Showing papers on "Pyridine published in 1985"
TL;DR: In this paper, a review is given on the possibilities of various nuclear magnetic resonance techniques which have been applied up till now to study quantitatively the acidity of zeolites and related catalysts.
196 citations
TL;DR: The macromolecular network structure of bituminous coals has been studied by using the classical solvent-swelling techniques of polymer chemistry as discussed by the authors, showing that solvents which are hydrogen bond acceptors show strongly enhanced coal swelling which correlates with the strength of the hydrogen bond between the solvent and pfluorophenol.
Abstract: The macromolecular network structure of bituminous coals has been studied by using the classical solvent-swelling techniques of polymer chemistry. Solutions of nonpolar solvents in coals follow regular solution theory. Solvents which are hydrogen bond acceptors show strongly enhanced solubility (coal swelling) which correlates with the strength of the hydrogen bond between the solvent and p-fluorophenol. A family of network active hydrogen bonds exists in bituminous coals. In native coals, their strength appears to range from 5 to 8 kcal/mol. The use of solvent-swelling data to calculate the number average molecular weight between cross-links (anti M/sub c/) has been explored. It is not yet possible to calculate correct absolute values for anti M/sub c/, but changes in anti M/sub c/ can be followed. The treatment of coals as macromolecular networks is possible and provides significant new insight into their structure. 39 references, 8 figures, 4 tables.
147 citations
TL;DR: In this paper, the effect of both nucleophile and silane on salt formation has been studied, and the implications for the design of more efficient silylation mixtures are discussed.
97 citations
92 citations
90 citations
TL;DR: In this paper, the results of an experiment with co-ordinated pyridine have been shown to be stable at room temperature, and the room-temperature spectra for the Fe2Mg, Cr2Ni, Fe2Ni and CrFeNi compounds have been fitted by using an exchange Hamiltonian.
Abstract: Reaction of Fe3+, M2+, and acetate ions in aqueous solution gives [FeIII2MIIO(MeCO2)6(H2O)3]·3H2O (M = Mg, Mn, Co, Ni, or Zn), which on crystallisation from pyridine (py) is converted into [FeIII2MIIO(MeCO2)6(py)3]. Reaction of chromium(II) acetate with metal(II) acetate in pyridine in the presence of air gives [CrIII2MIIO(MeCO2)6(py)3](M = Mg, Co, or Ni), and with [FeIII2MIIO-(MeCO2)6(py)3] in pyridine inthe absence of air gives [CrIIIFeIIIMnIIO(MeCO2)6(py)3](M = Mn or Fe) and [CrIII2FeIIIO(MeCO2)6(py)3]. The compounds with co-ordinated pyridine have been examined crystallographically and magnetically. The Cr2Mg, Cr2Ni, Fe2Ni, and CrFeNi compounds crystallise in the monoclinic system, space group Cc or C2/c, Z= 4, but the other seven compounds are rhombohedral and isomorphous with [M3O(MeCO2)6(py)3]·py (M = Mn or Fe), indicating that the three metal atoms are crystallographically equivalent as a result of disorder in the molecular orientation. Powder magnetic susceptibilities for the Cr2Co and Cr2Ni compounds(4.2–60 K), for the Fe2Mn and Fe2Ni compounds (4.2–295 K), and for the Fe2Ni(aquo) and Fe2Mg compounds (80–295 K) have been fitted by use of an exchange Hamiltonian to yield values of the exchange parameters J for the Cr–Cr, Fe–Fe, Cr–Ni, Fe–Ni, and Fe–Mn interactions, which are discussed in terms of superexchange mechanisms. The values of JFeFe in the Fe2Mg, Fe2Mn, and Fe2Ni compounds and of JCrCr in the Cr2Co and Cr2Ni compounds are approximately twice their values in the cations [MIII3O(MeCO2)6(H2O)3]+(M = Cr or Fe), indicating that the µ3-O atom provides the main super-exchange pathway. Diffuse-reflectance and solution spectra (6 000–40 000 cm–1) of the compounds have been recorded at room temperature and are discussed in terms of the ligand-field model; a band in the spectra of the FeIII2FeII and CrIIIFeIIIFeIII compounds at ca. 7 000 cm–1 is assigned to intervalence transfer. The room-temperature spectra of [M3O(MeCO2)6L3]Cl (M3= CrIII3, CrIII2FeIII, CrIIIFeIII2 or FeIII3; L = H2O or py) have also been obtained, and intense absorption bands at ca. 19 000 and 26 000 cm–1 are tentatively assigned to simultaneous (Cr3+, Fe3+) double excitations.
84 citations
TL;DR: In this article, a series of iron(III) complexes of thiosemicarbazones derived from 2-acetylpyridine, 6-methyl-2.acetyl pyridine and 2-polytopeptopyridineN-oxide have been prepared from Fe(ClO4)3 and FeCl3.
