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1.
The methylation of tin(II) chloride by methyl iodide in porewater and formation of monomethyltin as the only methyltin product are described. A factorial experiment tested the effects of concentrations of tin(II), methyl iodide, and oxygen on monomethyltin yields. The experiments gave 0.18 to 12.8 % yield. Analysis of variance (ANOVA) calculations showed that all three variables were significant at the 95 % level. Comparison of yields in aqueous 23 g kg?1 sodium chloride solutions to those in porewater and to those containing fulvic acid, salicylic acid, and EDTA showed that only fulvic acid significantly reduced yields. Reasons for this observation are discussed and the findings in the model system are related to methylation of tin compounds in sediments. 相似文献
2.
The methylation reaction of inorganic arsenic occurring in aquatic systems was studied by HPLC‐HG‐AFS as a method to separate and detect soluble methylarsenic species. Transformation from inorganic arsenic to methylarsenic was essential for major changes in toxicity to organisms. Monomethylarsenic [AsOCH3(OH)2] was the only product in the methylation reaction of inorganic arsenic(III) with methyl iodide (MeI). This process can be described as an oxidative carbonium‐ion transfer, with MeI acting as a methyl donor. From a thermodynamic point of view, the activity of the carbonium ion and pH were the two major influencing factors. The pH dependence of redox potential of As(III) was the reason for the effect of pH on methylation of arsenic. The influences of salinity and concentration of the methyl donor may be explained by their effects on the activity of carbonium. Moreover, kinetics experiments demonstrated that the methylation reaction was first‐order for both As(III) and methyl iodide. First‐order reaction rates were also calculated at different pH, salinity and MeI, and were found to be in the range 0.0026–0.0123 h?1. The methylation rate varied largely under different reaction conditions. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
3.
Piotr Matczak 《应用有机金属化学》2019,33(4)
The experimentally well‐known complexation of tin(II) and tin(IV) halides with pyridine (py) leads to structures showing N → Sn coordination. In the present work, the complexes SnXn·mpy (where X = F, Cl, Br, I; n = 2, 4; m = 1, 2) possessing this kind of coordination were studied using a computational quantum chemical approach. Various aspects in the theoretical picture of these complexes were examined to find similarities and differences in their N → Sn coordination. The aspects included, among others, the physical nature of intermolecular interactions, and their role in establishing the structure and energetic stabilization of the complexes. In this context, the effect of tin valency was inspected in great detail. As proven by several theoretical methods, a largely ionic character with a certain covalent component can be attributed to the studied N → Sn coordination, irrespective of tin valency. All complexes are destabilized by py‐py and three‐body interactions, but the Sn(II) complexes experience it to a greater extent. Marked differences are observed in the structural behavior of N → Sn and SnXn during complex formation. This affects the energetics of complexation and, in consequence, the penta‐coordinated Sn(IV) center shows a higher propensity to expand its coordination number, compared with the tri‐coordinated Sn(II) center. The present study supplements the experimental characterization of SnXn·mpy and, in general, it sheds light on the coordination of heteroaromatic nitrogen to tin. The survey of the Cambridge Structural Database revealed that such coordination occurred in a number of crystal structures. 相似文献
4.
The usual presence of mercury(II) with monodi-, and tri-methyltin in water, sediments, and plants in estuarine environments suggests possible abiotic formation of methylmercury via methyl transfer from methyltin compounds. Kinetics studies of reactions between mercury(II) and methyltin compounds under pseudo-first-order conditions in seawater show that relative rate of methylmercury formation under the same conditions are: monomethyltin <trimethyltin> dimethyltin. This order is explainable mainly by the speciation and charge of methyltin compounds in seawater and by the existence of mercury(II) as a tetrachloro anion. A factorial experiment with the variables pH and salinity (seawater diluted with deionized water) showed that pH, but not salinity, is significant at the 95% confidence level; and that reaction rates increase as pH increases. These results suggest the possibility of abiotic methylation of mercury(II) in seawater. Additional experiments in seawater demonstrated an absence of methylation of mercury(II) (14 days) and mercury(0) (35 days) by methyl iodide. 相似文献
5.
