Showing papers on "Pyridine published in 1972"
TL;DR: In this article, the structures of N-phenylbenzaldimine with palladium(II) acetate in boiling acetic acid have been confirmed by IR and proton NMR data, which are different from those reported by Molnar and Orchin.
220 citations
TL;DR: In this article, the effect of sorbed molecules on the cation distribution was studied by adding ammonia, pyridine, naphthalene and butene to the dehydrated zeolite.
144 citations
115 citations
TL;DR: Complexes of 2-pyridine thiol, 4-polycyclic pyridine and 2-methyl-6 pyridine thiol with cobalt(II), nickel, zinc, cadmium, mercury, platinum, and bismu... as discussed by the authors.
Abstract: Complexes of 2-pyridine thiol, 4-pyridine thiol, and 2-methyl-6-pyridine thiol, and some of their oxygen analogs with cobalt(II), nickel(II), zinc(II), cadmium(II), mercury(II), platinum(II), bismu...
88 citations
78 citations
76 citations
TL;DR: In this paper, the IR spectra of di-μ-halobis(halotricarbonylruthenium) complexes of formula [Ru(CO)3X2]2 (X = Cl, Br) have been studied in different solvents and a tentative assignment of the bands observed made.
70 citations
TL;DR: The green complex formed on treating commercial ruthenium trichloride hydrate with acetic acid and sodium acetate in ethanol is shown to be of the basic acetate oxo-centred triangular type with the formula [Ru3O(CO2Me)6-(H2O)3] as mentioned in this paper.
Abstract: The green complex formed on treating commercial ruthenium trichloride hydrate with acetic acid and sodium acetate in ethanol is shown to be of the basic acetate oxo-centred triangular type with the formula [Ru3O(CO2Me)6-(H2O)3](CO2Me). The complex may be cationic, neutral, or anionic depending on the pH of the solution, owing to ionisation of co-ordinated water. The water molecules may be replaced by pyridine to give [Ru3O(CO2Me)6py3]+. Both the aquo and pyridine complexes undergo successive one and two electron reductions to give complexes in which the metal atoms are in formal oxidation states + 2 ⅔ or (III, III, II) and +2 or (II, II, II) respectively. The reduction to the latter state involves loss of the central oxygen atom from the triangle of metal atoms; this atom may be reinserted using molecular oxygen, or more specifically by use of a reagent such as pyridine-N-oxide. In the presence of triphenylphosphine, [Ru3O(CO2Me)(H2O)3]+ gives the reduced species Ru3O(CO2Me)6(PPh3)3. The potentials and reversibility of the redox reactions have been studied electrochemically. Analogous complexes of other carboxylic acids are described. N.m.r., i.r., and electronic absorption spectra of the species are reported.
69 citations
TL;DR: Addition of the isomeric hydroxypyridines to a model hydroxylating system resulted in the formation of those diols predicted by theory.
Abstract: 1. Several species of micro-organisms that were capable of utilizing pyridine compounds as carbon and energy source were isolated from soil and sewage. Compounds degraded included pyridine and the three isomeric hydroxypyridines. 2. Suitable modifications of the cultural conditions led to the accumulation of pyridinediols (dihydroxypyridines), which were isolated and characterized. 3. Three species of Achromobacter produced pyridine-2,5-diol from 2- or 3-hydroxypyridine whereas an uncommon Agrobacterium sp. (N.C.I.B. 10413) produced pyridine-3,4-diol from 4-hydroxypyridine. 4. On the basis of chemical isolation, induction of the necessary enzymes in washed suspensions and the substrate specificity exhibited by the isolated bacteria, the initial transformations proposed are: 2-hydroxypyridine → pyridine-2,5-diol; 3-hydroxypyridine → pyridine-2,5-diol and 4-hydroxypyridine → pyridine-3,4-diol. 5. A selected pyridine-utilizer, Nocardia Z1, did not produce any detectable hydroxy derivative from pyridine, but carried out a slow oxidation of 3-hydroxypyridine to pyridine-2,3-diol and pyridine-3,4-diol. These diols were not further metabolized. 6. Addition of the isomeric hydroxypyridines to a model hydroxylating system resulted in the formation of those diols predicted by theory.
