Synthesis and Stereochemistry of Thiapyranothiazoles as Diels-Alder Adducts Obtained from Spirodimers of 1,3-Thiazolidines with Cinnamic Acid and its Ester

Thiation of 5-Arylmethylene-3-phenyl-2-thioxo-1,3-thiazolidin-4-ones ( 1a and b ) with either P 4 S 10 1 or Lawesson's reagent 2 , gave mainly the spirodimers 3'phenyl-2'-thoxo-1',3'-thiazolidino[2,3-d]-spiro[6',7' diaryl-5,5'-perhydrothiapyrano]-3-phenyl-1,3-thiazolidin-4-thiones ( 3a and b ) beside, 5-(3-bromo-4-methoxyphenylmethylene)-3-phenyl-1,3-thiazolidin-2,4-dithione ( 2b ) as a mixture with 3b . 2b was allowed to react with ethyl cinnamate as a dienophile producing 4b and 5b . Moreover, prolonged heating of either 3b or 3a with ethyl cinnamate gave a mixture contains 40% of 4b and a mixture of 4a and 5a respectively. Furthermore, the dimer 3b reacted with cinnamic acid in glacial acetic acid to give the Diels-Alder-adduct 6b and 7b . Structures and stereo-chemistry of obtained compounds have been studied.     

Synthesis of Carbamoyl-Containing N,S-Heterocyclic Compounds

Monothioxamides unsubstituted at the thioamidic nitrogen atom were obtained by the reaction of NS-morpholino-NO-R-thioxamides with ammonia. Carbamoyl-containing 5-phenylcarbamoyl-1,2,4-dithiazoles, 6-phenylcarbamoyl-5,6-dihydro-[1,2,4,5]-dithiadiazin-3-one, and 5-phenylcarbamoyl-2-oxy-1,3,4-thiadiazole were synthesized by the reaction of monothioxamides or thiohydrazides of oxamic acids with chlorocarbonylsulfenyl chloride.     

Dew Points of Binary Methane + Water: Measurement and Correlation

Experimental measurements of dew points for four methane + water mixtures between 2.6 2 10 5 Pa and 100.4 2 10 5 Pa and the temperature range from 225.5 K to 272.7 K were carried out. The experimental results were analysed in terms of both an equation of state model and an excess function-equation of state method, which reproduced the experimental data within AAD from 1.8 to 3.1 K and from 0.9 to 1.8 K, respectively.     

Complexation and Thermal Studies of Uric Acid with Some Divalent and Trivalent Metal Ions of Biological Interest in the Solid State

Nine new [metal uric acid] complexes [M(Ua) n ]°·XH 2 O have been synthesized. These complexes have been characterized by elemental analysis, X-ray diffraction (XRD), magnetic susceptibility ( w eff. ), FTIR spectra, thermal analysis (TG & DTA), and electronic spectra (UV/visible). Uric acid (HUa) coordinates as a bidentate ligand to Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Al(III), Cr(III) and Fe(III) through the protonated N-7 within the imidazole ring and O-6 within the pyrimidine ring. Uric acid forms neutral metal urate complexes with all the above metal ions. The quantitative compositions were determined as [M(Ua) 2 ·(H 2 O) 2 ]°·XH 2 O where M(II)=Mn, Fe, Co, Ni, Cu, Zn and X=2, 4, 2, 4, 2, 2, respectively. The M(II) complexes exhibit an isostructural octahedral coordination with N-7, O-6 of two uric acid ligand molecules, and O of two water molecules. Compositions were also determined as [M(Ua) 3 ]°·YH 2 O where M(III)=Al, Cr, Fe and Y=6, 3, 3 respectively. All the M(III) complexes form an isostructural octahedral coordination with N-7 and O-6 of three uric acid ligand molecules. Iron(III) complexes prepared with N 1 , N 3 and N 9 -methyl uric acid yielded brown complexes with a metal ligand ratio of 1 3, while N 7 -methyl uric acid did not yield a complex due to blockage of N-7 with a methyl group.     

