Polyethylene glycol (PEG-400): An efficient one-pot green synthesis and anti-viral activity of novel α-diaminophosphonates

Abstract

An efficient and eco-friendly protocol has been accomplished for a series of novel α-diaminophosphonates by a one-pot, three-component system via Kabachnik-Fields reaction of 4,4′-methylenedianiline, a variety of aryl/heteroaryl aldehydes and diphenylphosphite employing polyethylene glycol (PEG-400) as a green solvent at 80?°C. All products were obtained in good to excellent yields (80–95%). The identity of the new synthesized compounds was confirmed by IR, ¹H, 13C, and 31P NMR, LC-MS and elemental analysis. In vivo anti-viral activity was evaluated against tobacco mosaic virus (TMV). Compounds 4b, 4c, 4j and 4k exhibited the highest anti-viral activities against tobacco mosaic virus (TMV) when compared with the standard drug ningnanmycin.     

A C2 continuous approximation to the Mohr–Coulomb yield surface

In spite of the development of more sophisticated constitutive models for soil, the Mohr–Coulomb yield criterion remains a popular choice for geotechnical analysis due to its simplicity and ease of use by practising engineers. The implementation of the criterion in finite element programs, however, presents some numerical difficulties due to the gradient discontinuities which occur at both the edges and the tip of the hexagonal yield surface pyramid. Furthermore, some implicit techniques utilising consistent tangent stiffness formulations are unable to achieve full quadratic convergence as the yield criteria is not C2 continuous. This paper extends the previous work of Abbo and Sloan (1995) through the introduction of C2 continuous rounding of the Mohr–Coulomb yield surface in the octahedral plane. This approximation, when combined with the hyperbolic approximation in the meridional plane (Abbo and Sloan, 1995), describes a yield surface that is C2 continuous at all stress states. The new smooth yield surface can be made to approximate the Mohr–Coulomb yield function as closely as required by adjusting only two parameters, and is suitable for consistent tangent stiffness formulations.     

Synthesis of N-methyl imines in the presence of poly(N-vinylpyridine) as a reusable solid base catalyst by a mechanochemical process

Research on Chemical Intermediates - The synthesis of N-methyl imines was performed in the presence of catalytic amounts of poly(4-vinylpyridine) in high yields and rapidly at room temperature by a...     

Reactivity-selectivity study of the Friedel-Crafts acetylation of 3,3' -dimethylbiphenyl and the oxidation of the acetyl derivatives

ABSTRACT: BACKGROUND: Friedel-Crafts acetylation is an important route to aromatic ketones, in research laboratories and in industry. The acetyl derivatives of 3,3' -dimethylbiphenyl (3,3' -dmbp) have applications in the field of liquid crystals and polymers and may be oxidized to the dicarboxylic acids and derivatives that are of interest in cancer treatment. FINDINGS: The effect of solvent and temperature on the selectivity of monoacetylation of 3,3'-dmbp by the Perrier addition procedure was studied using stoichiometric amounts of reagents. 4-Ac-3,3' -dmbp was formed almost quantitatively in boiling 1,2-dichloroethane and this is almost twice the yield hitherto reported. Using instead a molar ratio of substrate:AcCl:AlCl3 equal to 1:4:4 or 1:6:6 in boiling 1,2-dichloroethane, acetylation afforded 4,4' - and 4,6' -diacetyl-3,3' -dmbp in a total yield close to 100%. The acetyl derivatives were subsequently converted to the carboxylic acids by hypochlorite oxidation. The relative stabilities of the isomeric products and the corresponding sigma-complexes were studied by DFT calculations and the data indicated that mono- and diacetylation followed different mechanisms. CONCLUSIONS: Friedel-Crafts acetylation of 3,3' -dmbp using the Perrier addition procedure in boiling 1,2-dichloroethane was found to be superior to other recipes. The discrimination against the 6-acetyl derivative during monoacetylation seems to reflect a mechanism including an AcCl:AlCl3 complex or larger agglomerates as the electrophile, whereas the less selective diacetylations of the deactivated 4-Ac-3,3' -dmbp are suggested to include the acetyl cation as the electrophile. The DFT data also showed that complexation of intermediates and products with AlCl3 does not seem to be important in determining the mechanism.     

1H and C-13 NMR Study of the Molecular Structure of New Di-(β-Keto) Schiff bases

New di-(β-keto) schiff bases were prepared. The molecular structure of those di-(β-keto) schiff bases was determined by ¹H and C-13 nmr spectroscopy.     

An Efficient Inclusion Complex Based Fluorescent Sensor for Mercury (II) and its Application in Live-Cell Imaging

Journal of Fluorescence - The formation of an inclusion complex between hydroxypropyl-β-cyclodextrin (H-CD) and 4-acetylphenyl-4-(((6-chlorobenzo[d]thiazol-2-yl)-imino)-methyl)-benzoate (L)...     

Bis(pyrazolyl)pyridine vanadium(III) complexes as highly active ethylene polymerization catalysts

The synthesis, characterization and catalytic activity in ethylene polymerization of novel mononuclear vanadium complexes bearing N^∧N^∧N-tridentate (pyrazolyl-pyridine) ligands are described. With AlEtCl₂ as co-catalyst, complexes 1 and 2 produce single-site catalysts that polymerized ethylene affording high density polyethylene with fairly narrow molecular weight distribution.     

Numerical simulation of the failure process of unreinforced masonry walls due to concentrated static and dynamic loading

Finite element analyses of brick masonry subjected to in-plane concentrated static and dynamic loads are carried out to study crack initiation and propagation during the failure process of unreinforced masonry walls. The numerical model is firstly validated by the experimental tests by using the same materials parameters and loading conditions. Then, the static and dynamic concentrated loads are applied to the mortar joints and brick, respectively, and numerical simulations are used to compare the fracture characteristics for these loads. In addition, a comparison of fracture mechanisms for the concentrated loads on the mortar joint and brick is also given. Finally, the effect of dynamic pressure (P_max) on the failure mechanism of brick masonry is considered.