Pyridinium Perchlorate Research Articles

The effect of the methoxy group on the geometry of the benzene ring supported by crystal structure studies and Ab Initio Calculations. Crystal and Molecular Structure of 4-(4-Methoxyphenyl)-2,6-diphenylpyridine and 1-Methyl-4-(4-methoxy-phenyl)-2,6-diphenylpyridinium perchlorate.

Crystal and molecular structures of 4-(4-methoxyphenyl)-2,6-diphenylpyridine (I) and 1-methyl-4-(4-methoxyphenyl)-2,6-diphenyl pyridinium perchlorate (II) are repoded, with R=0.052 and 0.070, respectively. The lower precision of II is due to disorder of the perchlorate anion. A geometrical analysis of 8 p-substituted derivatives of anisole shows that the methoxy group interacts strongly with the ring via the resonance effect. Significant deformations of the exo-cyclic bond angles at MeO- substituted carbon atom are due to steric hinderance between ortho CH and Me group. Ab initio calculations for anisole are in line with the observed planar conformation of these systems. The difference in energy between the planar and perpendicular conformers is 1.4 kcal/mole at the 6-31G* level. The intramolocular interactions between the -OMe group and C ipso-C orthoH are explored through additional ab initio calculations. They induce more double character of C ipso-C ortho bond, thereby causing one Kekule structure to be preferred.

Sterically Crowded Heterocycles. I. Molecular Structure of 3-Chain Substituted 2-Phenylimidazo[1,2-a]pyridinium Salts

2-Phenyl-3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridine (I) was converted to corresponding 1-alkyl-2-phenyl-3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridinium salts III - VI and 2-phenyl- 3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridinium perchlorate (VII). The protonation site is discussed in terms of calculated molecular energies of alternative cations. The X-ray structure analyses of enone I and its quaternary periodide III are reported and compared with the PM3 molecular optimizations. 1H NMR and 13C NMR spectra reveal well changes of molecular structures caused by the transformation of the base I into salts III - VII.

ChemInform Abstract: Allylation of Aldehydes with Allyl Bromides and Zinc Induced by Pyridinium Perchlorates.

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Composition-property relationships for poly((3-methylthiophene)-co-(1-methyl-3-(pyrrol-1-ylmethyl)-pyridinium)) electronically conducting ionomer films

3-Methylthiophene and 1-methyl-3-(pyrrol-1-ylmethyl)pyridinium perchlorate have been copolymerized electrochemically to form thin electronically conducting ionomer films on electrodes. The morphology and thickness of the films were investigated by scanning electron microscopy and the compositions were determined using an electron microprobe. The electrochemistry of the copolymers is similar to that of the two homopolymers and is very fast. In-situ electronic conductivities, measured by dual-electrode voltammetry and impedance spectroscopy, increase with increasing 3-methylthiophene content. The copolymers exhibit very high ionic conductivities in both their reduced and oxidized forms. Ionic conductivities increase with increasing 3-methylthiophene content owing to increasing porosity. An oxidized equimolar copolymer had an ionic conductivity of 6 × 10 −4 Ω −1 cm −1 in acetonitrile containing 0.1 M Et 4NClO 4.

C-13 and H-1 NMR Study of Alkyl and Aryl-Substituted 1-(4′-Dimethylaminobenzylideneamino)pyridinium Perchlorates

Abstract C-13 and H-1 NMR spectra of some 1-(4′-dimethylaminobenzylideneamino)pyridinium perchlorates show that the angle of twist of the pyridine ring in unsubstituted, 1, and 2-alkyl substituted compounds 2–5 is comparable. However, it is considerably increased in 2,6-dialkyl derivatives. As seen from the spectral data, pyridine and phenyl rings in 2,6-diphenyl derivative 15 are not coplanar. The effect of 4-alkyl substituent is of hyperconjugative chacter. In general, the amount of the positive charge at C-4 in 2,6-dialkyl substituted salts is higher as compared to 2-monosubstituted compounds.

Coupling of ion and electron transport during impedance measurements on a conducting polymer with similar ionic and electronic conductivities

The ionic and electronic conductivities of poly-[1-methyl-3-(pyrrol-1-ylmethyl)pyridinium perchlorate] have been measured as a function of potential in various solvents by impedance spectroscopy. The ionic conductivity of this polymer shows a strong solvent dependence, ranging from 0.31 mS cm–1 in water to 8.0 µS cm–1 in propylene carbonate. By changing the solvent and the potential, the ionic to electronic conductivity ratio for the polymer has been varied from 1 to 1, allowing a thorough exploration of the validity of a dual resistance transmission line model of the polymer. Overall, the experimental results support the model, and reasonably accurate electronic and ionic conductivities are obtained when data are analysed according to the model. However, an anomalous dependence of ionic conductivity on oxidation state has been observed. There appears to be a direct relationship between the electronic and ionic conductivities of the polymer when they are of similar magnitude, indicating a coupling of ion and electron transport.

