bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure–activity studies on the fungitoxicity of some triorganotin(IV) compounds
Authors: Kuthubtheen A J , Wickneswari R , Das V G Kumar 
Published: January 2005

AbstractSeventeen triorganotin(IV) compounds, with the general formula R3SnX, containing symmetrical and unsymmetrical combinations of alkyl and aryl groups on tin and with a wide variation in the non‐carbon‐bonded anionic (X) residues, were examined along with three formally pentacoordinated adducts of triaryltin chlorides with triphenylphosphine oxide for their antifungal activity against nine plant pathogenic and saprophytic fungi. The in vitro tests included inhibitory studies on radial growth, mycelial growth, spore germination, and germ tube elongation. A significant finding was the dependence of fungitoxicity on the nature of the X group in both the tributyltin and triaryltin series, in contrast to earlier published reports on the negligible influence of the X groups on overall toxicity relative to the R group. This suggests that the X group is significantly involved in transporting the biocide to the reactive sites, and that the X group which tends to confer increased solubility to the triorganotin compound gives rise to increased activity.In studies of R group variations, tri‐iso‐butyltin bromide was found to be much less fungitoxic than tri‐n‐butyltin compounds, a result which is reconcilable in terms of increased steric encumbrance at the tin site in the former case. The steric factor is also implicated in the reduced activities observed for tris(p‐tolyl)tin and tris(p‐chlorophenyl)tin compounds relative to (Ph3SnX) towards most of the fungi screened in this study. In general, it was also noted that the triaryltins were more selective in their antifungal action than the trialkyltins, which exhibited broad spectral activity when applied at the concentration level of 10 μg cm−3.
Efficacy of selected triorganotin(IV) compounds on leaves against Phytophthora palmivora (Butler) Butler isolated from black pepper and cocoa
Authors: Kuthubutheen A J , Wickneswari R , Kumar Das V G 
Published: January 2005

AbstractSeveral triorganotin(IV) compounds and Terrazole® 35 WP were screened for their in vitro antifungal activity against three isolates of Phytophthora palmivora. Two isolates (isolates Phy. 2 and Phy. 334) were obtained from black pepper (Piper nigrum L.) and one isolate (isolate Phy. 56) from cocoa leaves (Cacao theobromae). ED50 values for radial growth of the isolates ranged from 0.09 to 1,700 μg cm−3 for the triorganotin(IV) compounds and from 3.46 to 1 227 000 μg cm−3 for Terrazole®. Diphenylbutyltin bromide exhibited the highest antifungal activity against the three isolates of P. palmivora with ED50 values ranging from 0.30 to 0.73 μg cm−3.Diphenylbutyltin bromide was equally effective against a freshly isolated virulent culture of P. palmivora (isolate Phy. 346) from black pepper leaves in Sarawak, East Malaysia, yielding an ED50 value for radial growth of 0.87 μg cm−3 and a probit‐log concentration regression line slope value of 1.04. In vitro efficacy of diphenylbutyltin bromide against isolate Phy. 346 using detached healthy pepper leaves showed 40–75% infection of leaves at 100 μg cm−3 and no infection at 500 μg cm−3. Diphenylbutyltin bromide at 100 μg cm−3, however, inhibited the diameter of lesion by 43.3–73.7% compared with the untreated controls. Black pepper leaves treated with Terrazole® at 778 μg cm−3 exhibited 5.3–33.3% inhibition of lesion diameter compared with the untreated controls, where 90–100% of the leaves were infected. Concentrations of diphenylbutyltin bromide of 1000–2500 μg cm−3 caused some injury lesions on the leaves. From the results obtained, it appears that diphenylbutyltin bromide could be used as a protective spray or drench against P. palmivora infection of black pepper at 100–500 μg cm−3.
Biodegradation of bis(tri‐n‐butyltin) oxide
Authors: Shizhong Tian , Chau Y K , Liu D 
Published: January 2005

