19.3 Oxidation of Aldehydes and Ketones
2 min read•may 7, 2024
and react differently to due to their structures. Aldehydes easily form with oxidizing agents, while resist oxidation. This difference stems from the group's position and surrounding atoms.
Various oxidizing agents can convert aldehydes to carboxylic acids, each with unique properties. Understanding these reactions is crucial for predicting outcomes and choosing appropriate reagents in organic synthesis involving carbonyl compounds.
Oxidation of Aldehydes and Ketones
Aldehyde oxidation to carboxylic acids
Top images from around the web for Aldehyde oxidation to carboxylic acids
organic chemistry - Reaction mechanism for oxidation of primary alcohol to carboxylic acid ... View original
Is this image relevant?
22.1. Introduction | Organic Chemistry II View original
Is this image relevant?
18.3 Aldehydes, Ketones, Carboxylic Acids, and Esters | Chemistry View original
Is this image relevant?
organic chemistry - Reaction mechanism for oxidation of primary alcohol to carboxylic acid ... View original
Is this image relevant?
22.1. Introduction | Organic Chemistry II View original
Is this image relevant?
1 of 3
Top images from around the web for Aldehyde oxidation to carboxylic acids
organic chemistry - Reaction mechanism for oxidation of primary alcohol to carboxylic acid ... View original
Is this image relevant?
22.1. Introduction | Organic Chemistry II View original
Is this image relevant?
18.3 Aldehydes, Ketones, Carboxylic Acids, and Esters | Chemistry View original
Is this image relevant?
organic chemistry - Reaction mechanism for oxidation of primary alcohol to carboxylic acid ... View original
Is this image relevant?
22.1. Introduction | Organic Chemistry II View original
Is this image relevant?
1 of 3
- Aldehydes undergo oxidation to form carboxylic acids using various oxidizing agents (, )
- Oxidation occurs at the carbonyl carbon, converting the -CHO group to a -COOH group
- The hydrogen atom attached to the carbonyl carbon is replaced by a hydroxyl group (-OH)
- General reaction: ( = alkyl group or hydrogen, = oxidizing agent)
- Mechanism involves of oxidizing agent to carbonyl carbon, proton transfer, elimination of water, and formation of carboxylic acid product
- intermediate forms during the oxidation process
- Proton transfer from oxidizing agent to yields the final carboxylic acid
- The carbonyl group's electron-withdrawing nature facilitates nucleophilic addition during oxidation
Ketone resistance to oxidation
- Ketones resist oxidation due to their molecular structure and
- Two alkyl groups attached to the carbonyl carbon create steric hindrance, making it difficult for oxidizing agents to approach and react
- Lack of an -hydrogen prevents formation of the hydrate intermediate necessary for oxidation
- Oxidation of ketones requires breaking a carbon-carbon bond, which is energetically unfavorable compared to breaking a C-H bond in aldehydes
- Strong oxidizing agents (potassium permanganate under acidic conditions) can cleave the C-C bond adjacent to the carbonyl group, forming carboxylic acids
- of ketones can occur under specific conditions, yielding two carboxylic acid products
Oxidizing agents for aldehydes
- Chromic acid (): Prepared by dissolving chromium trioxide () in aqueous sulfuric acid (), produces carboxylic acids from aldehydes
- Potassium permanganate (): Used under acidic, neutral, or basic conditions, oxidizes aldehydes to carboxylic acids under acidic conditions
- (): Milder oxidizing agent compared to chromic acid, selectively oxidizes aldehydes to carboxylic acids without affecting other functional groups
- (): Prepared by mixing silver nitrate () with ammonia (), oxidizes aldehydes to carboxylate salts, producing a silver mirror on the reaction vessel
- : Prepared by mixing copper(II) sulfate () with sodium potassium tartrate (Rochelle salt) in aqueous sodium hydroxide (), oxidizes aldehydes to carboxylate salts, producing a red precipitate of copper(I) oxide ()
Oxidation and Reduction in Carbonyl Chemistry
- of carbon atoms in aldehydes and ketones affect their reactivity
- Oxidation involves an increase in oxidation state, while decreases it
- Aldehydes are more easily oxidized than ketones due to their lower oxidation state
- Reduction of carbonyls (aldehydes and ketones) produces alcohols through nucleophilic addition of hydride
Key Terms to Review (25)
Aldehydes: Aldehydes are a class of organic compounds characterized by the presence of a carbonyl group (C=O) with a hydrogen atom attached to the carbon. They are important intermediates in many chemical reactions and have a wide range of applications in various industries, from pharmaceuticals to fragrances.
Carbonyl: The carbonyl group is a functional group consisting of a carbon atom double-bonded to an oxygen atom. It is a key structural feature in many organic compounds, including aldehydes, ketones, carboxylic acids, and esters, and plays a crucial role in their chemical reactivity and properties.
Carboxylate Ion: The carboxylate ion is a negatively charged species formed when a carboxylic acid loses a proton (H+). It is a key intermediate in various organic chemistry reactions and plays a crucial role in understanding the structure and properties of carboxylic acids, as well as their reactions and the chemistry of acid anhydrides.
Carboxylic Acids: Carboxylic acids are a class of organic compounds containing a carboxyl functional group (-COOH) attached to an alkyl or aryl group. They are characterized by their acidic properties and play a crucial role in various chemical reactions and biological processes.
Carboxylic acids, RCO2H: Carboxylic acids are organic compounds characterized by the presence of a carboxyl group (-COOH), where "R" represents an alkyl or aryl group attached to the carbon atom of the carboxyl group. They are known for being acidic due to the ability of the hydroxyl (OH) part of the carboxyl group to release a proton (H+).
