Search

Low sulfur heavy stock (LSHS Premium) is a green alternative to Fuel oil. Asphaltene content is a very important quality parameter and is stipulated in LSHS (Premium) specifications. IP 143 is a standard method to conduct the asphaltene analysis; however it is a tedious process which requires around 48 h for analysis. In this study, a correlation of two standard methods (IP 143 and JPI-5S-45-95) has been carried out based on the experimentally determined asphaltene contents of LSHS (Premium) samples from different production sources. The correlation coefficient between two standard methods is observed to be near unity, suggesting an excellent correlation. This indicates that JPI-5S-45-95 can be used as a substitute of IP 143 method for asphaltene analysis consuming less time (1 h). A correlation equation has also been established between CCR (ASTM D4530) and asphaltene contents (JPI-5S-45-95) of LSHS (Premium) which indicate the linear dependency of CCR with its asphaltene content. For validation of correlation equation, the calculated asphaltene content was compared with experimentally determined values and it is observed that this correlation equation can be employed to fairly predict the asphaltene content accurately without conducting IP 143 or JPI-5S-45-95 methods. [ABSTRACT FROM AUTHOR]

We present a purely numerical approach in a Cartesian grid, for efficient computation of the Hartree-Fock (HF) exchange contribution in the HF and density functional theory models. This takes inspiration from a recently developed algorithm by Liu et al., in 2017, where the rate-determining step is the accurate evaluation of electrostatic potential. This introduces the Fourier convolution theorem in conjunction with a range-separated Coulomb interaction kernel. The latter is efficiently mapped into a real grid through a simple optimization procedure, giving rise to a constraint in the range-separated parameter. The overall process offers logarithmic scaling with respect to the molecular size. It is then extended toward global hybrid functionals such as B3LYP, PBE0, and BHLYP within pseudopotential Kohn-Sham theory, through an LCAO-MO ansatz in a Cartesian grid, developed earlier in our laboratory. For the sake of comparison, a parallel semi-numerical approach has also been worked out that exploits the familiar Obara-Saika recursion algorithm without any additional techniques. An excellent agreement between these two routes is demonstrated through total energy and orbital energy in a series of atoms and molecules (including 10 π-electron molecules), employing an LANL2DZ-type basis function. A critical analysis of these two algorithms reveals that the proposed numerical scheme could lead to very attractive and competitive scaling. The success of our approach also enables us for further development of optimally tuned range-separated hybrid and hyper functionals. [ABSTRACT FROM AUTHOR]

Abstract: Indium(I) iodide promotes cleavage of dialkyl disulfides generating thiolate anions that then undergo facile addition to α,β-unsaturated ketones, aldehydes, carboxylic esters, and nitriles under neutral conditions producing corresponding β-ketosulfides [...]

Diphenyl diselenides and disulfides undergo facile cleavages by indium(I) iodide and the corresponding generated selenate and thiolate anions condense in situ with alkyl or acyl halides present in the reaction mixture. The conclusion states that a one-pot procedure for the synthesis of alkyl phenyl selenides, sulfides (thioethers), selenoesters, and thioesters is developed.

Multicomponent reactions (MCR) are an efficient and attractive synthetic strategy in which three or more reactants come together in a one-pot reaction to form a new complex molecule or biological product. In recent times, ferrite nanoparticles (MFe2O4 NPs; M = Cu, Co, Ni, Zn, Mn, etc.) have attracted the attention of many chemists or researchers due to unique properties such as high stability, high activity, and simple separation. In this paper, we discussed ferrite nanoparticles and their catalytic activity in a variety of organic transformations via MCR. [ABSTRACT FROM AUTHOR]

Autonomous formation flight is a key approach for reducing energy cost and managing traffic in future high density airspace. The use of Unmanned Aerial Vehicles (UAVs) has allowed low-budget and low-risk validation of autonomous formation flight concepts. This paper discusses the implementation and flight testing of nonlinear dynamic inversion (NLDI) controllers for close formation flight (CFF) using two distinct UAV platforms: a set of fixed wing aircraft named “Phastball” and a set of quadrotors named “NEO.” Experimental results show that autonomous CFF with approximately 5-wingspan separation is achievable with a pair of low-cost unmanned Phastball research aircraft. Simulations of the quadrotor flight also validate the design of the NLDI controller for the NEO quadrotors. [ABSTRACT FROM AUTHOR]

