Reaction Of Pyrazine Research Articles

A theoretical study on the mechanism and kinetics of the reactions between diazine isomers and OH radicals

AbstractThe reactions of pyrazine, pyridazine, and pyrimidine with hydroxyl radicals are theoretically studied. The barrier heights obtained with different electronic structure methods indicate that the reactions can competitively proceed via either abstraction of a hydrogen atom by an OH radical or OH addition to carbon sites. However, the rate constants computed within the temperature range 200 to 1500 K suggest that tunneling play a role resulting in large branching ratios in favor of hydrogen abstraction channels at lower temperatures.

Effect of Heteroaromaticity on Adsorption of Pyrazine on the Ge(100)-2×1 Surface

The reaction of pyrazine with the Ge(100)-2×1 surface has been investigated by X-ray photoelectron spectroscopy (XPS) and density functional theory calculations. Results show that pyrazine reacts w...

Regioselective magnesiation of N-heterocyclic molecules: securing insecure cyclic anions by a β-diketiminate-magnesium clamp.

Using a specially designed magnesium metallating manifold, combining kinetically activated TMP amide base with a sterically amplified β-diketiminate ligand, this study has established a new regioselective strategy for magnesiation of challenging N-heterocyclic molecules. The broad scope of the approach is illustrated through reactions of pyrazine, triazoles and substituted pyridines by isolation and structural elucidation of their magnesiated intermediates.

Transforming LiTMP Lithiation of Challenging Diazines through Gallium Alkyl Trans‐Metal‐Trapping

This study establishes a new trans‐metal‐trapping (TMT) procedure based on a mixture of LiTMP (the base) and tris(trimethylsilylmethyl)gallium [Ga(CH2SiMe3)3, GaR3] (the trap) that, operating in a tandem manner, is effective for the regioselective deprotonation of sensitive diazines in hydrocarbon solution, as illustrated through reactions of pyrazine, pyridazine, and pyrimidine, as well as through the N‐S heterocycle benzothiazole. The metallo‐activated complexes of all of these compounds were isolated and structurally defined.

Transforming LiTMP Lithiation of Challenging Diazines through Gallium Alkyl Trans‐Metal‐Trapping

AbstractThis study establishes a new trans‐metal‐trapping (TMT) procedure based on a mixture of LiTMP (the base) and tris(trimethylsilylmethyl)gallium [Ga(CH2SiMe3)3, GaR3] (the trap) that, operating in a tandem manner, is effective for the regioselective deprotonation of sensitive diazines in hydrocarbon solution, as illustrated through reactions of pyrazine, pyridazine, and pyrimidine, as well as through the N‐S heterocycle benzothiazole. The metallo‐activated complexes of all of these compounds were isolated and structurally defined.

크롬(VI)-피라진 착물을 이용한 알코올류의 산화반응과 메카니즘

Cr(VI)-pyrazine complex (PZCC) was synthesized by the reaction of pyrazine with chromium (VI) trioxide in 6 M HCl. The structure was characterized using IR spectroscopy and inductively coupled plasma (ICP). The oxidation of benzyl alcohol using PZCC in various solvents showed that the reactivity increased with the increase of the dielectric constant, in the order: N,N’-dimethylform- amide > acetone > chloroform > cyclohexene. In the presence of N,N’-dimethylformamide solvent with an acidic catalyst such as sulfuric acid (H2SO4 solution), PZCC oxidized benzyl alcohol (H) and its derivatives (p-OCH3, m-CH3, m-OCH3, m-Cl, m-NO2). Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. Hammett reaction constant (ρ) was -0.70 (308 K). The observed experimental data were used to rationalize the hydride ion transfer in the rate-determining step.

Crystal structures and photoluminescence of the Zn(II) and Cd(II) complexes of N-methylpyrazinium obtained by a less hazardous approach

Abstract Compared to previously reported methods, a less hazardous approach has been used to synthesize N-methylpyrazinium cation (mpz+) by the reaction of pyrazine and ClCH2COONa. Although a few mpz+-containing complexes have been documented, there is no example of mpz+-containing group IIB metal complexes. Three novel complexes containing mpz+, (mpz)ZnI3 (1), [(mpz)CdCl3]n (2), and [(mpz)CdBr3]n (3), have been successfully obtained via a solution or hydrothermal method by reactions of ZnI2, CdCl2·2.5H2O, and CdBr2·4H2O with the mpz+ ligand, respectively. Complex 1 features an isolated structure, with each zinc atom coordinated by one mpz+ ligand and three terminal iodine atoms. The CD spectra of 1 reveal that it exhibits spontaneous resolution. Complexes 2 and 3 are isotypic, and exhibit chain structures made by linear arrays of Cd(II) bridged by halogen atoms. Photoluminescent analyses reveal that complexes 1–3 exhibit strong blue emissions originating from intra-ligand π–π∗ transition of the mpz+ ligand.

