Organozinc reagent: In order to explore the mechanism of a certain chemical reaction, people have developed more and more Multiple detection methods are used for analysis and verification. With the increasing number and complexity of reaction types, existing analytical methods sometimes cannot meet people’s needs for mechanism research. For example, Professor Paul Knochel of the University of Munich in Germany has made important contributions in the study of organometallic reagents (such as Grignard reagents, Organozincreagents) . He found that LiCl can accelerate the insertion of halogenated hydrocarbons into metal Zn to form organozinc reagents. Previously, only Grignard reagents could be prepared by directly inserting halogenated hydrocarbons into metal elements. This discovery subsequently led to the efficient synthesis of a range of other organometallic reagents.
People do not have a clear understanding of the role of LiCl in accelerating the formation of organozinc reagents and the changes in the structure of organozinc reagents. Previous studies have speculated that the possible effects of LiCl are as follows: (1) LiCl can promote the dissolution of the formed organozinc reagent, effectively exposing the zinc metal surface to continue to participate in the reaction; (2) LiCl can complex with the aromatic ring of halogenated aromatic hydrocarbons Its electrophilic activation promotes the electron transfer process; (3) LiCl solution has high ionic strength, which can promote charge separation and accelerate metal insertion. However, these assumptions were not confirmed by corresponding experiments.
Organozinc reagent – combining single metal particle fluorescence microscopy and nuclear magnetic resonance 1H spectroscopy technology to explain this problem. The sensitivity of single metal particle fluorescence microscopy is as high as the single molecule level, which can provide important information on intermediates formed in elementary reactions and overcome the limitations of insufficient sensitivity in monitoring reactions by other analytical methods in the past. Nuclear magnetic resonance spectroscopy analysis provides information on the overall reaction rate and product structure. The combination of the two can determine the influence of different lithium salts on each elementary step of synthesizing organometallic reagents and the structure of organozinc reagents in solution, thus laying the foundation for further expansion of similar salt promotion effects and other types of organometallic reagents. important foundation.
