关键词: Beckmann重排, 实验教学, 二苯甲酮肟, 反应机理

Abstract:

The Beckmann rearrangement, a pivotal reaction wherein carbonyl-rich aldehydes and ketones engage with hydroxylamines to forge organoximes, undergoes a rearrangement in the catalyst's presence and holds significant importance in organic synthesis. Addressing the perceptual gaps in understanding the experimental principles and the insufficient verification of reaction mechanisms during the instruction of Beckmann rearrangement of organoximes, this study utilizes the reaction between benzophenone and hydroxylamine hydrochloride. This reaction results in benzophenone oxime, which undergoes molecular rearrangement catalyzed by polyphosphoric acid to produce benzoyl aniline. This exercise adeptly interweaves elements from inorganic, analytical, and instrumental analysis chemistry, augmenting holistic design and innovative capabilities of students. Employing tools like melting point assessment, infrared spectroscopy, and nuclear magnetic resonance, this study elucidates the nuanced structures of both intermediate and final products. By juxtaposing macroscopic physicochemical attributes with their microscopic counterparts, it robustly deciphers and authenticates the underlying reaction mechanism, enhancing the pedagogical efficacy of the Beckmann rearrangement and kindling innovative sense. This paper can serve as a reference for comprehensive and design-focused experiments on oxime-type Beckmann rearrangements, and also provide valuable insights for the enhancement of teaching materials and experimental procedures.

Key words: Beckmann rearrangement, Laboratory teaching, Benzophenone oxime, Reaction mechanisms