Addition of trifluoromethyltrimethylsilane to acyl phosphonates: synthesis of TMS-protected 1-alkyl-1-trifluoromethyl-1-hydroxyphosphonates and 1-aryldifluoroethenyl phosphates

Addition reactions of nucleophilic CF3TMS to acyl phosphonates were investigated. Various acyl phosphonates reacted readily with CF3TMS in the presence of K2CO3 in DMF at rt to give 1-alkyl-2,2,2-trifluoro-1-trimethylsilyloxyethylphosphonate in 70-90% yields. When benzoyl phosphonates were used as starting material, after addition of CF3, the formed alcoholate undergoes phosphonate-phosphate rearrangement to form the acyl anion, followed by elimination of F- to give 1-aryldifluoroethenyl phosphates in 87-97% yields. As a representative example, vinylphosphate 6a was converted into 2,2-difluoro-1-phenylethanone 7 with 6 N HCl/EtOH/reflux or CAN/NaOH/MeOH/0 degrees C in 82-90% yields.     

HPLC determination of organic acids, sugars, phenolic compositions and antioxidant capacity of orange juice and orange wine made from a Turkish cv. Kozan

Organic acids, sugars, phenolic compositions and antioxidant capacities of orange juice and orange wine obtained from the cv. Kozan of Turkey were determined. High-performance liquid chromatographic methods were used to identify and quantify of these compounds. Three organic acids (citric, malic and ascorbic acids) and three sugars (sucrose, glucose and fructose) were determined. The major organic acid was found as citric acid. With regard to sugars, sucrose was present in the largest amounts for orange juice and wine. A total of 13 phenolic compounds were identified and quantified in orange juice and wine, including hydroxybenzoic acids (2), hydroxycinnamic acids (5), and flavanones (6). Hesperidin, narirutin and ferulic acid were the most abundant phenolic compounds in orange juice and wine. Antioxidant activities of orange juice and wine were measured using the DPPH^• (2,2-diphenyl-1-picrylhydrazyl) assay, and the antioxidant capacity of orange juice was found to be higher than that of orange wine.     

Determination of pK a of benzoic acid- and p-aminobenzoic acid-modified platinum surfaces by electrochemical and contact angle measurements

Acidity constant values of benzoic acid (BA)-modified platinum electrode (Pt-BA) and p-aminobenzoic acid (pABA)-modified platinum electrode (Pt-NHBA) surfaces were determined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and contact angle measurements (CAM). Diazonium tetrafluoroborate salt reduction and pABA oxidation reactions were used to prepare (Pt-BA) and (Pt-NHBA) surfaces, respectively. Both surfaces exhibited pH dependence with [Fe(CN)₆]^3?/4? redox probe solutions at different pH; this allowed us to estimate the surface pK _a values. Acidity constants for Pt-BA surface were found to be pK _a (3.09 ± 0.25), (4.89 ± 0.11), and (3.91 ± 0.54) by CV, EIS, and CAM techniques, respectively, while the values for Pt-NHBA surface were pK _a (3.16 ± 0.45), (4.24 ± 0.40), and (5.64 ± 0.12). The Pt-BA surface pK _a values were lower in CV and CAM measurements relative to the bulk solution of BA, while a higher value was observed in EIS for Pt-BA surface. The pK _a values determined for Pt-NHBA surface via both CV and EIS were lower than the bulk value; however, the result obtained from CAM was one unit higher than pK _a of bulk pABA.     

Ruthenium(II) complexes bearing pyridine‐based tridentate and bidentate ligands: catalytic activity for transfer hydrogenation of aryl ketones

Ru(II) complexes of the general formula [RuCl₂(′′)(L)] (1: ′N = N_b, L = MeOH; 2: ′N = N_b, L = CH₃CN; 3: ′N = N_d, L = CH₃CN; 4: ′N = N_p, L = CH₃CN), [Ru(p‐cymene)(_a–b)Cl]Cl (5a: N N_a = 2,2′‐bipyridine; 5b: N N_b = 4,4′‐dimethyl–2,2′‐bipyridine), [Ru(′′)(_a–b)Cl]Cl (6a: ′N = N_b, _a = 2,2′‐bipyridine; 6b: ′N = N_b, _b = 4,4′‐dimethyl‐2,2′‐bipyridine; 7a: ′N = N_d, _a = 2,2′‐bipyridine; 7b: ′N = N_d, _b = 4,4′‐dimethyl‐2,2′‐bipyridine; 8a: ′N = N_p, _a = 2,2′‐bipyridine; 8b: ′N = N_p, _b = 4,4′‐dimethyl‐2,2′‐bipyridine) and [Ru(′′)(_a)Cl]BF₄ (9a: ′N = N_b; _a = 2,2′‐bipyridine) were synthesized from the corresponding [RuCl₂(p‐cymene)]₂ dimer, ′′ and _a–b ligands. The compounds were characterized by elemental analysis, IR and NMR. Complex 9a was studied by X‐ray diffraction, confirming its cationic‐mononuclear [RuCl(_bb)(_a)]⁺ nature. The synthesized Ru(II) complexes (1–8) were employed as catalysts for the transfer hydrogenation of ketones to secondary alcohols in the presence of KOH using 2‐propanol as a hydrogen source at 82°C. The rates of the transfer hydrogenation reactions strongly depended on the type of and ancillary ligands. Copyright © 2012 John Wiley & Sons, Ltd.     