AbstractBis(tri‐n‐butyltin) oxide can be biodegraded by a mixed bacterial culture from activated sludge in cyclone fermentors under aerobic and anaerobic conditions with half‐lives of five and three days respectively. The degradation follows a sequential dealkylation process. All the intermediates and end products are determined in the degradation process for mass balance calculation. Degradation under different nutrient conditions has been investigated. Adsorption losses for each of the butyltin and inorganic tin species on container walls have also been assessed and discussed.
The determination of organotins (TBT) in fish and shellfish via gas chromatography–flame photometric detection and direct current plasma emission spectroscopy (GC–FPD/DCP)
Authors: Krull Ira S , Panaro Kenneth W , Noonan John , Erickson Donald 
Published: January 2005

AbstractGas chromatography (GC) has been interfaced very simply and inexpensively with a flame photometric detector (FPD) and a direct current plasma (DCP) atomic emission spectrometer in order to perform highly specific and selective determination of organotins in fish and shellfish samples. GC–FPD studies employed a fused‐silica, megabore column with a thin, immobilized stationary phase of DB‐17 (1 μm thickness), with a commercially available GC–FPD instrument. No prior alkylation or hydridization reactions were performed on the organotins; rather they were separated as the original, native species. Separate GC–FPD and GC–DCP injections and quantitative determinations have been performed, though simultaneous FPD/DCP detection on a single injection is suggested. This permitted routine qualitative and quantitative determinations of organotin species in complex food matrices (fish/shellfish) via both element selective detectors. Isothermal GC–FPD/DCP conditions permitted baseline resolution of all four tin species of interest today: monobutyl‐, dibutyl‐, tributyl‐ (TBT), and tetrabutyl‐tin. Optimization of the GC–DCP interface was accomplished, followed by a determination of detection limits and linearity of the calibration plots, and a comparison of the results with those obtained by the newer GC–FPD approach (which was also developed here). In three sample instances, qualitative and quantitative results for naturally occurring and spiked levels agreed for both the GC–FPD and GC–DCP approaches. Improved sample preparation and extraction procedures have been developed for organotins from fish samples involving extraction with an organic solvent, concentration, saponification, back‐extraction, and injection of the eluent onto the GC column. Quantitative levels of organotins (solely TBT) in fish and shellfish are reported for samples from Europe, Korea, Scandinavia, and the USA.
Conversion of arsenite and arsenate to methylarsenic and dimethylarsenic compounds by homogenates prepared from livers and kidneys of rats and mice
Authors: Hirata Miyuki , Mohri Takami , Hisanaga Akira , Ishinishi Noburu 
Published: January 2005

AbstractPooled livers and pooled kidneys from rats or mice were homogenized and spiked with arsenite or arsenate in the concentration range 1.3–20 μmol dm−3. Methylarsenic and dimethylarsenic compounds were determined by the hydride generation technique in the homogenates after a 90 min incubation at 37°C. The rat homogenates methylated arsenite and arsenate more efficiently than the mouse homogenates. Monomethylated arsenic was present in larger amounts than dimethylated arsenic in the rat homogenates. In the absence of reduced glutathione (GSH), no methylation occurred. Addition of GSH promoted monomethylation and dimethylation, whereas dithiothreitol and mercaptoethanol (10 mmol dm−3) fostered only monomethylation. The amounts of monomethylated arsenic in the rat liver homogenates increased with increasing arsenite concentration (1.3–20 μmol dm−3) however, the percentage of arsenic that had been methylated decreased. A similar trend, but with much less monomethylarsenic formed, was observed for arsenate‐spiked homogenates. Rat kidney homogenates methylated arsenite and arsenate to a much smaller extent than rat liver homogenates. The Km values for the monomethylation in rat liver homogenates were found to be 5.3 μmol dm−3 for arsenite and 59 μmol dm−3 for arsenate.
Thermolysis of the phenyltin chlorides, PhxSnCl4–x, (x=1−3): Products and pathways
Authors: Chandrasiri Jayakody A , Wilkie Charles A 
Published: January 2005

