Picolinic N-oxide Research Articles

UV-spectroscopic study of the influence of traces of water on the protolytic equilibria of substituted pyridine N-oxides in aprotic solvents

Using a UV-spectrophotometric method, an attempt has been made to estimate quantitatively the influence of traces of water in aprotic solvents on the acidic-basic equilibria involving heterocyclic N-oxides. The N-oxides under study were pyridine N-oxide (PyO), 4-methoxy-pyridine N-oxide (4-MeOPyO), and 2-, 3-, and 4-picoline N-oxide (2-, 3-, and 4-PicO). For particular N-oxide the UV-spectra of acetonitrile solutions containing the free base and/or its simple or semiperchlorate have been recorded. To carry out the calculations various equilibrium models which include the protolytic equilibrium with water and basic species present in the solvent have been tested using the program STOICHIO which is based on non-linear regression analysis. It turned out that apart from the acidic-basic dissociation of a protonated N-oxide and cationic homoconjugation (the equilibria which are usually considered in such systems) it is absolutely necessary to take into account the protolytic equilibrium between the cationic acid and water present as impurity. Implications concerning investigations of other equilibrium systems in aprotic solvents and, in particular, the quality of the acidity constants for the calibration agents used in potentiometry are discussed.

Diorganotin(IV) Adducts with Amine N-Oxides

Abstract Nineteen complexes of diorganotin(IV) dihalides of the general formula R2SnX2·L2 (R = CH3, C2H5, n-C3H7, n-C4H9, n-C8H17, C6H5, C6H5CH2; X = Cl or Br; L = pyridine N-oxide or 2-picoline N-oxide) have been prepared. The monomeric and non-conducting nature of the complexes has been shown by molecular weight and molar conductance measurements. A hexacoordinated structure has been proposed for all the complexes on the basis of IR, UV and 1H NMR spectral data.

Reactions of tetrachlorodioxouranate(VI) ion with neutral and protic ligands

The reactions of [bipyH2][UO2Cl4]·3H2O (bipyH2=diprotonated 2,2′-bipyridyl) with a series of neutral and protic oxygen donor ligands have been investigated. N,N-dimethyl formamide (DMF), N,N-dimethyl acetamide (DMA) and dimethyl sulphoxide (DMSO) gave compounds of the type [bipyH2][UO2Cl4(L)2] (L=DMF or DMA) and [bipyH2][UO2Cl4(DMSO)n] (DMSO)3-n (n=1 or 2), while [bipyH2][UO2Cl4-(3PNO)(DMSO)n](DMSO)2-n (n=1 or 2) and [bipyH][UO2Cl3(4PNO)(DMSO)] were obtained with 3-picoline N-oxide (3PNO) and 4-picoline N-oxide (4PNO) respectively from DMSO medium. With excess 2-picoline N-oxide (2PNO) the compound [bipyH][UO2Cl3(2PNO)](DMSO) was obtained. Reaction with acetyl acetone (AcAcH) and 8-hydroxy quinoline (QH) in 1:1 mole ratio in DMSO gave compounds of the type [bipyH2][UO2Cl3(L′)(DMSO)] (L′=AcAc or Q). The compounds have been investigated by i.r. spectra, powder x-ray diffraction and molar conductivity measurements.

A ligand-field probe of transition-metal-oxygen ligations

Ligand-field analyses of the electron spin resonance and optical absorption, single-crystal spectra of pentakis(pico1ine Noxide)cobalt(II) diperchlorate and dichlorobis(tripheny1phosphine oxide)cobalt(II) are reported. The ligations with the amine oxide and phosphine oxide donors are characterized by locally nondiagonal ligand fields. That for the phosphine oxide is interpreted in terms of a hybridization for the donor oxygen atom between sp2 and sp. For the amine oxide, the ligand-field effects of misdirected valency arise from the formally nonbonding sp2 oxygen lone pair. Significant differences between the local ligand fields of these picoline N-oxide groups and those of pyridine N-oxides in the complex hexakis(pyridine N-oxide)cobalt(II) diperchlorate are rationalized in terms of the coordination numbers in these complexes. These conclusions are underscored by Fenske-Hall molecular orbital calculations for the free picoline N-oxide and pyridine N-oxide.

