Highly selective sulfur transfer reaction in the solid state

Benzyltriethylammonium tetrathiomolybdate 1 reacts readily with benzyl halides, alkyl iodides and acyl halides in the solid state to give the corresponding disulfides in good yields and with remarkable selectivity.

Mechanistic studies on the effect of ferrocene bonding agents in composite solid propellents

Five compounds, viz. 1,1'-ferrocenediyldiethylidene bis(thiocarbonohydrazide) (DAFT), 1,1-diacetylferrocene disemicarbazone (DAFS), 1,1-diacetylferrocenebenzoyl hydrazone (FDBAH), 1,1-diacetylferrocene-p-nitrobenzoyl hydrazone (FDNBAH), and p-tolenesulfonic acid, 1,1'-ferrocenediyldiethylidene dihydrazide (TFDD) were found to be bonding agents as well as burning-rate modifiers for the ammonium perchlorate + hydroxy-terminated polybutadiene system. The tensile strength and percentage elongation significantly increased in the presence of these bonding agents (except FDBAH). The bonding agents generally did not adversely affect the slurry viscosity during processing. The bonding sites were located by infrared spectroscopy, supported by determination of the dissolution kinetics of the bonding agents and scanning electron microscopy. The bonding agents did not undergo any side-reactions with the curing agents.

Diffusion path during internal displacement reactions in multi-component oxides: Reaction between Fe and (Co,Mg)TiO3 solid solution at 1273 K

The reaction between Fe foil and a disc of ilmenite solid solution (Co-0.48 Ni-0.52) TiO3 was studied at 1273 K. At the metal/oxide interface, the displacement reaction, Fe + (Co,Mg)TiO3 = Co + (Fe,Mg)TiO3 occurs, resulting in an ilmenite solid solution containing three divalent cations. Ferrous ions diffuse into the oxide solid solution and cause the precipitation of Co-Fe alloy as discrete particles inside the oxide matrix. The morphology of the product layer was characterized by SEM. Only two phases, alloy and ilmenite, were detected in the reaction zone. This suggests that the local flux condition imposed by ilmenite stoichiometry (Co + Fe + Mg):Ti = 1:1] was satisfied during the reactive diffusion: (J(Co) + J(Fe) + J(Mg)) = J(Ti). The composition of the alloy and the oxide was determined using EPMA as a function of distance in the direction of diffusion. Although Mg does not participate in the displacement reaction, its composition in the ilmenite phase was found to be position dependent inside the reaction zone. The up-hill diffusion of inert Mg is caused by the development of chemical potential gradients as a result of displacement reaction. The evolution of composition gradients inside the reaction zone and the diffusion path in a ternary composition diagram of the system CoTiO3-FeTiO3-MgTiO3 are discussed. (C) 2010 Elsevier B.V. All rights reserved.

Reaction of normal and pseudo 2-formylbenzenesulfonyl chlorides with amines:experimental and theoretical studies on the structure of 2-formyl benzenesulfonamides in solid, solution and gas phases

The reaction of 2-formylbenzenesulfonyl chloride 1 and its pseudo isomer 2 with primary amines give either the corresponding sulfonamido Schiff bases or the corresponding 2-formylbenzenesulfonamide depending on the concentration of the amine used. The derivatives exist as an equilibrium mixture of the corresponding sulfonamide and 2-alkyl-3-hydroxy(or 3-aminoalkyl)-benzisothiazole-1,1-dioxide. Spectroscopic studies suggest that 2-formylbenzenesulfonamides exist as benzisothiazole-1,1-dioxides in the solid state, as a mixture of 2-formylbenzenesulfonamide and the corresponding benzisothiazole-1,1-dioxide in solution and as 2-formyl-benzenesulfonamides in the gas phase.

Soft-chemical routes to synthesis of solid oxide materials

We describe three different families of metal oxides, viz., (i) protonated layered perovskites, (ii) framework phosphates of NASICON and KTiOPO4 (KTP) structures and (iii) layered and three-dimensional oxides in the H-V-W-O system, synthesized by 'soft-chemical' routes involving respectively ion-exchange, redox deinteracalation and acid-leaching from appropriate parent oxides. Oxides of the first family, HyA2B3O10(A = La/Ca; B = Ti/Nb), exhibit variable Bronsted acidity and intercalation behaviour that depend on the interlayer structure. V2(PO4)3 prepared by oxidative deintercalation from Na3V2(PO4)3 is a new host material exhibiting reductive insertion of lithium/hydrogen, while K0.5Nb0.5 M0.5OPO4(M = Ti, V) are novel KTP-like materials exhibiting second harmonic generation of 1064 nm radiation. HxVxW1-xO3 for x = 0.125 and 0.33 possessing alpha-MoO3 and hexagonal WO3 structures, prepared by acid-leaching of LiVWO6, represent functionalized oxide materials exhibiting redox and acid-base intercalation reactivity.

