1-Alkyl-4-dialkylaminopyridinium Halides as Phase-Transfer Catalysts in Dichlorocarbene Reactions

Summary.  A series of 1-alkyl-4-dialkylaminopyridinium halides derived from 4-dimethylamino- and 4-morpholinopyridines were synthesized and tested as phase-transfer catalysts in three typical reactions of dichlorocarbene: dehydration of benzamide, N-formylation of diphenylamine, and dichlorocyclopropanation of styrene. The catalytic performance of the above compounds was found comparable or higher than that of conventional quaternary ammonium catalysts. The influence of catalyst structure on the reactivity was evaluated. Received June 27, 2001. Accepted (revised) September 25, 2001     

Phase-transfer agents as catalysts for a nucleophilic substitution reaction in microemulsions

The reaction between 4-tert-butylbenzyl bromide and potassium iodide was carried out in microemulsions based on different nonionic surfactants, and the reaction rates were compared with those obtained in two-phase systems with added phase-transfer agent, either a quaternary ammonium salt or a crown ether. The reactions were relatively fast in the microemulsions and extremely sluggish in the two-phase systems without additional phase-transfer agent. Addition of a phase-transfer agent did not accelerate the reaction when a hydrocarbon was used as organic solvent, neither in the two-phase system nor in the microemulsion. When a chlorinated hydrocarbon was used as solvent, phase-transfer catalysis became effective and the rate obtained in the two-phase system with an equimolar amount of phase-transfer agent added was higher than that obtained in the microemulsion. When a catalytic amount of phase-transfer agent was used, the rate in the two-phase system was about the same as the rate obtained in the microemulsion without the phase-transfer agent. The combined approach, that is, use of a microemulsion as the reaction medium and addition of a phase-transfer agent, gave the highest reaction rate. The quaternary ammonium salt (tetrabutylammonium hydrogen sulfate) was a more efficient catalyst in the microemulsion system than the crown ether ([18]crown-6).     

1-Alkyl-4-dialkylaminopyridinium Halides as Phase-Transfer Catalysts in Dichlorocarbene Reactions

 A series of 1-alkyl-4-dialkylaminopyridinium halides derived from 4-dimethylamino- and 4-morpholinopyridines were synthesized and tested as phase-transfer catalysts in three typical reactions of dichlorocarbene: dehydration of benzamide, N-formylation of diphenylamine, and dichlorocyclopropanation of styrene. The catalytic performance of the above compounds was found comparable or higher than that of conventional quaternary ammonium catalysts. The influence of catalyst structure on the reactivity was evaluated.     

Phase-transfer catalysis in reactions of electrophilic aromatic substitution

Electrophilic substitution in aromatic compounds under conditions of phase-transfer catalysis is considered. Catalysts of phase transfer of electrophilic reagents are used; their efficiency and the mechanism of their action in organic solvent-water systems are discussed.This review is based on materials of the report delivered at the Conference Phase-Transfer Catalysis. New Ideas and Methods (March 1994).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1895–1900, October, 1995.     

相转移催化合成吡啶三唑并噻二唑及舒张血管活性研究

3-(3-吡啶基)4氨基-5-巯基-1，2，4-均三唑(1)与羧酸在相转移催化剂四丁基碘化铵和三氯氧磷催化作用下，高收率制得3-(3-吡啶基)-6-取代-s-1，2，4-三唑并[3，4-b]噻二唑(2a-2s)．体外舒血管活性试验表明，大部分化合物具有较好的舒张生理活性．     

Metal-Organic Frameworks as Versatile Heterogeneous Solid Catalysts for Henry Reactions

Metal–organic frameworks (MOFs) have become one of the versatile solid materials used for a wide range of applications, such as gas storage, gas separation, proton conductivity, sensors and catalysis. Among these fields, one of the more well-studied areas is the use of MOFs as heterogeneous catalysts for a broad range of organic reactions. In the present review, the employment of MOFs as solid catalysts for the Henry reaction is discussed, and the available literature data from the last decade are grouped. The review is organized with a brief introduction of the importance of Henry reactions and structural properties of MOFs that are suitable for catalysis. The second part of the review discusses the use of MOFs as solid catalysts for the Henry reaction involving metal nodes as active sites, while the third section provides data utilizing basic sites (primary amine, secondary amine, amides and urea-donating sites). While commenting on the catalytic results in these two sections, the advantage of MOFs over other solid catalysts is compared in terms of activity by providing turnover number (TON) values and the structural stability of MOFs during the course of the reaction. The final section provides our views on further directions in this field.