Voprosy khimii i khimicheskoi tekhnologii (Issues of Chemistry and Chemical Technology)

8-13

Authors: S.A. Varenichenko, E.V. Zalizna, V.I. Markov

Modification of the chemical structure of already known compounds is one of the main methods of creating medicinal products, plant protection products, dyes and other types of substances of great practical importance. It is known that the introduction of functional groups can appreciably affect the chemical properties and biological actions of basic substances. The paper describes the synthesis of previously unknown polyfunctional derivatives based on 4-methyl-1,5-diazaspiro[5.5]undec-3-en-2-one. Thus, for example, Schiff bases were obtained by interaction with various amines, despite the reduced electrophilicity of the conjugated aldehyde group in 2-methyl-4-oxo-1,5-diazaspiro[5.5]undec-2-ene-3-carbaldehyde. The product of Knoevenagel condensation was obtained by interaction with malononitrile. When boiling carbaldehyde in DMF with hydrochloric acid hydroxylamine, the corresponding nitrile was obtained without the stage of oxime separation (water splitting occurs in the medium of a high-boiling solvent). When attempt was made to rearrange the carbon skeleton of 2-methyl-4-oxo-1,5-diazaspiro[5.5]undec-2-ene-3-carbonitrile under the action of the Vilsmeier-Haack reagent, we obtained the product of formylation of nitrile group, N-formyl-2-methyl-4-oxo-1,5-diazaspiro[5.5]undec-2-ene-3-carboxamide. The structures of all synthesized compounds were confirmed by the results of 1H NMR spectroscopy, mass spectrometry, and element analysis.

21-27

Authors: S.A. Konovalova, A.P. Avdeenko, E.N. Lysenko

A synthesis of new halogen derivatives of N-carbamoyl-1,4-benzoquinone monoimines has been described. This compounds are, on the one hand, derivatives of 4-aminophenol or 1,4-benzoquinone monoimine and, on the other hand, they are urea derivatives. Hydrohalogenation of N-carbamoyl-1,4-benzoquinone monoimines, unsubstituted and monomethyl substituted in quinoid ring, is an optimal way to synthesize the products containing one halogen atom. Halogenation of these quinone monoimines and their reduced forms yields a mixture of products which are extremely difficult to separate one from another. Regarding dimethyl derivatives of N-carbamoyl-1,4-benzoquinone monoimines and their reduced forms, 1-(4-hydroxylphenyl) urea, the halogenation seems to be an optimal method to obtain the desired products with one or two halogen atoms in one stage with minimal expenditures of time and reagents. Halogen derivatives of N-carbamoyl- 1,4-benzoquinone monoimines are synthons in the synthesis of heterocyclic compounds, such as benzoxazoles and benzoxatioles, with a wide range of biological activity.

37-45

Authors: Y.A. Chertihina, N.V. Kutsik-Savchenko, A.V. Prosyanik

The energy and electronic parameters of the nitrogen atom inversion in imines H2C=NXHn (where XHn = H, CH3, NH2, OH, F, SiH3, PH2, SH, and Cl) have been calculated using DFT (B3LYP/6-311+G (d,p)) method. It has been established that the inversion barriers correlate with the χ-constants of the XHn substituents. When imines containing elements of the second or third periods at the nitrogen atom are considered separately, the inversion barriers correlate with the s-character of the lone pairs (LP) of nitrogen atoms. The electronegativity of the substituent XHn has a decisive influence on the inversion barrier and s-character of the nitrogen lone pare. The intramolecular interactions promote the following effects: (a) reducing the inversion barriers of imines, (b) increasing the barriers with an increase in the electronegativity of XHn substituents containing elements of the second period (except C), and their decrease for XHn substituents containing elements of the third period (except Cl), and (c) increasing the barriers with a decrease in the electronegativity of XHn substituents, if X is an element from the fourth and fifth groups, and decreasing the barriers if X is an element from the sixth or seventh groups of the periodic table. The opposite vectors of energy change of intramolecular interactions are mainly determined by the interactions of lone pares of heteroatoms X and the orbitals of the X–H bonds with - and -orbitals of C=N bonds; nNCH2 and nNCH2 interactions have a minor importance, and nNX–H and nNRY*X interactions (including nN3d) are insignificant and practically should not affect the barriers of the nitrogen atom inversion in the considered imines.

49-56

Authors: V.A. Kucherenko, Yu.V. Tamarkina, G.F. Rayenko, A.F. Popov

The paper deals with the formation of nanoporous structure of activated carbons (ACs) prepared from brown coal under alkali activation with heat-shock (i.e. a rapid introduction of the sample in a reactor zone which is pre-heated up to 800 °C) and subsequent isothermal exposure (≤ 60 min). The following characteristics of ACs porosity were evaluated using nitrogen adsorption-desorption isotherms (77 К): the pore size distribution; total pore volume (VΣ) and surface area (SƩ); and volume and surface of micropores and subnanopores (i.e. pores with an average diameter of ≤1 nm). The dependences of these characteristics on the nature of alkali MOH (M = Li, Na, or K), the exposure time at 800 °C and the KOH/coal weight ratio (changing in the range of 0.1 to1.2 g/g) were determined. It was shown that the use of thermal shock in brown coal alkali activation allows developing specific surface of ACs to a greater extent (1.5-2.0 times) under the same value of KOH/coal weight ratio. The activating ability of MOH increases linearly (r2 ≥ 0.984) in the following sequence of cations: Li+ < Na+ < K+, that means with increasing their electronic polarizability. The exposure after heat shock additionally develops the surface and nanoporous structure. The kinetic dependences of the increment of SƩ value are characterized by the induction period decreasing in the following sequence: LiOH > NaOH > KOH. At an optimal KOH/coal weight ratio of 1.0 g/g, brown coal is converted with a yield of ca. 30% in a subnanoporous material with VΣ ~ 1 cm3/g, SƩ ≥ 1850 m2/g; subnanopore specific surface area being of about 1600 m2/g constituting 86% of the total surface area of all pores.

63-70

Authors: G.V. Mezhevich, M.F. Buller, V.A. Robotko

The authors studied the chemical transformations of diphenylamine in the course of its interaction with the decomposition products of single-base gunpowder during long term natural storage (50 years and more) as well as during accelerated ageing of single-base gunpowder at elevated temperatures (343-368 K). It was found that the composition of diphenylamine derivatives obtained during accelerated ageing of gunpowder exactly coincides with the composition of derivatives during natural storage of gunpowder if accelerated ageing is performed at the lowest possible temperatures. The authors analysed literature data on determination of kinetic parameters (activation energy) of the chemical decomposition of single-base gunpowder at different temperature intervals by means of various methods of the determination of decomposition rate. According to various authors, the values of activation energy change in a wide range (from 80 to 145 kJ mol-1) because gunpowder is a very complex chemical system. To experimentally determine the safe shelf-life of single-base gunpowder, it is necessary to consider the kinetic equation of the depletion of diphenylamine in gunpowder and use experimentally obtained activation energy and storage parameters (temperature and humidity).