Cleavage of Carbon-Carbon Bonds With Periodic Acid
TLDRThe video script explores the role of periodic acid, HIO4, in organic synthesis, focusing on its ability to cleave carbon-carbon bonds in polyhydroxy compounds with adjacent hydroxyl groups. It demonstrates how this reagent acts as an oxidizing agent, converting diols into aldehydes, ketones, or carboxylic acids, depending on the substrate. The script also explains the mechanism behind this transformation, involving the formation of a cyclic periodate ester and the subsequent cleavage of the carbon-carbon bond, resulting in the production of iodic acid and water. This technique is highlighted as a valuable addition to the organic synthesis toolkit.
Takeaways
- 🔍 Periodic acid (HIO4) is a reagent of interest in organic synthesis for forming and cleaving carbon-carbon bonds.
- 🧪 The prefix 'per' in periodic acid indicates the presence of multiple oxygen atoms, with iodine forming seven covalent bonds.
- 🌟 Periodic acid acts as an oxidizing agent rather than a Bronsted-Lowry acid in the cleavage of carbon-carbon bonds.
- ⚔️ Oxidation with periodic acid targets polyhydroxy compounds, especially when hydroxyl groups are adjacent on carbons.
- 📚 The reaction produces carbonyl compounds, which can be aldehydes or ketones, and iodic acid from periodic acid.
- 🧪 Glycerol, with three hydroxyl groups, requires two equivalents of periodic acid, yielding formaldehyde and formic acid.
- 🔄 Oxidation can occur multiple times depending on the number of adjacent hydroxyl or carbonyl groups.
- 🌀 Glyceraldehyde demonstrates how each oxygen-containing functional group is oxidized based on neighboring groups.
- 📉 Dihydroxyacetone shows that oxidation can lead to the production of carbon dioxide when a ketone has two adjacent hydroxyls.
- ⛓ The absence of oxygen-containing groups on intervening carbons prevents bond cleavage, as in the modified glycerol example.
- 🔬 The mechanism involves the formation of a cyclic periodate ester, which undergoes cyclization and cleavage to form products.
Q & A
Why are carbon-carbon bonds important in organic synthesis?
-Carbon-carbon bonds are crucial in organic synthesis because organic molecules consist of a carbon skeleton that needs to be assembled, and these bonds form the backbone of the molecule.
What is the significance of having techniques to cleave carbon-carbon bonds?
-Techniques to cleave carbon-carbon bonds are important for isolating specific fragments of larger molecules, which can be necessary for various reasons in organic synthesis.
What is the chemical formula of periodic acid and what does the prefix 'per' indicate?
-The chemical formula of periodic acid is HIO4. The prefix 'per' indicates the number of oxygen atoms in the compound, which in this case is four.
How does the iodine atom in periodic acid form its covalent bonds?
-The iodine atom in periodic acid forms seven covalent bonds using its seven valence electrons, resulting in three double bonds to oxygen and one bond to a hydroxyl group.
Why does periodic acid act as an oxidizing agent rather than a Bronsted-Lowry acid in this context?
-In the context of cleaving carbon-carbon bonds in polyhydroxy compounds, periodic acid acts as an oxidizing agent because it facilitates the oxidation of the substrate, leading to the formation of carbonyl groups and the cleavage of the carbon-carbon bond.
What type of compounds does periodic acid oxidize?
-Periodic acid oxidizes polyhydroxy compounds, specifically when the hydroxyl groups are on adjacent carbons, leading to the cleavage of the carbon-carbon bond and the formation of carbonyl groups.
What happens when periodic acid reacts with glycerol?
-When periodic acid reacts with glycerol, which has three hydroxyl groups on consecutive carbons, it results in the formation of two equivalents of formaldehyde and one equivalent of formic acid.
How does the oxidation of a hydroxyl group adjacent to a carbonyl group differ from that of terminal hydroxyls?
-A hydroxyl group adjacent to a carbonyl group is oxidized twice to give formic acid, whereas terminal hydroxyls, each having only one hydroxyl next door, are oxidized only once to produce the aldehyde.
What is the outcome of the oxidation of dihydroxyacetone with periodic acid?
