Pyridine Amine Research Articles

Copper(II) complex of a tridentate N-donor ligand with unexpected Cu–H interaction

The new pyridine–amine ligand, meophdpa (bis(dipyridylmethyl)-4-methoxyaniline) was synthesised and reacted with copper(II) perchlorate. The X-ray crystal structure of the resulting complex revealed a monomeric copper(II) site, with the copper bound to the three ligand nitrogens in a relatively unusual meridional fashion, as well as a chloride and a water molecule. The sixth coordination site was, unexpectedly, occupied by a phenyl ring hydrogen atom.

Nonreductive Deiodination of ortho-Iodo-Hydroxylated Arenes Using Tertiary Amines

A convenient and nonreductive deiodination is reported for the ortho-iodo-hydroxylated arenes including derivatives of quinolinol, phenol, and naphthol. Tertiary amines pyridine, triethylamine, and N-methylmorpholine in the presence of water initiated deiodination of ortho-iodo-hydroxylated arenes without affecting para-iodine and other reduction-susceptible groups. This reported method also works efficiently for polyiodinated systems. Simplicity, short reaction times, and absence of reducing catalyst are features of this method.

Novel Synthesis of Nucleoside 5‘-Phosphoramidates through Reaction of Nucleoside Triphosphates with Amines Mediated by Trimethylsilyl Chloride

Reaction of nucleoside triphosphates (NTPs) with amines in pyridine mediated by trimethylsilyl chloride produced nucleoside 5'-phosphoramidates in moderate yields without any preprotection of nucleosides and amino acid methyl esters. The reaction pathway is very similar to the mechanism of the RNA capping reaction, DNA or RNA ligation reaction, and catalysis of hydrolases and nucleases involving the formation of covalent enzyme-NMP (nucleoside 5'-monophosphate) intermediates in biological systems, which could provide a valuable clue for the enzymatic reactions.

Calorimetric data on intercalation of some aromatic amines into barium phenylphosphonate at the solid/liquid interface

Layered crystalline hydrated barium phenylphosphonate, Ba(HO 3PC 6H 5) 2 · H 2O compound was employed as host for aromatic amines pyridine and α-, β- and γ-picolines, intercalation by using the batch method in ethanol at 298 ± 1 K, gave maximum amounts of (1.13, 0.76, 0.84 and 0.97) mmol · g −1, respectively. The original interlamellar distance of 1532 pm increased after all intercalations. The thermochemical data were obtained on a differential isothermic microcalorimetric instrument by means of a titration procedure. From thermal effect data, the variation in enthalpy of intercalation for each system gave exothermic values of (−43.55 ± 0.32, −2.36 ± 0.04, −2.61 ± 0.01 and −3.07 ± 0.05) kJ · mol −1 for the above sequence. The variation in enthalpic values for pyridine derivatives can be interpreted through the influence of steric hindrance associated with the methyl group attached to the heterocyclic ring. In addition to exothermic enthalpy, the spontaneous negative Gibbs free energy and the positive entropic values indicate favorable thermodynamic data for such intercalations.

Catalytic Hydrosilylation of Furan, Thiophene, and Pyridine Aldimines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Catalytic Hydrosilylation of Furan, Thiophene, and Pyridine Aldimines

The addition of hydrosilanes (HSiEt3, HSiMe2Ph, H2SiPh2) to the CH=N bond of heterocyclic azomethines has been studied in the presence of monovalent complexes of rhodium and palladium. The effect on the reaction of the CF3 group of the aldimines, which were obtained from O-, S-, and N-heteroaromatic aldehydes and 2-trifluoromethylaniline, has been clarified, as were other regularities of the processes being studied. A series of corresponding furans, thiophenes, and pyridine amines has been synthesized.

Potentiometric determination of relative basicities of aliphatic amines in pyridine

Potentiometric titrations of methyl-, ethyl-, n-propyl-, n-butylamines and ammonia were carried out in pyridine using a standardized tetrabutylammonium hydroxide solution. The relative basicities were found in all cases to be in the order RNH 2 > R 2 NH > R 3 N, R being an alkyl group. Basicity of any amine was assumed to be the sum of the inductive contribution of alkyl group(s) and a contribution from pyridine solvent through hydrogen bonding. On this assumption, the experimental basicity order was rationalized. The order in pyridine is different from the order of gas phase basicities.

