8.9 Oxidative Cleavage of Alkenes | Ozonolysis, Permanganate Cleavage of Alkenes | Organic Chemistry

Chad's Prep
25 Nov 202005:28
EducationalLearning
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TLDRThis lesson delves into the oxidative cleavage of alkenes, focusing on ozonolysis and permanganate cleavage. Ozonolysis involves the reaction of alkenes with ozone (O3), leading to the formation of ozonides that can be further manipulated with either reducing agents like dimethyl sulfide (DMS) or zinc and water, or with oxidizing agents such as hydrogen peroxide. Under reducing conditions, aldehydes remain unoxidized, while under oxidizing conditions, aldehydes are converted to carboxylic acids. The process is neatly summarized by cleaving the carbon-carbon double bond and oxidizing both sides to form ketones and aldehydes or carboxylic acids, depending on the conditions. Permanganate cleavage, performed under hot concentrated acidic conditions, achieves similar results to ozonolysis under oxidizing conditions, yielding ketones and carboxylic acids. The lesson emphasizes the importance of understanding the conditions that affect the final products of these reactions, without requiring knowledge of the full mechanisms.

Takeaways
  • 🧪 Oxidative cleavage of alkenes is a chemical reaction that breaks down alkenes using oxidizing agents.
  • 📚 The lesson is part of an organic chemistry series released weekly during the 2020-21 school year.
  • 🌟 Ozonolysis is a common method for oxidative cleavage, involving the reaction of alkenes with ozone (O3).
  • 🔍 The mechanism of ozonolysis is not fully detailed in the lesson but involves the formation of a melosinide and subsequent rearrangement to an ozonide.
  • ➡️ Ozonolysis occurs in two steps; the first involves ozone, and the second involves the addition of either a reducing or oxidizing agent.
  • 🛠️ Under reducing conditions, agents like dimethyl sulfide (DMS) or zinc and water are used, keeping aldehydes as aldehydes.
  • ⏫ Under oxidizing conditions, hydrogen peroxide is used, which can oxidize aldehydes to carboxylic acids.
  • ✂️ The general prediction for ozonolysis products involves cleaving the carbon-carbon double bond and oxidizing both sides to form a ketone and an aldehyde or carboxylic acid.
  • 📉 Ketones remain unchanged through the process, regardless of the conditions used.
  • 🔮 An alternative to ozonolysis is the use of hot concentrated permanganate under acidic conditions, which also achieves oxidative cleavage.
  • 📝 Students are not typically responsible for knowing the full mechanism of ozonolysis, according to the instructor.
  • 🌐 For additional resources, including a study guide and practice problems, the instructor recommends visiting chadsprep.com.
Q & A

  • What is the topic of this lesson?

    -The topic of this lesson is the oxidative cleavage of alkenes, specifically focusing on ozonolysis under both reducing and oxidizing conditions and permanganate cleavage.

  • What is ozonolysis?

    -Ozonolysis is a chemical reaction where an alkene reacts with ozone (O3) to form an ozonide intermediate, which then undergoes further reactions based on the conditions applied (reducing or oxidizing).

  • What are the two different sets of conditions for ozonolysis?

    -The two different sets of conditions for ozonolysis are reducing conditions and oxidizing conditions. Reducing conditions typically involve the use of dimethyl sulfide (DMS) or zinc and water, while oxidizing conditions use a mild oxidizing agent like hydrogen peroxide.

  • What happens to the aldehyde group during ozonolysis under reducing conditions?

    -Under reducing conditions, the aldehyde group remains as an aldehyde because the reducing agents prevent it from being further oxidized.

  • What is the product formed from an aldehyde group during ozonolysis under oxidizing conditions?

    -Under oxidizing conditions, the aldehyde group is further oxidized to form a carboxylic acid.

  • What is the general rule for predicting the products of ozonolysis?