AbstractThe thermal degradation of triphenyltin chloride, diphenyltin dichloride and phenyltin trichloride has been studied by pyrolysis at 375°C in sealed tubes for various time periods. In all cases, biphenyl and tin(II) chloride are produced. For both phenyltin trichloride and diphenyltin dichloride, ter‐ and poly‐phenyls are also obtained. In some cases tin(IV) chloride or elemental tin are obtained. Pathways that account for all observed products are presented.
Synthesis of poly‐yne polymer containing platinum and silicon atoms in the main chain by oxidative coupling and its reactions with transition‐metal carbonyl complexes
Authors: Matsumoto Toshihiro , Kotani Sonae , Shiina Kyo , Sonogashira Kenkichi 
Published: January 2005

AbstractThe platinum poly‐yne polymer, [CCSiMe2CCPt(PBu3)2CCSiMe2CC]n (2), was synthesized by the oxidative coupling of a silicon–platinum monomer, trans‐(PBu3)2Pt(CCSiMe2–CCH)2 (1). The reaction of platinum poly‐yne polymer 2 with dicobaltoctacarbonyl gave μ‐coordinated complexes, {[CCSiMe2CCPt(PBu3)2CCSiMe2CC] [Co2(Co)6]2}n (4). the electric conductivity of iodine adducts of the polymer complexes 4 was 3.0×10−5 S cm−1. As an aid to spectroscopic characterization of the polymer complex 4, a model complex, {trans‐[(PBu3)2Pt(CCSiMe2CCH)2]} {[Co2(CO)6]2} (3), was also prepared by the reaction of 1 with dicobaltocatacarbonyl. Selective coordination of Co2(CO)6 groups to SiMe2CC CCSi(Me)2 Moieties and coordinative inertness of the PtCC moieties were confirmed by comparison of the NMR spectra of 3 with those of 4. All new compounds have been characterized by analytical and spectral analysis (IR, 1H NMR).
Synthesis of 2‐substituted pyridines catalyzed by cobalt(I) complexes and promoted by light
Authors: Heller Barbara , Reihsig Jonathan , Schulz Wolfgang , Oehme Günther 
Published: January 2005

AbstractA series of pyridines substituted in the 2‐position were synthesized by cobalt(I)‐catalyzed cotrimerization of alkynes and nitriles. The reactions are usually enhanced by light. The reaction conditions are very mild. Activity and selectivity are satisfactory with respect to formation of pyridines, but depend on the type of nitrile.
Synthesis of inorganic polymers as glass precursors and for other uses: Pre‐ceramic block or graft copolymers as potential precursors to composite materials
Authors: Youngdhal K A , Hoppe M L , Laine R M , Rahn J A , Harrod J F 
Published: January 2005

AbstractPre‐ceramic block or graft copolymers may offer entrée into nanocomposite ceramics provided the two homopolymers are immiscible and one can carefully control the size of the blocks or grafts. We are exploring the possibility of making copolymers from methylsilsesquioxane, [MeSi(O)1.5]x, (SiO), a precursor to ‘black glass’ and the polysilazane, [MeHSiNH]x, (SiMe), a precursor to silicon carbide nitride. Our initial effors have been directed towards delineating the chemical transformations that SiO, prepared by room‐temperature catalytic redistribution of [MeHSiO]x using Cp2TiMe2as the catalyst (0.1 wt %), undergoes as it is heated to 900 °C in nitrogen. We find that, although Cp2TiMe2will not catalyze the redistribution of SiMe at room temperature, in the presence of even small amounts of [MeHSiO]x it is an active catalyst precursor and a copolymer can be formed. Spectra and chemical composition studies on the pyrolysis products of the copolymers and SiO are described.
Synthesis of carboxylic esters from aldehydes using metal carbonyl anions, part 2. Dimerization of aldehydes to carboxylic esters catalyzed by disodium pentacarbonylchromate, na2[cr(co)5]
Authors: Ohishi Takahiro , Matsumoto Tokuji , Yamashita Masakazu 
Published: January 2005