Quinazoline Antifolate Thymidylate Synthase Inhibitors: Replacement of Glutamic Acid by Aminophosphonic Acids

The synthesis of six analogues of the potent thymidylate synthase (TS) inhibitor N -[4-[ N -[(3,4-dihydro-2-methyl-4-oxo-6-quinazolinoyl)-methyl]- N -prop-2-ynylamino]benzoyl]- L -glutamic acid 2 is described in which the glutamic acid residue has been replaced by DL -aminophosphonic acids. New antifolates were tested as inhibitors of TS isolated from mouse L1210 leukemic cells as well as inhibitors of growth mouse leukemic L5178Y cells. In general these modifications result in compounds that are considerably less potent than 2 as TS inhibitors with K i 's 0.17-1.10 w M. Very poor solubility in water limited their proper assay of growth cells inhibition.     

Synthesis and Structure of Complexes of the Diethyl Ester of 2-Dimethylamino-2-oxoethylphosphonic Acid with Lanthanide Nitrates

The lanthanide complexes LnL 2 (NO 3 ) 3 ( 3a-g ) are obtained where Ln is La, Sm, Yb, Er, Ce, Eu, Gd, and L is the diethyl ester of 2-dimethylamino-2-oxoethylphosphonic acid [(C 2 H 5 O) 2 P(O)CH 2 CON(CH 3 ) 2 ] 1 . They are characterized by elemental analysis, i.r. and NMR spectroscopy. The crystal structure of 3a is determined by single crystal X-ray diffraction. The complex is found to crystallize in the triclinic space group P 1 with a = 8.4220(17) Å, b = 11.123(2) Å, c = 17.560(4) Å, f = 87.20(3);, g = 82.27(3);, n = 76.89(3);, V = 1587.3(5) Å 3 , Z = 2, calcd = 1.614 mg/m 3 , R = 0.047, R w = 0.107, S = 1.034 for 5762 reflections with I > 2 (I). The structure contains monomeric units of the complex with the lanthanum atom coordinated by 10 oxygen atoms, six of them from the three bidentate nitrate ions and four from the two phosphonate ligands. The coordination is realized by both phosphoryl and amide-carbonyl oxygen atoms. The stereochemistry of the starting ligand 1 is investigated by NMR spectroscopy.     

Silylation of Hydroxy Groups with HMDS Under Microwave Irradiation and Solvent-Free Conditions

Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields.     

Preparation and Characterization of Novel Asymmetrical Schiff-Base Ligands Derived from 2-methyl-7-formyl-8-hydroxyquinoline and their Metal Complexes

Two novel asymmetrical Schiff-base ligands, H₂L¹ and H₂L², were prepared by reacting two half-unit Schiff-base compounds with 2-methyl-7-formyl-8-hydroxyquinoline. The two half-unit Schiff-base compounds were initially prepared by condensing dimedone with either ethylenediamine or p-phenylenediamine, respectively. Both ligands are dibasic and contain two sets of NO coordinating sites. Twelve metal complexes were obtained by reacting both ligands with Cu(II), Ni(II), Co(II), Mn(II), Fe(III), VO(IV) cations. The ligands and their metal complexes were characterized by elemental analysis, IR, UV-Vis, ESR and mass spectra, also magnetic moments of the complexes were determined. Visible spectra of the complexes indicated distorted octahedral geometries around the metal cations. ESR spectra indicated mononuclear and dinuclear structures of the complexes of ligands H₂L¹ and H₂L², respectively. Magnetic moments of the complexes were rather low compared with those expected for octahedral geometries and indicated polymeric linkage of the metal complex molecules within their crystal lattices. The insolubility of the metal complexes in most organic solvents support the polymeric structures.     

Polyamidophosphite Complexes of Metals as Catalysts

Interaction between the equimolecular amounts of glycols (diatomic phenols) and phosphorous acid triamides in diglyme or without solvent gives phosphorus-bearing polyamidophosphites. The structure of these compounds was studied by NMR spectroscopy, and it was shown that a partial disproportionation of amidophosphite fragments into phosphite ones can occur in the course of their synthesis. The chemical properties of the obtained compounds are being studied. First rhodium complexes with polyamidophosphite ligands were obtained. These complexes are shown to be more active hydrogenation catalysts than the corresponding low-molecular complexes. 1     

Reactions of S-Silyl Esters of Tetracoordinated Phosphorus Thioacids with Acetals and Ortho Esters

The reactions of S-trimethylsilyl esters of dithiophosphoric, diamidodithiophosphoric, aryldithiophosphonic, aryltrithiophosphonic, and arylamidodithiophosphonic acids with diethyl acetal of benzaldehyde and ortho formiate and acetate were studied. On the basis of these studies, new derivatives of tetracoordinated phosphorus thioacids were obtained.     

