Effect of aqueous and ethanolic extracts from pinhão coats on the properties of corn and pinhão starches

Journal of Thermal Analysis and Calorimetry - The Araucaria angustifolia seed, named pinhão, has a high content of carbohydrates, and it is considered an unconventional starch source. Its...     

Synthesis,Spectral Characterization,and Crystal Structure of Two Polymorphs of o,o’-Dichloro Dibenzyl Disulfide

2-Chlorophenyl methanethiol undergoes air oxidation catalyzed by different selenides and yields the corresponding disulfide 1 in two polymorphic forms, 1a and 1b. In the molecular structures of the two new polymorphs of o,o′-dichloro dibenzyl disulfide, the dihedral angles between the dibenzyl groups are 82.0(1)°, (1a), and 73.7(4)°, (1b), respectively [(1a): P-1, a = 8.424(2) Å, b = 8.838(2) Å, c = 10.5823(19) Å, α = 90.122(18)°, β = 112.19(2)°, γ = 95.19(2)°, V = 725.9(3) ų; (1b): P2₁/n, a = 10.5888(10) Å, b = 9.1590(6) Å, c = 15.2489(14) Å, β = 103.072(9)°, V = 1440.6(2) ų]. MOPAC computational studies yield dihedral angles of 89.6(5)° and 71.9(9)°. Crystal packing is stabilized by weak π-ring (C?H···Cg) intermolecular interactions in both 1a and 1b and by additional weak Cg ··· Cg intermolecular interactions in 1b, which influence the bond distances, bond angles, and torsion angles of the dibenzyl groups in each polymorph. Additional characterization of each polymorph has been carried out by TEM, IR, ¹H and ¹³C NMR spectroscopy, microanalysis, and by FAB mass spectrometry. TEM studies of a sample of 1a show that it contains cigar-shaped crystallites.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Salts of o,o′-diphenylenephenyloxonium ion

Summary o,o-Diphenylenephenyloxonium sulfate was prepared by us for the first time by heating an aqueous solution of o-phenoxy-o-biphenyldiazonium sulfate; a series of salts of this cation was prepared from this substance by double exchange reactions and the properties of these salts were studied.     

Studies on the Reaction Betweenα－Acetylthioformanilide and o－Phenylenediamine

ＳｔｕｄｉｅｓｏｎｔｈｅＲｅａｃｔｉｏｎＢｅｔｗｅｅｎα－Ａｃｅｔｙｌｔｈｉｏｆｏｒｍａｎｉｌｉｄｅａｎｄｏ－ＰｈｅｎｙｌｅｎｅｄｉａｍｉｎｅＺＯＵＪｉａｎ－ｐｉｎｇ，ＺＨＥＮＲｅｎ－ｓｈｅｎｇ，ＺＨＡＯＢｅｉ，ＦＡＮＧＤｏｎｇａｎｄＬＵＺｈｏｎｇ－...     

Molecular structure and conformations of a sterically hindered aryl derivative of 1,3,4-oxadiazole containing an o,o′-biphenyl ring system

The structure of sterically hindered molecules of 2,2-bis(5-phenyl-1-,3,4-oxadiazol-2-yl)biphenyl has been studied. Crystals that are suitable for x-ray diffraction analysis can be obtained for the different conformers of this compound. It has been found that during synthesis the molecule of this compound is obtained in an energetically less favorable conformation. On the basis of model calculations using the AMI method with geometry optimization it has been proposed that during synthesis there are no changes in conformation of either the intermediates or the final product and the conformation of the resulting oxadiazole system is governed by the conformation of the initial 2,2-diphenic acid dichloride.Khar'kov State University, Khar'kov 310077. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 984–991, July 1996. Original article submitted April 23, 1996.     