4- Tert-butyl-1-(4'-dimethylamino-benzylideneamino)pyridinium perchlorate (BDPP): a novel fluorescent dye

4- Tert-butyl-1-(4'-dimethylaminobenzylideneamino)pyridinium perchlorate (BDPP) is a novel dye showing unusual properties, viz. (i) it gives a yellow-green fluorescence which quenched on heating and in solution, and (ii) by heating at 180° or by simple squeezing, it is transformed into orange, non-fluorescent crystals (i.e. it is piezochromic). Surprisingly, among other 1- (benzylideneamino) pyridinium salts, BDPP was the only dye revealing the above properties.

Crystal Structure of 1‐(4‐Pyridylmethyl)‐2,4,6‐Triphenyl Pyridinium Perchlorate

Abstract1‐(4‐pyridylmethyl)‐2,4,6‐triphenyl pyridinium perchlorate crystallizes in space groups P1 with 3 molecules per asymmetric unit. The cell parameters obtained are: a = 12.142(3), b = 16.972(4), c = 20.229(7) Å, α = 83.66(4), β = 74.83(3), and γ = 69.47(2)°. The crystal structure was determined using the direct methods technique. Anisotropic refinement was undertaken using block diagonal least squares. In the final cycle of the refinement the reliability factor was found to be R0 = 0.084 for 3982 reflections with I ≧ 3σ (I). All rings are planar within experimental errors. Rings B, C, D, and E are twisted with respect to the central plane.

Carbonic Anhydrase Inhibitors. V: Pyrylium Salts in the Synthesis of Isozyme-Specific Inhibitors

AbstractSyntheses and physicochemical properties of 2,4,6-tri-, 2,3,4,6-tetra-, or 2,3,4,5,6-pentasubstituted 1-(2-sulfonamido-1,3,4-thiadiazol-5-yl)pyridinium perchlorates are presented. The new compounds, putative inhibitors of membrane-bound carbonic anhydrase, were tested for inhibitory action on the bovine red cell enzyme.

Allylation of Aldehydes with Allyl Bromides and Zinc Induced by Pyridinium Perchlorates.

The effects of inorganic and organic salts on the allylation of benzaldehyde with unactivated zinc powder and allyl bromide in acetonitrile were examined at room temperature. Although Li+, Na+, Mg2+, and R4N+ perchlorates exerted negligible effects on the allylation, various pyridinium perchlorates except the 2, 6-lutidinium salt promoted the formation of the corresponding homoallylic alcohol from benzaldehyde. In the presence of pyridinium perchlorate, the allylation of aliphatic and aromatic aldehydes with allyl bromide and zinc smoothly proceeded to give the corresponding products in good yields. Hydroxy-, methoxy-, and halogen-substituted aromatic aldehydes were tolerated under the reaction conditions emplyed. In the case of cinnamyl aldehyde, only 1, 2-addition was observed.

Oxidative and Basic Transformations of Some 1-Heteroaryloligophenylpyridinium Salts. Limitations to the Applicability of Ferricyanide Oxidation

Ferricyanide oxidation of 2,3,4,6-tetraphenyl-1-(2'-pyridyl)pyridinium perchlorate (III) gave, in addition to the biheterocyclic product Ib, two pyrrole derivatives IIb and IIc and in some conditions also the diketone IV. Additional pyrrole derivatives, VII and IX, were obtained analogously from the thiazole 2,4,6-triphenylpyridinium salts V and VIb. Alkalysis of the thiazole salts V and VIb and of the imidazole salts VIc and VId using alcoholic KOH afforded the biheterocyclic products XI-XIV. The mechanisms of the conversions involved are discussed.

Absolute structures of (–)-(SS,SC)-1-phenylethyl 2-pyridyl sulfoxide and (–)-(R)-1-methyl-2-(1-phenylethyl)pyridinium perchlorate

Absolute structures of (–)-(SS,SC)-1-phenylethyl 2-pyridyl sulfoxide and (–)-(R)-1-methyl-2-(1-phenylethyl)pyridinium perchlorate

ChemInform Abstract: Reaction of Pyridines with Epichlorohydrin.

