Graphene oxide was grafted with poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylamide) (GO-poly(AMPS-co-AM)) by free radical copolymerization of the corresponding monomers namely acrylamide (AM) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). The benzoyl peroxide (BPO) was used as initiator. The GO-poly(AMPS-co-AM) was characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis and fluorescence spectroscopy, and elemental analysis. The GO-poly(AMPS-co-AM) exhibited the acidic site loading of 0.85 mmol g À 1 , the maximum degradation temperatures (T max ) of 212, 292, and 406°C, the char yield of 30% at 800°C, the limiting oxygen index (LOI) of 29.5, an estimated band gap of 4.7 eV, and the fluorescence emission bands of 722, 800, and 880 nm at the excitation wavelengths (λ max ) of 360, 400, and 440 nm, respectively. The GO-poly (AMPS-co-AM) was used as a reusable catalyst for the preparation of 1,8-dioxo-octahydroxanthenes through the condensation of an aldehyde with 5,5-dimethyl-1,3-cyclohexanedione (dimedone) in H 2 O/EtOH (1:1) as green solvents at room temperature.[a] Prof.
Trimellitic anhydride was attached to Merrifield resin and a ketene was generated from polymer-bound phthaloylglycine. Then this polymer reacted with imines in the presence of Vilsmeier reagent and triethylamine to afford the solid-phase-tethered β-lactam products. Selective cleavage of supported β-lactams by trifluoroacetic acid and methylhydrazine gave 4-carboxyphthalimido- and 3-amino-β-lactams, respectively. The trans-stereochemistry was found in all products.
N-Acylation of glycine with carboxylic acids was carried out by using the Vilsmeier reagent. The resulting N-acyl-a-amino acids were subsequently cyclodehydrated into oxazol-5-ones via the Vilsmeier reagent. Finally, treatment of oxazol-5-ones with aldehydes in the presence of the Vilsmeier reagent delivered Erlenmeyer azlactones. By combining these steps, using the Vilsmeier reagent allowed direct one-pot conversion of carboxylic acids into oxazol-5-ones and direct one-pot conversion of carboxylic acids into Erlenmeyer azlactones in the presence of aldehydes. These Vilsmeier reagent-mediated multicomponent reactions proceeded smoothly in reasonable chemical yields at room temperature. The chemical structure of the title compounds was confirmed by spectral data.
Magnetite-containing sulfonated polyacrylamide was easily prepared through polymerization of the corresponding monomers followed by the reaction with Fe 3 O 4 nanoparticles. The characterization of the obtained catalyst was performed by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The acidic SO 3 H moiety was found to be 1.1 mmol per gram of the obtained polymer. The catalytic activity of the polymer was examined for the synthesis of biscoumarin derivatives by two-component one-pot domino Knoevenagel-type condensation/Michael reaction between aldehydes and 4-hydroxycoumarin. Biscoumarins were obtained in high to excellent yields in short time. The work-up procedure of this reaction was very simple. The catalyst is stable (as a bench top catalyst) with easy-handling and it can be used again.
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