AbstractNa2[Cr(CO)5] (1) was found to be an efficient catalyst for the dimerization of aldehydes to carboxylic esters. Several aromatic aldehydes including furfural gave the corresponding esters in good yields. This reaction also proceeded intramolecularly to give phthalide from phthalaldehyde. Compared with M2[Fe(CO)4] (M = Na, K), 1 was found to be a more efficient catalyst for this reaction. However, aliphatic aldehydes gave aldolcondensation products instead of the corresponding esters. In the reactions of p‐substituted benzaldehydes with 1, the reactivity decreased with the increase of the electron‐releasing ability of the substituents. However, even p‐anisaldehyde, which hardly reacted with M2[Fe(CO)4], reacted with 1 to give the ester in moderate yield. The reaction mechanism, including the nucleophilic attack of the pentacarbonylchromate dianion on the carbonyl carbon, is discussed.
Stannacycloalkyl and stannepinyl derivatives of dipeptides
Authors: Koch Jost , Huber Friedo , Ruisi Giuseppe , Barbieri Renato 
Published: January 2005

AbstractStannacyclohexyl and stannacycloheptyl derivatives of dipeptides (CH2)nSnAA · xH2O (H2AA = H2GlyGly, with n = 5, x = 2 or n = 6, x = 1; H2AA = H2GlyAla, H2GlyVal, H2GlyMet, with n = 5, 6, x = 1) and stannepinyl glycylglycinate monohydrate have been obtained by the reaction of (CH2)nSnCl2 or stannepinyl dichloride with Na2AA. According to infrared and 119Sn Mössbauer data of the solid compounds, AA acts as a tridentate ONN ligand and tin has a trigonalbipyramidal environment. An analogous structure has been inferred from 1H, 13C, and 119Sn NMR data for the undissociated molecules in methanol solution.
The lon‐chromatographic behavior of arsenite, arsenate, methylarsonic acid and dimethylarsinic acid on the hamilton PRP‐X100 anion‐exchange column
Authors: Gailer JÜRgen , Irgolic Kurt J. 
Published: January 2005

AbstractThe HPLC separation of arsenite, arsenate, methylarsonic acid and dimethylarsinic acid has been studied in the past but not in a systematic manner. The dependence of the retention times of these arsenic compounds on the pH of the mobile phase, on the concentration and the chemical composition of buffer solutions (phosphate, acetate, potassium hydrogen phthalate) and on the presence of sodium sulfate or nickel sulfate in the mobile phase was investigated using a Hamilton PRP‐X100 anion‐exchange column. With a flame atomic absorption detector and arsenic concentrations of at least 10 mg dm−3 all investigated mobile phases will separate the four arsenic compounds at appropriate pH values in the range 4–8. The shortest analysis time (˜3 min) was achieved with a 0.006 mol dm−3 potassium hydrogen phthalate mobile phase at pH 4, the longest (˜10 min) with 0.006 mol dm−3 sodium sulfate at pH 5.9 at a flow rate of 1.5 cm3 min−1. With a graphite furnace atomic absorption detector at the required, much lower, flow rate of ˜0.2 cm3 min−1 acceptable separations were achievable only with the pH 6 phosphate buffer (0.03 mol dm−3) and the nickel sulfate solution (0.005 mol dm−3) as the mobile phase. To become detectable approximately 100 ng arsenic from each arsenic compound (100 μl injection) must be chromatographed with the phosphate buffer, and approximately 10 ng with the nickel sulfate solution.
Biocidal organotin compounds: Part 1. Preparation and characterization of triorganotin(IV) 4‐pyridyl‐ and 2‐pyrimidyl‐ thioacetates and the crystal structure of triphenyltin(2‐pyrimidylthioacetate)
Authors: Chakrabarti A. , Kamruddin Sk. , Chattopadhyaya T. K. , Roy A. , Chakraborty B. N. , Molloy K. C. , Tiekink E. R. T. 
Published: January 2005

