Synthesis of Biginelli Compounds Using Cobalt Hydrogen Sulfate

Efficient synthesis of various 2‐oxo(thioxo)‐1,2,3,4‐tetrahydropyrimidines containing acetyl, carboethoxy, carbomethoxy and carboxamide groups on 5‐position of the N1‐substituted and N1‐unsubstituted heterocyclic ring was achieved using cobalt hydrogen sulfate Co(HSO₄)₂ under thermal conditions. Good to high yield, shorter reaction times, easy work up and simple preparation of Co(HSO₄)₂ are the advantages using this synthetic method.     

Synthesis and Derivatization of Expanded [n]Radialenes (n=3, 4)

Versatile, iterative synthetic protocols to form expanded [n]radialenes have been developed (n=3 and 4), which allow for a variety of groups to be placed around the periphery of the macrocyclic framework. The successful use of the Sonogashira cross‐coupling reaction to complete the final ring closure demonstrates the ability of this reaction to tolerate significant ring strain while producing moderate to excellent product yields. The resulting radialenes show good stability under normal laboratory conditions in spite of their strained, cyclic structures. The physical and electronic characteristics of the macrocycles have been documented by UV‐visible spectroscopy, electrochemical methods, and X‐ray crystallography (four derivatives), and these studies provide insight into the properties of these compounds as a function of pendent substitution in terms of conjugation and donor/acceptor functionalization.     

A facile and convenient approach for the one-pot synthesis of 2,4(1H,3H)-quinazolinediones

A fast and efficient method is described for the one-pot synthesis of 2,4(1H,3H)-quinazolinediones by cyclization reaction of anthranilic acid derivatives with potassium cyanate and acetic acid in PEG.Good to high yields of the products obtain in short reaction times with simple work-up.     

Ab‐Initio calculations of the CO adsorption and dissociation on substitutional Fe–Cu surface alloys relevant to Fischer–Tropsch Synthesis: bcc‐(Cu)Fe(100) and fcc‐(Fe)Cu(100)

Direct CO dissociation is seen the main path of the first step in the Fischer–Tropsch Synthesis (FTS) on the reactive iron surfaces. Cu/Fe alloy film is addressed with various applications over face‐centered‐cubic (fcc)‐Cu and body‐centered‐cubic (bcc)‐Fe in the FTS, i.e. preventing iron carbide formation (through direct CO dissociation) by moderating the surface reactivity and facilitating the reduction of iron surfaces, respectively. In this study by density functional theory, the stable configurations of CO molecule on various Cu/Fe alloys over fcc‐Cu(100) and bcc‐Fe(100) surfaces with different CO coverage (25% and 50%) have been evaluated. Our results showed that the ensemble effect plays a fundamental role to CO adsorption energy on the surface alloys over bcc‐Fe(100); on the other hand, the ligand effect determines the CO stability on the fcc‐Cu(100) surface alloys. CO dissociation barrier was also calculated on the surface alloys that showed although the CO dissociation process is thermodynamically possible on the more reactive surface alloys, but according to their high barrier, CO dissociation does not occur directly on these surfaces. Copyright © 2013 John Wiley & Sons, Ltd.     

Structural Characterization of Poly(α-Fluoroacrylonitrile) and Poly(Ethyl α-Fluoroacrylate)

Abstract

Monomers α-fluoroacrylonitrile (FAN) and ethyl α-fluoroacrylate (EFA) and homopolymers poly(α-fluoroacrylonitrile) (PFAN) and poly-(ethyl α-fluoroacrylate) (PEFA) have been synthesized and spectroscopi-cally characterized in detail for the first time. The ¹³C- and ¹⁹F-NMR spectroscopic results are reported, and the results are correlated to the tacticity and microstructure of both homopolymers. The major portion of the polymers is atactic. TGA analysis of PFAN indicates that the polymer is stable to about 200°C with subsequent loss of HF. PEFA is stable to 300 °C. Molecular weights determined by intrinsic viscosity (M_v ) are found to be about 130,000 for PFAN, and GPC analysis of PEFA indicates a molecular weight (M_n ) of about 36,000. Dielectric permittivities (ε) for PFAN and PEFA were determined to be 8.9 and 4.0, respectively, at 50 Hz.