Synthesis and Crystal Structure of the Novel Chiral o—Hydroxyphenyloxazoline Metal Complexes

1 INTRODUCTION Optically active oxazolines have been extensi- vely used as valuable chiral ligands for transition metals in asymmetric catalysis[1]. The design and syntheses of new chiral oxazoline ligands have inspired many scientists to work with great efforts during the recent years. Our interest has been focus- ed on the studies of enantioselective transition- metal catalysis of heterocyclic ligands. In the pre- sent work, we choose o-hydroxyphenyloxazoline ligand for it has a rigi…     

Analysis of phenolic compounds in Spanish Albrariño and Portuguese Alvarinho and Loureiro wines by capillary zone electrophoresis and high-performance liquid chromatography

The concentration of different phenolic compounds was measured in Spanish Albari?o and Portuguese Alvarinho and Loureiro white wines by capillary zone electrophoresis (CZE), in order to characterize them. Although all samples presented the same qualitative pattern (characterized by tyrosol; (-)-epicatechin; syringic acid; ferulic acid; p-coumaric acid; caffeic acid, gallic acid; 3,4-dihydroxybenzoic acid; cis-coumaroyl tartaric acid (COUTA); trans-COUTA; trans-caffeoyl tartaric acid (CAFTA), and hydroxycinnamic esters), some quantitative differences were observed. When samples were analyzed by high-performance liquid chromatography (HPLC), in order to compare the results obtained by both techniques, no significant qualitative or quantitative differences were obtained. Nevertheless, CZE proved to be a more convenient technique for the routinary analyses of these wines, due to better separation of the different compounds, better peak shapes, and higher speed than HPLC.     

Metals and semi-metals in street soils of São Paulo city,Brazil

São Paulo is the largest city in Brazil and South America with about 20 million inhabitants in the metropolitan area, more than nine million motor vehicles and intense industrial activity, which are responsible for increasing pollution in the region. Nevertheless, little is known concerning metal and semi-metal content in the soils of this metropolitan region. This type of information could be extremely useful as a fingerprint of environmental pollution. The present study determined the elements As, Ba, Co, Cr, Sb, and Zn concentrations in soils adjacent to avenues of highly dense traffic in São Paulo city to assess their levels and possible sources. The analytical technique employed was Instrumental neutron activation analysis. The results showed, except for Co, concentration levels higher than the reference values for soils of São Paulo, according to the Environmental Protection Agency of the State of São Paulo guidelines. When compared to similar studies in other cities around the world, São Paulo soils presented higher levels, probably due to its high density traffic and industrial activity. The concentrations obtained for As and Cr indicate anthropogenic origin. The high levels of the traffic-related elements Ba, Sb, and Zn in soils nearby high density traffic avenues indicate they may originate from vehicular exhausts.     

Arsenic and cadmium content in edible mushrooms from São Paulo,Brazil determined by INAA and GF AAS

Arsenic and cadmium contents in eight edible mushroom species (Agaricus bisporus, Agaricus sp, Pleurotus ostreatus, Pleorotus florida, Pleorotus eryngui, Pleurotus osteatus, Pleurotus salmoneostramineus, Lentinula edodes) consumed by Brazilian population were determined by instrumental neutron activation analysis (INAA) and graphite furnace atomic absorption spectrometry (GF AAS), respectively. Arsenic concentrations varied from 0.009 mg/kg in P. eryngui to 0.210 mg/kg dry weight in L. edodoes and Cd from 0.011 g/kg in P. eryngui to 0.229 mg/kg dw in P. salmoneostramineus. The consumption of mushrooms in São Paulo-Brazil may be considered safe from a toxicological point of view as As and Cd presented levels of ingestion are below the maximum levels recommended by the World Health Organization.     

Syntheses and Characterization of Half—Sandwich Zirconium Complexes with Dichalcogenolate o—Carborane Ligands

Metallocene complex Cp2^ttZrCl2(Cp^tt=η^5-1,3-^tBu2C5H3)(1)has been prepared from the reaction of LiCp^tt with ZrCl4 in good yield.Reactions of 1 with dilithium dichalcogenolate o-carboranes afforded new type of half-sandwich compounds with dichalcogenolate o-carboranyl ligands,[Li(THF)4][Cp^ttZr(E2C2B10H10)2](E=S,2a;E=Se,2b)in which only one cyclopentadienyl ring ligand existed.Complexes 1 and 2a were structurally characterized by X-ray analyses.In complex 2a,the Zr(IV)ion is η^5-bound to one 1,3-ditert-cyclopentadienyl ring and σ-bound to four μ2-sulfur atoms of two dithio-carboranes.the zirconium atom and four sulfur atoms form a distorted pyramid.The coordination sphere around the zirconium atom resembles in a piano stool structure with four legs of sulfur stoms and the fulcrum at the zirconium stom.     