Ionic equilibria in acetonitrile solutions of 2-, 3- and 4-picoline N-oxide perchlorates, studied by potentiometry and conductometry

Equilibrium constants for the ionic association of 2-, 3- and 4-picoline N-oxide perchlorates and semiperchlorates, as well as the limiting conductances of simple (BH+) and complex (BHB+) cations in acetonitrile have been determined conductometrically. Acidity constants of the protonated 2-, 3- and 4-picoline N-oxides and homoconjugation constants of the protonated picoline N-oxides with free N-oxides have been determined from potentiometric measurements. The influence of the position of the methyl group on ionic equilibria in acetonitrile solutions of the picoline N-oxides perchlorates has been discussed.

Lanthanoid methanesulfonate complexes with 3-picoline N-oxide. Spectral study of the neodymium and europium complexes

Lanthanide methanesulfonate (MS) 3-picoline N-oxide (3-picNO) complexes, with general formula [Ln(MS)3(3-picNO)2] (Ln LaYb, Y) present a non-electrolyte behavior in methanol, forming only one isomorphous series. The ligand is bonded through the oxygen, the MS − ion being probably bidentate coordinated according to the IR data. From the electronic absorption spectra of the neodymium compound, the nephelauxetic and Sinha's parameters, covalent factor and the oscillator strength in solution were calculated and interpreted. The fluorescence spectrum of the europium complex was interpreted in terms of a C 3v symmetry, with the geometry of a bicapped trigonal prism. The crystal-field parameters (B k q) were also calculated.

Synthesis and Thermal Decomposition of Rare Earth Complexes with Methanesulfonate and 3-Picoline N-oxide Ligands.

Synthese des complexes Lu(CH 3 SO 3 ) 3 -2(3-picNO). Spectres IR montrant la coordination par les anions CH 3 SO 3 et par les nitrones. Pyrolyse dans l'air et l'azote

Copper(II) complexes of 2-dimethylamino-3-picoline N-oxide (3MDM) and 2 diethylamino-3-picoline N-oxide (3MDE)

Copper(II) complexes with 2-dimethylamino-3- picoline N-oxide (3MDM) and 2-diethylamino-3- picoline N-oxide (3MDE) have been prepared from the following salts: tetrafluoroborate, nitrate, chloride and bromide. Solids of the general formula [CuL 2](BF 4) 2 and [CuLX 2] where L=3MDM and 3MDE and X=NO 3, Cl and Br were characterized using spectral methods ( i.e., IR, UV-Vis and ESR). Both of these N-oxides coordinate as bidentate ligands via the N-oxide oxygen and the amine nitrogen in all of the complexes. The steric effect of the diethylamino group is larger compared to the dimethylamino in the four pairs of complexes involving the different anions. Considerable distortion compared to the complexes of the analogous pyridine N-oxide ligands also occurs due to the ring methyl group.

A study on the UV spectra of 3-picoline N-oxide and 2,6-lutidine N-oxide 1:1 perchlorates solutions in propylene carbonate

The UV spectra of 3-picoline N-oxide perchlorate /3PicOHClO 4/ and 2,6-lutidine N-oxide perchlorate /2,6-LutOHClO 4/ solutions in propylene carbonate have been recorded for various concentrations. It has been found that the spectral characteristic of 2,6-LutOHClO 4 is concentration independent, while that of 3-PicOHClO 4 depends on the concentration of the salt. With the increasing of concentration the intensity of the band characteristic for the conjugated acid of 3-PicO /3-PicOH +/ is lowered and a new band at shorter wavelength appears. This can be explained in terms of the selfassociation of the cationic acid. Preliminary CNDO/S-CI calculations on the dimer of 3-PicOH + have been carried out.

