Manifestation of the Even–Odd Effect in the Spectral Properties of Solvated Electron and in the Probability of Positronium Formation in Alcohols

A change in the energy E _max of the solvated electron, which corresponds to the maximum intensity of its optical absorption spectrum in the homologous series of alcohols seems to be alternating in character. The effect is retained upon elevation of pressure up to 2 kbar but disappears in alcohols frozen at 77 K. Probably, the effect also holds for amines. The alternating character of variation is also observed for the intensity Y ₁ of the narrow components of the angular spectrum of -photons generated upon positron annihilation in alcohols and normal alkanes. The nature of alternation of E _max is associated with the mutual elimination of electric fields induced by the dipole moments of two neighboring CH₂ groups in each solvent molecule, including also the molecules forming the solvation shell of an excess electron. That fact that the E _max value correlates to Y ₁ led to the conclusion that Y ₁, rather than the intensity I ₃ of the long-lived component of the annihilation time spectrum generally used for the purpose, more adequately characterizes the positronium formation probability.     

Thermal diffusion in Lennard–Jones fluids in the frame of the law of the corresponding states

This work is related to the definition of a reduced thermal diffusion coefficient thanks to numerical microscale molecular dynamics simulations. This cross transport process, also called Soret effect, couples mass flux and thermal gradient and is still largely misunderstood. For this study, we have applied a boundary driven non-equilibrium molecular dynamics algorithm on Lennard–Jones spheres mixtures. Simulations have been performed at a constant reduced supercritical state, using a van der Waals’ one fluid approximation in order to fulfil the law of the corresponding states. In binary mixtures, we have studied the molecular parameters and the molar fraction influences on thermal diffusion separately and then combined. It is shown that, on pressure and on thermal conductivity, the corresponding states law is fulfilled for a wide range of molecular parameters ratios. In this frame, we have then constructed simple correlations which relate thermal diffusion factor to the mixture parameters. Combining the relations obtained, a reduced thermal diffusion factor taking into account all the various contributions has been defined. Finally, it is shown that this relation enables us to estimate thermal diffusion in various binary and ternary mixtures of Lennard–Jones spheres representing alkanes with a maximum deviation of 15%.     

Photooxidation of carbonyl sulfide in the presence of the typical oxides in atmospheric aerosol

Carbonyl sulfide (COS) is one of the most abun-dant sulfur containing gases in the troposphere andlower stratosphere[1,2]. It is relatively inert in the tro-posphere and can be transported into the stratosphere,where it dissociates under the solar ultravi…     

Correlation Analysis of the Runoff of the Rivers and the Seisms in China

In recent hundred years the annual discharge variations of the Changjiang River (represented by the Yichang station) and the Huanghe River (represented by Shanxian and Tangnaihe, respectively) have closely related to the geographical distribution of the earthquakes coming about in China in the same year, Both the occurrence of the destructive seism or seismic swarm in the river basins and the disappearance of the shocks in the east and south of the basins are the conditions that the Changjiang and Huanghe Rivers are the high flow while that the strong earthquake of magnitude 7 or more occurred in North China is the condition for the Changjiang low flow year and that of 6 or more in the Qilian Mountains area is for the Huanghe River. In the latter part of this paper, a 2-year sample is given to explain that the conditions of the 2 rivers being high flow years are that the north-south seismic belt is active and in the meanwhile no seism occurred in South China, and those of the low flow year are that the     

Anomalies in the Change of Volumetric Parameters of the Diels–Alder Reaction in Solution

In this article negative values of the activation volume in retro-Diels–Alder reactions are interpreted in terms of the different possibilities of penetration of the solvent molecules into the sterically branched structures of the adduct and activated complex. Empty spaces, inaccessible to penetration of solvent molecules, lead to increases of the molar volume of the screened adducts in solution and, consequently, to a less negative value of the Diels–Alder reaction volume. The values of partial molar volumes of anthracene, maleic anhydride and the adducts cyclopentadiene–maleic anhydride, anthracene–maleic anhydride and anthracene–tetracyanoethylene, in several solvents, were calculated from the solution density data.     

“Conjugate” Substitution of Hydrogen in the Methyl Group of Pentabromotoluene in the Presence of Strong Bases

The reactions of pentabromotoluene with i-PrONa or t-BuONa in pyridine give N-(pentabromobenzyl)pyridinium bromide and a mixture of isomeric tetrabromotoluenes. In the presence of bromine or carbon tetrabromide, the reductive debromination is blocked, and the reactions involve exclusively substitution of hydrogen in the methyl group of pentabromotoluene by the pyridinium residue.     

Thermodynamics of the solubility of sulfamethoxydiazine in organic solvents in the range 293.15–323.15 K

The solubilities of sulfamethoxydiazine in methanol, ethanol, 1-propanol, 2-propanol, acetone, and chloroform have been determined in the range 293.15–323.15 K by a static equilibrium method. The calculated results show that the correlation of the Apelblat equation for measured systems has less deviation than that of the λh equation. The positive Δ_sol H and Δ_sol S for each system revealed that sulfamethoxydiazine being dissolved in each solvent was an entropy-driven process.     