Synthesis of Hydrotalcite from Seawater and Its Application to Phosphorus Removal

10.0 wt% milk of lime was added to seawater containing AlCl 3 at Mg/Al molar ratio of 3.0 until pH 10.5 with stirring, and kept at 25;C for 1 h. Hydrotalcite (HT) was precipitated as a single phase, and Mg 2+ and Al 3+ were quantitatively precipitated. The chemical composition was [Mg 0.75 Al 0.25 (OH) 2 ][(SO 4 ) 0.06 (Cl) 0.02 (OH) 0.11 *];0.27H 2 O* (*Balance). A 100 mg-P/L Na 2 HPO 4 solution and the HT were shaken at 25;C. Phosphate removal increased with increasing time and the HT quantity, and was the highest at pH 7-9. Phosphate ion could be quantitatively removed, adding 8 times the stoichiometric quantity of the HT at pH 8.7 for 6 h.     

Synthesis and Study of the Thermal Epimerization of r -2-Ethoxy- cis -4- cis -5-Dimethyl-1,3,2-λ 3 -Dioxaphospholane Using 31 P NMR

The exclusive synthesis of r -2-ethoxy- cis -4- cis -5-dimethyl-1,3,2- u 3 -dioxaphospholane ( cis - 1 ) is reported. The kinetic measurements of the epimerization of cis - 1 to trans - 1 were performed by 31 P NMR from 50 to 80;C in toluene. The energy of activation (E a ) of the epimerization process was calculated from Arrhenius plot. The thermodynamic parameters of the transition state led us to conclude that the activation barrier of the inversion at phosphorus is driven by the enthalpy and by a large and negative entropy of activation.     

The Synthesis and Characterization of Aryloxy-Linear Phosphazenes

The reactions of N-dichlorophosphoryl-P-trichloromonophosphazene with sodium o-methylphenoxide, sodium p-methylphenoxide, sodium f -naphthalenoxide, monosodium 4-(2-pyridylazo)resorcinol, and sodium 1-nitroso-2-naphthaleneoxide have been investigated. Experimental studies were carried out in argon atmosphere. The sodium aryloxides were prepared from naphthalene or phenol derivatives and metallic sodium. The phosphazene and phenolate or naphthaleneoxide were reacted at 0°;C and then refluxed. After the reaction products were separated by using column chromatography, the structures of the compounds were defined by elemental analysis, IR, 1 H, 13 C, 31 P NMR, and mass spectroscopy. Tetra- and pentasubstituted monophosphazenes were obtained from sodium o-methylphenoxide. Pentasubstituted derivatives also were obtained from sodium p-methylphenoxide and sodium f -naphthaleneoxide. Phosphazene or any phosphorus compound could not be isolated from the reaction of phosphazene with monosodium 4-(2-pyridylazo)resorcinol and sodium 1-nitroso-2-naphthaleneoxide.     

Viscosity and Thermodynamics of Viscous Flow for the Systems of Isomeric Pentanols with Toluene

Viscosities of the isomers of pentanol (1-pentanol, 2-pentanol and 3-pentanol) and their binary solutions with toluene in the whole range of composition have been measured at different temperatures between 303.15 and 323.15 K. Viscosities of pure components have been plotted against temperature and for binary mixtures, against the mole fraction of pentanols at different temperatures. At lower concentrations of pentanols, viscosities increase slowly, but at an increasing rate on the continued addition of pentanols in toluene. The excess viscosities and excess free energies of activation for viscous flow are in the order, 3-pentanol + > 2-pentanol + > 1-pentanol + toluene. Excess entropies are found to be negative for the systems 2-pentanol + toluene and 3-pentanol + toluene in the whole range of composition, but for 1-pentanol + toluene the values are small and they are either positive or negative at different compositions. The disruption of H-bonds in pentanols either by thermal effect or by the force of dispersion is in the order: 3-pentanol > 2-pentanol > 1-pentanol. This effect is considered to be quite significant in explaining the temperature dependence of viscosity of pure pentanols, negative excess values of viscosity, free energy and entropy for viscous flow as well as their orders for all the systems.     