Deoxygenation of Tertiary Amine Oxides with Carbon Bisulfide

Abstract Reduction of various tertiary amine oxides with carbon disulfide was examined and kinetic experiments were carried out. Trialkylamine oxides and N,N-dialkylarylamine N-oxides were readily reduced by CS2 to give the corresponding tertiary amines in good yields, while heteroaromatic amine N-oxides such as picoline N-oxide were not affected. The oxygen atom in the N-oxide was found to be transferred to CO2 upon mass spectral analysis of the gas evolved. The kinetic experiments were carried out following the UV spectra of N,N-dimethylaniline N-oxide in CH3CN containing much excess of CS2 and the rate was found to be of 2nd order in the N-oxide and CS2. Activation parameters (ΔH\eweq=55.7 kJ mol−1, ΔS\eweq=−78.2 J K−1 mol−1 at 20 °C are characteristic of a normal bimolecular reaction. The logarithms of the rate constants for para-substituted N,N-dimethylaniline N-oxides are nicely correlated with Hammett σ values and a small negative ρ value (ρ=−0.2) was obtained. The rate of reaction was faster in polar aprotic solvents than in nonpolar or protic solvents. These observations seem to suggest that the reaction proceeds via an initial nucleophilic attack of the N-oxide oxygen at carbon disulfide followed by the rate-determining N–O bond fission to give the tertiary amine.

Application of the Water-gas Shift Reaction. III. Reduction of Oxidized Nitrogen Compounds with CO and H2O Catalyzed by [Ru(cod)py4](BPh4)2

Abstract The ruthenium(II) complex, [Ru(cod)py4](BPh4)2 (cod=1,5-cyclooctadiene, py=pyridine) has been shown to catalyze the reduction of oxidized nitrogen compounds with CO and H2O. In this reaction, primary, secondary, and tertiary nitroalkanes are converted into amides, ketones, and amines, respectively. Nitrosobenzene and picoline N-oxides are also reduciable to amines in good yields.

Reaction of 2-picoline N-oxide with benzophenone lithium ketyl

Reaction of 2-picoline N-oxide with benzophenone lithium ketyl

Addition reaction with 2-methyl-2-nitrosopropane and pressure dependence of ionized picoline N-oxides in the gas phase

The equilibrium of the addition reaction of ionized picoline N-oxides with 2-methyl-2-nitrosopropane as an ion-trapping reagent was determined at various temperatures in the gas phase. From the thermodynamic properties of the addition reaction, the structures of the addition products are discussed. In connection with the addition reaction, the pressure dependence of the mass spectra of picoline N-oxides is discussed, and it is concluded that the pressure dependence is caused by the effect of the charge transfer reaction between the (M– O)+ species and a neutral molecule of picoline N-oxide through an intermediate ion (M2– O)+. Upon the formation of this intermediate ion, picoline N-oxides acted as ion-trapping reagents in a similar manner to 2-methyl-2-nitrosopropane.

Magnetic properties of binuclear copper(II) propionate complexes with heterocyclic N-oxide adducts

The synthesis and characterisation of copper(II) propionate compounds of general formula Cu(CH 3CH 2COO) 2L (L = pyridine N-oxide, 2-picoline N-oxide, 3-picoline N-oxide or 4-picoline N-oxide) are reported. The characterisation of these compounds is based upon their electronic, IR and EPR spectra. The copper(II) carboxylates studied exhibit the binuclear structure.

ChemInform Abstract: CRYSTAL STRUCTURES OF THE PICOLINE N‐OXIDE COMPLEXES M(4‐CH3C5H4NO)6(CLO4)2 (M = COPPER,ZINC) AND EPR SPECTRA OF THE PURE AND ZINC‐DOPED COPPER COMPLEXES