Abstract: A series of iron(III) complexes of thiosemicarbazones derived from 2-acetylpyridine, 6-methyl-2-acetylpyridine and 2-acetylpyridineN-oxide have been prepared from Fe(ClO4)3 and FeCl3. All of the isolated solids have cations involving two monobasic tridentate ligands, and either perchlorate or tetrachloroferrate(III) anions and are 1∶1 electrolytes. Coordinationvia the pyridine nitrogen (or theN-oxide oxygen), the imine nitrogen and the sulphur atom are confirmed by infrared spectra and x-ray diffraction. The presence of two different iron(III) species is indicated by the electron spin resonance spectra of the tetrachloroferrate(III) solids. E.s.r. along with electronic spectra prove the spin-paired configuration of these cationic iron(III) complexes.
80 citations
TL;DR: l-proline uptake via the intestinal brush-borderIMINO carrier was tested for inhibition by 41 compounds which included sugars, N-methylated, α-,β-, γ- and ε-amino and imino acids, and heterocyclic analogs of pyrrolidine, piperidine and pyridine.
Abstract: L-proline uptake via the intestinal brush-border IMINO carrier was tested for inhibition by 41 compounds which included sugars, N-methylated, alpha-, beta-, gamma- and epsilon- amino and imino acids, and heterocyclic analogs of pyrrolidine, piperidine and pyridine. Based on competitive inhibitor constants (apparent Ki' 's) we find that the IMINO carrier binding site interacts with molecules which possess a well-defined set of structural prerequisites. The ideal inhibitor must 1) be a heterocyclic nitrogen ring, 2) have a hydrophobic region, 3) be the L-stereoisomer of 4) an electronegative carbonyl group which is 5) separated by a one-carbon atom spacer from 6) an electropositive tetrahedral imino nitrogen with two H atoms. Finally, 7) the inhibitor conformation determined by dynamic ring puckering must position all these features within a critical domain. The two best inhibitors are L-pipecolate (apparent Ki' 0.2 mM) and L-proline (apparent Ki' 0.3 mM).
79 citations
TL;DR: In this paper, the energy contributions of metal-carbon and metal-ligand bonds in a variety of organometallic compounds are examined to seek trends as the metal or the ligand changes.
Abstract: The energy contributions of metal-carbon and metal-ligand bonds in a variety of organometallic compounds are examined to seek trends as the metal or the ligand changes. In general, the bond energies D(M-X) for metals from the same group increase as the energy of atomization of the metal increases. Metal—carbon bond dissociation energies fall along the sequence D0(MC) in diatomic carbides > D(M-Cp) in cyclopentadienyls > D(M-arene) > D(M-alkyl) > D(M-CO) in metal carbonyls. For transition metals, the ligand bonding power of phosphine donors (PEt3 > PPh3) is larger than for nitrogen donors (pyridine > MeCN > NH3), and olefine donors have similar bonding power to CO and pyridine. The irregular changes in the dissociation energies, D(M2), of transition dimetals on moving across the Periodic Table are considered in relation to the 'valence-state' adopted by the metal in forming metal-metal bonds.
70 citations
TL;DR: In the presence of free pyridine, the process can be interrupted at a mono-arylplatinum intermediate by formation of a dinuclear Pyridine adduct whose molecular structure has been determined as mentioned in this paper.
Abstract: Thermal rearrangement of diaryl(2,2′-bipyridyl)platinum(II) complexes normally proceeds via consecutive 3-metallations of the bipyridyl ligand with hydrogen migration and elimination of two equivalents of arene, while, in the presence of free pyridine, the process can be interrupted at a monoarylplatinum intermediate by formation of a dinuclear pyridine adduct whose molecular structure has been determined.
67 citations
TL;DR: In this paper, the preparation and reactions electrochimiques du complexe donne dans de la pyridine and presence d'une electrode-bouton de platine are discussed.
Abstract: Donnees sur la preparation et les reactions electrochimiques du complexe donne dans de la pyridine et presence d'une electrode-bouton de platine
15 Mar 1985
TL;DR: In this article, the photochromism of DNBP single crystals was investigated by optical absorption spectroscopy in the temperature regime of the single crystal in the case of a single crystal.
Abstract: The photochromism of DNBP single crystals has been investigated by optical absorption spectroscopy in the temperature regime 10
TL;DR: The N1-methyl-N3-/purin-6-yl/imidazolium salt is generated in phosphorylation with TPSCl/1-methylimidazole as a coupling system and is representatives of a new family of ionic side-products in oligonucleotide synthesis involving hypoxanthine residues.
Abstract: Fluorescent N-/purin-6-yl/pyridinium salts are formed in pyridine assisted phosphorylations and arenesulphonations of the hypoxanthine lactam system under various conditions including those used in oligonucleotide synthesis. The N1-methyl-N3-/purin-6-yl/imidazolium salt is generated in phosphorylation with TPSCl/1-methylimidazole as a coupling system. Both salts are representatives of a new family of ionic side-products in oligonucleotide synthesis involving hypoxanthine residues. Their isolation procedure has been developed. High reactivity of N-/purin-6-yl/pyridinium salts towards some reagents used in oligonucleotide chemistry, e.g. pyridinium mediated conversion of hypoxanthine into 6-aminopurine, can result in point mutations in synthesized oligomer.