AbstractThe preparation and spectroscopic characterization of [R3Sn(O2CCH2SC5H4N‐4)], R == Ph, benzyl (Bz), cyclohexyl (c‐Hex) and n‐Bu, and of [R3Sn(O2CCH2SC4H3N2‐2,6)], R == Me, Ph and n‐Bu, are reported. The 2‐pyrimidyl compounds feature trigonal bipyramidal tin centres with trans‐R3SnO2 geometries as was confirmed by X‐ray crystallography for [Ph3Sn(O2CCH2SC4H3N2‐2,6)]. ¶ By contrast the 4‐pyridyl compounds have trigonal bipyramidal geometries in the solid state (arising from intermolecular Sn…N interaction) and tetrahedral geometries in solution. The biocidal activity of these compounds against the fungi Helminthosporium maydis (ITCC 2675) and H. oryzae (ITCC 2675), both of which damage crops such as maize and rice, shows promise. Encouraging is the observation that the compounds show no adverse phytotoxicity at concentrations to 10−3M.
Generation of (α‐aminoalkyl)samarium(III) by a new method of metalation and its carbon–carbon bond‐forming reactions
Authors: Murakami Masahiro , Hayashi Minoru , Ito Yoshihiko 
Published: January 2005

Abstract(α‐Aminoalkyl)samarium(III) is generated on treatment of a tertiary amine having a pendant o‐iodobenzyl group on the nitrogen atom with samarium(II) iodide (SmI2) in tetrahydropyran containing hexamethylphosphoramide. Deuterium incorporation experiments demonstrate that the reaction proceeds via a delivery of a radical center from the pendant benzyl group to the α‐position of nitrogen and the following one‐electron transfer from SmI2 to the delivered radical. Subsequent nucleophilic addition of (α‐aminoalkyl)samarium (III) to various electrophiles, such as enolizable ketones, isocyanate and isocyanide, furnishes the C‐C bond formation products in good yields. The pendant benzyl group of the product can be readily removed by hydrogenolysis to give the corresponding secondary amine. Therefore, the present reaction provides a useful synthetic process for a variety of nitrogen‐containing compounds including β‐amino alcohols and α‐amino acid derivatives, disclosing a new method for metalation and C‐C bond formation.
Ytterbium tricyanide: Preparation and catalytic activity for the addition of cyanotrimethylsilane to carbonyl compounds
Authors: Utimoto Kiitiro , Takai Tsutomu , Kasuga Yuri , Matsubara Seijiro 
Published: January 2005

AbstractYtterbium tricyanide was obtained quantitatively by the reaction of ytterbium tri‐isopropoxide with cyanotrimethylsilane. The addition of cyanotrimethylsilane to various carbonyl compounds was catalyzed effectively by ytterbium tricyanide to proceed under mild conditions giving the adducts in high selectivities. 2‐Methylcyclohexanone yielded the adduct in a highly diastereoselective manner and the reagent system also effectively gave the adducts from easily enolizable ketones as well as from acid‐sensitive ones. α,β‐Unsaturated ketones and aldehydes afforded 1,2‐adducts exclusively.
Synthesis of tertiary phosphine oxides mediated by SmCp2 or Sml2
Authors: Dallemer F. , Collin J. , Kagan H. B. 
Published: January 2005

AbstractTertiary phosphine oxides are prepared under mild conditions by sequential addition of diphenylphosphinoyl chloride to divalent samarium compounds (SmCp2 and SmI2) followed by reaction with various electrophiles such as organic halides, tosylates, epoxides or α,β‐unsaturated ketones. Biscyclopentadienylsamarium (SmCp2) gives better yields than SmI2. Similar reactions, using phenylphosphonoyl dichloride, SmI2 and subsequent addition of two equivalents of activated halides, yield the corresponding tertiary phosphine oxides.
A new reduction system by the combination of lanthanoid metals (Ln) and Lnl2: Deoxygenative coupling of amides to vic‐diaminoalkenes
Authors: Ogawa Akiya , Nanke Taizoh , Takami Noriaki , Sekiguchi Masahito , Kambe Nobuaki , Sonoda Noboru 
Published: January 2005

