Question

(a) Draw the four isomers of \(\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O}\) that can be oxidized to an aldehyde. (b) Draw the three isomers of \(\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O}\) that can be oxidized to a ketone. (c) Draw the isomers of \(\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O}\) that cannot be easily oxidized to an aldehyde or a ketone. (d) Name any isomer that is an alcohol.

Short answer

1-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2,2-dimethyl-1-propanol; 2-pentanol, 3-pentanol, 3-methyl-2-butanol; 2-methyl-2-butanol; 1-pentanol.

Step-by-step solution

Identify Isomers Oxidizable to Aldehyde

For this step, identify the primary alcohols, because primary alcohols can be oxidized to aldehydes. The formula \(\text{C}_5\text{H}_{12}\text{O}\) has four structural isomers able to be oxidized to aldehydes. They are: 1-pentanol, 2-methyl-1-butanol, 2,2-dimethyl-1-propanol, and 3-methyl-1-butanol.

Draw Isomers Oxidizable to Aldehyde

Draw the structures for the isomers identified: 1. 1-pentanol (CH3(CH2)4OH)2. 2-methyl-1-butanol (CH3CH(CH3)CH2CH2OH)3. 3-methyl-1-butanol (CH3CH2CH(CH3)CH2OH)4. 2,2-dimethyl-1-propanol ((CH3)3COH).

Identify Isomers Oxidizable to Ketone

Secondary alcohols can be oxidized to ketones. The three isomers of \(\text{C}_5\text{H}_{12}\text{O}\) that can be oxidized to ketones are 2-pentanol, 3-pentanol, and 3-methyl-2-butanol.

Draw Isomers Oxidizable to Ketone

Draw the structures for the isomers identified: 1. 2-pentanol (CH3CH2CH(OH)CH2CH3)2. 3-pentanol (CH3CH2CH2CH(OH)CH3)3. 3-methyl-2-butanol (CH3CH(OH)CH(CH3)CH3).

Identify Isomers Not Easily Oxidizable to Aldehyde or Ketone

Tertiary alcohols cannot be easily oxidized. There is one such isomer of \(\text{C}_5\text{H}_{12}\text{O}\): 2-methyl-2-butanol.

Draw Isomers Not Easily Oxidizable to Aldehyde or Ketone

Draw the structure for 2-methyl-2-butanol (CH3C(CH3)(OH)CH2CH3).

Name Any Isomer That is an Alcohol

All isomers identified above are alcohols, but let's name one specifically: 1-pentanol is an example of an alcohol.

Key concepts

Organic Chemistry

Organic chemistry is the study of carbon-containing compounds and their properties. Carbon atoms can form stable bonds with many elements, resulting in a multitude of structures like chains, rings, and complex frameworks.
Chemists often classify organic compounds based on functional groups - specific groupings of atoms within molecules that have distinct chemical properties.
In this exercise, we're focusing on isomers of \(\text{C}_5\text{H}_{12}\text{O}\), specifically the various ways to arrange the five carbon atoms and one oxygen atom to form different compounds.

Aldehyde Oxidation

Aldehydes are organic compounds containing a carbonyl group (\(\text{C=O}\)) bonded to at least one hydrogen atom. Primary alcohols can be oxidized to form aldehydes.
For the isomers of \(\text{C}_5\text{H}_{12}\text{O}\), we identified primary alcohols like 1-pentanol and 3-methyl-1-butanol, which can be oxidized into corresponding aldehydes by losing hydrogen atoms and forming a double bond with oxygen.

Ketone Oxidation

Ketones are organic compounds characterized by a carbonyl group (\(\text{C=O}\)) bonded to two carbon atoms. Secondary alcohols can be oxidized into ketones.
In the case of \(\text{C}_5\text{H}_{12}\text{O}\), examples of secondary alcohols include 2-pentanol and 3-pentanol. These structures can be transformed into ketones through the removal of hydrogen atoms, resulting in a carbonyl group's formation between two carbon atoms.

Primary and Secondary Alcohols

Alcohols are classified as primary, secondary, or tertiary based on the carbon atom bonded to the hydroxyl group (\(\text{-OH}\)).
Primary Alcohols: The \(\text{-OH}\) group is attached to a carbon atom with only one other carbon atom. Examples include 1-pentanol and 2-methyl-1-butanol.
Secondary Alcohols: The \(\text{-OH}\) group is bonded to a carbon atom that is connected to two other carbon atoms, like 2-pentanol and 3-methyl-2-butanol. These classes of alcohols have different oxidation behaviors.

Tertiary Alcohols

A tertiary alcohol is identified when the \(\text{-OH}\) group is bonded to a carbon atom attached to three other carbon atoms. This structure makes tertiary alcohols like 2-methyl-2-butanol resistant to oxidation.
Because no hydrogen atoms are available on the carbon bearing the hydroxyl group, this type of alcohol cannot easily form an aldehyde or ketone. This stability is an important feature of tertiary alcohols in organic reactions.