Alcohol Reactions: Oxidation Reactions - Online Tutor, Practice Problems & Exam Prep

Oxidation reactions of alcohols involve the use of oxidizing agents like Sodium Dichromate or Potassium Dichromate in sulfuric acid. These agents facilitate the formation of carbon-oxygen bonds without breaking carbon-carbon bonds. Alcohols can be oxidized to carbonyl compounds, such as aldehydes or ketones, and further to carboxylic acids. Understanding these transformations is crucial in organic chemistry, particularly in the context of functional groups and their reactivity.

Alcohol Reactions: Oxidation Concept 1

In this video, we're going to take a look at alcohol reactions in terms of oxidation reactions. So, we're going to say here that the oxidizing agent is either Sodium Dichromate or Potassium Dichromate. They're interchangeable because sodium and potassium are both group 1A elements. It's really the dichromate portion that's the oxidizing agent. So here we have the oxidizing agent of either one of these dissolved in sulfuric acid reacts with an alcohol. Now, an oxidizing agent is the compound used to oxidize alcohols. And here, we're going to say it adds as many carbon-oxygen bonds as possible without breaking any carbon-carbon bonds.

If we take a look here, we're graying out our hydrocarbon and we're graying out our carbon dioxide. We're focused mainly on the shaded portion. This is the portion in organic chemistry where we deal with oxidation reactions. So here we have an alcohol, and this alcohol here, we could oxidize it to a carbonyl compound. In this example, we see it as an aldehyde, but it could also represent a ketone. So here, this middle section could represent an aldehyde or a ketone. Then, that could also further oxidize to give us a carboxylic acid. So when we're talking about oxidation, we're really focusing on these types of functional groups: alcohols to aldehydes or ketones, to carboxylic acid if necessary. Just remember, we're trying to add as many carbon-oxygen bonds without breaking any carbon-carbon bonds. This is the rule that we have to follow to get our proper oxidized product.

Alcohol Reactions Oxidation Reactions Example 1

Here it says, determine the product created under the following oxidation reaction. So here we have our alcohol, we have Potassium dichromate as our oxidizing agent over sulfuric acid. So remember, we want to add as many carbon-oxygen bonds without breaking any carbon-carbon bonds. So if we take a look here, we have CH₃CH₂CH₂. And here it's going to be important that I show the bonds that could potentially be affected for this alcohol. Now we know that if we're oxidizing this, we know that we're going to form at least a carbon double bonded to an oxygen. And if I do that, this carbon is already making 3 bonds. Remember, it can only go up to 4 bonds. Here, if I just had it as an H here, we'd have an aldehyde. But have I gone the full distance to replace any carbon-hydrogen bonds with as many carbon-oxygen bonds? I haven't because I could remove this H and put an oxygen there. So I've made as many carbon-oxygen bonds as possible, and remem

Determine the product created under the following oxidation reaction.

• A.
• B.
• C.
• D.

Which of the following alcohols cannot undergo an oxidation reaction?

• A. 2-butanol
• B. 3-heptanol
• C. 2-methyl-2-propanol
• D. 1-propanol

Here’s what students ask on this topic:

What are the common oxidizing agents used in the oxidation of alcohols?

Common oxidizing agents used in the oxidation of alcohols include Sodium Dichromate (Na₂Cr₂O₇) and Potassium Dichromate (K₂Cr₂O₇). These agents are typically dissolved in sulfuric acid (H₂SO₄) to facilitate the oxidation process. The dichromate ion (Cr₂O₇^2-) is the active component that oxidizes the alcohol by increasing the number of carbon-oxygen bonds without breaking any carbon-carbon bonds. This process can convert primary alcohols to aldehydes and further to carboxylic acids, and secondary alcohols to ketones.

How does the oxidation of primary alcohols differ from the oxidation of secondary alcohols?

The oxidation of primary alcohols typically proceeds in two stages. First, the primary alcohol is oxidized to an aldehyde. If further oxidation occurs, the aldehyde can be converted to a carboxylic acid. In contrast, the oxidation of secondary alcohols results in the formation of ketones. Secondary alcohols do not oxidize further to carboxylic acids because there is no hydrogen atom attached to the carbonyl carbon in ketones, which is necessary for further oxidation.

What is the role of sulfuric acid in the oxidation of alcohols?

Sulfuric acid (H₂SO₄) acts as a solvent and a catalyst in the oxidation of alcohols. It helps to dissolve the oxidizing agents, such as Sodium Dichromate or Potassium Dichromate, and provides an acidic environment that facilitates the oxidation reaction. The acidic medium helps to protonate the alcohol, making it more susceptible to oxidation by the dichromate ion (Cr₂O₇^2-).

Why is it important to avoid breaking carbon-carbon bonds during the oxidation of alcohols?

In the oxidation of alcohols, it is important to avoid breaking carbon-carbon bonds to ensure the integrity of the carbon skeleton of the molecule. Breaking carbon-carbon bonds would lead to fragmentation and the formation of smaller, often undesired, products. The goal of oxidation reactions in organic chemistry is to increase the number of carbon-oxygen bonds while maintaining the original structure of the molecule, thereby converting alcohols to more oxidized functional groups like aldehydes, ketones, or carboxylic acids.

Can tertiary alcohols be oxidized using Sodium Dichromate or Potassium Dichromate?

Tertiary alcohols cannot be oxidized using Sodium Dichromate (Na₂Cr₂O₇) or Potassium Dichromate (K₂Cr₂O₇). This is because tertiary alcohols lack a hydrogen atom attached to the carbon bearing the hydroxyl group, which is necessary for the oxidation process. As a result, tertiary alcohols are resistant to oxidation under these conditions and do not form carbonyl compounds or carboxylic acids.