Complexation of the pyridine bases in the products from the coking of coal with organic solvents (review)

Published data on the complexation of pyridine bases with organic substances of various chemical types are reviewed. Examples of the use of these data for the isolation of individual heterocycles are discussed.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 3–22, January, 1997.     

Carbazoles,phenazines and dibenzofuran in petroleum products; methods of isolation,separation and determination

Alkylindoles, -carbazoles and -phenazines were isolated from a petroleum distillate by adsorption on activated aluminum oxide and desorption with methanol. After removal of methanol and dilution with benzene, the concentrate was extracted with 72% perchloric acid to obtain the alkylindoles and alkylcarbazoles as soluble perchlorates. These compound types were then isolated from the acidic layer by addition of water and extraction with benzene. A concentrate of the benzene extract was separated by gas chromatography into alkylindoles and 6 different carbazoles, the latter being characterized by ultraviolet and mass spectrometric techniques. The carbazoles were determined photometrically with 2-bromo-2-nitroindandione-1,3 reagent and by gas chromatography. Phenazine and several alkylphenazines were isolated from the nitrogen compound concentrate as solid perchlorates, liberated by alkali treatment of their perchlorates, and separated by gas chromatography ; ultraviolet and mass spectra were used for their identification. Dibenzofuran was identified in the residual concetrate after the acid extraction.     

Synthesis and properties of Schiff bases of mesoformylporphyrins (Review)

A summary is presented on the use of intermediate immonium salts formed in the Vilsmeier reaction in porphyrin chemistry for the synthesis of various Schiff bases of mesoporphyrins. Special attention is given to the formation and properties of porphyrins with a five-membered exocycle.     

Characteristic x-rays from (n, γ) products and their utilization in activation analysis

The possibility of using characteristic X-rays from radioactive elements in activation analysis was investigated during this work with particular emphasis on (n, γ) products. At least 27 of 56 elements investigated during this work were found to yield themselves to activation analysis employing characteristic X-rays from electron capture or internal conversion processes during isomeric transition. In presenting the results, a survey made of several elements and the limits of detection of 21 elements have been reported. Specific applications of this method were studied for the analysis of copper in a variety of samples (ores, minerals, steels, spent lubricants and human blood). The results of this investigation show that the use of characteristic X-rays in activation analysis has several advantages because the energies of these radiations are closely related to the periodicity of the elements themselves. Presented at the First IMR International Symposium, Trace Characterization—Chemical and Physical, National Bureau of Standards, USA (October, 1966).     

Use of comparative calculation methods to study the equilibrium of tautomers and acids (bases)

Conclusions On the example of the Meyer equation it was shown that comparative calculation methods can be used when the properties have unknown values.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 940–941, April, 1973.     

Thermal methods for the synthesis of thiophene, selenophene, and their derivatives. (Review)

The literature data concerned with thermal reactions producing thiophene, selenophene, and their derivatives are systematized and reviewed. The mechanisms of these reactions are examined and conditions for the formation of thiophene and selenophene heterocycles are formulated.Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk 664039, Russia; e-mail: vlad@irioch.ira.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 3–18, January, 2000.     

Preparation,isolation and properties of diastereomeric copper(II) chelates of the schiff bases of 2-formyl(N,N-dimethylaminomethyl)cymantrene with dipeptides

The optical isomers of 2-formyl(N, N-dimethylaminomethyl)cymantrene (I) can be separated by liquid chromatography of Cu²⁺ chelates of the Schiff bases formed from I and a number of dipeptides, in those cases where no racimization of the amino acid residues in the initial dipeptide occurs. Hydrolysis of the chelates gives optically pure enantiomers of I. Under the conditions of the preparation of the chelate from L-Ala-L-Ala (NH₂C(CH₃)HCONHC(CH₃)HCOOH) slow epimerization of the dipeptide into D-Ala-L-Ala takes place. Formation of Cu²⁺ chelates of the Schiff bases from L-Ala-L-Ala, D-Ala-L-Ala and L-AlaGly (NH₂C(CH₃)HCONHCH₂COOH) with (+) - and (-) -I proceeds stereospecifically.     

