Related Experiment Video
Updated: Jun 6, 2025
08:23
Analyzing the Photo-oxidation of 2-propanol at Indoor Air Level Concentrations Using Field Asymmetric Ion Mobility Spectrometry
Published on: June 14, 2018
8.8K
Competing Reaction Pathways in Gas-Phase Oxidation of C6H6 by Protonated H2O2
Sverre Løyland1, Einar Uggerud1
1Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern 0315 Oslo, Norway.
The Journal of Physical Chemistry. A
|November 25, 2024
Summary
Protonated hydrogen peroxide reacts rapidly with benzene via multiple oxidation pathways, including proton transfer and electron transfer. Gas-phase studies reveal a more complex reaction landscape than previously known for condensed-phase reactions.
Area of Science:
- Physical Chemistry
- Gas-Phase Ion Chemistry
- Organic Reaction Mechanisms
Background:
- The reaction of protonated hydrogen peroxide (H3O2+) with arenes is not fully understood.
- Condensed-phase studies suggest limited reactivity, primarily electrophilic substitution by solvated HO+.
Purpose of the Study:
- To investigate the gas-phase reaction mechanisms between protonated hydrogen peroxide and benzene.
- To elucidate the competing reaction pathways and determine the reactivity of H3O2+.
Main Methods:
- Gas-phase reactions studied using Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry.
- Reaction mechanisms modeled using quantum chemical calculations.
Main Results:
- Identified four competing bimolecular reaction pathways: proton transfer, hydride abstraction, dissociative single-electron transfer, and electrophilic addition.
- The latter three pathways represent distinct benzene oxidation mechanisms.
- Observed reaction rates near the collision limit, indicating high reactivity of H3O2+ with arenes.
- Calculations align with experimental observations.
Conclusions:
- Gas-phase reactions of H3O2+ with benzene exhibit a significantly richer chemical landscape than previously inferred.
- H3O2+ is highly reactive towards arenes, proceeding through multiple oxidation channels.
Related Concept Videos
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
5.6K
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
5.6K
01:46Oxidative Cleavage of Alkenes: Ozonolysis
9.9K
In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
9.9K
02:50Catalysis
26.7K
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
26.7K
02:36Regioselectivity and Stereochemistry of Hydroboration
8.0K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
8.0K
01:17Radical Anti-Markovnikov Addition to Alkenes: Mechanism
3.7K
The reaction of hydrogen bromide with alkenes in the presence of hydroperoxides or peroxides proceeds via anti-Markovnikov addition. The radical chain reaction comprises initiation, propagation, and termination steps.
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy...
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy...
3.7K
03:08Hydroboration-Oxidation of Alkenes
7.9K
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
7.9K