Synthesis of Two Natural Furan‐Cyclized Diarylheptanoids via 2‐Furaldehyde

Two natural diarylheptanoids, 2‐benzyl‐5‐(2‐phenylethyl)furan ( 1 ) and 2‐methoxy‐4‐{[5‐(2‐phenylethyl)furan‐2‐yl]methyl}phenol ( 2 ), were synthesized starting from 2‐furaldehyde. A Wittig reaction of 2‐furaldehyde with benzyltriphenylphosphonium bromide followed by reduction of the alkene C?C bond with Mg gave 2‐(2‐phenylethyl)furan ( 5 ). Lithiation of 5 with BuLi at ?78° followed by alkylation with benzyl bromide gave natural product 1 . In another approach, Friedel? Crafts acylation of compound 5 with benzoyl chloride followed by deoxygenation of the C?O group afforded 1 . The natural product 2 was also synthesized by acylation of 5 with 4‐acetoxy‐3‐methoxybenzoyl chloride ( 16 ) followed by deoxygenation and deacetylation.     

Biosorbent for tungsten species removal from water: effects of co-occurring inorganic species

The effect of co-occurring inorganic species on the removal of tungsten from water was investigated using biosorbent (i.e., chitosan coated montmorillonite clay). Simulated natural water and well water from Fallon, NV were used for this study. The concentrations of tungsten (21-541 mg/L) and inorganic species ([H(2)CO(3)]=0-4.2 mg/L, [H(4)SiO(4)]=0-90 mg/L, and [SO(2-)(4)]=0-400 mg/L) in simulated feed water were varied. The concentration of tungsten in the well water was 26 microg/L. The pH level of simulated feed water and well water was adjusted to 4 since this pH was found to be the most effective pH for the tungsten removal using chitosan coated clay. Tungsten removal without the existence of co-occurring inorganic species decreases from 99.8 to 87.1% with an increase in initial tungsten concentration from 21 to 541 mg/L. It reduces further as the co-occurring inorganic species concentration increases. The percentage of the tungsten removal ranges between 68.2-93.8%, 66.7-94.2%, and 53.6-93.7% for simulated natural water containing varied amount of H(2)CO(3), H(4)SiO(4), and SO(2-)(4), respectively. The adsorption kinetic data could be best described by the pseudo second order expression. The adsorption equilibrium data was modeled with the Langmuir, Temkin, and Freundlich equations and was found to be represented well by the Langmuir equation. The essential characteristics of the Langmuir isotherm indicate that the adsorption of tungsten on chitosan coated clay is favorable regardless of the presence of interfering species. Compared to natural clay, chitosan coated clay has about 116 times larger adsorption capacity per gram of chitosan, which makes it a superior adsorbent. However, the maximum tungsten adsorption capacity decreases in the presence of co-occurring species since the co-occurring species suppress the adsorption. For the well water treated with biosorbent, the tungsten concentration in the product water was found to be lower than the detection limit (1 microg/L) of the inductively coupled plasma mass spectrometer (ICP-MS). The repeatable results obtained from the treatment of both simulated and well water suggest that using chitosan coated clay can be an efficient adsorbent for tungsten removal from contaminated sites.     

Novel plastoquinone analogs containing benzocaine and its analogs: structure‐based design,synthesis, and structural characterization

Introducing new biologically active organic molecules or their analogs into the pharmaceutically important molecules significantly enables the discovery and development of the medicines that improve the health of patients. Chemical synthesis has a key role in pharmaceutical research and development, aiming to design and build molecules with the essential biological activity needed in drugs. For that reason, herein, three series of novel PQ analogs (the nonhalogenated (PQ1-6) and the halogenated PQ analogs (BrPQ1-6 and ClPQ1-6)) containing benzocaine and its analogs were designed and synthesized starting from the commercially available dimethylhydroquinone (1) with benzocaine and its analogs. The structures of all synthesized analogs were characterized by using spectroscopic methods. The in vitro antibacterial and antifungal activities were evaluated for the PQ analogs.