ChemInform Abstract: Concerning Amination of Pyridines by Hexamethyltriamidophosphate.

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Poly(4-vinyl pyridine)/Zinc Dodecyl Benzene Sulfonate Mesomorphic State Due to Coordination Complexation

Recently, it has been shown that the properties of flexible and semi-rigid polyelectrolytes can be tailored by using specific surfactants. In these cases, mesomorphic structures in bulk and in solution and network. morphologies in blends have been achieved. In polyelectrolytes, the available electrostatic interaction to bond the surfactants is large due to the charges bound to the polymer backbone. In this work, we show that mesomorphic behavior of even noncharged flexible polymers can be achieved if the interaction between the polymer and the surfactant is selected properly. The model system is atactic poly(4-vinyl pyridine) (P4VP) in combination with zinc dodecyl benzene sulfonate (Zn(DBS)(2)). FTIR measurements indicate that transition metal coordination between the Zn cation and the pyridine amines takes place, SAXS and birefringence show that mesomorphic structures are obtained, the long period being 27.8 Angstrom in the nominally fully complexed case and 26.1 Angstrom when the degree of complexation is 25%. Also pure Zn(DBS)(2) is mesomorphic with the long period of 23.7 Angstrom. The difference between the layer thicknesses of Zn(DBS)(2) and P4VP(Zn(DBS)(2))(x) can be explained by the atacticity of the polymer.

Synthesis of 3-amino derivatives of benzo[b]furo[2,3-c]pyridines

The reaction of 1,7-dimethyl-3(2H)-benzo[b]furo[2,3-c]pyridone with phosphoric acid amides gave 1,7-dimethyl-3-dimethylamino (morpholino)benzo[b]furo[2,3-c]pyridines. A method for the synthesis of 3-amino derivatives of 4-nitrobenzo[b]furo[2,3-c]pyridines, which consists in heating 1,7-dimethyl-4-nitro-3(2H)-benzo[b]furo[2,3-c]pyridone with hexamethyldisilazane and secondary or primary amines in pyridine, was developed.

ChemInform Abstract: Synthesis and Characterization of Amine‐Alkylcyanoboranes.

AbstractAs demonstrated for the compounds (V), twelve examples are prepared in moderate yield with the amines pyridine, tetramethylethylenediamine and quinuclidine.

High Molecular Weight Pyridine Amines as Solvents for Uranium(VI) and Its Separation from Thorium

Abstract Three high-molecular-weight pyridine amines, 5-(4-pyridyl)nonane, 2-hexylpyridine, and diphenyl-2-pyridylmethane, have been studied as components of solvent extraction systems. Results are presented to show the dependence of the uranium extraction coefficient (D a o = [Uorg]/[Uaq]) on equilibrium concentrations of hydrochloric, nitric, and sulfuric acid solutions with and without thiocyanate ions. The optimal conditions for the extraction have been carefully selected from an extensive and critical investigation of the various factors involved; e.g., the effects of diluents, concentration of the mineral acids, thiocyanate ions, salting and complexing agents, and the concentration of the solvents. The extraction mechanism and composition of the extracted complexes of uranium have been studied from partition and slope-analysis data. The results obtained give an orderly picture of the mechanism of extraction of uranium thiocyanate complexes (partly in relation to the hydration and solvation of the compounds extracted). Anomalous extraction behavior was observed at solvent concentrations greater than 0.05 M. The results have been interpreted on the basis of the formation of micelles of the salt molecules of the solvents. It has been shown that these pyridines will extract the metal efficiently and reversibly from dilute acid chloride, nitrate, and sulfate solutions containing thiocyanate. Common salts have no depressing effect on extraction. Distribution coefficients and separation factors of several metal ions, with respect to uranium(VI), are reported for the three mineral acid systems, and a method for the separation of thorium-234 from uranium is also described.

