A pd-zn bimetallic catalyst for the preparation of aromatic cyano compounds

Abstract

The invention discloses a Pd-Zn bimetallic catalyst for preparing an aromatic cyano compound. The catalyst is prepared by the following steps: uniformly stirring palladium acetate and zinc salt in DMF, adding a certain amount of PVP as a stabilizer, stirring until the solution is clear and transparent, adding a reducing agent KBH4, and stirring for reaction to obtain the Pd-Zn bimetallic catalyst. A reaction process using the Pd-Zn bimetallic nanoparticles as a catalyst does not need additional ligand. The catalyst is at nano level, the probability of contact of catalytic active sites with a reaction substrate is larger, the catalytic activity is higher, and Pd and Zn in the catalyst form an alloy structure to effectively prevent Pd metal poisoning and prolong catalysis life.

Description

technical field [0001] The invention belongs to the field of organic synthesis, and in particular relates to a preparation method of an aromatic cyano compound. Background technique [0002] The general formula of the cyanation product is RCN, and the functional group is cyano (-CN). Aromatic cyanation products are very important intermediates in organic synthesis. It is of great significance in pesticides, dyes, medicines, etc. And it can be used as an intermediate to synthesize many important compounds, such as hydrolysis to prepare acids and amides, and reduction to prepare amines. It is also an important raw material in biology, pharmacy, pesticide chemistry and natural products. Therefore, the cyanation reaction not only plays an important role in theory, but also in practical application. [0003] At present, the preparation of cyano compounds is mainly prepared by substitution method, among which the halogen substitution method is relatively simple, and is current...

AI Technical Summary

Problems solved by technology

However, these homogeneous metal catalysts are difficult to separate, and most of them cannot be recycled and used mechanically. Moreover, the Pd complex of homogeneous catalysts is unstable at higher temperatures, and it is easy to form low-activity or inactive Pd black.

[0005] Because the cost of homogeneous catalysts is too high, which limits its industrial application, research and development of heterogeneous catalytic systems to overcome these disadvantages of homogeneous catalytic systems has become a research hotspot in recent years.

Seki group reported Pd / C as catalyst, PPh 3 as a ligand, and added Zn powder and ZnBr 2 As an additive, the cyanation reaction of halogenated aromatic hydrocarbons is carried out. However, Pd / C is a catalyst with low reactivity, and it is still necessary to add phosphine ligand PPh 3 To promote the reaction, at the same time, Pd / C catalyst is easily poisoned in the cyanation reaction, and zinc powder needs to be added to promote the reduction of high-priced metal atoms to a low-priced state to maintain the stability of the metal catalyst