-The oxidation of dihydroxyacetone with periodic acid results in the formation of formaldehyde from the terminal hydroxyls and carbon dioxide from the ketone, which has two hydroxyls adjacent.
Why is it necessary for hydroxyl or carbonyl groups to be on adjacent carbons for the oxidation reaction with periodic acid to occur?
-For the oxidation reaction with periodic acid to occur, it is necessary for hydroxyl or carbonyl groups to be on adjacent carbons because the mechanism of the reaction involves the interaction of these functional groups with the periodic acid, leading to the cleavage of the carbon-carbon bond.
What is the key intermediate formed during the oxidation of polyhydroxy compounds by periodic acid?
-The key intermediate formed during the oxidation is a cyclic periodate ester, which undergoes cyclization and leads to the cleavage of the carbon-carbon bond and the formation of carbonyl groups.
Outlines
🧪 Formation and Cleavage of Carbon-Carbon Bonds in Organic Synthesis
This paragraph introduces the significance of forming and cleaving carbon-carbon bonds in organic synthesis, emphasizing the importance of the carbon skeleton in organic molecules. It introduces periodic acid (HIO4) as a reagent that can cleave carbon-carbon bonds in polyhydroxy compounds, specifically when hydroxyl groups are adjacent. The paragraph explains that the cleavage results in the formation of carbonyl groups, which can be aldehydes or ketones, and that periodic acid acts as an oxidizing agent in this process. It also provides examples, such as the reaction of periodic acid with glycerol, leading to the production of formaldehyde and formic acid, and discusses the oxidation of terminal and internal hydroxyl groups, as well as hydroxyl groups adjacent to a carbonyl.
🔍 Mechanism of Periodic Acid Oxidation in Organic Synthesis
The second paragraph delves into the mechanism of how periodic acid oxidizes compounds with adjacent hydroxyl groups. It describes the electron-deficient nature of the iodine atom in periodic acid, which allows it to form a complex with hydroxyl groups. The paragraph outlines the steps of the reaction, starting with the coordination of hydroxyl groups to iodine, followed by the transfer of protons and the formation of a cyclic periodate ester intermediate. This intermediate then undergoes a cyclization reaction, leading to the cleavage of the carbon-carbon bond and the formation of two carbonyl groups, while also producing iodic acid and water. The summary highlights the reliability of this method for predicting the products of oxidation based on the number of neighboring oxygen-containing functional groups and notes that no reaction occurs if there are intervening carbons without such functionality.
Mindmap
Keywords
💡Organic Synthesis
💡Carbon-Carbon Bonds
💡Periodic Acid
💡Oxyacids
💡Covalent Bonds
💡Vicinal Diol
💡Oxidation
💡Glycerol
💡Glyceraldehyde
💡Dihydroxyacetone
💡Cyclic Periodate Ester
Highlights
Importance of forming and cleaving carbon-carbon bonds in organic synthesis.
Introduction to periodic acid (HIO4) as a reagent for cleaving carbon-carbon bonds.
Periodic acid acts as an oxidizing agent rather than a Bronsted-Lowry acid.
Oxidation of polyhydroxy compounds with adjacent hydroxyl groups by periodic acid.
Conversion of vicinal diols into carbonyls through periodic acid oxidation.
Glycerol's reaction with periodic acid yielding formaldehyde and formic acid.
Oxidation of terminal and internal hydroxyls in glycerol by periodic acid.
Glyceraldehyde's oxidation by periodic acid involving multiple oxygen-containing functional groups.
Method to determine the number of oxidations based on neighboring functional groups.
Dihydroxyacetone's unique oxidation to produce carbon dioxide.
Requirement of adjacent hydroxyl or carbonyl groups for periodic acid oxidation.
No reaction occurs without adjacent oxygen-containing functionality.
Mechanism of periodic acid oxidation involving electron-deficient iodine.
Formation of a cyclic periodate ester intermediate in the oxidation process.
Cyclization and cleavage of carbon-carbon bonds in the oxidation mechanism.
Production of iodic acid and water as byproducts in the oxidation reaction.
Use of periodic acid oxidation in breaking up molecules or opening cyclic substrates.
Periodic acid oxidation as a valuable technique in the organic synthesis toolkit.
Transcripts
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