possible Answers:

Correct answer:

Explanation:

In order to convert a secondary alcohol into a ketone, we must employ  as a reagent.

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