Organic Chemistry : Identifying Carbonyl Compounds

Study concepts, example questions & explanations for Organic Chemistry

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Example Questions

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Example Question #1 : Identifying Carbonyl Compounds

Identify the given organic functional group.

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Possible Answers:

Aldehyde

Ketone

Acid anhydride

Ester

Carboxylic acid

Correct answer:

Aldehyde

Explanation:

Aldehydes are carbonyls with one R-group and one hydrogen attached to the carbonyl carbon.

Example Question #2 : Identifying Carbonyl Compounds

Identify the given organic functional group.

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Possible Answers:

Ester

Aldehyde

Carboxylic acid

Acetal

Ketone

Correct answer:

Ketone

Explanation:

Ketones are carbonyls with two R-groups attached the the carbonyl carbon.

Example Question #1 : Identifying Carbonyl Compounds

Identify the given organic functional group.

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Possible Answers:

Acid halide

Ester

Acid anhydride

Amide

Carboxylic acid

Correct answer:

Acid halide

Explanation:

This is an acid halide, were X is any halogen (group VII). They are the most reactive of all the carboxylic acid derivatives.

Example Question #3 : Identifying Carbonyl Compounds

Identify the given organic functional group.

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Possible Answers:

Ketone

Ester

Aldehyde

Carboxylic acid

Acid anhydride

Correct answer:

Carboxylic acid

Explanation:

Carboxylic acids are composed of one R goup and a hydroxy group bound to the carbonyl carbon. The hydroxyl group gives the molecule acidic properties.

Example Question #4 : Identifying Carbonyl Compounds

Identify the given organic functional group.

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Possible Answers:

Acid anhydride

Acetal

Hemiketal

Aldehyde

Ester

Correct answer:

Hemiketal

Explanation:

This is a hemiketal. Hemiketals are formed from the reaction of a ketone with an alcohol. The alcohol attacks the carbonyl carbon, reducing the double bond and adding a hydroxyl group.

Example Question #5 : Identifying Carbonyl Compounds

Identify the given organic functional group.

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Possible Answers:

Hemiacetal

Acetal

Ketal

Acid anhydride

Hemiketal

Correct answer:

Ketal

Explanation:

Ketals have two -OR groups bound to a central carbon. The R groups attached to the oxygens are not necessarily the same. Ketals result from the reaction of a ketone with two equivalents of alcohol.

Example Question #2 : Identifying Carbonyl Compounds

Identify the given organic functional group.

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Possible Answers:

Carboxylic acid

Hemiacetal

Ester

Acid anhydride

Acetal

Correct answer:

Acid anhydride

Explanation:

Acid anhydrides are relatively reactive, since they have a fairly good leaving group (the conjugate base of a carboxylic acid) [COO-]. They are formed by reacting two carboxylic acids via dehydration synthesis.

Example Question #6 : Identifying Carbonyl Compounds

Identify the given organic functional group.

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Possible Answers:

Amine

Ether

Ester

Amide

Imine

Correct answer:

Amide

Explanation:

This is an amide. It is very unreactive since its leaving group is the conjugate base of an amine [HNR-]. 

Example Question #7 : Identifying Carbonyl Compounds

Identify the given organic functional group.

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Possible Answers:

Ketone

Ester

Carboxylic acid

Ether

Aldehyde

Correct answer:

Ester

Explanation:

Esters are relatively unreactive since the leaving group is an alkoxide ion (OR-), which is the conjugate base of an alcohol (a relatively weak acid). 

Example Question #1 : Identifying Carbonyl Compounds

Sigma and pie bonds

How many sigma and pi bonds, respectively, are there in the given molecule?

Possible Answers:

 pi bonds,  sigma bond

 pi bonds,  sigma bond

 sigma bonds,  pi bond

 sigma bonds,  pi bond

Correct answer:

 sigma bonds,  pi bond

Explanation:

To answer this question, it's important to recall what sigma bonds and pi bonds are. Sigma bonds are the result of overlapping s orbitals, and are contained in all bonds. Pi bonds, on the other hand, are the result of p orbitals overlapping.

Double bonds between atoms consist of one sigma bond (from overlapping s orbitals) and one pi bond (from overlapping p orbitals). Triple bonds, though not shown in this molecule, consist of one sigma bond and two pi bonds.

In the molecule shown in this question, we can recognize the following bonds:

1 carbon-oxygen double bond, which is equal to one sigma bond and one pi bond

2 carbon-carbon single bonds, which equates to two sigma bonds

6 carbon-hydrogen single bonds, which equals six sigma bonds

Adding these up, we obtain a total of nine sigma bonds and one pi bond.

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