120317-69-3Relevant articles and documents
Practical methylation procedure for (1H)-1,2,4-triazole
Belletire, John L.,Bills, Robert A.,Shackelford, Scott A.
, p. 738 - 745 (2008)
Conversion of (1H)-1,2,4-triazole to its sodium salt with methanolic sodium methoxide is followed by reaction with iodomethane. A scalable approach that overcomes problems associated with water-soluble starting material and water-soluble product combined continuous extraction (chloroform/water) with a final short-path distillation under a controlled vacuum to obtain spectroscopically pure 1-methyl-1,2,4-triazole in 63% yield. Adaptation to microwave synthesis conditions, while providing a faster reaction time, offers no product yield or purification advantages over the conventional approach described. Conversions of this product to related derivatives such as 1,4-dimethyl-1,2,4-triazolium iodide and 1-methyl-1,2,4-triazolium hydrochloride are readily achieved. Copyright Taylor & Francis Group, LLC.
A New Mode of Operation of Pd-NHC Systems Studied in a Catalytic Mizoroki-Heck Reaction
Astakhov, Alexander V.,Khazipov, Oleg V.,Chernenko, Andrey Yu.,Pasyukov, Dmitry V.,Kashin, Alexey S.,Gordeev, Evgeniy G.,Khrustalev, Victor N.,Chernyshev, Victor M.,Ananikov, Valentine P.
, p. 1981 - 1992 (2017/06/14)
Metal complexes bearing N-heterocyclic carbene (NHC) ligands are typically considered the system of choice for homogeneous catalysis with well-defined molecular active species due to their stable metal-ligand framework. A detailed study involving 19 different Pd-NHC complexes with imidazolium, benzimidazolium, and triazolium ligands has been carried out in the present work and revealed a new mode of operation of metal-NHC systems. The catalytic activity of the studied Pd-NHC systems is predominantly determined by the cleavage of the metal-NHC bond, while the catalyst performance is strongly affected by the stabilization of in situ formed metal clusters. In the present study, the formation of Pd nanoparticles was observed from a broad range of metal complexes with NHC ligands under standard Mizoroki-Heck reaction conditions. A mechanistic analysis revealed two different pathways to connect Pd-NHC complexes to "cocktail"-type catalysis: (i) reductive elimination from a Pd(II) intermediate and the release of NHC-containing byproducts and (ii) dissociation of NHC ligands from Pd intermediates. Metal-NHC systems are ubiquitously applied in modern organic synthesis and catalysis, while the new mode of operation revealed in the present study guides catalyst design and opens a variety of novel opportunities. As shown by experimental studies and theoretical calculations, metal clusters and nanoparticles can be readily formed from M-NHC complexes after formation of new M-C or M-H bonds followed by C-NHC or H-NHC coupling. Thus, a combination of a classical molecular mode of operation and a novel cocktail-type mode of operation, described in the present study, may be anticipated as an intrinsic feature of M-NHC catalytic systems.
Synthesis and crystal structures of new 1,4-disubstituted 1,2,4-triazoline-5-thiones
Laus, Gerhard,Kahlenberg, Volker,Wurst, Klaus,Schottenberger, Herwig
, p. 950 - 964 (2015/06/16)
Introduction of sulfur into the 5-position of 1,4-disubstituted quaternary 1,2,4-triazolium salts (1-9; Cl, Br, I, BF4, PF6, CH3OSO3 were used as anions) by two methods was investigated. The syntheses of nine 1,
