Aldehydes and Ketones Chapter 4

Questions and Answers

What is the characteristic of the carbonyl group in aldehydes?

It has two carbons attached to the oxygen atom.

It has at least one hydrogen attached to the carbonyl group. (correct)

It is a non-polar group.

It has a strong hydrogen bond between molecules.

What is the process of naming aldehydes?

Find the longest chain that contains the aldehyde group and change the ending of the root hydrocarbon name by adding –e.

Name and number other substituents using the standard IUPAC system only.

Number the longest carbon chain so the C=O group has the highest number.

Find the longest carbon chain that contains the aldehyde group and change the ending of the root hydrocarbon name by dropping –e and adding –al. (correct)

What is the purpose of formaldehyde?

It is used as a solvent in nail polish remover.

It is used as a medicine for hormone imbalance.

It is used as a starting material for plastics. (correct)

It is used as a flavoring in food.

What is the characteristic of the physical properties of aldehydes and ketones?

The carbonyl group is moderately polar, but it cannot hydrogen bond between molecules. Signup and view all the answers

Which of the following is an example of a ketone?

Acetone Signup and view all the answers

What is the reason for the higher boiling point of aldehydes and ketones compared to alkanes?

The formation of hydrogen bonds with water molecules Signup and view all the answers

What is the product of the oxidation of aldehydes and ketones?

Carboxylic acids Signup and view all the answers

Why are aldehydes and ketones classified in separate families?

Due to their different reactivity towards oxidation Signup and view all the answers

What is the result of the hydrogenation of aldehydes and ketones?

The reduction to alcohols Signup and view all the answers

What type of bonding occurs between the oxygen atom in the carbonyl group and the hydrogen atom in the water molecule?

Hydrogen bonding Signup and view all the answers

Study Notes

Aldehydes and Ketones

Aldehydes have at least one hydrogen attached to the carbonyl group, while ketones have two carbons attached to the carbonyl group.

Naming Aldehydes

Find the longest carbon chain that contains the aldehyde group.
Change the ending of the root hydrocarbon name by dropping –e and adding –al.
Number the longest carbon chain so the C=O group has the lowest number.
All other branches and groups are named and located using standard IUPAC system.

Naming Ketones

Find the longest chain that contains C=O.
Using the root alkane name, drop the –e ending and change to –one.
Number the longest carbon chain so the C=O group has the lowest number.
Name and number other substituents as before.

Important Aldehydes and Ketones

Formaldehyde: a gas at room temperature, used as a sterilizer, embalming fluid, and starting material for plastics such as Formica and Bakelite.
Acetone (propanone): an important organic solvent, used in nail polish remover, and miscible with water.
Progesterone and Testosterone: female and male sex hormones, respectively, which are ketones.
Some aldehydes and ketones are used in flavorings, such as Vanillin (vanilla), Cinnamaldehyde (cinnamon), Citral (citrus flavoring), and Camphor (medicinal odor).

Physical Properties of Aldehydes and Ketones

The carbonyl group is moderately polar, but it cannot hydrogen bond between molecules.
The polarity of the C=O group allows for interactions, but the attraction is not as strong as hydrogen bonding.
The boiling point of aldehydes and ketones is higher than alkanes, but lower than alcohols.
Low molecular weight aldehydes and ketones are water-soluble due to hydrogen bonding with water molecules.

Reactions of Aldehydes and Ketones

Oxidation: aldehydes and ketones can be oxidized to produce other compounds.
The difference in reactivity toward oxidation is the chief reason why aldehydes and ketones are classified in separate families.
Hydrogenation: aldehydes and ketones can be reduced to alcohols by the addition of H2 in the presence of catalysts.