AbstractDeoxygenative coupling of aromatic amides takes place successfully by the use of a mixed system comprising of ytterbium metal and ytterbium diiodide, providing the corresponding vic‐diaminoalkenes in good yields. The same reaction does not take place if Yb metal or YbI2 is used alone. These results suggest novel enhancement of reducing ability by the combination of ytterbium(0) and ytterbium(II) diiodide. The Yb/YbI2 system is also effective for dethiolative coupling of thioamides, as sulfur analogues of amides. This paper also deals with reductive coupling of thioamides and selenoamides by using an Sm/SmI2 mixed system.
Reaction of (Cp2*LnH)2 (LnY, La) and Cp2* Y(2‐C6H4CH2NME2) with esters and amides and molecular structure of [Cp2* Y (μ‐OCMeCHC(OEt)O)]2
Authors: Deelman Berth‐Jan , Wierda Feike , Meetsma Auke , Teuben Jan H. 
Published: January 2005

AbstractThe activation of esters and amides by (Cp2* LnH)2 [LnY (1a), LnLa (1b), Cp*C5Me] and Cp2* Y (2‐C6H4CH2NMe2) (2) is described. Compounds 1a and 1b react with ethyl acetate to form Cp2* YOEt (3a) and Cp2*LaOEt (3b). With 1a and ethyl benzoate a 1:1 mixture of 3a and Cp2*YOCH2Ph (4a) is produced and the corresponding 1:1 mixture of 3b and Cp2*LaOCH2Ph (4b) is observed with 1b. Ethyl acrylate is polymerized rapidly by both 1a and 1b. The reaction of 1a with N,N‐dimethyl‐acetamide leads to a mixture of the carbonyl insertion product Cp2* Y(OCH(NMe2)Me) (5) and the aldol condensation product Cp2*Y(OC(NMe2)(Me)CH2C(O)NMe2) (6.). Formation of the condensation product [Cp2*Y(μ‐OCMe=CHC(OEt)O)]2 (7) occurred when 2 was reacted with ethyl acetate. The molecular structure of 7 was determined by X‐ray diffraction: a = 10.129(1) Å, b = 10.650(1) Å, c = 12.093(1) Å, α = 77.642(6)°, β = 79.402(7), γ = 86.408(9), V, 1252.2(2) Å3, space group P 1―, Z = 1. Anisotropic least‐squares refinement based on 4871 reflections converged to RF = 0.034 and Rw = 0.041 for 428 refined parameters. The more sterically hindered ester ethyl 2‐methylpropanoate reacted with 2 to produce the enolate complex Cp2*Y{OC(2‐C6H4CH2NMe2)=CMe2} (Me2CHCOOEt) (8). With N,N‐dimethylacetamide 2 gives a clean aldol condensation to form 6.
Relationships between hydrodynamics and rheology of flocculating yeast suspensions in a high‐cell‐density airlift bioreactor
Authors: Klein Jaroslav , Maia João , Vicente António A. , Domingues Lucília , Teixeira José A. , Juras̆c̆ík Martin 
Published: January 2005

AbstractIn this article a hydrodynamic and rheological analysis of a continuous airlift bioreactor with high‐cell‐density system is presented. A highly flocculating recombinant strain of Sacharomyces cerevisiae containing genes for lactose transport (lactose permease) and hydrolysis (β‐galactosidase) was exploited to ferment lactose from cheese whey to ethanol. The magnetic particle‐tracer method was used to assess the effect of operational conditions (air‐flow rate, biomass concentration) on hydrodynamic behavior of an airlift bioreactor during the fermentation process. Measurements of liquid circulation velocity showed the existence of a critical value of biomass concentration at which a dramatic deceleration of net liquid flow appeared with increasing biomass quantity. Rheological analysis revealed exponential increase of viscosity of the yeast floc suspension at the same biomass concentration of about 73 g/dm3 corresponding to 42.8% v/v of solid fraction. These facts have a particular importance for the successful processing of a high‐cell‐density airlift bioreactor as only a circulated flow regime will be favorable to keep the solid particles in suspension state and evenly distributed throughout the bioreactor. © 2004 Wiley Periodicals, Inc.