A Mild and Efficient Route to 3-Vinylchromones in Aqueous Micellar Media

A simple, mild, and ecofriendly method has been developed for the synthesis of 3-vinylchromones from 4-oxo-4H-1-benzopyran-3-carboxaldehyde (3-formylchromone) by simple Knoevenagel condensation with various active methylene compounds (AMC) in aqueous micellar media in the presence of catalytic amounts of cetyl trimethylammonium bromide (CTAB) and 1,4-diazabicyclo[2.2.2]octane (DABCO). In the case of malonic acid as AMC, the reaction resulted in formation of only Doebner decarboxylated products under the standard reaction condition. It has been also observed that 3-formylchromone derivatives primarily undergo tandem Knoevenagel and Michael reactions in the presence of > 2 equiv. of ethyl acetoacetate to produce benzophenone derivatives, by opening of pyran ring, as the sole product in good yields.     

Activation of Iron (III) and Bismuth (III) Nitrates by Tungstophosphoric Acid: Solvent‐Free Oxidative Deprotection of Oximes to Carbonyl Compounds

Abstract

Tungstophosphoric acid (H₃PW₁₂O₄₀ · 6H₂O) has been used as a catalyst for a simple, rapid, selective, and solvent‐free cleavage of oximes to carbonyl compounds using iron (III) and bismuth (III) nitrates as oxidants.     

Synthesis and characterization of new selective Zn fluorescent probes for functionalization: in vitro Cell imaging applications

Herein the synthesis and characterization of new, lipophilic highly Zn²⁺-selective fluorescent probes are reported. High affinity for zinc (K_d 1.1–8.0 nM) over other biologically relevant metals and mixtures of metals was observed. Excitation at 360 nm afforded an emission spectrum with maximum at 530 nm for the zinc bound complex. The linear relationship between fluorescence intensity and zinc concentration indicates that FZnA-probes can be used for quantification. The probes have been synthesized in 28–45% overall yield and the feasibility for further functionalization with biologically relevant side chains has been demonstrated. In vitro studies using PC12 cells and 10 μM of one of the novel probes (FZnA-Ada) visualized endogenous labile Zn²⁺ after 45 min incubation time.     

Recyclable Siloxy Serine Organocatalyst for the Direct Asymmetric Mannich Reactions in Ionic Liquids

A recyclable siloxy-L-serine organocatalyst has been developed to catalyze the asymmetric direct three-component Mannich reactions in ionic liquid hmim[PF₆], furnishing the β-amino carbonyl scaffold in high enantio- and diastereoselectivities. The direct Mannich reaction between a selection of aromatic aldehydes and ketones resulted in good yields and high enantioselectivities.

Synthesis of fluorinated malonamides and use in L/L extraction of f-elements

Synthesis of new fluorinated tertiary malonamides (F-malonamides) was accomplished, and their liquid/liquid (L/L) extraction properties with f-elements were investigated. These molecules are fluorinated analogues of well known extractants used in several processes designed towards the treatment of nuclear wastes, and the efficient separation of lanthanides from minor actinides; however, the synthesis of F-malonamides deserved a modification of the general synthetic route commonly employed to prepare H-malonamides. Extraction of neodymium from various aqueous media into both fluorous and classical solvents was studied, which revealed an opposite trend between F-malonamides and H-malonamides: L/L extraction ability is very sensitive to the nitrogen atoms substitution pattern, and the most efficient F-malonamide is compound 3 (R₁ = Me), whereas the best H-malonamide is compound 5 (R₁ = Bu, DMDBTDMA).     

Synthesis,Structures, Luminescent and Magnetic Properties of Heterometallic 5p‐4f Compounds with Ethylenediaminetetra­acetate

A series of heterometallic Ln^III–Sb^III edta‐containing compounds with the formulas [Sb₂(edta)₂Ln]NO₃ · nH₂O [edta = ethylenediaminetetraacetate; Ln = Eu, n = 7 ( 1 ); Gd, n = 7.5 ( 2 ) and Tb, n = 8 ( 3 )] were synthesized and characterized by elemental analyses (EA), powder X‐ray diffraction (PXDP), Fourier transform infrared spectroscopy (FT‐IR), and thermogravimetric analyses (TGA). Their fluorescence and magnetic properties were also studied. The thermal analysis demonstrates the compounds formation of the antimony, lanthanide ions, and edta^4– ligands. FT‐IR spectra reveal that the antimony and lanthanide ions are connected through the carboxylate bridges. The studies of luminescence properties show that compounds 1 and 3 exhibit typical luminescence in the visible region. Furthermore, magnetic properties reveal compounds 2 and 3 have weak ferromagnetic behavior.     