Thegeneral and efficient palladium-catalyzed indium-mediated allylationof chiral hydrazones was accomplished with excellent yield (72–92%)and diastereoselectivity (up to 99:1). The development of this reactionand the substrate scope are described. The conversion was found tobe proportional to the phosphine concentration, which provided insightinto the mechanism and competing pathways of the redox transmetalationprocess. [ABSTRACT FROM AUTHOR]

The self-assembly of the precatalyst modules, which are amino acids and cinchona alkaloid derivatives, leads to the direct formation of the desired organocatalysts without any synthesis. These modularly designed organocatalysts (MDOs) may be used for catalyzed asymmetric aldol reaction. Depending on structure of the aldehyde substrates, the corresponding aldol products may be obtained in mediocre to excellent ee values (up to 92% ee) with moderate diastereoselectivities (up to 79:21 dr). [ABSTRACT FROM AUTHOR]

A convenient and efficient procedure for the synthesis of β-alkyl/arylsulfanyl carbonyl compounds has been developed by a simple one-pot reaction of dialkyl/diaryl sulfides with α,β-unsaturated aldehydes, ketones, carboxylic esters, and nitriles in presence of indium and trimethylsilyl chloride under sonication. [ABSTRACT FROM AUTHOR]

The highly selective anti-Markovnikov addition of thiols to unactivated alkenes is demonstrated in water at room temperature without any additive. This is a very simple and efficient method for the synthesis of linear thioethers. [ABSTRACT FROM AUTHOR]

Indium(I) iodide promotes cleavage of dialkyl disulfides generating thiolate anions that then undergo facile addition to α,β-unsaturated ketones, aldehydes, carboxylic esters, and nitriles under neutral conditions producing corresponding β-ketosulfides or β-cyanosulfides. This strategy has also been used for the regioselective nucleophilic ring opening of epoxides by thiolate anions in presence of indium(III) chloride producing corresponding β-hydroxyphenyl sulfides. The reactions are in general, very clean, high yielding, and reasonably fast. Thus, simple and convenient procedures for the synthesis of β-ketosulfides or β-cyanosulfides and β-hydroxyalkyl sulfides have been developed using this cleavage reaction. [ABSTRACT FROM AUTHOR]

A wide range of cyclic dithioacetals are prepared from the corresponding aldehydes in the presence of aqueous solution of zinc tetrafluoroborate. [ABSTRACT FROM AUTHOR]

Diphenyl diselenides and disulfides undergo facile cleavages by indium(I) iodide and the corresponding generated selenate and thiolate anions condense in situ with alkyl or acyl halides present in the reaction mixture. Thus, a simple, efficient, and general procedure has been developed for the synthesis of unsymmetrical diorganyl selenides, sulfides (thioethers), selenoesters, and thioesters by this one-pot reaction at room temperature. [ABSTRACT FROM AUTHOR]

Within the finite‐field Kohn–Sham framework, static electric response properties of diatomic molecules are presented. The electronic energy, dipole moment (μ), static dipole polarizability (α), and first‐hyperpolarizability (β) are calculated through a pseudopotential‐DFT implementation in Cartesian coordinate grid, developed in our laboratory earlier. We engage the Labello–Ferreira–Kurtz (LFK) basis set; while four local and nonlocal exchange‐correlation (LDA, BLYP, PBE, and LBVWN) functionals have been adopted. A detailed analysis of grid convergence and its impact on obtained results is presented. In each case the electric field optimization was carefully monitored through a recently prescribed technique. For all three molecules (HCl, HBr, HI) considered, the agreement of all these quantities with widely successful and popular atom‐centered‐grid procedure, is excellent. To assess the efficacy and feasibility, companion calculations are performed for these on a representative molecule (HCl) at distorted geometries, far from equilibrium. Wherever possible, relevant comparison is made with available all‐electron data and experimental results. This demonstrates that Cartesian grid provides accurate, reliable results for such properties of many‐electron systems within pseudopotential representation. Static electric response properties of three diatomic molecules are calculated using finite‐field Kohn–Sham method within pseudopotential approximation in Cartesian grid. Effect of electric field strength is monitored by evaluating relative error for different exchange‐correlation functionals. Spatial grid optimization and electric field optimization are analyzed in detail. Extension of the method is made at distorted geometry far from equilibrium. This demonstrates that Cartesian grid can provide viable alternative for such properties within DFT. [ABSTRACT FROM AUTHOR]

An abstract of the article "Highly Diastereoselective Palladium-Catalyzed Indium-Mediated Allylation of Chiral Hydrazones" by Narayanaganesh Balasubramanian, Tanmay Mandal, and Gregory R. Cook, is presented.