克里吉中间体CH2OO与基基的反应的温度依赖动力学
Zachary A Cornwell1, Jonas J Enders1, Aaron W Harrison2
1Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States.
The journal of physical chemistry. A
|March 1, 2024
概括
这项研究研究了Criegee中间体 (CH2OO) 与基基反应的动力学. 这些反应通常太慢,无法影响大气,除了在非常低的温度下.
科学领域:
- 大气化学 大气化学
- 化学动力学 化学动力学
- 有机化学 有机化学
背景情况:
- 克里奇中间体 (CH2OO) 是在大气氧化过程中形成的反应性物种.
- 虽然已知与简单碳基因的反应,但与功能化碳基因 (如氧基) 反应的理解较少.
研究的目的:
- 为了确定CH2OO与酸 (AcOH) 和4-基-2-butanone (4H2B) 的反应的温度依赖的动力学.
- 为了阐明反应机制,并比较与简单的碳酸的反应性.
主要方法:
- 激光闪光光电解短暂吸收光谱法用于测量反应速率.
- 量子化学计算 (CBS-QB3方法) 描述了反应路径和过渡状态.
主要成果:
- 在275-335K之间确定了AcOH和4H2B与CH2OO的双分子速率常数.
- 这两种反应都表现出负温度依赖性和类似的慢速常数.
- 碳基组的1,3-双极循环添加被确定为主要途径,形成循环二次臭氧化物.
结论:
- 氧基与CH2OO的反应类似于乙甲,主要是通过循环添加.
- 确定的反应速率表明,在典型条件下,CH2OO + 基反应对大气的意义最小.
- 这些反应可能只有在非常低的大气温度下才有意义.
相关概念视频
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
8.4K
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
8.4K
Preparation of Aldehydes and Ketones from Alcohols, Alkenes, and Alkynes
3.7K
Aldehydes and ketones are prepared from alcohols, alkenes, and alkynes via different reaction pathways. Alcohols are the most commonly used substrates for synthesizing aldehydes and ketones. The conversion of alcohol to aldehyde, which involves the oxidation process, depends on the class of the alcohol used and the strength of the oxidizing agent. For instance, primary alcohol will form an aldehyde when treated with a weak oxidizing agent; however, it gets over-oxidized to a carboxylic acid in...
3.7K
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
3.7K
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
3.7K
Aldehydes and Ketones with Water: Hydrate Formation
3.2K
An oxygen-based nucleophile, like water, can undergo addition reactions with aldehydes and ketones. The reaction leads to the formation of hydrates, also referred to as 1,1-diols or geminal diols.
The formation of hydrates is a reversible reaction. Hydrate formation is influenced by steric and electronic factors accompanying the alkyl substituents on the carbonyl group: The rate of hydrate formation increases with a decrease in the number of alkyl groups attached to the carbonyl carbon. Hence,...
The formation of hydrates is a reversible reaction. Hydrate formation is influenced by steric and electronic factors accompanying the alkyl substituents on the carbonyl group: The rate of hydrate formation increases with a decrease in the number of alkyl groups attached to the carbonyl carbon. Hence,...
3.2K
α-Hydroxy Ketones via Reductive Coupling of Esters: Acyloin Condensation Overview
2.9K
The pinacol and McMurry reactions involve the reductive coupling of ketones or aldehydes. Similarly, the bimolecular reductive coupling of two ester molecules in the presence of sodium metal in an aprotic solvent yields an α-hydroxy ketone product. The α-hydroxy ketone is also called acyloin, so the reaction is referred to as ‘acyloin condensation.’
2.9K
Regioselective Formation of Enolates
2.6K
As depicted in the figure below, the unsymmetrical ketones can form two possible enolates: less substituted or more substituted enolates. Usually, the thermodynamic enolates are formed from the more substituted α-carbon atom, while the kinetic enolates are formed faster by deprotonation from the less substituted position. The thermodynamic enolates have lower energy, so they are more stable. But the energy required to form kinetic enolates is less.
2.6K