63 citations
TL;DR: A new type of mixed metal oxide TiO2·ZnO was prepared by either heterogeneous or homogeneous co-precipitation and the acidic property was measured by n-butylamine titration and by observation of infrared spectra of adsorbed pyridine as discussed by the authors.
Abstract: A new type of mixed metal oxide TiO2·ZnO was prepared by either heterogeneous or homogeneous co-precipitation and the acidic property was measured by n-butylamine titration and by observation of infrared spectra of adsorbed pyridine. It was found that TiO2·ZnO containing about 7 or 57% of ZnO shows a very large acid amount of 0.5–0.9 mmol/g and a fairly high acid strength of H0≤−3, the acid sites being both Bronsted and Lewis type and the acid sites of high strength created by heterogeneous precipitation. The catalytic activity and selectivity of TiO2·ZnO were found very high for the hydration reaction of ethylene. The catalyst was active also for the alkylation of phenol by methanol and gave only monoalkylated products.
61 citations
TL;DR: The reaction of halonitrobenzenes with t-butyl N-hydroxy carbamate (2, 3) gave t-Butyl N(nitroaryloxy)carbamates (3, 4), which yielded on acidolysis with trifluoroacetic acid, O-(nitro)-hydroxylamines (4, 5) as mentioned in this paper, used for amination of anionic nitrogens and of carbanions.
TL;DR: A series of monoalkylchromium complexes, RCrCl 2 (THF) 3 where R = methyl, ethyl, n-propyl and isobutyl and THF = tetrahydrofuran, have been prepared by reactions of chromium trichloride with organoaluminum compounds as mentioned in this paper.
TL;DR: In this article, the synthesis of tetrabenzylhafnium was described by means of NMR spectroscopy and the equilibrium quotient was found to be 12.6±0.6 for the zirconium compound and 460±30 for the hafnium compound.
TL;DR: In this paper, the results of homolytic acylation of compounds containing pyridine and pyrazine rings are reported, aldehydes being used as source of acyl radicals.
Abstract: The results of the homolytic acylation of compounds containing pyridine and pyrazine rings are reported, aldehydes being used as source of acyl radicals. The reactions proceed in high yields and with complete selectivity at positions α and γ to a heterocyclic nitrogen atom. The factors affecting mono- and poly-substitution and the formation of 9-acyl-9,10-dihydro-derivatives with acridine are discussed. A new process of homolytic acylation, based on decarboxylation of α-keto-acids, is also reported.
TL;DR: In this article, the half-wave potentials of the voltammetric oxidation and the reduction of various heterocyclic amine N-oxides have been measured in CH3CN by the technique of a rotating platinum electrode.
Abstract: The half-wave potentials of the voltammetric oxidation and the reduction of various heterocyclic amine N-oxides have been measured in CH3CN by the technique of a rotating platinum electrode. The reversibility of the electrode process was particularly examined for the oxidation reaction by analyzing the oxidation wave and by recording the ESR spectra. Then, the mutual relationship between the electronic spectra of these N-oxides and the values of the oxidation-reduction potentials was discussed in detail; we found that this kind of treatment is very useful in assigning the spectra. Finally, a good linear relation between the oxidation potentials of substituted pyridine N-oxides and the Hammett σ+ (Brown-Okamoto) constants was demonstrated and discussed.
TL;DR: The reaction of several variously substituted pyridines with bis(acetylacetonato)oxovanadium(IV), VO(ACA)2, has been studied as mentioned in this paper.
TL;DR: In this article, the synthesis of 1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid derivatives is described, most of which have either an alkoxy or a basic substituent in position 4.
TL;DR: The pyrazine ring, like the pyridine ring, is stable to oxidizing agents as discussed by the authors, and it is more resistant to alkaline permanganate th.an the benzene ring itself; it also survives strong acid and alkaline treatments that destroy the pyrimidine ring.
