Investigation of the influence of the polarity of the solvent on the composition of the extractive substances and post-extraction residues of the bark ofAbies sibirica

The chemical compositions of the initial bark of the Siberian firAbies sibirica and of the solid residues after extraction with carbon dioxide, water, and alcohol have been studied. On successive extraction, the yield of extractive substances amounted to 25.05% of the absolutely dry bark. The carbon dioxide, aqueous, and alcoholic extracts obtained have been investigated. The carbon dioxide extract was found to contain 34.97% of essential oil, while only traces of it were detected in the aqueous and alcoholic extracts.Krasnoyarsk State Technological Academy. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 42–45, January–February, 1996. Original article submitted August 14, 1995.     

Determination of the mechanism of the oxidation of the trichloromethyl radical by the photolysis of chloral in the presence of oxygen

The photooxidation of chloral was studied by infrared spectroscopy under steady-state conditions with irradiation of a blackblue fluorescent lamp (300 nm < λ < 400 nm, λ_max = 360 nm) at 296 ± 2 K. The products were hydrogen chloride, carbon monoxide, carbon dioxide, and phosgen. The kinetic results reveal that the reaction proceeds via chain reaction of the Cl atom: The results lead to the conclusion that mechanism (B) is confirmed to be more likely than mechanism (A), which was favored at one time by Heicklen for the mechanism of the oxidation of trichloromethyl radicals by oxygen molecules: The ratio of the initial rates of CO and CO₂ formation gave k₇/k₆ = 4.23M^?1, and the lower limit of reaction (5) was found to be 3.7 × 10⁸M^?1 sec^?1.     

Elements of the topology of the region of the existence of the metastable states of a two-component vapor

Entire regions of the metastable states for binary and single-component systems were constructed. It was established that the regions include temperature intervals from absolute zero to critical temperatures, and from vapor—condensate equilibrium to the conditions of spinodal decomposition of supersaturated vapor in the system. Algorithms for determining the regions of metastable states are presented. The data obtained on their basis are noted to coincide qualitatively with known results. Correlations found earlier are employed to calculate the critical pressures and temperatures for the binary systems in the study.     

On the mechanism of the formation of ozonides of the alkali metals

Conclusions A mechanism of the formation of ozonides of alkali metals was proposed on the basis of data obtained in an investigation of the reaction of oxygen-labeled KOH with ozone, the reaction of KOH with atomic oxygen, and the reaction of KOH with ozone; this mechanism is based upon: the catalytic decomposition of ozone on the surface of the solid alkalies into molecular and atomic oxygen, the interaction of the latter with the hydroxide, forming a superperoxide, and an interaction of the superperoxide with ozone, forming the ozonide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1183–1187, June, 1967.     

Effect of the Polarity of the Medium on the Kinetics of the Radical-Chain Oxidation of Cumene in the Presence of Ascorbic Acid

Russian Journal of Physical Chemistry A - The inhibition of the initiated oxidation of cumene by oxygen under homophase conditions, where acetonitrile or dimethylsulfoxide are used as the solvent,...     

Dependence of the composition of the lipids of the seeds ofPlectranthus glaucocalyx on the conditions of growth

A change in the geographical growth zone and in the density of the soil has a substantial influence on the amount of lipids in the seeds ofPlectranthus glaucocalyx Maxim. and their degree of unsaturation, and also on the structure of the triacylglycerols.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 30–35, January–February, 1984.     

Synthesis of the amide of the C-terminal tetrapeptide of the sequence of oxytocin

The synthesis has been effected of the amide of the tetrapeptide forming the sequence 6–9 of oxytocin with the use of benzyl protection of the thiol function of cysteine by two main schemes 1+3 and 2+2. The advantageousness of performing the synthesis by the 2+2 scheme has been shown. The overall yield of tetrapeptide using the method of condensation with the formation of mixed anhydrides amounted to 51% by the scheme proposed.All-Union Scientific-Research Institute of the Technology of Blood Substitutes and Hormone Preparations, Moscow. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 393–400, May–August, 1992.     