Temperature and pH dual-responsive coatings of oligoperoxide-graft-poly(N-isopropylacrylamide): Wettability, morphology, and protein adsorption

Poly(N-isopropylacrylamide) (PNIPAM) coatings attached to glass with novel approach involving polymerization from oligoperoxide grafted to surface with (3-aminopropyl)triethoxysilane exhibit not only temperature- but also pH-dependence of wettability and protein adsorption. Wettability and composition of coatings, fabricated with different polymerization times, were determined using contact angle measurements and Time Of Flight-Secondary Ion Mass Spectrometry (TOF-SIMS), respectively. Thermal response of wettability, measured between 20 and 40 °C, was prominent at pH 9 and 7 and diminished or absent at pH 5 and 3. This indicates a transition between hydrated loose coils and hydrophobic collapsed chains that is blocked at low pH. Higher surface roughness and dramatically increased adsorption of model protein (lentil lectin labeled with fluorescein isothiocyanate) were observed with AFM and fluorescence microscopy to occur in hydrophobic phases (at pH 3, for pH varied at constant temperature of 22 °C and at ∼33 °C, for temperature varied at constant pH 9). Protein adsorption response to pH was confirmed by TOF-SIMS and Principal Component Analysis.     

Isochoric Heat Capacity in the Critical Region

We study the isochoric heat capacity in the critical region. We have modified the results of Kiselev and Friend, and Chen, Albright and Sengers (CAS). Crossover parameters are chosen so that the isochoric heat capacity curve at T = 648.0 K fits the experimental data accurately. We demonstrate that the experimental data is consistent with the modified CAS theory.     

ELECTRON IMPACT STUDIES ON NITROAROYLTHIOPHENES

Abstract

A comparative electron impact study on 2-(2′-nitrobenzoyl)thiophene¹(1), 2-(2′-nitrobenzoyl)-3-methylthiophene²(2) and the corresponding 4′-nitrobenzoyl derivatives (3 and 4)^3,4 is presented. The results suggest that the presence of nitro group β-to the carbonyl affects the general fragmentation pattern recorded in the literature for 2-acyl and 2-aroylthiophenes.     

HY Zeolite as an Extremely Active and Reusable Catalyst in Acylation of Alcohols with Acid Anhydride in a Solventless System

HY Zeolite is a practical and useful catalyst for acylation of various alcohols and phenols.     

Anomalies in Noble-Metal-Based Liquid Alloys

Experimental data on liquid noble-metal-based alloys were analysed in terms of a pseudopotential approach. The anomalies in the heat of mixing, the electrical resistivity and the magnetic susceptibility were found to be reflected by the theory in a qualitative manner even if compound formation or short range order is not taken into account. The emphasis was placed on liquid Ag-In, but other examples of this particular class of alloys were also included in the discussion.     

Novel Bis(2‐(5‐((5‐phenyl‐1H‐tetrazol‐1‐yl)methyl)‐4H‐1,2,4‐triazol‐3‐yl)phenoxy)Alkanes: Synthesis and Characterization

In this study, 10 different substituted aromatic bis‐benzaldehydes were synthesized by treating hydroxy benzaldehydes with various dihaloalkanes. Bis aldehydes 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j were treated with 2‐(5‐phenyl‐1H‐tetrazole‐1‐yl)acetohydrazide ( 3 ) in acidic medium and in the presence of ammonium acetate to yield a series of new isomeric bis(2‐(5‐((5‐phenyl‐1H‐tetrazol‐1‐yl)methyl)‐4H‐1,2,4‐triazol‐3‐yl)phenoxy)alkanes ( 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h , 6i , 6j ) in excellent to good yield. The newly synthesized compounds were characterized by the available spectroscopic analysis.