瓜尼丁酸:在THF和气相中设计,合成和基本性
Alexander A Kolomeitsev1, Ilmar A Koppel, Toomas Rodima
1Institute of Inorganic & Physical Chemistry, University of Bremen, Leobener Strasse, D-28334 Bremen, Germany. kolomeit@chemie.uni-bremen.de
Journal of the American Chemical Society
|December 15, 2005
概括
研究人员开发了一种创建非离子超基的新原理,通过将瓜尼迪诺基团连接到酸基. 这大大提高了基地的强度,对于未来的超级基地设计,潜在增加超过40个数量级.
科学领域:
- 有机化学 有机化学
- 超级数据库的合成
- 计算化学的计算化学
背景情况:
- 非离子超基在有机合成中至关重要.
- 现有的超级基地在力量和范围上有局限性.
- 酸化学为新型超基开发提供了一个平台.
研究的目的:
- 提出一种创建非离子超级基的新原理.
- 为了合成和描述基于酸的新型超基.
- 评估这些新化合物的增强基础性.
主要方法:
- 合成瓜尼迪诺替代的酸.
- 在THF中进行光谱光度计定位,以确定基强度.
- 高级密度函数理论对气相基本性的计算.
- 用于结构分析的X射线晶体学.
主要成果:
- 合成了七个新的非离子超基基基.
- 在THF中,四甲基guanidino替代增加了10个数量级的基强度.
- 计算预测新型结构的潜在基本性增加超过40个数量级.
- 确定了关键化合物的晶体结构.
结论:
- 瓜尼迪诺基团与素的附着是一种非常有效的原理,用于创建强大的非离子超基.
- 这一策略为超级数据库提供了一条前所未有的高基础性的途径.
- 这些发现为设计化学中先进的催化剂和试剂开辟了新的途径.
相关概念视频
Carboxylic Acid Derivatives: Overview
Carboxylic acid derivatives are formed by replacing the hydroxyl group of carboxylic acids with a different functional group. The most common carboxylic acid derivatives are:
Structures of Carboxylic Acid Derivatives
Structure of Carboxylic Acid Derivatives
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
Acid 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...
Acid Halides to Amides: Aminolysis
Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively.
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
Acid Halides to Ketones: Gilman Reagent
Lithium dialkyl cuprate, also known as Gilman reagents, selectively reduces acid halides to ketones. The acid chloride is treated with Gilman reagent at −78 °C in the presence of ether solution to produce a ketone in good yield.
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen double...
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen double...
Preparation 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...