Effects of the composition of the reaction mixture and the nature of the template on the structure of mesoporous aluminosilicates formed in the presence of lecithin

It has been established that supramolecular structures of lecithin can act as templates in the synthesis of mesoporous aluminosilicates. Mesoporous substances, with pore dimensions up to 100 Å and biporous materials can be obtained when various combinations of lecithin with cetyltrimethylammonium bromide or octadecylamine are used as template agents in the aluminosilicate system.     

Effect of the nature of the solvent and the temperature on the frequency and intensity of the stretching vibration of the Ge-H bond in the IR spectra of 1-hydrogermatranes

Conclusions The Ge-H stretching vibration in the IR spectra of 1-hydrogermatranes varies under the influence of the solvent and the temperature as a result of the presence of the transannular Ge N bond. The change in the length of this bond with variation in the polarity of the solvent and the temperature of the solutions is smaller in germatranes than for the Si N bond in the isostructural silatranes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1758–1761, August, 1985.     

A study of the lignin of the cotton plant of the subspeciesmexicanium

p-Hydroxybenzoic, vanillic, ferulic, and syringic acids, and also p-hydroxybenzalde-hyde and vanillin, have been found in an ethanol-benzene extract of the stems of cotton plants of the subspeciesmexicanium. The dioxane lignin (DLA) has been isolated by Pepper's method, the semiempirical formula of its phenylpropane structural unit and its molecular-mass distribution have been established, and its UV, IR, and PMR spectra have been recorded. The DLA has a comparatively low molecular mass and a lower degree of polydispersity than the dioxane lignin of the cotton plant of variety Tashkent-1, while the amounts of functional groups in them coincide, with the exception of a lower amount of carboxy groups in the DLA.     

Characteristics of the cholinesterase of the venom of the central Asian cobra

Summary 1. By rechromatography on sulfoethyl-Sephadex C-50, an electrophoretically homogeneous preparation of cholinesterase has been obtained from the venom ofNaja oxiana Eichwald.2. The activity of the cholinesterase isolated depends on the concentration of the enzyme and the time and temperature of incubation, and also on the pH. The following must be considered the optimum conditions: time of incubation of the enzyme with the substrate 20–30 min, pH 8.0–8.5, temperature 37–38°C.3. Diisopropyl phosphorofluoridate (DIPF) in a concentration of 2 µM completely suppresses the activity of the cobra venom cholinesterase.4. The venom cholinesterase hydrolyzes acetylcholine chloride and acetylthiocholine bromide but has no effect on butyrylthiocholine bromide, in which respect it resembles the true cholinesterases.5. Preparations of cobra venom cholinesterase do not possess a lethal action and do not potentiate the activity of the neurotoxins of the same venom.Institute of Biochemistry, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 783–789, November–December, 1972.     

An improvement of the resolution of the identity approximation for the formation of the Coulomb matrix

A straightforward modification of the resolution of the identity (RI) approximation to the Coulomb interaction is described. In the limit of basis sets that are dominated by high angular momentum functions the observed speedups in realistic test systems reach a factor of 2 compared to the standard RI algorithm, and a factor of up to 300 compared to the standard algorithm to form the Coulomb matrix. More moderate savings on the order of 0-20% are obtained for the more commonly used smaller basis sets. A series of test calculations is reported to illustrate the efficiency of the algorithm.     

Investigation of the cardiotoxic peptides of the venom of the cobraNaja oxiana

Six populations of basic polypeptides have been found in the venom of the Central Asian cobraNaja oxiana Eichwald, and four of them — V″c-1, V″c-2, V″c-5, and V″c-6 — have been obtained in the electrophoretically homogeneous state. On a perfused frog heart preparation, all the basic polypeptides proved to be cardiotoxic. However, only some of them (V′c-2, V″c-3, and V″c-4) were characterized by arrhythmic activity as well as by the negative ino- and chronotropic effects, common for all of them. An enhancement of the specific cardiotoxic effect of each of the polypeptides by pure phospholipase A-2 has been shown.     