Recent methods for the synthesis of (E)-alkene units in macrocyclic natural products

(E)-Alkene units are frequently found in macrocyclic natural products. Among the reactions that form the double bond during the cyclization, the classical Horner-Emmons coupling is still frequently used with success. During the last decade, ring-closing metathesis has emerged as a very powerful tool for the synthesis of large rings, but the E/Z selectivity, which is rarely predictable, depends on many factors which will be discussed in this review. The best solution might be a two-step procedure involving ring-closing alkyne metathesis (RCAM) followed by stereoselective reduction of the macrocyclic alkyne unit to the corresponding E double bond.     

煤焦油重组分沥青质性质分析及对加氢裂化生焦影响的推测

从中/低温煤焦油中切取重组分,提取了重组分C7-沥青质,并以此重组分为原料进行了高压釜加氢实验,通过1H-NMR、XRD、FT-IR、SEM、元素分析和相对分子量测定等手段对重组分沥青质结构参数、官能团、表观形态等方面进行了分析,并将其与加氢过程中生焦情况进行了关联。结果表明,C7-沥青质基本结构单元以稠环芳烃为中心,周围分布少而短的侧链,侧链以小于3个碳的短直链正构烷基为主,相对分子量小,芳香片层没有堆积结构。O是该沥青质中氢键主要来源,大多分布在环氧烷烃和醚类结构中,外围的O数量低,分子间氢键更难形成,结构单元之间缔合性弱,沉积聚合慢而均匀。沥青质中短侧链不易断裂,在反应过程中产生的稠环芳烃自由基少,缩合能力小,使该馏分油生焦能力低,具有较高的加氢潜质。     

Influence of temperature gradients on the composition of crystallization products of ammonium chloroplatinum(IV) and chlorohodium(III) complex salts

The influence of temperature gradients on the particle size and component composition of solid phases in heterogeneous systems of ammonium chloroplatinum(IV) and chlorhodium(III) complex salts was studied. A Benard cell was implemented as applied to not only homogeneous but also heterogeneous systems. Two contributions to the cocrystallization of rhodium with platinum are distinguishable and kinetically resolved: the formation of nonequilibrium solid solutions by ammonium chlorometalates and equilibrium Ostwald ripening. The elucidation of both factors helps in finding crystallization parameters for minimizing the rhodium contamination of platinum in refining practice.     

Synthesis, isolation, and characterization of an organometallic triiodopalladium(IV) complex. Quantitative and regioselective synthesis of two C-I reductive elimination products

Iodine and the pincer complex [Pd(O,N,C-L)I], where L is the monoanionic ligand resulting from deprotonation of the acetyl group of the dimethylmonoketal of 2,6-diacetylpyridine, are in equilibrium at low temperatures with the palladium(IV) complex [Pd(O,N,C-L)I(3)], which can be isolated at -40 °C and characterized by (1)H NMR spectroscopy and X-ray diffraction studies, in spite of its great instability. When the same reaction is carried out at room temperature, a quantitative reductive elimination process occurs, giving L-I, which in the presence of water affords L'-I, resulting from hydrolysis of L-I.     

Some observations on the determination of organic bases with cobalt(II) thiocyanate for the identification of synthetic pharmacological products

A method for the detection of frequently used pharmacological products has been developed. A number of commonly used analgetics, tranquilizers, antihistamines, and antimalarial drugs were examined on thin-layer silica gels. Two types of developing solvent were used, and visualization was achieved with a cobalt(II) thiocyanate reagent.     

Anhydro bases of the pyridine series (review)

Methods for the preparation of anhydro bases of the pyridine series by deprotonation of the corresponding quaternary salts under the influence of bases, as well as by the direct reaction of quaternary pyridinium or halopyridinium salts with CH acids in the presence of bases, are examined. The reactions of anhydro bases with various reagents (alkyl cations, acylium cations, the proton, aldehydes, isothiocyanates, carbon disulfide, the hydroxide ion, etc.), which constitute evidence for their high reactivities, are examined. The participation of anhydro bases as intermediates in many reactions intended for the preparation of new heterocyclic systems is demonstrated.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.3, pp. 291–311, March, 1982.