Structural kinetic rules governing the thermal decomposition of pyridine N-oxides

The Arrhenius parameters of the thermal composition of pyridine N-oxides in the liquid phase have been determined. The conclusion has been reached that the formation of an oxaziridine activated complex can be considered as the initial act of the thermolysis. A correlation has been found to exist between the rate constants of the thermal decomposition and the calculated values of the fractional electron charge at the oxygen of the N-oxide, and the length of the N- O bonds.Kazan' State Technological University, Kazan' 420015. Biisk Liceum of the Altai Region, Biisk 659322. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 644–646, May, 1994. Original article submitted April 4, 1994.     

Halogen Bonding Adsorbent Pyridine N-oxides for Iodine Capture in Water

Rapid capture of ¹²⁹I with high volatility and toxicity in the environment has attracted much attention. Herein we reported a firstly synthesized nonporous material: pyridine N-oxides (NTPO and ATPO) as iodine adsorbent. Both of NTPO and ATPO exhibit remarkable performance on the adsorption of iodine in aqueous solution, vapor state and organic solvents. Upon the capture of iodine, pyridine N-oxides were transformed to binary cocrystals combined with the pyridine N-oxides and iodine which is driven by halogen bond between iodine and oxygen atoms. Moreover, pyridine N-oxides shows high chemical, thermal and moisture stability.     

Thermal oxidative destruction of complexes of heterocyclic N-oxides with Zn(II)tetra-phenylporphyrin

Thermogravimetry, differential thermal analysis and differential scanning calorimetry were applied for investigation of molecular complexes of heterocyclic N-oxide with zinc(II)tetraphenylporphyrin. The kinetic characteristics of the process of the thermal oxidative destruction for individual compounds and their molecular complexes have been calculated. The obtained results indicate that the complex formation of ZnTPhP with heteroaromatic N-oxides leads to an increase of the thermal stability both the metalloporphyrin and the ligands. It has been shown that the stability of the molecular complexes of ZnTPhP with heteroaromatic N-oxides depends on basicity of the coordinated ligand.     

Electronic spectra and structure of 2,4-dihalopicolines and their N-oxides

UV spectra of 2,4-dihalopicolines and their N-oxides are presented, and the influence of substituents on spectral parameters is discussed. The electronic spectra were calculated by a modified INDO method. Transition energies, intensities, and assignments were compared with UV spectra. The degree of intramolecular charge transfer in 2,4-dihalopicolines is greater than in 2-halopicoline N-oxides and smaller than in 2-halo-4-nitropicoline N-oxides. Difference values of HOMO-LUMO energies point out that the susceptibility on photochemical reaction lies in the order: 2-halo-4-nitropicoline N-oxides > 2,4-dihalopicoline N-oxides > 2-halopicoline N-oxides > pyridine N-oxide. Department of Organic Chemistry, University of Economics, PL-53-342 Wroclaw, Poland. Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 34, No. 10, pp. 1352–1366, October, 1999.     

Investigation of alkaloid N-oxides by secondary-ion mass spectrometry

An advantage of theSIMS method for investigating alkaloid N-oxides has been shown. In the case of N-oxides of steroid, diterpene, tropane, and pyrrolizidine alkaloids, fragments including the oxygen of the N-oxide group are revealed. The protonation of N-oxide molecules in a glycerol matrix takes place mainly through the negatively polarized oxygen atom of the N-oxide function. On fragmentation, theMH ⁺ ions of N-oxides of monoester tropane and pyrrolizidine alkaloids tend to form fragmentary ions of the protonated forms of the aminoalcohols (A+). The energies of the metastable transitionsMH ⁺ A⁺ have been calculated for the Noxides of the pyrrolizidine alkaloids viridif lorine, trachelanthamine, and echinatine.Institute of the Chemistry of Plant Substances [IKhRV], Academy of Sciences of the Republic of Uzbekistan [AN RUz], Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 833–837, November-December, 1995. Original article submitted February 20, 1995.     

