Organic Chemistry : Organic Chemistry

Study concepts, example questions & explanations for Organic Chemistry

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Example Questions

Example Question #3 : Carbonyl Reactions

Which of the following best summarizes a Claisan condensation?

Possible Answers:

The enolate of a dicarbonyl compound attacks a beta carbon of an alkene

The enolate of an ester attacks another ester

An alkyl halide reacts first with the phthalimide ion, then with 

A methyl ketone is treated with iodine and 

A carboxylic acid reacts first with then with water

Correct answer:

The enolate of an ester attacks another ester

Explanation:

The most acidic hydrogen of the ester gets abstracted and the enolate form of the compound is attained. The electrons from the carbon-carbon double bond attack the carbonyl carbon of the other ester. Deesterfication occurs in this same step. The final product has one ketone and one ester.

Example Question #11 : Carbonyl Reactions

What is the product of the following reaction?

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Possible Answers:

 and 

Correct answer:

Explanation:

The reaction uses a Grignard reagent's nucleophilic carbon to attack the carbon in carbon dioxide. Following treatment with water the resulting molecule (a carboxylate anion, of the form ) the carboxylate oxygen will be protonated, and the result is a carboxylic acid. Thus, the resulting molecule is a benzene ring with a carboxyl group attached (this is also known as benzoic acid).

Example Question #1 : Help With Other Named Reactions

 

 Wesag2o

Why does the reaction above require the use of Ag2O? 

Possible Answers:

The Ag2O reduces the alcohol to form the alkoxide ion

The Ag2O attacks the alcohol to form the ether

The Ag2O is an inert solvent and allows the alcohol to attack and from the product without interference

The Ag2O oxidizes the alkyl halide to form the ether

The Ag2O oxidizes the alcohol to form the alkoxide ion

Correct answer:

The Ag2O oxidizes the alcohol to form the alkoxide ion

Explanation:

The Ag2O oxidizes the alcohol to form the alkoxide ion. The Ag2O is a reducing agent, and it oxidizes the alcohol because the alcohol loses a proton. Ag2O is a strong base, meaning it will accept protons readily. The given reaction is an example of Williamson ether synthesis. This reaction occurs via an SN2 pathway. 

Example Question #2 : Help With Other Named Reactions

What is the IUPAC name of the following compound?

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Possible Answers:

2-bromo-1-methylcyclohexene

6-bromo-1-methylcyclohexene

1-bromo-2-methyl-2-cycloxene

None of the other answers

3-bromo-2-methylcyclohexene

Correct answer:

3-bromo-2-methylcyclohexene

Explanation:

The numbering of the molecule begins across the double bond and goes in the direction where the lowest numbers for substituents can be achieved. Thus, the methyl group will be on carbon two and the bromine on carbon 3. Substituents are ordered alphabetically. The base molecule is a six-membered ring with one double bond. This is called a cyclohexene.

Example Question #3 : Help With Other Named Reactions

What is the proper name of this molecule?

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Possible Answers:

Z-2-isohexene

E-3-methyl-3-pentene

E-2-ethyl-2-butene

E-3-methyl-2-pentene

None of the other answers

Correct answer:

E-3-methyl-2-pentene

Explanation:

The longest chain has five carbons and a double bond, so the base molecule is pentene. There is a methyl group on carbon 3. The double bond is between carbons two and three. The highest priority substituents are the ethyl group on one side and the methyl group on the other. One is up and one is down, so the molecule is E as opposed to Z.

Example Question #4 : Help With Other Named Reactions

Which of the following best summarizes the Michael reaction?

Possible Answers:

An alkyl halide reacts first with the phthalimide ion, then with 

A methyl ketone is treated with iodine and 

The enolate of a dicarbonyl compound attacks a beta carbon of an alkene

The enolate of an ester attacks another ester

A carboxylic acid reacts first with then with water

Correct answer:

The enolate of a dicarbonyl compound attacks a beta carbon of an alkene

Explanation:

The most acidic carbon in a dicarbonyl gets abstracted to form an enolate. The reaction involves a ketone with a double bond between the alpha and beta carbons. The carbon-carbon souble bond electrons attack the beta carbon of the alkene. At this point, the electrons from the alkene move to form a double bond between the carbonyl and alpha carbon and an enolate is fromed. The negative oxygen bonds to a hydrogen, forming the enol. Through enol-ketone tautamerization, a ketone is formed.

Example Question #5 : Help With Other Named Reactions

Which of the following best summarizes a Gabriel synthesis?

Possible Answers:

An alkyl halide reacts first with the phthalimide ion, then with

A methyl ketone is treated with iodine and

A carboxylic acid reacts first with then with water

The enolate of an ester attacks another ester

The enolate of a dicarbonyl compound attacks a beta carbon of an alkene

Correct answer:

An alkyl halide reacts first with the phthalimide ion, then with

Explanation:

An alkyl halide and phtalimide react under basic conditions to form a primary amine. The halogen leves and the nitrogen of the phtahlimide bonds to that carbon on the alkane. In the next step, the nitrogen leave the phthalimide. In the presence of base, the phthalimide gains two negative oxygens in the stead of the nitrogen. The final product is a primary amine. 

Example Question #6 : Help With Other Named Reactions

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For the given free radical halogenation reaction, which of the following is the product?

1.1

2. 2

3. 3

 4. 4

5. 5

Possible Answers:

2

Correct answer:

Explanation:

In a free radical halogenation, a bromine group will form a bond with the most substituted carbon atom. This method leads to the most stable radical intermediate.

Example Question #6 : Help With Other Named Reactions

Screen shot 2015 12 19 at 12.32.57 pm

Which of the following is the correct IUPAC name for the compound given?

Possible Answers:

2-methyl-4-hexanal

2-ethyl-4-methylpentanal

2-methyl-4-ethylpentanal

2-ethyl-4-methylpentanal

Correct answer:

2-ethyl-4-methylpentanal

Explanation:

The compound given has an aldehyde functional group and the parent chain has to have the -CHO group. Below is how the compound given should be numbered:

Screen shot 2015 12 20 at 9.45.33 pm

Aldehydes are named by changing the ending -e from the corresponding alkane with -al. The substituents on the parent chain should be named in alphabetical order. Therefore the answer is 2-ethyl-4-methylpentanal.

Example Question #7 : Help With Other Named Reactions

Screen shot 2015 12 19 at 12.45.00 pm

Which of the following is the correct IUPAC name for the compound given?

Possible Answers:

4-chloro-3-methylhexanol

4-chloro-6-hydroxy-3-methylhexane

3-chloro-4-methylhexanol

4-methyl-3-chlorolhexanol

Correct answer:

3-chloro-4-methylhexanol

Explanation:

The compound given has an alcohol functional group and the parent chain has to have the hydroxyl functional group. Below is how the compound given should be numbered:

Screen shot 2015 12 20 at 10.23.57 pm

Alcohols are named by changing the ending -e from the corresponding alkane with -ol. The substituents on the parent chain should be named in alphabetical order. Therefore the answer is 3-chloro-4-methylhexanol.

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