Cobalt-catalyzed direct arylation and benzylation by ch/co cleavage with sulfamates, carbamates, and phosphates

Inexpensive cobalt catalysts enable the first direct arylation and benzylation of (hetero)arenes with aryl carbamates, sulfamates, and phosphates with ample scope. The non-radical C?H/C?O arylation reaction even proved viable at ambient temperature.     

New pentacyclic ring systems: intramolecular cyclization of o,o′-disubstituted bibenzothiazoles

Efficient methods for the preparation of isomeric o,o′-diaminobibenzothiazoles (8a and 11a) and o,o′-diamino-2,2′-dimethylbibenzothiazoles (8b and 11b), potentially valuable building blocks for construction of hitherto unknown dithiazolo annulated pentacyclic heterocycles, have been developed. The dithiazolo annulated benzo[c]cinnolines 9a, 9b, and 12a were prepared from the corresponding diamines by oxidation with PhI(OAc)₂ in good yield. The dithiazolo annulated carbazoles 13 and 14 were efficiently prepared from the corresponding diamines by thermal cyclization in H₃PO₄. The unusual course of reduction and product formation of o,o′-dinitrosubstituted bibenzothiazoles 6a and 6b with SnCl₂ under acidic conditions was rationalized by DFT quantum-mechanical calculations. It was suggested that cyclic products are formed from dinitroso derivatives and open-shell species immediately following on a reduction path.     

Synthesis and characterization of α-, β-, and γ-Ga2o3 prepared from aqueous solutions by controlled precipitation

α, β and γ-Ga₂O₃ have been successfully obtained in an easily scalable synthesis using aqueous solution of gallium nitrate and sodium carbonate as starting materials without any surfactant and additive. α and β-Ga₂O₃ were obtained by calcination at 350 and 700 °С, respectively, of α-GaOOH, prepared by controlled precipitation at constant pH 6 and T = 55 °С, with 24 h of aging. Aging was necessary to fully convert the initially preciptated gel into a well-crystalline and phase-pure material. γ-Ga₂O₃ was obtained after calcination at 500 °С of gallia gel, synthesized at constant pH 4 and T = 25 °С, without aging. These three polymorphs have a for gallia relatively high surface area: 55 m²/g (α-Ga₂O₃), 23 m²/g (β-Ga₂O₃) and 116 m²/g (γ-Ga₂O₃). The combination of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), nitrogen physisorption and thermogravimetry (TG) was employed to characterize the samples and their formation.     

A single phosphine ligand allows palladium-catalyzed intermolecular co bond formation with secondary and primary alcohols

Forging a bond: An efficient, general palladium catalyst for C?O bond-forming reactions of secondary and primary alcohols with a range of aryl halides has been developed using the ligand 1. Heteroaryl halides, and for the first time, electron-rich aryl halides can be coupled with secondary alcohols. A diverse set of substrate combinations are possible with just a single ligand, thus obviating the need to survey multiple ligands.     

Synthesis,Structures, and Properties of Novel N‐Aryl‐phenanthren‐o‐iminoquinones

The interaction of 9,10‐phenanthrenquinone with primary amines has been studied. Use of sterically hindered anilines gave the phenanthren‐o‐iminoquinones in good yields. These compounds are structural analogues of o‐benzoquinones. Using single‐electron reduction, o‐iminoquinones may synthesize metal's free‐radical complexes.     

Major and trace element assessment of Tietê river sediments, São Paulo, Brazil

The objective of this study was to quantify major and trace elements present in sediments collected from the one of Brazil’s most important rivers, Tietê River. Sediments from 5 different sampling points (P₀–P₄), in 3 campaigns (2008/2009), from the headwaters to Suzano County upstream from São Paulo city were collected. X-ray fluorescence was applied for measuring total concentration of major elements and instrumental neutron activation analysis (INAA) for trace elements. The elements Cd, Hg and Pb were determined by atomic absorption spectrometry after digestion using the US EPA 3,051 procedure. These metal concentrations were compared to the PEL and TEL oriented values from CCME. The sampling sites P₃ and P₄, near industrialized areas, showed the highest concentrations for potentially bioavailable metals, mainly Pb and Hg. The results obtained by INAA were compared to upper continental crust values. A strong enrichment was found for the elements As, Br, Sb, Th, U and Zn. These results evidenced contamination by industrial effluents and sewage even relatively close to the Tietê River headwaters. The worst biological effects (acute toxicity) on benthonic organism Hyalella azteca were also observed at P₃ and P₄.     

