Synthesis of novel 1,2,3,4 -tetrahydroisoquinoline -3 -carboxylic acid derivatives through the application of rongalite: a synergistic combination of [2+2+2]-and [4+2]-cycloaddition reactions

An efficient route for the synthesis of several novel 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic) derivatives has been reported. A synergistic combination of [2+2+2]- and [4+2]-cycloaddition reactions has been used for the synthesis of the desired targets

AIMS simulation study of ultrafast electronically nonadiabatic chemistry of methyl azide and UV-VIS spectroscopic study of azido-based energetic plasticizer bis(1,3-diazido prop-2-yl)malonate

To gain insight into the ultrafast electronically nonadiabatic chemistry of azido-based energetic plasticizer, we have explored the nonadiabatic chemical dynamics of an azido-based model analog molecule, methyl azide (MAz), using ab initio multiple spawning (AIMS) simulation and electronic structure theory calculations. Molecular nitrogen (N-2) is predicted to be the initial product of MAz following its electronic excitation to the S-1 electronically excited state. AIMS-based simulation reveals that electronically excited azido-based molecules undergo extremely fast (approximately in 40 femtoseconds) relaxation to the ground state via the (S-1/S-0) CI conical intersection. Furthermore, this relaxation process involves the N-N bond elongation along with the bending of N-3 moiety. This is the first report on the electronically non-adiabatic chemical dynamics (in ultrafast time domain) of methyl azide. Finally, using ultraviolet-visible (UV-VIS) spectroscopy, we comment on the electronically nonadiabatic chemistry of azido-based energetic plasticizer, bis(1,3-diazido prop-2-yl) malonate. (C) 2017 Elsevier B.V. All rights reserved

Effect of precursor on the formation of different phases of iron oxide nanoparticles

International audienc

Effect of precursor on the formation of different phases of iron oxide nanoparticles

International audienc

Synthesis of novel quinone-amino acid hybrids via cross-enyne metathesis and Diels-Alder reaction as key steps

A "Building Block Approach" for the synthesis of various quinone-amino acid hybrids through ethylene cross-enyne metathesis and Diels-Alder reaction as key steps is described. A library of comformationally constrained quinone-based phenylalanine derivatives and dicarba analogs of cystine have been generated starting from a common precursor using Grubbs' catalysts. This methodology has also been extended for the synthesis of fullerene-based dicarba analogs of cystine

Influence of Dispersion Methods on the Mechanical, Thermal and Rheological Properties of HTPB-based Nanocomposites: Possible Binders for Composite Propellants

The present study reports on the methods of preparation for HTPB-clay nanocomposites and their mechanical, thermal and rheological properties for their functional utility as an improved binder system for composite propellants. HTPB-clay nanocomposites were prepared by dispersing organoclay Cloisite 30B (1-3 wt.%) in the polymer matrix by magnetic stirring and high shear mixing. Critical parameters like time, temperature and RPM were optimized. These nanocomposites were cured with toluene diisocyanate in the presence of the cure catalyst DBTDL. The dispersion of the nanoclay was evaluated by using small angle X-ray scattering (SAXS) and energy dispersive X-ray (EDX) spectroscopy. EDX suggested homogeneous distribution while SAXS revealed partial exfoliation of the clay particles in the polymer matrix. Superior dispersion of the nanoclay was obtained by high shear mixing. The tensile properties of the nanocomposites prepared by high shear mixing showed 10-20% more strength and elastic modulus. The nanocomposites showed thermal stability higher than the pristine HTPB. Swelling behavior revealed increased cross linking, and the rheological behavior exhibited higher viscosity of the nanocomposites. In addition, the clay amount was increased up to 10 wt.% and its effect on the mechanical, thermal and swelling behavior was observed. Theoretical performance predictions of composite propellants with nanocomposites revealed their possible functional utility

Composite Propellant Formulation of Poly (16-, 32- and 64-) Azido Dendritic Esters as Energetic Plasticizer and Evaluation of Properties

16-, 32- and 64-Polyazido hyperbranched dendrimers were synthesized from hydroxy terminated dendritic ester by following two steps namely, tosylation and azidation. The poly azido dendrimers were incorporated in composite propellant formulations as an energetic plasticizer. The physical, thermal sensitivity and ballistic properties of these composite propellants such as burning rate, Cal-val, density, ignition/decomposition temperature (AET), DSC-TGA, mechanical properties, impact and friction sensitivity were evaluated experimentally while the specific impulse (Isp) and characteristic velocity (C*) were obtained theoretically. A significant enhancement in heat release was noted in the propellant formulation having 16-azido dendritic ester as an energetic plasticizer compared to 32- and 64-azido dendritic esters and a reference composition

Pd-Catalyzed Regioselective Arylation on the C‑5 Position of <i>N</i>‑Aryl 1,2,3-Triazoles

We herein report a highly efficient method for the arylation at the C-5 position of <i>N</i>-aryl 1,2,3-triazoles via a direct palladium catalyzed arylation reaction. The optimal reaction conditions required a combination of Pd­(OAc)₂ and tris­(<i>o</i>-tolyl)­phosphine as catalyst, and Cs₂CO₃ as the base under inert atmosphere. A variety of C-5 substituted <i>N</i>-aryl 1,2,3-triazoles were prepared using these conditions with yields in the 70–88% range. Regioselective C-5 arylations were also performed on 1,4-disubstituted 1,2,3-triazoles. The regioselectivity in triazole substitution at the C-5 position was confirmed by single crystal XRD. In addition, computational investigations of key steps of the catalytic cycle using the density functional theory have provided a rationalization to the selective C-5 arylation of <i>N</i>-aryl 1,2,3-triazoles

Tailoring of energetic groups in acroyloyl polymers

<p>Acryloyl based novel energetic monomers having nitro acrylates and nitro triazole acrylates were synthesized and further used for polymerization. Due to scavanging properties of nitro groups, syntheses of nitro aromatic polymers are not facile at normal conditions. In this regard, we report a simple protocol to synthesize these energetic group embeded acroloyl polymers. These polymers were characterized by FTIR, and NMR spectroscopic techniques. gel permeation chromatography (GPC) technique was employed in order to understand molecular mass of these polymers along with average molecular weight, number average weight and poly dispersity index. Glass transition temperature (<i>T</i>_g) was determined by using DSC analysis. It was observed that with increase in nitro groups in polymers there is a decrease in glass transition temperature. Two steps degradation were depicted in the TGA thermograph in nitro containing polymers. Heat release during this reaction was found up to 951 J/g. Increase in nitrogen content in polymer unit enhanced the heat release of polymers.</p