Immobilization of novel the semicarbazone derivatives of calix[4]arene onto magnetite nanoparticles for removal of Cr(VI) ion

A series of novel the semicarbazone derivatives of calix[4]arene have been synthesized and then immobilized onto amino functionalized magnetic nanoparticles. Magnetic Fe₃O₄ nanoparticles were prepared by the chemical co-precipitation of Fe(III) and Fe(II) ions and the nanoparticles were modified directly by 3-aminopropyltriethoxy silane (APTES) to introduce reactive amine groups onto the particles’ surface. The characterization of the prepared compounds was made by FT-IR, elemental analysis, TGA/DTG and NMR techniques. The sorption properties of the new calix[4]arene based magnetic sorbents toward Cr(VI) ion were also studied. The results showed that the prepared magnetic nanoparticles were effective sorbents for the removal of Cr(VI) ion. Also, Langmuir and Freundlich isotherm models were applied for Cr(VI) ion sorption by using MN-C2 and it was found that the experimental data confirmed to Langmiur isotherm model.     

Synthesis of New Quinoline-Conjugated Calixarene as a Fluorescent Sensor for Selective Determination of Cu2+ Ion

Journal of Fluorescence - A novel quinoline-functionalized calix [4] arene derivative (Quin-Calix) has been successfully synthesized at partial cone conformation and duly characterized by using...     

Synthesis and Spectrothermal Studies of Thermochromic Diamine Complexes of Cobalt(III), Nickel(II) and Copper(II) Squarate. Crystal Structure of [Co(en)3](sq)1.5 · 6H2O

New adducts of ethylenediamine (en), N,N-dimethylethylenediamine (ndmen) and N,N′-dimethylethylenediamine (dmen) with squarate as counter-ions were synthesized and characterized by physico-chemical methods (IR and UV/vis spectroscopy, magnetic susceptibility and thermoanalytical measurements). The crystal structure of tris(ethylenediamine)cobalt(III) 1.5 squarate hexahydrate, [Co(en)₃](sq)_1.5 · 6H₂O, was determined by single crystal X-ray diffraction. Co(III), Ni(II) and Cu(II) ions in the monomeric octahedral tris(ethylenediamine)cobalt(III) 1.5 squarate hexahydrate (1), tris(ethylenediamine)nickel(II) squarate 0.5 hydrate (2) and diaquabis(ethylenediamine)copper(II) squarate dihydrate (3) are chelated by ethylenediamines through two amine nitrogen atoms. Cu(II) atoms in the diaquabis(ndmen)copper(II) squarate (4) and diaquabis(dmen)copper(II) squarate (5) monomeric octahedral complexes are coordinated by ndmen and dmen molecules through two amine nitrogen atoms in a bidentate chelating manner. Water molecules complete the octahedral coordination. The orange (1), violet (4) and violet (5) complexes upon heating transform to claret, green and green species on dehydration, respectively, which revert immediately after cooling in the open atmosphere. The violet (3) complex upon heating loses water molecules yielding a deep blue dehydrated species, which on further heating undergoes an exothermic phase transition accompanied by thermochromism, deep blue to brown in the solid state. The decomposition mechanism and thermal stability of the solid complexes are interpreted in terms of their structures. The final decomposition products – the respective metal oxides – were identified by IR spectroscopy.     

On weighted q-Daehee polynomials with their applications

In this paper, we first consider a generalization of Kim’s $p$-adic $q$-integral on ${\mathbb{Z}}_p$ including parameters $\alpha$ and $\beta$. By using this integral, we introduce the $q$-Daehee polynomials and numbers with weight $\left(\alpha ,\beta \right)$. Then, we obtain some interesting relationships and identities for these numbers and polynomials. We also derive some correlations among $q$-Daehee polynomials with weight $\left(\alpha ,\beta \right)$, $q$-Bernoulli polynomials with weight $\left(\alpha ,\beta \right)$ and Stirling numbers of second kind.     

Synthesis of Tetraalkenylmethane: Building Blocks for Three-Dimensional Hydrocarbon Networks

In this paper, we show a common strategy to synthesize tetraalkenylmethanes, a cross-linker series for building three-dimensional hydrocarbon networks. To demonstrate the feasibility of this method, we have synthesized tetrapentenylmethane. Attempts to synthesize this cross-linker from pentaerythrityl tetrabromide using substitution reactions resulted in the formation of a spiro compound due to intramolecular cyclization. We also show that the difficulty in reactions at the neopentyl carbon site is due to the neopentyl carbanion stability, not the sterics.