AbstractThe (fused) pyridinium perchlorates (I) are coupled with one equivalent epichlorohydrin (II) to give the N‐chlorohydroxypropyl derivatives (III).

ChemInform Abstract: N,N‐Dimethoxyamine. A New Methylating, Aminating, and Epiminating Reagent.

AbstractWhen the acid (I), pyridinium perchlorate (IV), or diethyl ether (VI) are treated with N,N‐dimethoxyamine (II), methylation takes place to produce the ester (III), N‐methylpyridinium perchlorate (V), and the oxonium salt (VII) respectively.

ChemInform Abstract: Reaction of Pyrylium Salts with Nucleophiles. Part 21. Unexpected Formation of 6,6‐Dimethyl‐5‐isopropyl‐2,4‐cyclohexadienylidene‐1‐imines from Primary Amines and 2,6‐Diisopropylpyrylium Salts.

AbstractThe pyrylium perchlorates (I) react with the primary amines (II), producing the pyridinium perchlorates (III) and the iminium salts (IV).

ChemInform Abstract: Oxidation of Saturated Hydrocarbons by Hydrogen Peroxide in Pyridine Solution Catalyzed by Copper and Iron Perchlorates.

AbstractOxidation of cyclohexane (I) and 2‐methylbutane (IV) with hydrogen peroxide in the presence of copper(II) perchlorate and pyridinium perchlorate yields cyclohexanone (II) and 2‐methylbutan‐3‐one (V) as the main products.

Electrochemical synthesis of heterocyclic compounds. 17. Anodic oxidation of hydrazones in the presence of heteroaromatic and Schiff bases

Anodic oxidation of a series of hydrazones in the presence of heteroaromatic and Schiff bases were performed in acetonitrile-tetraethylammonium perchlorate electrolyte solution at platinum using controlled potentials. As a result of four-electron oxidation several s-triazolo [4,3-a] pyridinium perchlorates, s-triazolo [4,3-a] quinolinium perchlorate s-triazolo [3,4-a] isoquinolinium perchlorate and s-triazolo [4,3-a] benzo [f] quinolinium perchlorate were obtained in yields ranging from 30% to 90%

Condensed pyridines. 6. Synthesis and strucutre of adamantyl-, cyclopropyl- and alkyl-substituted 3-halomethyl-2,3-dihydro-8-cyanothiazolo[3,2-a]pyridinium salts and their oxazolo and selenazolo derivatives

The reaction of substituted 2-cyanopyridin-2(1H)-ones and their thione and selenone derivatives with allyl bromide gives the corresponding 2-allyloxy-, 2-allylmercapto-, and 2-allylseleno-3-pyridines, which upon treatment with halogens, form intramolecular quaternization products, namely, 3-halomethyl-2,3-dihydro-8-cyanooxazole[3,2-a]pyridinium salts and their thiazolo and selenazolo analogs. X-ray diffraction structural analysis was used to determine the structure of 3-bromomethyl-2,3-dihydro-5,7-dimethyl-8-cyanothiazolo[3,2-a]pyridinium perchlorate.

ChemInform Abstract: Fluorocarbon Derivatives of Nitrogen. Part 13. Reaction of Perfluoroalkanenitriles with Pyridinium Alkoxycarbonylmethylides: Synthesis of Perfluoroalkylated Imidazo(1,2‐a)pyridines (1‐Azaindolizines). X‐Ray Molecular Structure of Pyridinium 4,5‐Dihydro‐4‐oxo‐2,6‐bis(trifluoromethyl)pyrimidin‐5‐ylide.

AbstractPyridinium t‐butoxycarbonylmethylide ‐ generated in situ by treatment of the pyridinium perchlorate (I) with NaH or NEt3 ‐ reacts with the cyanides (II) to give the imidazopyridines (III), the propenylpyridinium perchlorates (IV) and the ylides (V); the product ratios are varied by changing the reactant ratios.

Synthesis of N-unsubstituted and N-methyl derivatives of 4-aryl-2,6-dimethyl-1,2-dihydropyridine-3,5-dicarbonitriles

In the reduction of 2,6-dimethyl-4-arylpyridine-3,5-dicarbonitriles or their N-oxides by sodium borohydride, a mixture of 1,2- and 1,4-dihydropyridine-3,5-dicarbonitriles is formed. 1,2,6-Trimethyl-4-aryl-1,2-dihydropyridine-3,5-dicarbonitriles were obtained by reducing the corresponding pyridinium perchlorates or by alkylating 4-aryl-2,6-dimethyl-1,2-dihydropyridine-3,5-dicarbonitrile derivatives by methyl iodide.