Nucleophilic reactivity of the peroxide anion in microemulsions of the “oil-in-water” type in the decomposition of phosphate and toluenesulfonate esters

The kinetics of the reaction of the 4-nitrophenyl esters of diethylphosphoric and 4-toluenesulfonic acids with HO^– and HOO^– anions in microemulsions of the “oil-in-water” type was studied. It was shown that the reactivity of the HOO^– anion depends on the nature of the detergent forming the microemulsion and decreases in the order cetyltrimethylammonium bromide > Triton X-100 > sodium dodecyl sulfate. It was established that concentration of the reagents on the surface of the microdrops leads to an increase of 2–3 orders of magnitude in the rate during the transition from aqueous solutions to the microemulsion.     

On the role of the functional group in determining the strength of hydrophobic interactions in aqueous solutions of α-amino acid derivatives

Calorimetric measurements were carried out at 25°C on binary aqueous solutions containing N-acetyl derivatives of the following -amino acids: glycine, alanine, valine, leucine, norleucine, aspartic acid, glutamic acid, phenylalanine, methionine, asparagine, glutamine, cysteine, histidine, serine. The N-acetyl derivative of the -amino acid proline was also studied. The results obtained have been used to calculate the pairwise enthalpic interaction coefficients and these are compared with results reported in the literature concerning free -amino acids, and their acetylamide derivatives. The coefficients largely increase passing from free amino acids to N-acetyl derivatives. The derivatives of -amino acids bearing unsubstituted alkyl chains present an increased cooperativity of hydrophobic interactions.     

Transformations of ortho-quinones in the γ-radiolysis of their solutions in cyclohexane

The transformations of 4-tert-butyl-1,2-benzoquinone (I), 3,5-di-tert-butyl-1,2-benzoquinone (II), and 4-methoxy-5-tert-butyl-1,2-benzoquinone (III) in deaerated cyclohexane solutions under exposure to γ-radiation were studied. It was found by chromatography-mass spectrometry and ¹H and ¹³C NMR spectroscopy that the addition of cyclohexyl radicals at the C=O bond in compounds I–III resulted in monoalkyl ethers, whereas cyclic ketal XXI was also formed in the case of compound II. Moreover, quinone I afforded mixed O-and C-alkylation products, and the adduct of cyclohexyl radicals and quinone II at the C=C bond was the source of dimeric products.     

The applicability of the “straight-line method” of asmus in the determination of the composition of polynuclear complexes

The straight-line method of Asmus was originally developed for the determination of n in mononuclear complexes of the general form AB_n (n≧ 1). In the present investigation it is demonstrated that the method also can be used for determining the value of n in polynuclear complexes of the form A[_mB_n (m > 1). The method as suggested by Asmus, is, however, not capable of distinguishing between mono- and polynuclear species. It is further shown, that the straight-line method can be applied for the determination of the value of m.     

Synthesis of two peptides of α-bungarotoxin and the participation of the amino acid residue Trp-28 of the neurotoxin in the antigenicity of the molecule

Using the method of solid-phase peptide synthesis, two peptides have been synthesized, one of which corresponds to the central ring structure of -bungarotoxin (-BTX), while the second has in position 28 a Gly residue in place of the Trp in the first peptide, and their interrelationship with antitoxin antibodies has been investigated. It has been shown that the amino acid residue Trp-28 of -BTX, which is the contact residue in binding with the acetylcholine receptor, also participates directly in binding with the active centers of antibodies to -BTX.Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 628–631, July–August, 1997.     

The Stereochemistry of the Migrating Groups in the Pyrolysis of Stable Steroidal Ozonides

ＴｈｅＳｔｅｒｅｏｃｈｅｍｉｓｔｒｙｏｆｔｈｅＭｉｇｒａｔｉｎｇＧｒｏｕｐｓｉｎｔｈｅＰｙｒｏｌｙｓｉｓｏｆＳｔａｂｌｅＳｔｅｒｏｉｄａｌＯｚｏｎｉｄｅｓＪｉｏｎｇＹＡＮＧ；ＴｏｎｇＳｈｕａｎｇＬＩａｎｄＹｕＬｉｎＬＩ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅ...     

ESR study of the free radicals formed in the photolysis of α-ketofluorosulfates

ESR spectroscopy was used to establish that the UV irradiation of -ketofluorosulfates containing an OSO ₂ F group at a tertiary carbon atom gives radicals formed upon cleavage of the C-OSO ₂ F bond. If the OSO ₂ F group is attached to a primary or secondary carbon atom, we observe ordinary photodecomposition with cleavage of the acyl—carbon bond. The ESR spectra of the new radicals were studied. Replacement of fluorine by the OSO ₂ F group in the trifluoromethyl radical leads to compression of the radical site. Branched -oxoperfluoroalkyl radicals are not heteroallylic and the unpaired electron is localized largely on the carbon atom. The [(CF ₃ ) ₂ CF] ₂ C(O)CF ₃ radical is stable in the air.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 757–761, March, 1992.     

Intensity of the 1001 keV γ-ray in the decay of234mPa

The intensity of the 1001 keV -ray occurring in the decay of^234mPa in equilibrium with natural uranium sources is found to be (0.818±0.030)%. This value is in agreement with a recent measurement employing depleted uranium sources, but does not agree with earlier reports employing radiochemically pure sources.     

“Matrix effects” in the activation of compounds with a system of conjugation in the inhibition of oxidative processes

Russian Chemical Bulletin -