Determination of Acidity Functions of Liquid Acids by Carbon-13 Nuclear Magnetic Resonance and Development of Theoretically Justified Calibration of Solid Acidity

本项目的目标是开发一种基于碳-13核磁共振化学位移的新方法，用于测定液体和固体酸的热力学酸度函数。通过使用同一分子中两个碳原子之间的化学位移的差异作为测量参数来消除介质效应。新方法适用于缺乏使用传统Hammett指示剂所需的可见光和紫外光透明度的体系，并可扩展到固体。为了将固体酸度与溶液酸度联系起来，在化学计量酸碱比下研究了指示剂碱在溶液中的质子化平衡，然后在等摩尔碱酸比下研究了相同指示剂碱在固体酸上的质子化平衡。最后，考察了溶剂对酸强度的影响。虽然酸度的概念经常被用来解释固体催化剂的影响，但事实上，没有可靠的技术来测量或量化固体的这一性质。这个项目直接解决了这个问题；成功将为理解许多催化体系，以及腐蚀、复合稳定性和发色显示提供一个更合理的框架。

The objective of this project is the development of a new method based on carbon-13 nuclear magnetic resonance chemical shifts for determining thermodynamic acidity functions for liquid and solid acids. Medium effects are eliminated by using the difference in chemical shift between two carbon atoms in the same molecule as the measurement parameter. The new method is applicable to systems lacking the transparency to visible and ultraviolet light required for use of traditional Hammett indicators, and is extendable to solids. To relate solid acidity to solution acidity, the protonation equilibrium of indicator bases in solution is studied at the stoichiometric acid-to-base ratio and the same indicator bases are then studied on solid acids at equimolar ratios of base to acid sites. Finally, the effects of solvents on acid strengths is examined. Although the concept of acidity is often used to interpret the effects of solid catalysts, there is, in fact, no sound technique to measure or quantify this property for solids. This project addresses this problem directly; success would provide a more rational framework for understanding of many catalytic systems, and also of corrosion, composite stability, and chromophoric displays.