Action of the products of the deglycosylation of the nuclear glycoprotein of rabbit brain neurons on the polymerase activity of the neuronal nuclei

The influence of a glycoprotein and its fragments on the RNA polymerase activity of nuclei has been studied. Both the glycoprotein itself and its fragments suppress the RNA polymerase activity of the systemin vitro, and the carbohydrate moiety suppresses the activity more strongly than the protein moiety.A. S. Sadykov Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 62 70 71. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 271–275, March–April, 1997.     

Composition of the complex of biopolymers of the cell walls of the grape

The complex of high-molecular-weight substances of the cell walls of the grape has been studied. It has been shown that the complex contains polysaccharides, proteins, and phenolic substances presumably linked through O-glycosidic bonds."Magarach" Scientific-Research Institute of Wine-Making and Wine-Growing, Yalta, M. V. Frunze Simferopol' State University, Khimiya Prirodnykh Soedinenii, No. 5, pp. 564–567, September–October, 1984.     

Investigation of the mechanism of the polarographic reduction of the sydnoneimmonium cation

The polarographic reduction of the sydnoneimmonium cation (I) was investigated in the case of 3--phenylisopropylsydnoneimine hydrochloride (sydnophen). The effect of the pH, alcohol concentration, ionic strength, and surface-active substances was studied, and the electrolysis was carried out at a controllable potential under various conditions. The cyclic voltampefograms were recorded. A mechanism for the reduction of I is proposed. Cleavage of the ring of I in the near-electrode space is observed in unbuffered media. The first direct proof of the existence of the unstable sydnoneimine base was obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1042–1048, August, 1975.     

The dynamics of the accumulation of the alkaloids of the genus Ungernia

Summary A study ofU. victoris, U. tadshicorum, andU. trisphaera with respect to the vegetation periods and growth sites has shown that the maximum accumulation of alkaloids takes place in the early vegetation period and that naturally dried leaves do not contain alkaloids. The alkaloid content also depends on the growth site.In the period of the vigorous development of the epigeal part, some alkaloids are possibly converted into one another (hippeastrine into lycorine, galanthamine into narwedine, and narwedine into galanthamine).Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 60–64, January, 1971.     

The influence of the structure of the double layer on the morphology of the polarographic curves

Conclusions It is emphasized that proper account of the effect allows not only a better understanding of the morphological pecularities of the polarographic curves and a more accurate evaluation of the kinetic constants, but may reciprocally bring useful information about the fine structure of the double layer itself. On a more practical point of view, as only irreversible waves are shifted by variation of ₀, careful adjustement of the supporting electrolyte may improve some simultaneous polarographic determinations. A typical example is the dosage of traces of Zn in Ni, which can be carried successfully in presence of tetraethylammonium ions, which are specifically adsorbed and displace negatively the wave of Nickel only.Enlarged Abstract.     

Study of the composition of the total products of the oxidation of lignin

Institute of Chemistry of Plant Substances, Academy of Sciences Of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 503–504, May–June, 1995. Original article submitted October 31, 1994.     

FTIR study of the mode of binding of the reactants on the Pd nanoparticle surface during the catalysis of the Suzuki reaction

In the Suzuki reaction between phenylboronic acid and iodobenzene catalyzed by palladium nanoparticles, our previous studies suggested that the phenylboronic acid adsorbs on the nanoparticle surface and then interacts with the iodobenzene that is present in solution. In the present study, FTIR is used to examine the change in the vibrational frequencies of phenylboronic acid in films with and without the addition of palladium nanoparticles. The large change in the B-O stretching frequency of phenylboronic acid from 1348 to 1376 cm(-1) in the presence of sodium acetate and palladium nanoparticles strongly suggests that the mode of binding of phenylboronic acid to the Pd nanoparticle surface involves a B-O-Pd type of bonding. Shifts in the B-C stretching mode and the out-of-plane phenyl C-C ring deformation bands associated with phenylboronic acid provide additional confirmations of the binding process. It is also shown that the phenylboronic acid needs to be in the deprotonated form in the presence of sodium acetate (phenylboronate anion) to bind to the palladium nanoparticle surface. No changes in the characteristic bands of iodobenzene were observed in films made in the presence of the palladium nanoparticles. The FTIR studies provide proof of the mode of binding that occurs in the nanoparticle surface for the first time and also confirms the mechanism of the Suzuki reaction that we proposed previously.