Study of the initial stages of alkoxo synthesis involving Ti(OBu)4 and cyclophosphites

The reactivities of cyclophosphite precursors in alkoxo syntheses involving titanium(iv) tetra(n-butoxide) were studied by ³¹P NMR and IR spectroscopy. 2-Diethylamido-4-methyl-1,3,2-dioxaphosphinane and 4-ethyl-2,6,7-trioxaphosphabicyclo[2.2.2]octane in benzene are inert toward Ti(OBu)₄. Gelation is accompanied by hydrolysis 2-diethylamido-4-methyl-1,3,2-dioxaphosphinane to give the corresponding hydrophosphoryl compound, while 4-ethyl-2,6,7-trioxaphosphabicyclo[2.2.2]octane remains intact during gelation.     

Structure of 2-Amino-4-phenyl-9H-pyrimido[4,5-b]indole and Its Nitrate in Crystal and Solution

The crystal structures of 2-amino-4-phenyl-9H-pyrimido[4,5-b]indole and its nitrate were determined by XRD analysis. ¹³C NMR, XRD, and quantum-chemical data indicate that the acid proton is predominantly localized at the N(3) atom of the pyrimidine ring in both isolated nitrate molecules and in molecules in crystal and solution.     

N-Amino Derivatives of Condensed Imidazole Systems

The previously unknown 1-amino- and 3-aminonaphtho[1,2-d]imidazoles, 1-aminonaphtho[2,3-d]imidazole, 1-aminophenanthro[9,10-d]imidazole and the N-amino-N'-methylimidazolium picrates corresponding to them have been obtained by direct amination of a series of condensed imidazoles with O-picrylhydroxylamine. An X-ray structural investigation of 1-amino-3-methylnaphtho[1,2-d]imidazolium picrate showed that, in difference to 1-aminobenzimidazolium salts, a conformation exists in it in which the hydrogen atoms of the N-NH₂ group are directed to the side of the meso carbon atom.     

Composition and Physicochemical Properties of Schungite Sorbent as Influenced by Thermal Treatment

The chemical composition, specific surface area, and pore structure of a schungite sorbent were studied as influenced by the conditions of thermal treatment.     

Vibrational spectra and structure of 4-cyano-4′-pentalkoxybiphenyl in different physical states

The polymorphism, conformation mobility and structure of 4-cyano-4′-pentalkoxybiphenyl (5OCB) in different physical states are studied by IR spectroscopy. The spectra were measured in the frequency range 400–4000 cm⁻¹ at temperatures from 300 to 350 K. The IR spectra of 5OCB are modeled using the concept of conformational mobility of these molecules. An analysis of the experimental and theoretical spectra reveals absorption bands whose spectroscopic parameters are sensitive to variations of temperature (experiment) and conformation (theory); a relationship between these changes is established. It is concluded that the polymorphism of 5OCB is of conformation type. In the solid crystalline state, 5OCB molecules have conformations with a planar biphenyl fragment; the angle of orientation of the plane of the carbon framework of the alkyl radical relative to the biphenyl fragment decreases as the temperature increases from 35° in the solid crystalline state to 10° in the liquid crystalline and isotropic liquid states. In both of these states the biphenyl fragment becomes nonplanar. The angle between the phenyl rings is up to 30°. Saratov State University. Institute of Physics, Ukrainian Academy of Sciences. Samarkand State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 1, pp. 55–60, January–February, 1998. This work was supported by RFFR grant No. 97-03-32175a.     

Oxidation of 2-dialkylaminomethyl-4,6-di-tert-butylphenols

Oxidative transformations of 2-dialkylaminomethyl-4,6-di-tert-butylphenols depend on the nature of the oxidant, the character of the substituents at the nitrogen atom, and the medium. A mechanism of the oxidation of these compounds is suggested. The molecular structure of the compound obtained as a result of oxidative trimerization of 2-dimethylaminomethyl-4,6-di-tert-butylphenol was established by X-ray structural analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1328–1335, July, 1997.     

Defect concentration in Ti-substituted YIG from TG curves

The article discusses theory and experiment about the measurement of defect concentration in Ti-substituted yttrium iron garnet by means of thermogravimetry techniques. The two possible cases arising from oxygen interchange with atmosphere, oxygen vacancies and interstitial cations, may be analyzed quantitatively from the derived expressions. The possibility of another type of defects being present in the samples, not associated to oxygen evolution, is not excluded. Measurements were carried out in air and CO₂ for different Ti contents. The substitution tends to increase slightly the defect parameter θ in YIG, while a CO₂ reducing atmosphere is much more effective than the Ti substitution for increasing θ. Calculations for a given single-phased sample sintered in air show two possibilities: a deficit of one oxygen atom for every 2.5 unit cells of 96 atoms, or one excess cation for every 3.5 cells. Other samples show very similar results. The accuracy involved in the measurements is about 2–3%.     

Complex Compounds Based on 1-Isopropenylimidazoles and -pyrazole

With respect to Co²⁺, Ni²⁺, Zn²⁺,Cd²⁺, Cu²⁺, Pd²⁺, and Sn⁴⁺ salts, 1-isopropenyl-substituted imidazole, 2-methylimidazole, and pyrazole behave as monodentate ligands with only one coordination center on the N¹ and N² atoms, respectively; 1-isopropenylpyrazole under complex-formation conditions is dealkylated to form pyrazole complexes. The reaction with HCl leaves the unsaturated substituent in 1-isopropenylimidazole intact and yields corresponding hydrochlorides by the N³ atom of the heterocycle. The least basic 1-isopropenylpyrazole takes up HCl also by the double bond of the alkenyl group.     

Synthesis of N-heteroaromatic onium betaines of indane-1,3-dione

Betaines are formed in good yields in the reaction of N-heteroaromatic compounds with 2-dicyanomethyleneindane-1,3-dione oxide and its 4- and 5-halo derivatives in dioxane. The corresponding oxides were obtained by oxidation of 2-dicyanomethyleneindane-1,3-dione and its 4- and 5-substituted derivatives with hydrogen peroxide in dioxane. Data from the IR spectra of the compounds are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 889–892, July, 1978.