Chromic Acid: Chromic acid, also known as chromium(VI) oxide, is a strong oxidizing agent commonly used in organic chemistry. It is a bright orange-red crystalline compound with the chemical formula CrO3, which can be used to oxidize various organic compounds.
Electron-Withdrawing Groups: Electron-withdrawing groups are functional groups or substituents in a molecule that have a strong affinity for electrons, making them attractive to electrons. This property can significantly influence the reactivity, stability, and spectroscopic properties of the molecule.
Fehling's Solution: Fehling's solution is a reagent used to test for the presence of aldehydes and reducing sugars. It is a copper-based solution that undergoes a color change and precipitate formation when reacted with these compounds, indicating a positive test result.
Hydrated Aldehyde: A hydrated aldehyde, also known as a gem-diol, is the product of the reversible addition of water to the carbonyl carbon of an aldehyde. This structural feature is important in the context of the oxidation of aldehydes and ketones, as it can influence the reactivity and stability of these carbonyl compounds.
Jones Oxidation: The Jones oxidation is a chemical reaction used to selectively oxidize primary and secondary alcohols to their corresponding aldehydes and ketones, respectively. It is a powerful tool in organic chemistry for the controlled conversion of alcohols to carbonyl compounds.
Ketones: Ketones are organic compounds characterized by a carbonyl group (C=O) bonded to two other carbon atoms within the molecule. They are formed by the oxidation of secondary alcohols.
Ketones: Ketones are a class of organic compounds containing a carbonyl group (C=O) bonded to two alkyl or aryl groups. They are characterized by the presence of a carbonyl carbon flanked by two carbon atoms. Ketones are important in various organic chemistry topics, including chirality, oxidation reactions, mass spectrometry, infrared spectroscopy, and NMR spectroscopy.
Nucleophilic Addition: Nucleophilic addition is a fundamental organic reaction in which a nucleophile, a species that donates electrons, adds to an electrophilic carbon center, typically a carbonyl carbon, to form a new product. This reaction is central to understanding many important topics in organic chemistry, including functional groups, polar reactions, carbocation stability, reaction stereochemistry, and the chemistry of aldehydes, ketones, alcohols, and other carbonyl-containing compounds.
Nucleophilic addition reaction: A nucleophilic addition reaction is a chemical process where a nucleophile forms a bond with an electrophilic carbon atom of a compound, typically found in aldehydes and ketones. This reaction results in the conversion of the carbonyl group into a more complex, often larger, molecule.
Oxidation: Oxidation is a fundamental chemical process in which a substance loses electrons, resulting in an increase in its oxidation state. This term is central to understanding various reactions and transformations in organic chemistry, from the hydration of alkenes to the oxidation of alcohols and aldehydes.
Oxidation States: Oxidation states are the measure of the degree of oxidation of an atom in a chemical compound. They represent the number of electrons an atom has lost or gained compared to a neutral atom, and are used to keep track of electron transfer during chemical reactions.
Oxidative Cleavage: Oxidative cleavage is a chemical reaction that involves the breaking apart of a molecule through the use of an oxidizing agent, resulting in the formation of two or more smaller molecules. This term is particularly relevant in the context of organic chemistry, specifically in the oxidation of alkenes, alkynes, and aldehydes/ketones.
PCC: PCC, or Pyridinium Chlorochromate, is a versatile oxidizing agent used in organic chemistry for the selective oxidation of alcohols to aldehydes and ketones. This powerful reagent is widely employed in various reactions across multiple topics, including the hydration of alkynes, the oxidation of alcohols, and the preparation and oxidation of aldehydes and ketones.
Potassium Permanganate: Potassium permanganate is a strong oxidizing agent with the chemical formula KMnO4. It is a dark purple crystalline solid that is widely used in various chemical reactions and processes due to its powerful oxidizing properties.
Pyridinium Chlorochromate: Pyridinium chlorochromate (PCC) is an oxidizing agent commonly used in organic chemistry for the selective oxidation of alcohols to aldehydes and ketones. It is a versatile reagent that plays a key role in the preparation and oxidation of carbonyl compounds.
Reduction: Reduction is a chemical process that involves the gain of electrons by a molecule or atom, resulting in a decrease in its oxidation state. This term is particularly important in the context of various organic chemistry reactions and transformations.
Silver Mirror Test: The silver mirror test is a chemical reaction used to identify the presence of aldehydes. It involves the reduction of silver ions (Ag+) to metallic silver (Ag), which forms a shiny, mirror-like deposit on the surface of the reaction vessel, hence the name 'silver mirror' test.
Steric Hindrance: Steric hindrance, also known as steric strain or steric effect, refers to the repulsive forces that arise between atoms or groups of atoms in a molecule due to their physical size and spatial arrangement. This phenomenon can significantly impact the stability, reactivity, and conformations of organic compounds.
Tollen's Reagent: Tollen's reagent is a chemical reagent used in organic chemistry to test for the presence of aldehydes. It is a sensitive test that can detect even small amounts of aldehydes in a sample.
α-Hydrogen: α-Hydrogen refers to the hydrogen atom that is directly bonded to the carbon atom adjacent to a carbonyl group (a carbon-oxygen double bond). This term is particularly relevant in the context of various organic chemistry topics, including the names and properties of ethers, the oxidation of aldehydes and ketones, carbonyl condensations, and mixed Claisen condensations.