TL;DR: L'etude est faite pour une serie de 6 systemes: trimethylamine, triethylamines, methyl-1 pyrrolidine, pyridine, fluoro-2 pyridines, acetonitrile as mentioned in this paper.
Abstract: L'etude est faite pour une serie de 6 systemes: trimethylamine, triethylamine, methyl-1 pyrrolidine, pyridine, fluoro-2 pyridine, acetonitrile
TL;DR: In this paper, infrared spectra of adsorbed pyridine showed the presence of Bronsted acid sites and two types of Lewis acid sites on oxidized molybdena-alumina.
TL;DR: Two mild new chromium (VI) reagents derived from nicotinic acid and isonicotinic Acid oxidize alcohols into carbonyl compounds, mercaptans into disulfides and hydroquinones into quinones and Oxidtion of polynuclear aromatic hydrocarbons is made.
TL;DR: In this article, the preparation of trans-type trans-complexes de type trans-X(CO) 2 L 2 M≡CR(M=Cr, Mo, N; R=C 6 H 5,CH 3 ; X=Cl, Br, CF 3 C(O)O, L 2 =2 pyridine, tetramethylethylenediamine)
TL;DR: In this paper, three aroyl hydrazones, pyridoxal isonicotinoyl hydrazone (H2pih), H2pbh and H2sbh, were synthesized and characterized.
TL;DR: Heats of solution of triethylamine, aniline, pyridine, and model compounds (3-ethylpentane, benzene) in 17 organic solvents (n-heptane, cyclohexane, carbon tetrachloride, 1,2-dichloroethane, α,α,α-α-...
Abstract: Heats of solution of triethylamine, aniline, pyridine, and model compounds (3-ethylpentane, benzene) in 17 organic solvents (n-heptane, cyclohexane, carbon tetrachloride, 1,2-dichloroethane, α,α,α-...
TL;DR: In this article, the authors investigated the catalytic properties of Ni-Tetra(3-methylphenyl) porphyrin (Ni-T3MPP) over the oxide form of CoMo Al 2 O 3 catalyst and without pyridine over the sulfided catalyst.
Patent•
14 Feb 1985
TL;DR: In this article, the authors present antihypertensive and coronary dilating asymmetric diesters of 1,4-dihydro-2,6-dimethyl-pyridine-3,5-dicarboxylic acid (or the stereoisomers or pharmaceutically acceptable acid addition salts thereof) with the general formula (I):
Abstract: Novel antihypertensive and coronary dilating asymmetric diesters of 1,4-dihydro-2,6-dimethyl-pyridine-3,5-dicarboxylic acid (or the stereoisomers or pharmaceutically acceptable acid addition salts thereof) have the general formula (I): ##STR1## wherein Ph is phenyl, Ar is 2-nitrophenyl, 3-nitrophenyl, 2,3-dichlorophenyl or benzofurazan-4-yl, A is a straight or branched chain alkylene radical having from 2 to 6 carbon atoms, R is a straight or branched chain alkyl radical having from 1 to 6 carbon atoms, optionally mono-substituted by an alkoxy substituent having from 1 to 6 carbon atoms, R 1 is hydrogen, hydroxy or an alkyl radical having from 1 to 4 carbon atoms, and R 2 is hydrogen or methyl. The subject diesters are facilely prepared from the aldehydes ArCHO and esters of acetoacetic and 3-aminocrotonic acids.
TL;DR: In this paper, the cyanation of 3-halo, 3-methoxy-, and 3-dimethylaminopyridine 1-oxide with trimethylsilanecarbonitrile gave predominantly the corresponding 3-substituted 2-pyridine carbonitriles.
Abstract: The cyanation of 3-halo-, 3-methoxy-, and 3-dimethylaminopyridine 1-oxide with trimethylsilanecarbonitrile gave predominantly the corresponding 3-substituted 2-pyridinecarbonitriles. The deoxygenation of nitropyridine 1-oxides to nitropyridines with the same reagent is also described.
TL;DR: Autooxydation de trimethylamine, N,N-dimethylaniline, (dimethyl lauryl)-,(dimethyl benzyl)-amines, pyridine et methyl-4 morpholine
Abstract: Autooxydation de trimethylamine, N,N-dimethylaniline, (dimethyl lauryl)-, (dimethyl benzyl)-amines, pyridine et methyl-4 morpholine
TL;DR: In this article, carbonaceous mesophase of high solubility was prepared from A240 petroleum and coal tar (QI free) pitches by assuring homogeneous heating under a vigorous nitrogen flow and stirring.
TL;DR: Etude des melanges CH 2 Br 2 +pyridine +β-picoline, pyridine+β-icpicoline+cyclohexane, benzene+toluene+dichloroethane as discussed by the authors.
Abstract: Etude des melanges CH 2 Br 2 +pyridine+β-picoline, pyridine+β-picoline+cyclohexane, benzene+toluene+dichloroethane, benzene+o-xylene+dichloroethane, benzene+p-xylene+dichloroethane