Reactions of levulinic acid and pseudolevulinic esters with various C-nucleophiles

The reactions of levulinic acid and its pseudo esters, which are readily available from carbohydrate-containing raw materials, with various C-nucleophiles are described. Different reaction pathways were demonstrated depending on the nature of the leaving groups and nucleophiles. For 5-methyl-5-methoxydihydrofuran-2(3H)-one, the reaction was found to proceed by a route giving hept-6-enoic acid derivatives. In contrast, the reaction of 2-methyl-5-oxotetrahydrofuran-2-yl acetate proceeds via intramolecular cyclization to form γ-valerolactone derivatives.     

Dielectric Spectroscopy Study of Butadiene–Nitrile Rubbers

Russian Journal of Physical Chemistry A - A number of butadiene-nitrile rubbers of different composition are studied in a wide range of temperatures and frequencies via dielectric relaxation...     

Magnetic Nanoparticles Obtained by Electrophysical Technique: Focus on Biomedical Applications

Physics of the Solid State - The possibilities of producing large batches of magnetic nanoparticles (MNPs) using electrical explocion of the wire (EEW), laser target evaporation, and spark...     

Convenient synthesis of O-functionalized mandelic acids via Lewis acid mediated transformation of 1,3-dioxolan-4-ones

An efficient method for the synthesis of O-substituted mandelic acids containing alkenyl, alkynyl, methoxycarbonyl, or phenacyl fragments via the Lewis acid-catalyzed reaction of 1,3-dioxolan-4-ones with different C-nucleophiles is proposed.     

Ion distribution function at the boundary with an electrode

The ion distribution function is found in the case in which the Langmuir layer freely passes the ions incident from the plasma while the reverse ion flux is zero. These conditions are realized near the cathode in an arc discharge and at the surface of a probe operating on the ion branch of the characteristic. The electric field outside the Langmuir layer is assumed small. We obtain the connection between ion current and plasma density at the boundary with the electrode, the expressions for the ion mean kinetic energy and for the mean energy removed from the plasma by the ion, which differ markedly from the corresponding expressions in the Maxwellian distribution case.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, Vol. 10, No. 3, pp. 47–54, May–June, 1969.     

Reaction of the Dioxane Complex of Dichlorogermylene with Siloxanes

The major organogermanium compounds formed by reactions of the dioxane complex of dichlorogermylene with hexamethyldisiloxane, octamethyltrisiloxane, and hexamethyltricyclotrisiloxane are bis(trimethylsiloxy)dichlorogermane, 3,3-dichloro-1,1,1,5,5,7,7,7-octamethyl-3-germa-2,4,6-trioxa-1,5,7-trisilaheptane, and a cyclic germatetrasiloxane.     

Synthesis,Structure, and Alkylation of 4-Nitroamino-1,2,4-triazole

Nitration of 4-amino-1,2,4-triazole with nitric acid in acetic anhydride gives the corresponding N-nitroamino derivative which has an inner salt structure. Its alkylation with alkyl halides, as well as with oxiranes, occurs only at the endocyclic nitrogen atom, while the exocyclic reaction center is not involved. All the 1-substituted products have the structure of 1-alkyl-1,2,4-triazol-1-io-4-N-nitroimides.     

The applicability of TD-DFT methods to calculations of the electronic absorption spectrum of hexaamminoruthenium(II) in aqueous solution

The nonstationary density functional theory method (time-dependent DFT, TD-DFT) was used to theoretically estimate the frequencies and intensities of absorption bands of the complex hexaamminoruthenium(II) ion in aqueous solution. The spectrum simultaneously contained both valence (ligand-field, LF) transitions and an intense band of charge transfer to the solvent (CTTS). A comparison of the quality of the results obtained with the use of various exchange-correlation functionals was performed. The closest agreement with the experimental absorption spectrum was obtained with the use of the LC-BLYP hybrid functional with exchange potential corrections at large distances.     

Mechanisms of 5'-O-Benzoyl-2,3'-anhydrothymidine Reactions with Nucleophiles: IV.* Kinetics and Thermodynamics of Azidation with Dimethylammonium Azide in DMF-1,4-Dioxane

The reaction of 5'-O-benzoyl-2,3'-anhydrothymidine with dimethylammonium azide in the system DMF-1,4-dioxane in the temperature range from 80 to 100°C follows the overall second-order kinetics and first-order kinetics with respect to each reactant. The activation parameters in the systems containing 30, 40, and 50 vol % of dioxane are, respectively: H 298 99, 85, and 79 kJ mol^{- 1}; S 298 -46, -83, and -101 J mol^{- 1} K^{- 1}. A refined model of the transition state for the rate-determining stage was proposed, which takes into account specific interaction with 1,4-dioxane.