在冰中合作化酸
Marcelo I Guzmán1, Lea Hildebrandt, Agustín J Colussi
1W. M. Keck Laboratories, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|August 10, 2006
概括
大约3.5个水分子在冰中化2-氧酸 (PA). 这种水合在微流体中保持稳定,直到玻璃化,正如热力学和NMR分析所显示的那样.
科学领域:
- 物理化学 物理化学
- 生物化学 生物化学
背景情况:
- 2-oxopropanoic 酸 (PA) 经历了外热水化到其单酸 (PAH).
- 了解冷溶液中的水化对于各种化学和生物过程至关重要.
研究的目的:
- 为了研究2-oxopropanoic酸在冷溶液中的水合状态和行为.
- 为了确定PA在冰中的水合的热力学和结构方面.
主要方法:
- 在不同度下对冷的PA溶液进行热力学分析.
- 差分扫描热量计 (DSC) 用于分析热过渡.
- 质子核磁共振 (NMR) 谱学用于研究分子动力学.
主要成果:
- 热力学分析表明,水合的温度独立性低于250 K.
- 氧化的度 (-22 kJ mol-1) 是由融化冰的度平衡的.
- 核磁共振 (NMR) 数据显示,微流体中的合作性水合,直到230 K左右的玻璃化.
结论:
- 2-oxopropanoic 酸在冰中的间隙微流体中保持合作性水合.
- 补水持续到微流体在低温下玻璃化为止.
- 这项研究提供了对冷水系统中分子行为的洞察.
相关概念视频
Acids, Bases and Neutralization Reactions
An acid-base reaction is one in which a hydrogen ion, H+, is transferred from one chemical species to another. Such reactions are of central importance to numerous natural and technological processes, ranging from the chemical transformations within cells or lakes and oceans to the industrial-scale production of fertilizers, pharmaceuticals, and other substances essential to the society.
Weak Acid Solutions
Few compounds act as strong acids. A far greater number of compounds behave as weak acids and only partially react with water, leaving a large majority of dissolved molecules in their original form and generating a relatively small amount of hydronium ions. Weak acids are commonly encountered in nature, being the substances partly responsible for the tangy taste of citrus fruits, the stinging sensation of insect bites, and the unpleasant smells associated with body odor. A familiar example of a...
Common Ion Effect
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Châtelier’s principle. Consider the dissolution of silver iodide:
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...
Acids, Bases and Neutralization Reactions
Acids and bases play several important roles in biology. The pH of a biological system can significantly impact the function of biological molecules, including enzymes, proteins, and nucleic acids. For example, enzymes have optimal pH ranges for their activity, and changes in pH can denature or alter their structure, affecting their function. Acids and bases also play a crucial role in cellular signaling and communication. The pH of the extracellular fluid around cells can influence the...
Carbon-dioxide Fixation
Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ecosystems, and contributing to the global carbon cycle. It also has industrial applications in carbon capture and bioproduct synthesis. Autotrophic organisms rely on this process to utilize CO₂ as a carbon source in diverse environments.The Calvin CycleThe Calvin cycle is the most widespread carbon fixation mechanism, primarily used by...