Micellar Catalysis of Composite Reactions—The Effect of SDS Micelles and Premicelles on the Alkaline Fading of Crystal Violet and Malachite Green

ABSTRACT

The effect of SDS micelles and premicelles on the reversible alkaline fading reactions of crystal violet and malachite green were studied. Micellar and premicellar catalysis models for 1-1 type reversible reactions were proposed. The rate constants of forward and backward reactions and equilibrium constants of these reversible alkaline fading reactions in SDS micellar solutions were obtained from a micellar catalytic model. Under the premicellar condition the average number of SDS molecules per substrate molecule with n surfactant molecules was obtained from a premicellar catalytic model. The results indicated that both SDS micelles and premicelles exhibited an inhibiting effect on the forward reaction, while they exhibited an accelerating effect on the backward reaction. These results can reasonably be accounted for in terms of electrostatic interactions.     

pH-Sensitive Dye-Polyether Derivatives as Dispersants for Its Parent Dye. Part 1: Synthesis and Hydrolysis Behavior

A series of dye-polyether derivatives, supposedly to be used as dispersants for parent dye, were synthesized by grafting poly(oxyalkylene)-amines based on differing both molecular weights and degrees of hydrophilicity/hydrophobicity, onto C.I. disperse red 60 via a stable urea linkage. The structures of the dye-polyether derivatives were characterized by FTIR, ¹H NMR, and SEC. The influence of pH on the hydrolysis behaviors of the dye-polyether derivatives were studied in buffered aqueous solutions within the pH range of 4 to 10. The hydrolysis of dye-polyether derivatives was pH dependent and relatively faster in mild alkaline buffer solution than in acidic one. The influence of poly(oxyalkylene)-amine structure on the hydrolysis behavior was also investigated; it was found that the hydrolysis rate is affected little by the molecular weight and increases with the increasing hydrophilicity of the poly(oxyalkylene)-amine.     

Syntheses and Crystal Structures of Two New Macrocyclic Compounds

Two new macrocyclic compounds, [Cu2(L)2](ClO4)4·2CH3OH (1) and [Cu(L)](ClO4)2·2H2O (2) (L = 1,3,10,12,15,18-hexaazatetracyclodocosane) were synthesized by condensation reactions involving amines and formaldehyde in the presence of copper anion. Compound 1 crystallizes in triclinic, space group Pí with a = 10.442(2), b = 14.197(3), c = 17.388(4), α = 91.218(4), β = 90.69(3), γ = 93.756(4)o, V = 2520.4(9)3, Z = 2, F(000) = 1260, Dc = 1.589 Mg/m3, Mr = 1205.92, μ = 1.137 mm-1, λ = 0.71073, the final R = 0.0668 and wR = 0.1573 for 9703 observed reflections with I > 2σ(I). Compound 2 crystallizes in monoclinic, space group C2/c with a = 16.911(2), b = 11.4172(15), c = 27.059(4), β = 107.787(2)o, V = 4974.7(12)3, Z = 8, F(000) = 2504, Dc = 1.610 Mg/m3, Mr = 602.92, μ = 1.155 mm-1, λ = 0.71073 , the final R = 0.0419 and wR = 0.1131 for 4374 observed reflections with I > 2σ(I).     

Synthesis and thermotropic studies of a novel series of nematogenic liquid crystals 2-(6-alkoxynaphthalen-2-yl)-5-cyanopyridines

A novel series of highly birefringent liquid crystalline compounds, 2-(6-alkoxynaphthalen-2-yl)-5-cyanopyridines (nO-NpPyCN, n?=?2–8) that have potential as commercially useful, were synthesised using a short two-step reaction with overall yields between 55% and 85%. Spectral analyses were in accordance with the expected structures. Their thermotropic behaviours were investigated by polarising optical microscopy and differential scanning calorimetry. It was found that the desymmetrised core results in a nematic phase with a broad mesophase range.