    -To predict the products of ozonolysis, one should cleave the carbon-carbon double bond in half and then give both sides a double bond to oxygen. Ketones remain ketones regardless of the conditions, but aldehydes can be oxidized to carboxylic acids under oxidizing conditions.

  • What is the role of permanganate in oxidative cleavage?

    -Permanganate, under harsh conditions such as hot concentrated and acidic, acts as a strong oxidizing agent and can perform oxidative cleavage similar to ozonolysis under oxidizing conditions, resulting in the formation of a ketone and a carboxylic acid.

  • What is the structure of ozone involved in ozonolysis?

    -The structure of ozone involved in ozonolysis is O3.

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  • What does the term 'oxidative cleavage' imply in the context of alkene reactions?

    -Oxidative cleavage refers to the process where an alkene is broken down into two separate parts by the addition of oxygen, typically resulting in the formation of products like ketones, aldehydes, or carboxylic acids depending on the reaction conditions.

  • Why might a student not be expected to know the mechanism for ozonolysis?

    -Students might not be expected to know the mechanism for ozonolysis because it is complex and not typically a focus area in standard organic chemistry courses. The instructor suggests it's unlikely they would be held responsible for it.

  • How can one support the channel and get access to study guides and practice problems?

    -To support the channel, one can give a like and share the content. For access to study guides and practice problems, one can check out the instructor's premium courses on chadsprep.com.

  • What is the significance of the bell notification feature on the channel?

    -The bell notification feature ensures that subscribers are alerted every time a new lesson is posted, helping them to stay updated with the latest content without missing any lessons.

Outlines
00:00
🧪 Oxidative Cleavage of Alkenes through Ozonolysis

This paragraph introduces the topic of oxidative cleavage of alkenes, focusing on ozonolysis. It explains that the process involves the reaction of alkenes with ozone (O3), leading to the formation of a melosinide, which then rearranges to form an ozonide. The ozonide is the key intermediate that undergoes further reactions depending on the conditions applied in step two of ozonolysis. Two sets of conditions are discussed: reducing conditions, which might involve dimethyl sulfide (DMS) or zinc and water, and oxidizing conditions, which use hydrogen peroxide. The outcome of the reaction varies based on these conditions, with aldehydes being converted to carboxylic acids under oxidizing conditions, while they remain as aldehydes under reducing conditions. The paragraph also mentions that ketones formed during the process are not further oxidizable. Additionally, the concept of permanganate cleavage is introduced as an alternative to ozonolysis, which yields similar products under oxidizing conditions.

05:02
📚 Further Insights and Study Resources for Alkenes

The second paragraph provides additional commentary on the complexity of the ozonolysis mechanism and acknowledges that students are rarely expected to understand the entire mechanism. It emphasizes the practical aspects of the lesson and encourages viewers to like and share the content to support the channel. The speaker also directs viewers to his premium courses on chadsprep.com for further study materials and practice problems related to alkenes, suggesting that these resources can be beneficial for a deeper understanding of the subject matter.