Chemischer InformationsdienstVolume 12, Issue 39 Physical Organic Chemistry ChemInform Abstract: CRYSTAL STRUCTURES OF THE PICOLINE N-OXIDE COMPLEXES M(4-CH3C5H4NO)6(CLO4)2 (M = COPPER,ZINC) AND EPR SPECTRA OF THE PURE AND ZINC-DOPED COPPER COMPLEXES J. S. WOOD, J. S. WOODSearch for more papers by this authorR. O. DAY, R. O. DAYSearch for more papers by this authorC. P. KEIJZERS, C. P. KEIJZERSSearch for more papers by this authorE. DE BOER, E. DE BOERSearch for more papers by this authorA. E. YILDIRIM, A. E. YILDIRIMSearch for more papers by this authorA. A. KLAASSEN, A. A. KLAASSENSearch for more papers by this author J. S. WOOD, J. S. WOODSearch for more papers by this authorR. O. DAY, R. O. DAYSearch for more papers by this authorC. P. KEIJZERS, C. P. KEIJZERSSearch for more papers by this authorE. DE BOER, E. DE BOERSearch for more papers by this authorA. E. YILDIRIM, A. E. YILDIRIMSearch for more papers by this authorA. A. KLAASSEN, A. A. KLAASSENSearch for more papers by this author First published: September 29, 1981 https://doi.org/10.1002/chin.198139068AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue39September 29, 1981 RelatedInformation

Crystal structures of the picoline N-oxide complexes M(4-CH3C5H4NO)6(ClO4)2 (M = copper,zinc) and EPR spectra of the pure and zinc-doped copper complexes

Crystal structures of the picoline N-oxide complexes M(4-CH3C5H4NO)6(ClO4)2 (M = copper,zinc) and EPR spectra of the pure and zinc-doped copper complexes

ChemInform Abstract: ESR SPECTRA OF LOW‐SYMMETRY HIGH‐SPIN COBALT(II) COMPLEXES. 7. TRIGONAL‐BIPYRAMIDAL PENTAKIS(PICOLINE N‐OXIDE)COBALT(II) PERCHLORATE

Chemischer InformationsdienstVolume 12, Issue 10 Physical Organic Chemistry ChemInform Abstract: ESR SPECTRA OF LOW-SYMMETRY HIGH-SPIN COBALT(II) COMPLEXES. 7. TRIGONAL-BIPYRAMIDAL PENTAKIS(PICOLINE N-OXIDE)COBALT(II) PERCHLORATE A. BENCINI, A. BENCINISearch for more papers by this authorC. BENELLI, C. BENELLISearch for more papers by this authorD. GATTESCHI, D. GATTESCHISearch for more papers by this authorC. ZANCHINI, C. ZANCHINISearch for more papers by this author A. BENCINI, A. BENCINISearch for more papers by this authorC. BENELLI, C. BENELLISearch for more papers by this authorD. GATTESCHI, D. GATTESCHISearch for more papers by this authorC. ZANCHINI, C. ZANCHINISearch for more papers by this author First published: March 10, 1981 https://doi.org/10.1002/chin.198110053AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue10March 10, 1981 RelatedInformation

Magnetic and spectroscopic characterisation of copper(II) 2-halogenobenzoates with some heterocyclic N-oxides

The preparation of Cu(2X-C 6H 4COO) 2·pyNO (X = F, Cl, Br or I; pyNO = pyridine N-oxide) and Cu(2BrC 6H 4COO) 2·picNO (picNO = 2-, 3-, or 4-picoline N-oxide) is described. The spectroscopic and magnetic behaviours of the compounds are compared with those of binuclear copper(II) alkanoates. The EPR spectra of the powdered solid are consistent with spin S = 1. The exchange interaction parameters are −2J ≈ 380 cm −1, except for Cu(21C 6H 4COO) 2pyNO. The structures of the compounds are discussed.

Flash vacuum pyrolysis of 2-picoline N-oxide. Formation of 2-picolyl radical.

The flash vacuum pyrolysis of 2-picoline N-oxide was found to give 2-picoline, pyridine, 2-vinylpyridine, bis (2-pyridyl) methane, and 1, 2-bis (2-pyridyl) ethane. From the mechanistic consideration of the formation of these products, intermediacy of 2-picolyl radical (i. e., 2-pyridylmethyl radical) is strongly suggested.

ESR spectra of low-symmetry high-spin cobalt(II) complexes. 7. Trigonal-bipyramidal pentakis(picoline N-oxide)cobalt(II) perchlorate

ESR spectra of low-symmetry high-spin cobalt(II) complexes. 7. Trigonal-bipyramidal pentakis(picoline N-oxide)cobalt(II) perchlorate