Abstract: Publisher Summary This chapter discusses the recent advances in pyazine chemistry. Pyrazine, or 1,4–diazine is a highly symmetrical molecule. Synthetic pyrazines exhibit a wide range of physiological activity, in some cases superior to those of pyridine or pyrimidine analogs. Alkylpyrazines are important flavor constituents of roasted food products such as coffee, cocoa, and peanuts; coffee, for instance, contains 2-isopropyl-5-methylpyrazine. Pyrazine and its alkyl derivatives are potentially useful bidentate ligands and form complexes with the following common transition metals. Pyrazines also possess considerable aromatic character. The main features of their reactivity may be predicted by regarding them as pyridines into which nitrogen has been inserted in the para position. Pyrazines also show close similarity in their reactions to the other diazines, pyrimidines, and pyridazines. The pyrazine ring, like the pyridine ring is stable to oxidizing agents. It is more resistant to alkaline permanganate th.an the benzene ring itself; it also survives strong acid and alkaline treatments that destroy the pyrimidine ring. Pyrazines are more resistant to electrophilic substitution reactions at the ring carbon atoms than the corresponding pyridines.
TL;DR: Condensation reactions of o-halogenopyridine-carboxylic acids with carbanions in the presence of copper or copper salts have been investigated in this paper.
Abstract: Condensation reactions of o-halogenopyridinecarboxylic acids with carbanions in the presence of copper or copper salts have been investigated. For example, 2-bromopyridine-3-carboxylic acid reacted with acetylacetone and with ethyl acetoacetate to give 2-acetonylpyridine-3-carboxylic acid and ethyl 3-carboxy-2-pyridylacetate respectively. This bromo-acid condensed similarly with β-diketones and β-keto-esters, and with diethyl malonate, an acyl group being eliminated by ethanolysis in each case. 2-Substituted 1,3-dicarbonyl compounds did not react. Examples of such condensations have been obtained with three of the four possible o-halogeno-acid isomers of the pyridine series. 4-halogenopyridine-3-carboxylic acid being the exception. These products are useful intermediates in the synthesis of naphthyridine derivatives. Thus 2-acetonylpyridine-3-carboxylic acid condensed with ammonia to form 7-methyl-1,6-naphthyridin-5(6H)-one and with amines, hydroxylamine, and hydrazine to give corresponding 6-substituted compounds, but reaction with methylhydrazine yielded 2,5-dihydro-2,4-dimethylpyrido[3,2-d][1,2]diazepin-1-one.
TL;DR: In this paper, the crystal and molecular structure of diaquobis(picolinato)cobalt(II) dihydrate has been determined from three-dimensional MoKα X-ray collected by the multiple-film Weissenberg method.
Abstract: The formation constants of the following have been measured with a polarographic method: binary copper(II) complexes of pyridine-2-carboxamide (picolinamide) and pyridine-2-carboxylic acid (picolinic acid), a ternary copper(II) complex of picolinic acid and imidazole, and a binary copper(I)-imidazole complex. The larger formation constant for picolinic acid over picolinamide is ascribed to the greater chelating ability of a carboxylate group over an amide carbonyl oxygen. The crystal and molecular structure of diaquobis(picolinato)cobalt(II) dihydrate, [Co(H2O)2(pc)2].2H2O, has been determined from three-dimensional MoKα X-ray collected by the multiple-film Weissenberg method. The unit cell dimensions are: a=9.89 ± 0.02 A, b=5.17 ± 0.01 A, c=17.50 ± 0.06 A, β=123.8 ± 0.4°. The space group is P21/c, and the calculated density is 1.67 g cm−3 with two formula weights per cell. The measured density is 1.67 g cm−3. The structure was solved by the Patterson method and refined by a least-squares method....
TL;DR: In this paper, the complexes formed by zinc(II), cadmium(II) and mercury (II) thiocyanates with pyridine have been examined spectroscopically (down to 222 cm−1) in the solid state.
TL;DR: The 6,6′-dichloro derivative was obtained from 6 by nucleophilic substitution using pyridinium hydrochloride as mentioned in this paper, which on hydrogenation was converted into 6, 6',dideoxysucrose hexabenzaote.