Study Of Dynamic Covalent Reactions Of 2-Formylbenzoic Acid And Photoacid Properties

Dynamic covalent chemistry has the characteristics of thermodynamic control,stimuli responsiveness,and adaptiveness.It has a wide range of applications in supramolecular chemistry,polymers,and covalent organic frameworks.In this thesis,2-formylbenzoic acid was used as a model compound to explore dynamic reactivity and component exchange,and two different reaction mechanisms were proposed.Dithiophene ethylene and leaving groups were further incorporated into the above-mentioned structure,and a new type of photoacids was prepared.The details are as follows:1.2-Formylbenzoic acid and its derivatives are commonly used in organic synthesis,but their application for dynamic covalent chemistry is rarely reported.In this thesis,the ring-chain tautomerization equilibrium of 2-formylbenzoic acid was regulated by changing p H,and the reactivity of 2-formylbenzoic acid with a series of alcohols,thiols,primary amines,and secondary amines was explored.In addition,the dynamic nature of the system was verified by component exchange,and the switching of dynamic covalent reactions was realized by manipulating substrate selectivity.Finally,two mechanisms for the reactions of2-formylbenzoic acid with nucleophilic reagents were revealed through kinetic measurements.This work verified the ring-chain tautomerism equilibrium of2-formylbenzoic acid and demonstrated the dual reactivity of two equilibrating isomers in one compound,providing a new building block for future assembly studies.2.The research on photoacids has been very detailed,but there are still few photoacids based on diarylethene structures.Based on previous studies,we designed and synthesized compounds 3-10,3-11,and 3-12.Through ~1H-NMR spectral analysis,it was confirmed that compound 3-12 could decompose and generate acid under UV light irradiation.The compound structure was further optimized,and compounds 3-18 and 3-19were designed and synthesized.Compound 3-19 inhibits the phenomenon of re-opening after photocyclization between the two thiophene rings,but cannot inhibit the side reactions under ultraviolet light irradiation.Finally,compound 3-20 was successfully synthesized,which produced Bronsted acid without side reactions.This work explored the ability of a series of compounds to generate acids under light,and optimized the structure of photoacids,laying the foundation for future applications in catalysis and cationic polymerization.