概括
高能电子脉冲在液态二氧化中产生短暂的自由基和化电子. 盐酸添加显著抑制了这些反应性物种和分子离子的形成.
科学领域:
- 物理化学 物理化学
- 辐射化学 辐射化学
- 有机化学 有机化学
背景情况:
- 了解有机溶剂在高能辐射下的行为对于各种应用至关重要.
- 自由基和化电子是辐射诱导化学反应中的关键中间体.
- 溶剂放射溶解上的溶液效应可以提供对反应机制的见解.
研究的目的:
- 为了研究在暴露于高能电子脉冲后,在液态二氧化中形成的短暂物种.
- 检查溶解物质 (二和二) 对二氧化放射溶解的影响.
- 为了确定盐酸对这些过渡物种形成的影响.
主要方法:
- 脉冲放射溶解技术使用4 MeV电子束,脉冲持续时间为2微秒.
- 暂时吸收的光谱分析,以识别激素和离子物种.
- 纯二氧化,二氧化与溶液,二氧化与溶液和酸的比较研究.
主要成果:
- 液态二氧化的辐射产生了因自由基和化电子而导致的短暂吸收.
- 索的溶液产生了基和基离子.
- 炭溶液生成了三重体状态的炭和炭离子.
- 盐酸的存在大大抑制了这些观察到的物种的形成.
结论:
- 在高能电子辐射下,液态二氧化很容易形成反应性中间体.
- 溶解的溶液如二和二被转化为特有的基和离子物种.
- 盐酸作为一种有效的清除剂,抑制了二氧化溶液中主要的放射性溶解过程.
相关概念视频
Radical Formation: Homolysis
A bond is formed between two atoms by sharing two electrons. When this bond is broken by supplying sufficient energy, either two electrons can be taken up by one atom forming ions by the cleavage called heterolysis, or the two electrons are shared by two atoms, with one each creating radicals by the cleavage called homolysis.
Carboxylic Acids to Methylesters: Alkylation using Diazomethane
Carboxylic acids react with diazomethane in an ether solvent via alkylation at the carboxylate oxygen atom to give methyl esters of the corresponding acid with excellent yields.
Radical Formation: Elimination
Another method of radical formation is the elimination process. It is the opposite of the addition route and is driven by the instability of the radical. For example, as depicted in Figure 1, dibenzoyl peroxide yields a pair of unstable radicals upon homolysis. Given its instability, this radical spontaneously undergoes elimination via a C–C bond cleavage to form a relatively more stable phenyl radical. The mechanism involves cleavage of the bond between the α and β positions with respect to...
Autoxidation of Ethers to Peroxides and Hydroperoxides
Ethers represent a class of chemical compounds that become more dangerous with prolonged storage because they tend to form explosive peroxides when standing in the air. Autoxidation is the spontaneous oxidation of a compound in air. In the presence of oxygen, ethers slowly oxidize to form hydroperoxides and dialkyl peroxides.
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
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.
Preparation of Diols and Pinacol Rearrangement
Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.