     

Energetics and structural properties of carbon and oxygen doped hexagonal boron nitride sheets

Energetics and structural properties of carbon and oxygen doped hexagonal boron nitride sheets have been investigated by performing density functional theory calculations. Substitutional doping model has been considered in the neutral charge state. C and O atoms replaced either B or N site in the system as impurities. A systematic study has been performed to see the effect of cell size on the calculated quantities, such as formation energy, relaxation energy, charge and bond length. It has been found that substitution of O atom on the N site in the hexagonal BN sheet is more favorable.     

4-Vinylbenzenesulfonic acid adduct of epoxidized soybean oil: Synthesis, free radical and ADMET polymerizations

In this work new radically polymerizable triglyceride based monomers were synthesized by the reaction of epoxidized methyl oleate (EMO) and epoxidized soybean oil (ESO) with 4-vinyl benzene sulfonic acid (4VBSA). The products are 1-(4-vinylbenzene sulfonyl)oxy-2-alkonols of epoxidized soybean oil (SESO) and 1-(4-vinylbenzene sulfonyl)oxy-2-alkonols of epoxidized methyl oleate (SEMO). These adducts were characterized by ¹H NMR, ¹³C NMR, IR and CHNS elemental analysis. SESO was found to contain, on the average, 2.47 4VBSA units per triglyceride. SESO was free radically polymerized and co-polymerized with styrene and the mechanical and thermal properties of the resulting thermosets were determined by DMA, DSC and TGA. SEMO was used as a model compound to determine the efficiency of metathesis catalysts for these fatty acid derivatives. The second generation Hoveyda–Grubbs catalyst was found to give best yields. ADMET polymerization of SESO with this catalyst with and without solvent gave ∼80% yield of a thermoset polymer. Polymers obtained by free radical route swelled in water at room temperature, and hydrolyzed in water at 60 °C.     

Acyclic diene metathesis: a versatile tool for the construction of defined polymer architectures

Two decades have passed since the metathesis polymerisation of α,ω-dienes was successfully demonstrated by the group of Wagener and the term acyclic diene metathesis (ADMET) polymerisation was coined. Since then, the advances of metathesis chemistry have allowed to expand the scope of this versatile polymerisation reaction that nowadays finds applications in different fields, such as polymer, material, or medicinal chemistry. This critical review provides an insight into the historical aspects of ADMET and a detailed overview of the work done to date applying this versatile polymerisation reaction (221 references).     

On the Quaternionic B 2-Slant Helices in the Euclidean Space E 4

In this paper we give a new definition of harmonic curvature functions in terms of B ₂ and we define a new kind of slant helix which we call quaternionic B ₂–slant helix in 4–dimensional Euclidean space E ⁴ by using the new harmonic curvature functions. Also we define a vector field D which we call Darboux quaternion of the real quaternionic B ₂–slant helix in 4–dimensional Euclidean space E ⁴ and we give a new characterization such as: "a: I ì \mathbb R ? E⁴{``\alpha : I \subset {\mathbb R} \rightarrow E^4} is a quaternionic B ₂–slant helix ${\Leftrightarrow H^\prime_2 -KH_{1} = 0"}${\Leftrightarrow H^\prime_2 -KH_{1} = 0"} where H ₂, H ₁ are harmonic curvature functions and K is the principal curvature function of the curve α.     

Design,Synthesis and Characterization of 3,4-Dihydro-2H-pyran Containing Copolymer/Clay Nanocomposites

We introduce briefly surface modification of clay minerals, structure, properties and, characterization techniques of polymer-clay (PCN's) nanocomposites. Organically modified layered-silicates or nanoclays have become an attractive class of hybrid materials due to their prospective use in a great variety of applications from industry to health. For design, synthesis and characterization for potential biomedical nanocomposites, antitumor-active copolymer; poly(DHP-alt-MA) were used to prepare copolymer/clay nanocomposites. The functional copolymers, having a combination of rigid/flexible linkages and an ability of complex-formation with interlayered surface of organo-silicate, and their nanocomposites have been synthesized by interlamellar complex-radical copolymerization of intercalated monomer complexes of maleic anhydride (MA) and 3,4-Dihydro-2H-pyran (DHP) with three alkyl ammonium salts surface modified bentonite and monomer mixtures. Poly(DHP-alt-MA) pristine copolymer and poly(DHP-alt-MA)/organically modified bentonite nanocomposites were characterized by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), HR-Raman, X-ray diffraction (XRD) and TEM methods.