相关实验视频
Updated: May 22, 2026
09:10
Synthesis of Indoxyl-glycosides for Detection of Glycosidase Activities
Published on: May 27, 2015
马龙酸无水化物的分解
Charles L Perrin1, Agnes Flach, Marlon N Manalo
1Department of Chemistry, University of California-San Diego, La Jolla, California 92093-0358, USA. cperrin@ucsd.edu
Journal of the American Chemical Society
|May 26, 2012
概括
马龙酸无水化物分解成烯和二氧化碳. 甲基马龙化物由于活性能较低,分解速度最快,而二甲基马龙化物分解速度最慢.
科学领域:
- 有机化学 有机化学
- 化学动力学 化学动力学
背景情况:
- 众所周知,马龙无水化物很容易分解.
- 了解它们的分解机制对于合成化学至关重要.
研究的目的:
- 为了研究马龙,甲基马龙和二甲基马龙无水化物的热分解动力学.
- 阐明影响分解速度和机制的因素.
主要方法:
- 使用核磁共振 (NMR) 光谱测量了速率常数.
- 激活参数由速率常数的温度依赖性来确定.
- 运用计算方法来支持机械解释.
主要成果:
- 甲基马洛尼无水化物表现出最快的分解速度.
- 甲基甲基氨酸无水化物显示了最慢的分解速度.
- 观察到分解速率与甲基群数量的非线性依赖.
结论:
- 分解过程通过协调的循环逆转机制进行.
- 提出了一个扭曲的过渡状态结构,得到计算数据的支持.
- 替代模式显著影响了分解途径和动力学.
相关概念视频
01:35Loss of Carboxy Group as CO2: Decarboxylation of Malonic Acid Derivatives
Just like β-keto acids—which upon thermal decarboxylation form ketones—β-dicarboxylic acids undergo decarboxylation to generate monocarboxylic acids with the liberation of carbon dioxide.
01:14Alkylation of β-Diester Enolates: Malonic Ester Synthesis
Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
01:19Reactions of Acid Anhydrides
The reactions of acid anhydrides are analogous to the reactions of acid chlorides and proceed via a nucleophilic acyl substitution. They only differ in the identity of the leaving group. During an acid chloride reaction, the leaving group is a chloride ion, and the by-product is hydrochloric acid. However, in an acid anhydride reaction, the leaving group is a carboxylate ion, and the by-product is a carboxylic acid.
01:07Preparation of Acid Anhydrides
One of the methods for preparing symmetrical or unsymmetrical acid anhydrides involves the treatment of acid chlorides with the sodium salt of carboxylic acids. The reaction proceeds via a nucleophilic acyl substitution.
The carboxylate ion acts as a nucleophile that attacks the carbonyl carbon of the acid chloride to form a tetrahedral intermediate. Subsequently, the re-formation of the carbonyl group with the loss of the chloride ion as a leaving group leads to the formation of an acid...
The carboxylate ion acts as a nucleophile that attacks the carbonyl carbon of the acid chloride to form a tetrahedral intermediate. Subsequently, the re-formation of the carbonyl group with the loss of the chloride ion as a leaving group leads to the formation of an acid...
01:16Nomenclature of Carboxylic Acid Derivatives: Acid Halides, Esters, and Acid Anhydrides
Naming Acid Halides
The IUPAC and common names of acid halides are derived from the corresponding carboxylic acids, by changing “ic acid” to “yl halide.” For example, as shown below, the IUPAC name ethanoyl chloride is derived from ethanoic acid, and the common name, acetyl chloride, is obtained from acetic acid.
The IUPAC and common names of acid halides are derived from the corresponding carboxylic acids, by changing “ic acid” to “yl halide.” For example, as shown below, the IUPAC name ethanoyl chloride is derived from ethanoic acid, and the common name, acetyl chloride, is obtained from acetic acid.
01:01Acid Halides to Carboxylic Acids: Hydrolysis
Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...