Electrochemically induced processes of formation of phosphorus acid derivatives. 4. Synthesis of trialkyl phosphates from white phosphorus

The products of electrolysis in dipolar aprotic solvents on the background of tetraethylammonium iodide in the presence of white phosphorus are trialkyl phosphite (the primary product after splitting of all the P-P bonds in the phosphoric oligomers) and triaryl phosphate. It was found that the formation of triaryl phosphate from white phosphorus proceeds by way of electrochemical reduction of pentaaroxyphosphorane — an intermediate product of the reaction of triaryl phosphite with iodine and phenol. A strong dependence of the yields and distribution of the products on the composition of the electrolyte has been observed.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center of the Russian Academy of Sciences, 420083 Kazan'. V. I. Ul'yanov-Lenin Kazan' State University, 420008 Kazan'. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2039–2043, September, 1992.     

Electrogenerated cation radicals of heteroaromatic N-oxides and oxidation of cyclohexane induced by them

The primary products of electrooxidation of heteroaromatic N-oxides are the corresponding cation-radicals. The redox properties of N-oxides, and also the stability of the cation-radicals generated from them, are determined by the number of N atoms and N-oxide groups in the heterocyclic ring and also by the nature of the substituents. Using phenazine di-N-oxide as an example, it was shown that the generation of the cation radical induces the oxidation of cyclohexane into cyclohexanol and cyclohexanone and is accompanied by deoxygenation of the di-N-oxide into a mono-N-oxide. The oxidation of cyclohexane proceeds by two paths, in one of which molecular oxygen participates, while in the second path an oxygen transfer probably takes place from the di-N-oxide cation radical to cyclohexane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 994–999, May, 1990.The authors wish to express their gratitude to A. E. Shilov for his participation in the discussion of the results, and also to R. E. Lokhov and A. V. Ryzhakov for providing samples of a series of N-oxides.     

Fragmentation of N-oxides (deoxygenation) in atmospheric pressure ionization: investigation of the activation process.

The diagnostic fragmentation of N-oxides resulting from loss of the oxygen atom (MH+ --> MH+-O) in electrospray and atmospheric pressure chemical ionization (APCI) mass spectra was investigated. When the temperature of the heated capillary tube was elevated, the ratio of the intensity of the [MH+ -16] fragment to the precursor ion (MH+) increased. This 'deoxygenation' process was associated with thermal activation and did not result from collisional activation in the desolvation region of the API source. Although the extent of 'deoxygenation' is compound-dependent, it can provide evidence for the presence of an N-oxide in a sample and can be used to distinguish N-oxides from hydroxylated metabolites (Ramanathan et al. Anal. Chem. 2000; 72: 1352). To demonstrate the practical application of thermal fragmentation of N-oxides, liquid chromatography (LC)/APCI-MS was used to distinguish an N-oxide drug from its hydroxylated metabolite in an unprocessed rat urine sample, despite the fact that the drug and its metabolite were not fully resolved by HPLC.     

Electrochemically induced processes in the formation of phosphorus acid derivatives. 2. The role of polymerization processes in the electrosynthesis of the esters of phosphorus acids from white phosphorus

The mechanism of the electrosynthesis of phosphate esters from white phosphorus was investigated. It was shown that the reaction takes place by two paths, i.e., monomeric (with the participation of dissolved phosphorus) and polymeric (with the participation of phosphorus on the surface of an emulsion drop). It was established that in an alcohol solution of tetraethylammonium iodide the main part of the final product is formed through an intermediate polymeric compound. It was noticed that by studying the dynamics of the accumulation of the dissolved product during electrolysis it is possible to trace the mechanism of reaction of the phosphorus at the individual stages of the process.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420028 Kazan'. V. I. Ul'yanov-Lenin Kazan' State University, 420028 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1328–1333, June, 1992.     

Synthesis and heterocyclization of osazones of carbonyl-substituted glyoxals

Enolates of α-chloro-β-oxoaldehydes react with arylhydrazines in the presence of acetic acid, forming osazones of carbonyl-substituted glyoxals. The same osazones are obtained by the reaction of β-oxo-α-chlorenamines with arylhydrazines. Under conditions of acid catalysis, these osazones undergo intramolecular heterocyclization to the corresponding functionalized pyrazoles. Kazan' State Technological University. Kazan' 420015, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 190–193, February, 1998.     

Reactions of camphene oxide with sulfur-containing nucleophiles

Sulfur-containing derivatives of the camphene series have been obtained by the nucleophilic addition of isothiouronium salts and thiourea under the conditions of base catalysis.S. V. Kurashov Kazan' State Medical Institute, 420012 Kazan', ul. Butlerova, 12. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 244–246, March–April, 1994.     