Sonochemical synthesis of nano-sized metal-organic lead(II) polymer: A precursor for the preparation of nano-structured lead(II) iodide and lead(II) oxide

Nanoparticles of a new Pb II metal-organic polymer, [Pb(μ-pyr)(μ-I) 2] n ( 1), with a net-like morphology have been synthesized by the reaction of pyrazine with Pb(NO 3) 2 and NaI via sonochemical irradiation. Nano-structured PbI 2 and PbO were synthesized from compound 1 by calcination at argon and air atmospheres, respectively. The structure of 1 was determined by single crystal X-ray crystallography and the nano-structures were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of nano-sized and single crystalline samples of 1 were studied and compared.

Spin-Gap Formation and Thermal Structural Studies in Reduced Hybrid Layered Vanadates

Reduced layered M(C4H4N2)V4O10 ((I, M = Co; II, M = Ni; III, M = Zn); C4H4N2 = pyrazine, pyz) hybrid solids were synthesized via hydrothermal reactions at 200-230 degrees C, and their structures determined by single-crystal X-ray diffraction (Cmcm, No. 63, Z = 4; a = 14.311(2), 14.2372(4), 14.425(1) A; b = 6.997(1), 6.9008(2), 6.9702(6) A; and c = 11.4990(8), 11.5102(3), 11.479(1) A; for I, II, and III, respectively). All three solids are isostructural and contain V4O102- layers condensed from edge- and corner-shared VO5 square pyramids. A single symmetry-unique V atom is reduced by 1/2 electron (on average) and bonds via its apical oxygen atom to interlayer Mpyz2+ chains. Magnetic susceptibility measurements show a strong temperature dependence and a Curie constant that is consistent with two randomly localized spins per V4O10(2-) formula for III. Further, the unusual discovery of a remarkably well-defined transition to a singlet ground state, as well as formation of a spin gap, is found for III at 22(1) K. The temperature-dependent electrical conductivities show apparent activation energies of 0.36 (I), 0.46 (II), and 0.59 eV (III). During heating cycles in flowing N2, the samples exhibit weight losses corresponding to the removal of predominantly pyrazine, pyrazine fragments, and CO2 via reaction of pyrazine with the vanadate layer. The complete removal of pyrazine without loss of crystallinity is found for well-ground samples of I and III. The SEM images of I and II after heating at 400-500 degrees C show relatively intact crystals, but at 600 degrees C further structural collapse results in the formation of macropores at the surfaces.

The first molecular structure containing four hydroperoxo groups: piperazine-2,3,5,6-tetrayl tetrahydroperoxide pyrazine disolvate dihydrate

The reaction of pyrazine with hydrogen peroxide resulted in piperazine-2,3,5,6-tetrayl tetra­hydro­peroxide, crystallizing as its pyrazine disolvate dihydrate, C4H10N2O8·2C4H4N2·2H2O. In the crystal structure, the tetra­peroxo mol­ecules, which possess a crystallographically imposed centre of symmetry, are linked into a three-dimensional network by hydrogen-bonding inter­actions involving the pyrazine and water mol­ecules.

SHN Reactions of Pyrazine N‐Oxides and 1,2,4‐Triazine 4‐Oxides with CH‐Active Compounds.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Reactions and syntheses of pyrazines

This review deals with syntheses and reactions of pyrazines, especially, of 2,5-disubstituted pyrazines. The description was made in due to order of 1) synthesis and properties of 2,5-disubstituted pyrazines, 2) synthesis of 2,5-disubstituted pyrazine N-oxides, 3) synthesis of pyrazinols, 4) synthesis and utilization of pyrazinethiols; preparation of aldehydes, utilization as an acyl carrier, and preparation of olefins via the elimination of pyrazinylsulfinyl group, 5) synthesis of aminopyrazines, 6) synthesis of azidopyrazines and their transformation to imidazoles, 7) palladium-catalyzed reactions of chloropyrazines; dechlorination, introduction of cyano, alkenyl, alkynyl, alkyl, and aryl groups to the pyrazine ring. The cross-coupling of chloropyrazines with aromatic heterocycles such as furan, thiophene, pyrroles, indoles, benzo[b]furan, benzo[b]thiophene, oxazole, thiazole, benz[b]oxazole, and benzo[b]thiazole is also described.