Investigation of Spectroscopic and Thermal Properties of Poly(o‐toluidine) Doped with Polymeric Acids

Single step polymerization of poly(o‐toluidine) was carried out by using ammonium persulphate as an oxidizing agent. Formation of the conducting emeraldine salt phase of the polymer was confirmed by the UV‐visible and FT‐IR spectroscopic analysis. The elemental composition of the polymer was evaluated by using a CHNS analyzer. Thermal stability of these polymers was investigated by the thermogravimetric analysis. Among the three polymeric acids used for doping purposes, poly(acrylic acid) doped material was found to show less thermal stability compared to poly(styrene sulphonic acid) and poly(vinyl sulphonic acid) doped poly(o‐toluidine).     

Synthesis and characterization of poly(ɛ-caprolactone)/Fe3o4 nanocomposites by in situ polymerization

A series of magnetic nanocomposites based on poly(?-caprolactone) (PCL) and Fe₃O₄ nanoparticles were prepared using a facile in situ polymerization method. The chemical structures of the PCL/Fe₃O₄ nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy. Results of wide-angle X-ray diffraction (WAXD) showed that the incorporation of the Fe₃O₄ nanoparticles did not affect the crystallization structure of the PCL. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the morphology and dispersion of the Fe₃O₄ nanoparticles within the as-synthesized nanocomposites. Results of differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) showed that the crystallization temperature was raised and the spherulites size decreased by the presence of Fe₃O₄ nanoparticles in the nanocomposites due to the heterogeneous nucleation effect. The thermal stability of the PCL was depressed by incorporation of Fe₃O₄ nanoparticles from thermogravimetric analysis (TGA). The superparamagnetic behavior of the PCL/Fe₃O₄ nanocomposites was testified by the superconducting quantum interference device (SQUID) magnetometer analysis. The obtained biodegradable nanocomposites will have a great potential in magnetic resonance imaging contrast and targeted drug delivery.     

Syntheses and structural aspects of rigid aryl- palladium(II) and -platinum(II) complexes. X-ray crystal structure of o,o′-bis[(dimethylamino)methyl]phenyl- platinum(II) bromide

The tridentate monoanionic ligand o,o′-(Me₂NCH₂)₂C₆H₃ (NCN′) has been used to synthesize novel aryl-palladium(II) and -platinum(II) complexes [PtR(NCN′)] and [MX(NCN′)] (M = Pt, Pd). Three synthetic procedures are described, namely: (i) reaction of the cationic complex [M(NCN′)(H₂O)]⁺ with KX or NaX to give [MX(NCN′)] (X = Cl, I, O₂CH, NCS, NO₂, NO₃); (ii) displacement reactions using AgX with [MBr(NCN′)] to give [MX(NCN′)] (X = CN, O₃SCF₃. O₂CMe, O₂CCF₃) and (iii) transmetallation reactions of [PtBr{C₆H₃(CH₂NMe₂)₂-o,o′}] with organolithium to give [PtR{C₆H₃(CH₂NMe₂)₂-o,o′}] (R = Ph, o-, m-, p-tolyl, CCPh, CC-p-tolyl). All complexes have been characterized by elemental analysis, and IR, ¹H and ¹³C NMR spectroscopy.An X-ray diffraction study has shown that [PtBr{C₆H₃(CH₂NMe₂)₂-o,o′}] (2) has a square-planar structure, in which the tridentate ligand is bonded via C(ipso) (PtC 1.90(1) Å), and two mutually trans-N donor atoms (PtN(1) 2.07(1), PtN(2) 2.09(1) Å). The fourth site trans to C(ipso) is occupied by bromine (PtBr 2.526(2) Å). The two chelate rings (NPtC(ipso) 82.9(5) and 81.5(5)°) are distinctly puckered, with the two NMe₂ groups on opposite sides of the aryl plane. The PtC bond in 2 is shorter than analogous bonds in other arylplatinum(II) complexes, as a result of (i) the rigid structure of the tridentate ligand and (ii) the presence of two hard N donor atoms trans to one another across the platinum centre.