Cascade heterocyclization in the reaction of tetrafluorobenzobarrelene with 3-methoxycarbonyl-2-pyridinesulfenyl chloride

Russian Chemical Bulletin -     

Intramolecular heterocyclization of N-(pyrimidin-2-yl)imines of methyl trifluoropyruvate

The reactions of N-(pyrimidin-2-yl)imines of methyl trifluoropyruvate with trimethyl phosphite afforded methyl 3-fluoroimidazo[1,2-a]pyrimidin-2-carboxylates, which were transformed into N-substituted methyl 3-aminoimidazo[1,2-a]pyrimidine-2-carboxylates by the reactions with amines.     

Spectrophotometric determination of nickel with cyclohexylidine-ammonium 2-aminocyclohexylidene-1-cyclohexene-1-dithiocarboxylate

An (extraction)-spectrophotometric method is reported for the determination of nickel(II) with cyclohexylidineammonium 2-aminocyclohexylidene-l-cyclohexene-l-dithiocarboxylate. The violet 1:2 chelate is soluble in aqueous ethanolic or acetonic media at pH 6–9, or can be extracted into methyl isobutyl ketone. The molar absorptivity of the complex is about 2.5 × 10⁴ l mol^?1 cm^?1 at 550 nm.     

Synthesis of decahydrophenanthridine-1,7-dione and hexahydroisoquinol-8-one derivatives in the reaction of 2-acetyl-2-cyclohexene-1-ones with conjugated enaminocarbonyl compounds

Derivatives of decahydrophenanthridine-1,7-dione were obtained by the reaction of 2-acetyl-2-cyclohexen-1-ones with enamines of cyclic -diketones (dihydroresorcinol, dimedone). Derivatives of hexahydroisoquinol-8-one having electron-acceptor substituents at the 4-position were obtained by the reaction of 2-acetyl-5,5-dimethyl-2-cyclohexen-1-one with acyclic enaminocarbonyl compounds. The reaction mechanism is discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 66–71, January, 1990.     

Alcoholysis of 3-alkoxy-2-cyclohexene-1-thiones

Russian Journal of Organic Chemistry -     

Spectrophotometric determination of nickel in vegetable oil with ammonium 2-amino-1-cyclohexene-1-dithiocarboate

The reaction between nickel and ammonium 2-amino-1-cyclohexene-1-dithiocarboate in aqueous acetone medium at pH 3.0-8.0 results in a stable dark red complex. The ratio of reagent to nickel in the complex is 2:1 and the formation constant is 7.38 +/- 0.12 x 10(10). Beer's law is obeyed up to 4 microg/ml nickel at the absorption maximum at 535 nm. The apparent molar absorptivity is 2.8 x 10(4) l.mole(-1). cm(-1), and the detection limit is 10 ng/ml nickel. The method is applied to the determination of nickel in vegetable oil.     

Intramolecular heterocyclization of N-allyl(phenyl)thiosemicarbazides of morpholinylacetic acid

Intramolecular heterocyclization of N-allyl(phenyl)thiosemicarbazide of N-morpholinylacetic acid in aqueous alkaline medium results in cyclic 5-(morpholinomethyl)-4-allyl(phenyl)-1,2,4-triazole-3-thiones.     

Oxidative alkylamination of aromatic and heteroaromatic substrates and accompanying heterocyclization reactions

The review is devoted to the history and state of the art in the study of oxidative alkylamination of a wide range of aromatic and heteroaromatic substrates. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 899–913, May, 2008.     

Cation-exchange reaction with accompanying current discharge

When a cation-exchange membrane swollen with propylene carbonate was placed in tight contact with lithium foil, an ion-exchange reaction of lithium ions with the cation-exchange membrane occurred. The assembly exhibited properties of a lithium cell (3.0-3.2 V without load). The ion-exchange capacity of various cation-exchange membranes and their degree of swelling with propylene carbonte were related to the capacity of the formed lithium cell. A discharge current of 0.32 mA was observed through a 3 cm² cell. Analysis of lithium ions in the membrane phase after discharge revealed that the ion-exchange reaction of lithium ions with the cation-exchange groups of the membrane was directly related to the current discharge of the cell. However, the formed lithium cell showed high self-discharge.     

Products of endic anhydride reaction with cyclic amines and their heterocyclization

Products of reaction between bicyclo[2.2.1]hept-5-ene-endo-endo-2,3-dicarboxylic anhydride (endic anhydride) and cyclic amines were obtained. By an example of one of amido acids a conformational analysis was performed and character of hydrogen bonds was studied using quantum-chemical calculations by PM3 procedure. endo-3-(4-Antipyrylcarbomoyl)-bicyclo[2.2.1]hept-5-ene-endo-2-carboxylic acid with a secondary amide group was converted into the corresponding carboximide which was epoxidized by performic acid.     