Abstraction of multiple surface atoms by pyrazine, pyrene and HC2N ions on low‐energy collisions with self‐assembled monolayer surfaces

AbstractIon/surface reactions of pyrazine and pyrene molecular ions and the HC2N+· ion were investigated using an alkyl self‐assembled monolayer surface consisting of hydrogenated and perdeuterated chains (CH3(CH2)15S–Au and CD3(CD2)15S–Au) intimately mixed in a 1:1 ratio. Each of these projectile ions is known to react upon collision at hydrocarbon‐covered surfaces, HC2N+· by abstraction of multiple hydrogen atoms and the pyrazine and pyrene molecular ions by abstraction of groups containing one or more carbon atoms. Data from the isotopically mixed surface show that pyrazine and pyrene abstract multiple carbon units from a single chain and that the units are transferred as intact alkyl units. The isotopic peak pattern arising from addition of two hydrogens to the HC2N+· ion on collision with the mixed surface differs from that expected from random addition of H and D, and the results indicate that multiple hydrogen atoms are abstracted from the same surface chain. Translational energy measurements on the ion/surface reaction products show that they leave the surface with very low kinetic energies (<5 eV).

Synthesis and characterisation of a pyrazine bridged bis-allyl ruthenium(IV) complex. Crystal structure of [{(η 3:η 3-C 10H 16)RuCl 2} 2(μ-C 4H 4N 2)]·2CHCl 3

The reaction of pyrazine with the ruthenium(IV) bis-allyl dimer [(η 3:η 3-C 10H 16)RuCl(μ-Cl)] 2 gives the bridged binuclear complex [{(η 3:η 3-C 10H 16)RuCl 2} 2(μ-C 4H 4N 2)] in high yield. The complex has been characterised by 1H NMR spectroscopy and by a single-crystal X-ray diffraction study.

ChemInform Abstract: Intramolecular Diels‐Alder Reactions of Pyrazines with Alkynylphenyl Moieties as Side‐Chain Dienophiles.

AbstractThe pyrazines (I), (IV) and (VII) react under neutral and acidic conditions to give tricyclic b‐ and c‐anellated pyridines.

ChemInform Abstract: Preparation and Crystal Structure of Dipyrazinium Trichromate and Bond Length Correlation for Chromate Anions of the Form CrnO2‐ 3n+1.

AbstractThe title compound is obtained by reaction of pyrazine with CrO3 in water with 45% yield and is characterized by an X‐ray structure analysis (space group P21, Z=2).

X-Ray crystal structure and properties of (1,4-pyrazinio)bis(dicyanomethylide)(diazaTCNQ)

The title compound has been synthesized by the reaction of pyrazine with tetracyanoethylene oxide in refluxing toluene. Single-crystal X-ray structure analysis has been performed on tetragonal crystals of space group P42/mnm with Z= 2. The cell constants are a= 8.781(2), c= 5.916 8(7)A, and V=456.2(2)A3. Block-diagonal least-squares refinement, based on 341 independent reflections with |F0|>3σ(F), yields R 0.047. The centres of the strictly planar diazaTCNQ (DATCNQ) molecules are located on (0,0,1/2) and on (l/2,1 /2,0), the molecular planes being parallel to the c plane and perpendicular to one another. DATCNQ exhibits a band at 635 nm due to an intermolecular interaction in the powder reflectance spectrum and behaves as a semiconductor with an electrical resistivity of 2.6 × 1010Ω cm as a compacted pellet at 25 °C. DATCNQ reacts with bromine in hexane to give DATCNQ·Brx(X=0.05 and 0.1 1), which exhibits resistivities of 2.2 × 108 and 3.2 × 106Ω cm at 25 °C.

Palladium Catalyzed Reactions of Pyrazines

Palladium Catalyzed Reactions of Pyrazines

ChemInform Abstract: Pyrazine Chemistry. Part 13. Preparation and Reactions of Pyrazine N‐Oxides Related to Mycelianamide.

AbstractAus dem DL‐Alanin (I) und dem L‐Tyrosinester (II) wird das geschützte Dipeptid (III) dargestellt und zur Deblockierung der Hydrogenolyse unterworfen, wobei das Benzylpiperazindion (IVa) entsteht, das das Gerüst des biologisch aktiven Stoffes Mycelianamid (X) aufweist.

Reaction of pyrazine with indoles in acetic anhydride

Reaction of pyrazine with indoles in acetic anhydride