Single step conversion of UO2 and U3U8 into uranyl sulphate solution

A direct and simple method for the conversion of UO₂ and U₃O₈ powder into uranyl sulphate solution is described, eliminating many tedious chemical steps. UO₂ and U₃O₈ are not soluble in concentrated or dilute sulphuric acid, as uranium in lower oxidation state does not react with sulphuric acid. However, nitric acid oxidizes uranium from lower valency to higher valency state, i.e., tetravalent to the hexavalent uranyl ion in solution. Sufficient amount of sulphuric acid present in the reaction mixture makes it possible for uranyl ions, formed by oxidation of nitric acid, to react with sulphuric acid forming uranyl sulphate.     

A synthesis of potential new antiarrhythmic agents

N‐Ethylation of substituted ethyl 1H‐indole‐2‐carboxylates with iodoethane and potassium carbonate gave substituted ethyl 1‐ethyl‐1H‐indole‐2‐carboxylates. The later compounds on treatment with a range of aryl amines with varying structural complexity, gave the desired ethyl 1H‐indole‐2‐carboxamide analogues.     

Closing the Ring to Bring Up the Light: Synthesis of a Hexacyclic Acridinium Cyanine Dye

The synthesis of a geometrically constrained and near‐planar hexacyclic acridinium cyanine dye 9 is reported. When compared to its unlocked and non‐fluorescent monomethine cyanine dye analogue 3 , this photostable dye emits in the green area of the spectrum with a remarkable quantum yield close to unity in organic solvents and above 0.5 in water. A detailed steady‐state and time‐resolved spectroscopic study revealed that dye 9 forms emissive aggregates in water, which are responsible for a red‐shifted and broadened emission band and longer emission lifetime, τ≈33 compared to 6.5–7.0 ns for the monomeric dye. Dye 9 also binds strongly to DNA (both duplex and quadruplex) in its monomeric form and is very efficiently taken up by cells, in which it accumulates primarily into the nucleus.     

Fish Oil Recovery from Viscera of Indian Mackerel (Rastrelliger kanagurta) by Supercritical Fluid: An Optimization Approach

Fish viscera, a waste of fish processing industry, can be exploited as a source of PUFA‐rich fish oil for use in food or pharmaceutical industry and at the same time the environment can be protected from pollution by fish wastes. Fish oil was recovered from viscera of Indian Mackerel (Rastrelliger kanagurta), by different supercritical fluid extraction (SFE) e.g. continuous, co‐solvent, soaking, and pressure swing techniques and the yields were compared with that of the solvent extraction method. The SFE parameters such as pressure, temperature, and CO₂ flow rate were optimised by employing Response Surface Methodology (RSM) with a view to maximize the oil yield and minimize CO₂ consumption. The central composite rotatable design (CCRD) consisting of three variables provided 20 experimental settings. Multiple regressions determined the coefficients of the second‐order polynomial equation. The optimum parameters for all 4 techniques applied were found to be 35 MPa, 60 °C, and 2 mL min^?1 with an Oil recovery ranging from 93 to 99%. The study demonstrated a lower CO₂ consumption by the soaking and pressure swing techniques at the optimized conditions. Thus, the soaking and pressure swing techniques were most effective for extracting oil from fish viscera.     

SYNTHESIS AND CONFORMATIONAL ANALYSIS OF 16H-DINAPHTHO AND 12 H-DIBENZO [D,G][1,3,2]DIOXASILOCINE

Abstract

The conformation of the heterocyclic eight-membered ring in 16H-dinaphtho and 12H-dibenzo [d,g][1,3,2]dioxasilocine was investigated in solution by ¹H NMR spectroscopy. The barrier to ring inversion in the 16H-dinaphtho compound 3a was found to be 8.6±0.2 Kcal/mol and for the 12 H-dibenzo compound 4a, 8±0.2 Kcal/mol. Molecular mechanics calculations show three energy minima conformations for both compounds, boat chair(BC), twist boat(TB) and twist boat boat(TBB). Twist boat form is estimated to be the global minimum for the dibenzo compounds while TBB is the global conformation of the dinaphtho compounds. The result of molecular mechanics calculations are supported by analysis of the ¹H-NMR spectra.     