Interamination of some aminooxypyrimidines

Bis(pyrimidinyl)amines have been prepared by reaction of aminooxypyrimidines with aminooxypyrimidine hydrochlorides.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420083 Kazan'. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 169–173, January, 1992.     

Reactions of camphene oxide with sulfur-containing nucleophiles

Sulfur-containing derivatives of the camphene series have been obtained by the nucleophilic addition of isothiouronium salts and thiourea under the conditions of base catalysis. S. V. Kurashov Kazan' State Medical Institute, 420012 Kazan', ul. Butlerova, 12. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 244–246, March–April, 1994.     

Nucleophilic thiylation of limonene 8,9-oxide

Thioterpenols of the menthane series have been obtained by reactions of limonene 8,9-oxide with thiols and with isothiuronium salts.S. V. Kurashov Kazan' State Medical University, 420012, Kazan', ul. Butlerov, 49, Korp. B Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 197–200, March–April, 1999.     

Chemical properties of N'-cyanodiazene N-oxides. Reactions involving the nitrile group

The reactivity of the nitrile group in N'-cyanodiazene N-oxides has been examined for the first time. A general approach to the synthesis of nitrogenous functional derivatives of azoxycarboxylic acids by reaction of N'-cyanodiazene N-oxides with nucleophiles (water, alcohol, and hydroxylamine) is described. A method of synthesis of novel azoxy-1,2,4-oxadiazoles and tetrazoles has been developed in which aliphatic, aromatic, or heterocyclic N'-cyanodiazene N-oxides are reacted with benzonitrile N-oxide or sodium azide. Trimerization of N-cyanodiazene N-oxides, catalyzed by anhydrous HCl, has given novel symm-triazines in which the heterocycle bears three diazene N-oxide groups.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1647–1653, July, 1991.     

Decomposition of prop-2-ynylic N-oxides to acrolein and schiff bases via O-allenyl hydroxylamines

Prop-2-ynylic N-oxides rearrange thermally via O-allenyl hydroxylamines to acrolein and an imine. The second rearrangement step, falling in the class of thermal cis-eliminations, is shown with variously ²H-substituted pargyline N-oxides.     

New routes for the synthesis of 2,5-disubstituted 4-formylthiazoles

New 2,5-disubstituted 4-formylthiazoles have been obtained by the reaction of acetal-containing -chloroxiranes or their rearrangement products, chloroketones, with thioamides and N-allylurea.Kazan' State Technological University, Kazan' 420015, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 124–129, January, 1998.     

Perfluorocyclobutane aromatic ether polymers. II. Thermal/ oxidative stability and decomposition of a thermoset polymer

The results of thermal and oxidative stability studies are reported for one perfluorocyclo-butane aromatic ether thermoset polymer. The polymer was prepared from 1,1,1-tris (4-trifluorovinyloxyphenyl)ethane by the thermal cyclodimerization of the trifluorovinyl either functionality, resulting in a network polymer comprising alternating perfluorocy-clobutane and aromatic either groups. The results of isothermal and dynamic thermal gravimetric analysis (TGA) studies are reported with kinetic approximations for de-composition in nitrogen, along with FTIR studies of the oxidative process in air and TGA/mass spec determination of the gasses evolved from decomposition in air. Based on these results, thermal and oxidative decomposition mechanisms are proposed. © 1995 John Wiley & Sons, Inc.     

Thiophene-2-aldehyde in the Darzens reaction

The reaction of the title compound with dichloroacetic acid esters in the presence of butyllithium gave esters of 3-thienyl-3-hydroxy-2,2-dichloropropionic acid.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center of the Russian Academy of Sciences, 420083 Kazan', Russia. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1870–1873, August, 1992.     

Reactivity of heterocyclic compounds in nitration. 8. Nitration of 3-hydroxypyridine and its substituted forms

Nitration of 3-hydroxypyridine and its substituted forms has been studied under various conditions. It is shown that, depending on the reaction temperature and the nitrating agent, the end products of the synthesis can be 3-hydroxy-2,6-dinitropyridine or 3-hydroxy-2,4,6-trinitropyridine. The possibility of substitutional nitration of iodine derivatives of 2- and 3-hydroxypyridine is demonstrated.For Communication 7, see [1].Kazan' State Technological University, Kazan' 420015, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 958–961, July, 1998.