Mindmap
Keywords
💡Oxidative Cleavage
Oxidative cleavage refers to the chemical process where a molecule, such as an alkene, is broken down into two or more parts by the addition of oxygen. In the context of the video, it is the main theme as it discusses the breaking down of alkenes using ozone (ozonolysis) or permanganate, which is crucial for understanding the reactions and products formed.
💡Ozonolysis
Ozonolysis is a specific type of oxidative cleavage that involves the reaction of an alkene with ozone (O3). The process results in the formation of an ozonide intermediate, which then breaks down to yield smaller molecules. In the video, ozonolysis is detailed with two sets of conditions: reducing and oxidizing, which affect the final products obtained.
💡Reducing Conditions
Reducing conditions in chemistry refer to the use of reagents that can donate electrons to other molecules, thereby reducing them. In the video, dimethyl sulfide (DMS) or zinc and water are used as reducing agents during ozonolysis, which prevents further oxidation of aldehydes to carboxylic acids.
💡Oxidizing Conditions
Oxidizing conditions are the opposite of reducing conditions and involve reagents that accept electrons, leading to the oxidation of other molecules. In the context of the video, hydrogen peroxide is used as a mild oxidizing agent in ozonolysis, which allows for the oxidation of aldehydes to carboxylic acids.
💡Alkene
An alkene is a type of hydrocarbon with at least one carbon-carbon double bond. Alkenes are the primary substrates for the oxidative cleavage reactions discussed in the video. The double bond in alkenes is central to the reactions, as it is the site where the cleavage occurs.
💡Ketone
A ketone is a type of organic compound featuring a carbonyl group (C=O) bonded to two other carbon atoms. In the video, it is mentioned that regardless of the reaction conditions, if one side of the cleaved alkene forms a ketone, it remains a ketone and is not further oxidized.
💡Aldehyde
An aldehyde is a compound containing a carbonyl group with at least one hydrogen atom attached to the carbonyl carbon. The video explains that the fate of the aldehyde depends on the reaction conditions: under reducing conditions, it remains an aldehyde, while under oxidizing conditions, it is converted to a carboxylic acid.
💡Carboxylic Acid
A carboxylic acid is an organic compound consisting of a carboxyl group (-COOH). In the video, it is shown that aldehydes can be further oxidized to carboxylic acids under oxidizing conditions during ozonolysis.
💡Permanganate Cleavage
Permanganate cleavage is an oxidative process using potassium permanganate (KMnO4) as an oxidizing agent. In the video, it is discussed that this method can achieve the same oxidative cleavage as ozonolysis under oxidizing conditions, resulting in the formation of a ketone and a carboxylic acid.
💡Dimethyl Sulfide (DMS)
Dimethyl sulfide, often abbreviated as DMS, is an organosulfur compound used in the video as a reducing agent during ozonolysis. It helps to maintain the aldehyde as an aldehyde by preventing its oxidation to a carboxylic acid.
💡Hydrogen Peroxide
Hydrogen peroxide (H2O2) is a common oxidizing agent. In the context of the video, it is used under oxidizing conditions during ozonolysis to oxidize aldehydes to carboxylic acids, thus affecting the final products of the reaction.
Highlights

Oxidative cleavage of alkenes is the main topic, focusing on ozonolysis under both reducing and oxidizing conditions.

Permanganate cleavage is discussed as an alternative to ozonolysis, yielding the same products under oxidizing conditions.

The lesson is part of an organic chemistry playlist released weekly throughout the 2020-21 school year.

Ozonolysis involves the reaction of an alkene with ozone (O3) to form a melosinide, which rearranges to an ozonide.

In ozonolysis, step one is the reaction with ozone, and step two involves adding either a reducing or oxidizing agent.

Dimethyl sulfide (DMS) or zinc and water are common reducing agents used in ozonolysis under reducing conditions.

Hydrogen peroxide is used as a mild oxidizing agent under oxidizing conditions in ozonolysis.

The products of ozonolysis can be predicted by cleaving the alkene and oxidizing both sides to form a ketone and an aldehyde or carboxylic acid.

Under reducing conditions, aldehydes remain aldehydes due to the action of reducing agents.

Under oxidizing conditions, aldehydes are oxidized to carboxylic acids.

Permanganate, when used under harsh conditions (hot and concentrated), achieves oxidative cleavage similar to ozonolysis under oxidizing conditions.

Ketones formed in oxidative cleavage remain ketones regardless of the conditions.

The mechanism for ozonolysis is not typically required knowledge for students, according to the lecturer's experience.

The lesson provides a practical approach to understanding the products of ozonolysis and permanganate cleavage without delving into complex mechanisms.

The importance of the conditions used in ozonolysis is emphasized, as they determine whether aldehydes are oxidized to carboxylic acids.

The lecture encourages subscribing to the channel and turning on notifications for new lesson updates.

Additional resources, including a study guide and practice problems, are available on the lecturer's website, chadsprep.com.

Transcripts

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