The Use of Protonation Induced Changes in Carbon-13 NMR Chemical Shifts to Investigate the Solution Microscopic Structure of Partially Protonated Polybasic Molecules

Abstract Changes in the NMR chemical shift of carbon-13 nuclei upon protonation of a nearby basic center are shown to be a useful method of probing the microscopic site of protonation of molecules containing multiple basic centers, such as diethylenetriaminepenta-acetic acid (DTPA). This approach is also shown to support the predominance of the pyridine amine protonated tautomer in the 4-pyridone ↔ 4-hydroxypyridine equilibrium.

Extraction Separation Studies of Gold by 2-Hexylpyridine

Abstract The high molecular weight pyridine amine, 2-hexylpyridine, has been studied as a component of solvent extraction systems. Extraction of mineral acids by the compound is described. The ionization constant (pKBH +) has been determined by potentiometric titration and spectrophotometrically. The distribution of Au(III) between solutions of 2-hexylpyridine in benzene and different mineral acid solutions has been investigated as a function of the concentration of the acids, extractant, and salting-out agents. The extraction mechanism and the composition of extracted complexes of Au(III) are discussed. Separation factors of a number of metal ions relative to gold have been reported, and the determination of gold from a number of synthetic and ore samples was made by neutron activation analysis. 2-Hexylpyridine has been shown as a selective extraction reagent for gold. It has been shown that 2-hexylpyridine dissolved in benzene will extract gold efficiently and reversibly from moderate acid chloride, nit...

Reaction of acetoacetaldehyde tetraethylacetal with quaternary salts of heterocyclic bases and some reactions of the products

δ-Alkoxy-δ-methylbutadienyl salts were obtained by condensation of acetoacetaldehyde tetraethylacetal with quaternary salts of nitrogen-containing heterocyclic bases. δ-Methyl-substituted tetramethylidynehemicyanines were obtained by the reaction of the acetal with quaternary salts of heterocyclic bases and amines in pyridine. β-Methyl-substituted dicarbocyanine and α-methyl-substituted tetramethylidynemerocyanine dyes were synthesized.

Tetracoordination of copper(I) by monofunctional amines

The highest complexes of the monofunctional amines pyridine, quinoline, isoquinoline, piperidine, n- and sec-butylamine, aniline, p-methoxyaniline, and N-benzylidenemethylamine with copper(I) ion in propylene carbonate have been determined by polarography. A maximum coordination of four ligands has been noted in the cases of pyridine and isoquinoline. Solid tetrakis(pyridine)copper(I) percholorate has been isolated, and by infrared examination of 3:1, 4:1, and 5:1 mole-ratio mixtures of the monofunctional amines with tetrakis(acetonitrile)copper(I) perchlorate, the tetracoordination of quinoline, isoquinoline, piperidine, and N-benzylidenemethylamine to copper(I) has been established. The polarographic data have been used to estimate the appropriate overall stability constants in propylene carbonate.

Acid-base strengths in pyridine

Although pyridine is a solvent with a low dielectric constant, spectrophotometric determinations show simple dissociation without ion pairs as intermediates for some sulfonphthaleins and polynitrophenols in pyridine. The salts of a number of amines and hydrochloric acid, perchloric acid and picric acid are not completely dissociated in pyridine. Dissociation constants of these salts were determined from differential vapour pressure measurements. For the titrations in pyridine of an acid with an amine, calculations were based on the following reactions : HX∡H + + X −; B + H + ∡BH +; BH + +X −∡BH +X −. With this reaction scheme it was possible to determine pK a values for protonated amines in pyridine from the curves of titrations carried out with a calibrated glass electrode. Evidence for the occurrence of homoconjugation of some polynitrophenols in pyridine was found in the titration of these compounds with tetramethylguanidine. Homconjugation constants were estimated from the titration curves.

AROMATIC SUBSTITUTION: PART VIII. SOME ASPECTS OF THE MECHANISM OF THE TSCHITSCHIBABIN REACTION

The mechanism of the direct amination of pyridines is discussed in terms of both addition–elimination and elimination–addition pathways. The absence of deuterium kinetic isotope effects as well as the orientations observed in such reactions rule out the intervention of 2,3- or 2,6-dehydropyridines. The effect of a 3-methyl group upon the reactivities towards the amide ion of the various nuclear positions in pyridine has been determined. Predictions based on molecular orbital (m.o.) calculations are discussed in terms of the detailed mechanism of this reaction and of the orientations observed.