为什么酸催化羧酸及其衍生物的反应是羰基氧质子化  

Why Is the Carbonyl Oxygen Atom of Carboxylic Acids and Derivatives Protonated in the Acid-Catalyzed Reactions

作　　者：许家喜 麻远[2] XU Jia-Xi;MA Yuan(College of Chemistry,Beijing University of Chemical Technology,Beijing 100029,China;Department of Chemistry,Tsinghua University,Beijing 100084,China)

机构地区：[1]北京化工大学化学学院,北京100029 [2]清华大学化学系,北京100084

出　　处：《化学教育（中英文）》2024年第2期127-129,共3页Chinese Journal of Chemical Education

基　　金：有机化学本科育人团队项目;有机化学和中级有机化学一流课程建设项目。

摘　　要：醇醚中的氧原子比醛酮羰基的氧原子碱性强,而羧酸及其衍生物在酸催化下的反应却是其羰基氧原子质子化;另外,羧酸及其衍生物作为亲核试剂时,也是其羰基氧原子作为亲核位点。通过分析羧酸及其衍生物中羰基和氧/氮原子形成的π34共轭体系的电子效应,合理地解释了为什么羧酸及其衍生物中羰基氧原子更易被质子化和作为亲核位点,并且拓展到了亚胺酯、脒和胍类化合物的质子化。The oxygen atom in alcohols and ethers is more basic than that of the carbonyl group in aldehydes and ketones.However,the carbonyl oxygen atom of carboxylic acid and de-rivatives is protonated in their acid-catalyzed reactions.In addition,when carboxylic acids and de-rivatives are used as nucleophiles,their carbonyl oxygen atom serves as the nucleophilic site.This article rationally explains the reason why the carbonyl oxygen atom of carboxylic acids and derivatives is readily protonated in their acid-catalyzed reactions and serves as the nucleophilic site when they are used as nucleophiles through analyzing the electronic effect in theirπg conjugative systems between the carbonyl group with the oxygen/nitrogen atom.The rationale can be ex-tended to the protonation of imidates,amidines,and guanidines.It would provide a deeper un-derstanding on the influence of the electron density of different atoms in isolated systems and con-jugative systems for students.

关 键 词：氧原子 碱性 羧酸 酯 酰胺 

分 类 号：O621.251-4[理学—有机化学] G642[理学—化学]