Chemoselective Deprotection of Thioacetals/Thioketals Using HIO3 in the Presence of Wet SiO2 Under Mild Solvent-Free Conditions

Abstract

HIO ₃ in the presence of wet SiO ₂ is highly efficient and a mild reagent for selective deprotection of a variety of thioacetals/thioketals to the corresponding parent carbonyl compounds at room temperature and under solvent-free conditions.     

Densities and refractive indices of imidazolium- and phosphonium-based ionic liquids: Effect of temperature,alkyl chain length,and anion

A systematic study of densities and refractive indices of 17 room temperature ionic liquids is presented at four different temperatures ranging from 293 K to 333 K. The ionic liquids are grouped into four families: 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [C_nmim][Ntf₂], ionic liquids (with n = 2, 4, 6, 8, 10, 12, and 14); 1-alkyl-3-methylimidazolium hexafluorophosphate, [C_nmim][PF₆], ionic liquids (with n = 4, 6, 8); ionic liquids based on the trihexyl(tetradecyl)phosphonium cation, [P_{6 6 6 14}], combined with the anions bis(trifluoromethylsulfonyl)amide, [Ntf₂], acetate, [OAc], and triflate, [OTf]; and [C₄mim]-based ionic liquids combined with the anions [OAc], [OTf], methylsulfate [MeSO₄], and tetrafluoroborate [BF₄]. The data obtained were analysed to determine the effect of (i) temperature, (ii) the alkyl chain length of the 1-alkyl-3-methylimidazolium cation, and (iii) the nature of the anion. Different empirical models for the calculation of the densities of the ionic liquids were tested. Molar refractions were also calculated from the volumetric and refractive index data and the values were discussed with the aim of checking their utility in obtaining insights on the intermolecular forces and behaviour in solution of the different ionic liquids.     

Effect of Polymerization Temperature on Propylene Polymerization with Cs-symmetric Metallocene Catalyst

The synthesis of bridged ansa metallocenes usually gives a diastereomeric mixture ofracemic and meso metallocene isomers and in many cases the meso form is about 50 % ofthe product of metallocene synthesis"'. The amount of desired racemic isomer is ratherpoor and can be separated from the meso isomer by fractional crystallization'. The racemicansa-metallocene isomer acts as catalyst for propylene polylnerization to produce isotacticpolypropylene (PP) while the corresponding meso isomer gives a…     

Synthesis,characterization and study of antibacterial activity of enaminone complexes of zinc and iron

Complexes of enaminones; 4-N,N-diethylamine-pent-3-ene-2-one [HL¹], 4-N,N-di n-propylamine-pent-3-ene-2-one [HL²] and 4-N,N-dicyclohexylamine-pent-3-ene-2-one [HL³] with Fe(II) and Zn(II) ions were prepared by reacting the equimolar ethanolic solutions of the ligands (HL¹, HL² and HL³) with ethanolic metal solutions. The complexes formed, were characterized by infrared, ultraviolet and atomic absorption spectroscopy. Ligands and their metal complexes were tested against Escherichia coli and Staphylococcus aureus bacteria to assess their antibacterial action using disc diffusion method. Ligands were completely inactive against bacteria whereas the complex Zn (HL¹) has significant action on both bacteria, indicating that it has a good potential as bactericide. Other complexes have normal antiseptic character.     

Prediction of water content of sour and acid gases

Estimating the feasibility of acid gas geological disposal requires the knowledge of the water content of the gas phase at moderate pressures and temperatures (typically below 50 MPa, below 380 K) and up to 6 mol NaCl. In this paper, a non-iterative model is developed to predict the water content of sour and acid gases at equilibrium with pure water and brine. This model is based on equating the chemical potential of water and using the modified Redlich–Kwong equation of state to calculate the fugacity of the gas phase. The water content of pure CH₄, CO₂ and H₂S are represented with average absolute deviations of less than 3.36, 7.04 and 8.4%, respectively. Experimental data of the water content of mixtures of the acid gases were reproduced with average absolute deviations of less than 6.32%.