[en] The kinetics of radiolysis processes of 9 chlorous-organic pesticides (hexachlorbenzene, α- HCH, β-HCH, lindan, 4,4'-DDE, 4,4'-DDD, 4,4'-DDT, aldrin and heptachlor) solutions (10 - 1000 ug/l) in hexane at 13,8; 27,7; 67,4 and 105,4 kGy doses was studied and the radiation-chemical yields of conversion processes were calculated in the work. It was identified that the conversion of pesitides of 105,4 kGy dose is 65-95 percent, radiation-chemical yields are (0,009 - 1,247) · 10^-3 molecules/100 eV. Increasing of initial concentration leads to the radiation-chemical yields raising. Different radiation-chemical yields observed for various pesticide conversion processes may be due to the variations in their reaction rate with hydrogen atoms and radicals. The difference observed in various isomers (α-HCH, β-HCH and γ-HCH) may be due to the energy of spherical isomeric structures with C - Cl bonds in their molecules

[en] Six flavonoids, including one flavan-3-ol epicatechin (1), one flavone glycoside apigenin 7-O-β-D-glucopyranoside (2), three flavones namely dimethylchrysin (3), trimethylapigenin (4) and luteolin (5) and one flavonol quercetin (6) were isolated from the hexane and chloroform extracts of the leaves of Sterculia foetida Linn. collected in Binh Thuan Province by using various chromatographic methods. Their chemical structures were identified by comparing their spectroscopic data as well as physical properties with those in literature. Compounds 1-4 were obtained for the first time in Sterculia genus. (author)

No abstract available

[en] A simple regioselective synthesis of cinnoline derivatives was achieved by a one-pot three component synthetic methodology. New substituted 7,8-dihydrocinnolin-5(6H)-ones are prepared via one-pot three component reaction of arylglyoxals with 1,3-cyclohexanedione and dimedone in the presence of hydrazine hydrate in moderate to good yields

[en] This paper reports the stereoselective synthesis of a novel nucleoside, 4'-methyl branched and bicyclo [3.1.0] hexane locked-nucleoside 12, using a sequential [3,3]-sigmatropic rearrangement/carbene cycloaddition reaction/Curtius reaction strategy with a high stereoselectivity

No abstract available

[en] The kinetics of the accumulation of molecular hydrogen during the radiolysis of hexane and hexane-mixture is studied at different concentration of the components in the presence of nanoparticles ZrO₂ at T=300/673 K. It is found that n-ZrO₂ displays radiation catalytic activity in the decomposition of hexane and hexane-water mixture, as a result of which the rate of accumulation of molecular hydrogen increases. It is established that the radiation chemical yield of molecular hydrogen G(H₂) grows sharply along with the temperature.

[en] Highlights: • We calculate post-CCSD(T) atomization energies of n-alkanes by means of W4 theory. • Post-CCSD(T) contributions to the TAE increase linearly with the size of the n-alkane. • The post-CCSD(T) contributions to the TAE of hexane reach 0.65 kcal/mol. • Post-CCSD(T) contributions to the TAE of decane are expected to exceed 1 kcal/mol. The CCSD(T) method is often considered as the gold standard in quantum chemistry for single-reference systems. Using W4 and W4lite theories, we calculate post-CCSD(T) contributions to the total atomization energies (TAEs) of n-alkanes and show that they reach up to 0.65 kcal/mol for n-hexane. Furthermore, we find that post-CCSD(T) contributions increase linearly with the size of the n-alkane, indicating that they will reach ∼1 kcal/mol for n-decane (C₁₀H₂₂) and ∼2 kcal/mol for n-icosane (C₂₀H₄₂). These results are significant since today CCSD(T)/CBS-type methods are being applied to hydrocarbons of increasing size and are assumed to give TAEs with chemical accuracy for these systems.

[en] Graphical abstract: - Highlights: • Experimental enthalpies for the mixtures MTBE + pentanol + hexane and pentanol + hexane were measured. • No experimental ternary values were found in the currently available literature. • Excess molar enthalpies are positive over the whole range of composition. • The ternary contribution is also positive with the exception of a range located around the rich compositions of 1-pentanol. - Abstract: Excess molar enthalpies for the ternary system {x₁ 2-methoxy-2-methylpropane (MTBE) + x₂ 1-pentanol + (1 − x₁ − x₂) hexane} and the involved binary mixture {x 1-pentanol + (1 − x) hexane}, have been measured at T = 298.15 K and atmospheric pressure over the whole composition range. We are not aware of the existence of previous experimental measurement of the excess enthalpy for the ternary mixture under study in the literature currently available. Values of the excess molar enthalpies were measured using a Calvet microcalorimeter. The results were fitted by means of different variable degree polynomials. The ternary contribution to the excess enthalpy was correlated with the equation due to Verdes et al. (2004), and the equation proposed by Myers–Scott (1963) was used to fit the experimental binary mixture measured in this work. Smooth representations of the results are presented and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. The excess molar enthalpies for the binary and ternary system are positive over the whole range of composition. The binary mixture {x 1-pentanol + (1 − x) hexane} is asymmetric, with its maximum displace toward a high mole fraction of decane. The ternary contribution is also positive with the exception of a range located around the rich compositions of 1-pentanol, and the representation is asymmetric. Additionally, the group contribution model of the UNIFAC model, in the versions of Larsen et al. (1987) [18] and Gmehling et al. (1993) [19] was used to estimate values of binary and ternary excess enthalpy. The experimental results were used to test the predictive capability of several empirical expressions for estimating ternary properties from binary results

[en] The picosecond risetime of the 430 nm T_nreverse arrowT¹ transient absorption and the T¹ formation quantum yield for acridine in n-hexane are temperature independent within experimental error between -51 and 25₀C, in sharp contrast to the large temperature dependence of the fluorescing state of acridine in n-hexane is not a kinetic precursor to T¹. The absence of marked tempertaure dependence in the T¹ formation yield presents and exception to the general observation that fluorescence and T¹ yields both decrease with increasing temperature in N-heterocycles and aromatic carbonyls with closely spaced lowest--energy n, π( and π, π( singlet states