Reaction of N′-(Arylmethylidene)-2-oxo-2H-chromene-3-carbohydrazides with Methyl 1-Bromocycloalkanecarboxylates and Zinc

Russian Journal of General Chemistry - Depending on the ring size in the Reformatsky reagent and the nature of substituents in arylmethylidene fragment, the reactions of Reformatsky reagents...     

Role of Water in the Photochemical Synthesis of Methyl 12-Oxo-6,12-dihydroazepino[2,1-b]quinazoline-8-carboxylates

Russian Journal of General Chemistry - Methyl 12-oxo-6,12-dihydroazepino[2,1-b]quinazoline-8-carboxylate and methyl 3H-azepin-2(1H)-one-5-carboxylate were synthesized by photoinduced...     

exo- and endo-Complexes of Fe(0) with Carbon Allotropic Modifications on the Example of Fullerene С60: a Density Function Theory Study

Russian Journal of General Chemistry - Structures of exo- and endo-complexes of fullerene C60 with zero-valent Fe0, in which the metal is localized inside and outside fullerene molecule,...     

Synthesis of 1,2,3-Triazole Derivatives by Cyclocondensation of Alkyl Azides with Active Methylene Ketones in the System K2CO3/DMSO

Russian Journal of Organic Chemistry - The reaction of β-keto esters or acetylacetone with alkyl azides in the system K2CO3/DMSO proved to be a convenient method of synthesis of tri- and...     

Corrosion of Gold Anode in an Aqueous Solution of N,N-Dimethylpropane-1,3-diamine

Russian Journal of Organic Chemistry - The kinetics and mechanism of corrosion of gold anode in a weakly basic aqueous solution of N,N-dimethylpropane-1,3-diamine have been studied by cyclic...     

Crystal-to-crystal transitions in nylon M5T

Journal of Thermal Analysis and Calorimetry - Crystal-to-crystal transitions of a high-temperature nylon, poly(2-methtyl pentamethylene terephthalamide, nylon M5T), were studied by conventional and...     

Efficiency analysis of thermosyphon solar flat plate collector with low mass concentrations of ND–Co3O4 hybrid nanofluids: an experimental study

Journal of Thermal Analysis and Calorimetry - In the present study, the thermal efficiency, convective heat transfer and friction factor analysis are investigated for a flat plate solar collector...     

Synthesis of novel non-natural spiro[2.3]hexane amino acids,the conformationally restricted analogs of γ-aminobutyric acid

3-Methylenecyclobutanecarboxylic acid and its methyl ester were used as the starting compounds for the synthesis of new spiro[2.3]hexane amino acids, the conformationally rigid analogs of γ-aminobutyric acid, namely, 5-aminospiro[2.3]hexanecarboxylic and 5-amino-spiro[2.3]hexanephosphonic acids, promising modulators of GABAergic cascades in the human central nervous system. The methods developed for the synthesis of the target amino acids are based on the reactions of catalytic [1+2] cycloaddition of diazoacetic and diazophosphonic esters to 3-substituted methylenecyclobutanes, as well as on a modified Curtius reaction for the transformation of a carboxy group to the amine one.     

Nature and strength of weak intermolecular interactions with metal atoms in crystals of square-planar nickel(<Emphasis Type="SmallCaps">ii</Emphasis>) complexes

The results of geometric analysis of 588 crystal structures of square-planar nickel complexes containing short intermolecular Ni…X contacts (X is a non-metal atom) are reported. The frequency of occurrence of Ni…X interactions of a particular type was evaluated depending on the nature of the X atom and geometric characteristics. The promolecular functions RDG and sign(λ₂)?ρ(r) were used to analyze the character of Ni…X interactions in attractive/repulsive terms. The relative strength of these interactions was determined as the function of the nature of the X atom and the direction of charge transfer.     

Quantum chemical studies of azoles

The results of theoretical search for model transition states of the electrophilic substitution reaction in 2H-tetrazole (1) without the preliminary formation of N-protonated azolium salts are presented for two routes that were previously suggested by the authors and thermodynamically investigated: A, the attack of molecule 1 by the nucleophile (HO^–(aq)) to form the anion to which the electrophile H₃O⁺(aq)) is added and B, the attack of molecule 1 by the same electrophile followed by the addition of the same nucleophile to the specifically solvated protonated species formed in the preceding reaction step. The calculations were performed using the DFT/B3LYP/6-31G(d) method and the scanning procedure of the potential energy surface (PES). Both steps of route A turned out to be nearly barrierless, while in route B only its first step is barrierless and the second one is conjugated with passing an activation barrier of ～45 kcal mol^–1 between non-interacting or weakly interacting reactants and electrophilic substitution products. Unlike the specifically solvated protonated species of 1H-tetrazole in an aqueous solution, a similar species of 2H-tetrazole does not form a prereaction complex with the attacking nucleophile (HO^–(aq)) and the five-membered ring is destroyed in fact in the nitrogen-containing reaction product formed after passing the activation barrier. The optimized structure of the transition state differs strongly from the nitrogen-containing structure of the reaction product with the destroyed ring, which was found by scanning of the PES.