Mechanism and kinetics of the reaction of the 2-propargyl radical with ammonia

Gas-phase mechanism and kinetics of the reactions of the 2-propargyl radical (H₂CCCH), an important intermediate in combustion processes, with ammonia were investigated using ab initio molecular orbital theory at the coupled-cluster CCSD(T)//B3LYP/6-311++G(3df,2p) method in conjunction with transition state theory (TST), variational transition state theory (VTST), and Rice–Ramsperger–Kassel–Macus (RRKM) calculations for rate constants. The potential energy surface (PES) constructed shows that the C₃H₃ + NH₃ reaction has four main entrances, including two H-abstraction and two addition channels in which the former are energetically more favorable. The H-abstraction channels occur via energy barriers of 24 (T0/P2) and 26 kcal/mol (T0/P3) forming loose van de Waals complexes, COM_1 (12 kcal/mol) and COM_2 (14 kcal/mol), respectively. These complexes can easily be decomposed via barrier-less processes resulting HCCCH₃ + NH₂ (P2, 14 kcal/mol) and HCCCH₃ + NH₂ (P3, 15 kcal/mol), respectively. The additional channels occur initially by formation of two intermediate states, H₂CCCHNH₃ (35 kcal/mol) and H₂CC(NH₃)CH (37 kcal/mol) via energy barriers of 37 and 40 kcal/mol at T0/1 and T0/5, respectively, followed by isomerization and decomposition yielding 21 different products. These processes are fully depicted in an as-complete-as-possible PES. The rate constants and product branching ratios for the low-energy channels calculated show that the C₃H₃ + NH₃ reaction is almost pressure-independent. For the temperature range of 300–2000 K, the HCCCH₃ + NH₂ is the major product, whereas the minor one, HCCCH₃ + NH₂, has more contribution when temperature increases. Theoretical results on the mechanism and kinetics of the reaction considered may be helpful for future experiments as well as for understanding the role of the propargyl radical in combustion chemistry.     

The reaction of nitrolignin with ammonia

The reaction of nitrolignin with ammonia has been studied. It has been established that it takes place mainly through the carbonyl and carboxy groups of the lignin. A dark brown product with a high nitrogen content readily soluble in water and exhibiting biological activity was obtained. On the basis of the results of elementary and functional analyses, a semiempirical formula has been calculated for the substance obtained, and its viscosity and electrical conductivity have been determined. The molecular weight, determined by the sedimentation method in an ultracentrifuge, was more than 60,000. It was established by gel chromatography that the product of the interaction of nitrolignin with ammonia was polydisperse.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, Vol. 5, pp. 827–829, November–December, 1985.     

The reaction of nitrolignin with ammonia

The reaction of nitrolignin with ammonia has been studied. It has been established that it takes place mainly through the carbonyl and carboxy groups of the lignin. A dark brown product with a high nitrogen content readily soluble in water and exhibiting biological activity was obtained. On the basis of the results of elementary and functional analyses, a semiempirical formula has been calculated for the substance obtained, and its viscosity and electrical conductivity have been determined. The molecular weight, determined by the sedimentation method in an ultracentrifuge, was more than 60,000. It was established by gel chromatography that the product of the interaction of nitrolignin with ammonia was polydisperse.     

Solvation of yttrium with ammonia revisited. Di-amide formation in the reaction of yttrium with ammonia

The reactivity of yttrium atoms toward ammonia is revisited using expanded density functional theory calculations. The new results reveal that absorption of NH3 on YNH is dissociative to form Y(NH2)2.The di-amide species can adsorb further NH3 molecules molecularly to form Y(NH2)2NH3 and Y(NH2)2(NH3)2. The calculations aimed to reveal the detail of the potential energy curves between the imide and the di-amide forms. The Y(NH2)2(NH3)x species are more stable than those of YNH(NH3)x by more than 20 kcal/mol.     

Regioselective reaction of 5,6-dialkyl-2-halopyridine-3,4-dicarbonitriles with ammonia

The reaction of 5,6-dialkyl-2-halopyridine-3,4-dicarbonitriles with alcoholic ammonia under elevated pressure gave 5,6-dialkyl-2-aminopyridine-3,4-dicarbonitriles as a result of nucleophilic replacement of the halogen atom by amino group. 6,7-Dialkyl-4-halo-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diimines were formed in analogous reaction at room temperature in the presence of potassium carbonate.     

The reaction of ammonia with nitrogen dioxide in a flow reactor: Implications for the NH2 + NO2 reaction

The NH₃/NO₂ system has been investigated experimentally in an isothermal flow reactor in the temperature range 850–1350 K. The experimental data were interpreted in terms of a detailed reaction mechanism. The flow reactor results, supported by a theoretical analysis of the NH₂? NO₂ complex, suggest that the NH₂ + NO₂ reaction has two major product channels, both proceeding without activation barriers: Our findings indicate that the N₂O + H₂O channel is dominant at low temperatures while H₂NO + NO dominates at high temperatures. The rate constant for reaction (R21) is estimated to be 3.5 · 10¹² cm³/mol-s in the temperature range studied with an uncertainty of a factor of 3. © 1995 John Wiley & Sons, Inc.     

Bromination of N-(o-Aminophenyl)-cis-4-cyclohexene-1,2-dicarboximide and cis-2-(2-Benzimidazolyl)-4-cyclohexene-1-carboxylic Acid

Exhaustive oxidative bromination of N-(o-aminophenyl)-cis-4-cyclohexene-1'2-dicarboximide and2-(2-benzimidazolyl)-cis-4-cyclohexene-1-carboxylic acid results in bromine addition at the double bond.Under more severe conditions, the addition of bromine at the double bond is accompanied by bromination ofthe aromatic ring. The latter process does not occur in the exhaustive bromination of cis-2-(2-benzimidazolyl)-4-cyclohexene-1-carboxylic acid.