Solid finite elements through three decades

conventionally, solid finite elements have been looked upon as just generalizations of two-dimensional finite elements. In this article we trace their development starting from the days of their inception. Keeping in tune with our perceptions on developing finite elements, without taking recourse to any extra variational techniques, we discuss a few of the techniques which have been applied to solid finite elements. Finally we critically examine our own work on formulating solid finite elements based on the solutions to the Navier equations.

Solid state physics through the years: Need for new initiatives

Solid state physics developed in India later than elsewhere in the world. What is particularly disconcerting is the poor state of experimental solid state physics today. A new thrust and better funding are essential if this field has to thrive in the country.

Study of the reaction between 1,2,3-trihydroxybenzene and 8-hydroxyquinoline in the solid state

1.2,3-Trihydroxybenzene (THB) reacts with 8-hydroxyquinoline (8HQ) in the solid state forming an orange-coloured charge transfer complex THB* (8HQ)(2). When the reaction was carried out in a petri dish, or when the vapours of 8HQ were allowed to react with solid THB (gravimetric study), the reaction product separated out as good quality, shiny single crystals. X-Ray diffraction studies on single crystals showed that they belong to the orthorhombic system with a = 15.408(1), b = 16.276(1), c = 7.825(1) Angstrom, Z = 4, D-x = 1.413 g cm(-3) and space group Pnaa. From the crystallographic evidence it has been found that the proton of the middle OH group of THB is transferred to the N atom of 8HQ. This accounts for the observed colour change. Kinetic studies on the solid state reaction showed that the 8HQ molecules diffuse towards THB, and the lateral diffusion occurs through surface migration, grain boundary diffusion and vapour phase diffusion. Gravimetric studies of the reaction between solid THB and 8HQ vapour showed that the diffusion of 8HQ molecules into the crystal lattice of THB has a higher energy of activation than that observed when the reactants are in contact. The nature of the crystal packing in the reaction product indicates diffusion of 8HQ molecules into the crystal lattice of THB along the c-axis, to occupy the cavities present between the THB molecules in the unit cell.

Whither solid state physics

The physics of the solid state has grown into that of condensed matter and is now expanding into the study of a bewildering variety of complex systems. After a brief survey of this progression, I enquire into the health of solid state physics; many signs of vitality and growth are found. The Indian scene in this field is briefly sketched, and some suggestions are offered on how to make it more lively,

C-13 MAS NMR spectra of cis,cis-mucononitrile in liquid-crystalline media and in the solid state. Orientation of the carbon chemical-shift tensors

The spinning sidebands observed in the C-13 MAS NMR spectra of cis,cis-mucononitrile oriented in liquid-crystalline media and of the neat sample in the solid state are studied. There are differences in the sideband intensity patterns in the two cases. These differences arise because the order parameters which characterize the orientation of the solute in the liquid-crystalline media differ for different axes. It is shown that, in general, the relative intensities of the sidebands contain information on the sign and magnitude of an effective chemical-shift parameter which is a function of the sum of the products of the principal components of the chemical-shift tensor and the corresponding order parameters with respect to the director. A method for obtaining the orientation of the carbon chemical-shift tensor is proposed. The carbon chemical-shift tensors obtained from gauge-including atomic orbital calculations are also presented for comparison. (C) 1996 Academic Press, Inc.

Construction of solid model from measured point data

This paper describes an algorithm for constructing the solid model (boundary representation) from pout data measured from the faces of the object. The poznt data is assumed to be clustered for each face. This algorithm does not require any compuiier model of the part to exist and does not require any topological infarmation about the part to be input by the user. The property that a convex solid can be constructed uniquely from geometric input alone is utilized in the current work. Any object can be represented a5 a combznatzon of convex solids. The proposed algorithm attempts to construct convex polyhedra from the given input. The polyhedra so obtained are then checked against the input data for containment and those polyhedra, that satisfy this check, are combined (using boolean union operation) to realise the solid model. Results of implementation are presented.

Investigations Of Iron Adducts Of C-60 - Novel Fec60 In The Solid-State With Fe Inside The C-60 Cage

By carrying out contact-arc vaporization of graphite in a partial atmosphere of Fe(CO)5, an iron-adduct with C60 has been obtained. The adduct has been characterized by various techniques including mass spectrometry, Fe-57 Mossbauer spectroscopy and Fe K-EXAFS. Properties of this adduct are compared with those of an adduct prepared by solution method where Fe is clearly outside the cage. Results suggest that FeC60 obtained from the gas phase reaction has the Fe atom in the cage.