Alkynylation of halo pyrimidines under Pd/C-copper catalysis: regioselective synthesis of 4- and 5-alkynylpyrimidines

5-Bromo-4-chloro-6-methylpyrimidines underwent facile Pd/C-Cu catalyzed coupling reactions with a variety of terminal alkynes, which resulted in the corresponding 4-alkynyl-5-bromopyrimidines, regioselectively, with good yields. 4-Chloro-5-iodo-6-methylpyrimidine, however, yielded the corresponding 5-alkynyl-4-chloropyrimidines under the same reaction conditions.     

Iodine as a versatile reagent for the Prins-cyclization: an expeditious synthesis of 4-iodotetrahydropyran derivatives

Iodine is found to be an efficient reagent for the coupling of homoallylic alcohols with aldehydes under mild conditions to produce 4-iodotetrahydropyran derivatives in excellent yields in a short reaction time with high selectivity. The use of iodine makes this procedure simple, convenient and cost-effective.     

Determination of specific surface area of uranium oxide powders using differential thermal analysis technique

The two step oxidation of UO_2+x and reduction of U₃O₈ powders observed during Differential Thermal Analysis (DTA) has been exploited to determine their Specific Surface Areas (SSAs). The results obtained by this method have been compared with the Braunauer, Emmett and Teller (BET) method and are found to be in good agreement in the SSA range of 2–4 m²/gm in the case of UO_2+x obtained from ADU route and 4–8 m²/gm in the case of AUC route. A precision of ±0.1 m²/gm is obtained. The maximum temperature of oxidation and reduction of these oxides are dependent upon their preparative routes such as Ammonium Diuranate (ADU) and Ammonium Uranyl Carbonate (AUC).     

Bi(OTf)3-catalyzed allylation of quinones with allyltrimethylsilane

p-Quinones react smoothly with allyltrimethylsilane in the presence of 2 mol% of Bi(OTf)₃ under mild reaction conditions to afford the corresponding allyl substituted benzene derivatives, p-allylquinols and allyl substituted 1,4-naphthoquinones in excellent yields with high regioselectivity. This method is very useful for the direct introduction of an allyl functionality onto a quinone moiety.     

Effect of rare earth ions on the catalytic activity of Ln2MnNiO6 perovskites

Abstract A series of rare earth transition metal perovskites has been synthesized and the catalytic activity tested for 2-propanol decomposition. The effect of rare earth ions on the catalytic activity can been understood from the correlations obtained between the physico-chemical properties and the catalytic activity of the perovskites.

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Bi(OTf)3-catalyzed acylation of p-quinones: a facile synthesis of acylated hydroquinones

p-Quinones undergo smooth acylation with acetic anhydride in the presence of 2 mol % of bismuth triflate under mild conditions to afford the corresponding 1,4-diacylated-2-acetoxylated hydroquinones in excellent yields with high selectivity.     

EPR of vanadyl ion in a natural mineral, apophyllite

Single crystal EPR spectra of a natural mineral, apophyllite, containing VO(II) ion as an impurity have been investigated. The EPR spectra of the mineral, as obtained, was complex in nature, but was simplified by annealing the crystals at 490 K. The EPR parameters of the VO(II) species in the annealed crystal,g _∥ = 1.924 (2);g _⊥ = 1.983 (2);A _∥ = 18.35 (5); andA _⊥ = 7.24 (5)mT, are very close to a typical VO(II) impurity. Theoretically calculated line positions, using second-order hyperfine terms in the spin Hamiltonian with an axially symmetricg andA tensor values, agreed very well with the experimental ones. The EPR analysis of the annealed crystal has further revealed that the most preferred location of the VO(II) impurity is a substitutional Ca(II) site. The calculated bonding parameters and admixture coefficients indicate a fair amount of covalent bonding in the complex.     

Water dispersed gold nanoparticles catalyzed aerobic oxidative cross-dehydrogenative coupling: An efficient synthesis of α-ketoamides in water

An effective green synthesis of α-ketoamides was developed for the first time in water via gold nanoparticles (AuNPs) catalyzed aerobic oxidative cross-dehydrogenative coupling of secondary amines with phenylglyoxals with a broad substrate scope.