John S Thayer 《应用有机金属化学》1989,3(2):123-128
Formation of bonds between methyl groups and heavy elements (metals or metalloids) alters various physical properties such as solubility or volatility. This alteration enhances the mobility of the heavy metal and can play a major role in the environmental cycles for these elements. Environmental methylation has been established as a major factor in the environmental movement of mercury and arsenic, and very probably affects other elements similarly. Two methylating agents (methylcobalamin and methyl iodide) have been found to mobilize metals out of water-insoluble compounds and/or anoxic sediments. These two compounds react with quite different substrates, but the kinetics of the resulting dissolutions follow virtually identical patterns. These reactions proceed through formation of a methylated intermediate on the substrate surface, followed by movement of the heavy element out of the solid lattice into the surrounding solution. 相似文献
6.
Carbonyl allylations by allylic chlorides either with tin(IV) iodide and tetrabutylammonium iodide (TBAI) in dichloromethane or with tin(IV) iodide and sodium iodide in 1,3-dimethylimidazolidin-2-one at room temperature produced the corresponding homoallylic alcohols. The carbonyl allylations probably proceeded via the reduction of tin(IV) iodide to triiodostannate(II) species with iodide sources such as TBAI and NaI, which led to the construction of a tin(IV)-catalytic cycle based on regeneration of tin(IV) iodide via the transmetalation of homoallyloxytriiodotin to homoallyloxytrimethylsilane with iodotrimethylsilane. 相似文献
7.
8.
The methylation of several tin compounds by strains of Saccharomyces cerevisiae strains (yeast) is described. The production of the methyl tin species was established by gas chromatography and mass spectrometry. Monomethyl tin (IV) products dominated but some dimethyl tin products were observed. This appears to be the first report of a tin methylation by a pure strain of a methylating species rather than a complex mixture obtained from an environmental source. 相似文献
9.
E. A. Mukhutdinov An. M. Kuznetsov A. A. Mukhutdinov V. I. Garvilov F. R. Garieva 《Russian Chemical Bulletin》1998,47(11):2298-2299
The structure of 10-alkyl(aryl)phenoxarsines has been investigated by the semiempirical quantum-chemical PM3 method. The AsIII atom has a positive charge and simultaneously exhibits nucleophilic properties in the reaction with methyl, iodide. The reactions
of 10-alkyl(aryl)phenoxarsines with methyl iodide are probably controlled by charge distribution.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2368–2371, November, 1998. 相似文献
10.
Marcelo Kobelnik Douglas Lopes Cassimiro Diógenesdos Dos Santos Clóvis Augusto Ribeiro Marisa Spirandeli Crespi 《中国化学》2011,29(11):2271-2277
Solid state compounds of general formula Sr(Diclof)2·5.7H2O and Ba(Diclof)2·4.8H2O were obtained. Thermogravimetry (TG), differential scanning calorimetry (DSC), X‐ray diffraction powder patterns and microscopy analysis were used to characterize these compounds. Details concerning the dehydration and thermal decomposition as well as data of kinetic parameters have been described here. The kinetic behaviors of these stages were evaluated from several heating rates with samples masses of 2 and 5 mg in open crucibles under a nitrogen atmosphere. The results of the present study improve the knowledge on these compounds including their dehydration and thermal stability. The obtained data depend on the mass of the sample which results in two kinetic behavior patterns. 相似文献
11.
Different tributyltin phenoxides react at room temperature with ethyl propiolate in benzene, in the presence of tin(IV) chloride, triethylamine and their mixture to give the derivatives of 3‐phenoxyacrylic acid ethyl ester. Exceptionally, 3‐(2‐hydroxyphenyl)acrylic acid ethyl ester and 3‐(2‐hydroxy‐5‐methylphenyl)acrylic acid ethyl ester have been obtained from the reaction of tributylphenoxytin and tributyl(p‐tolyloxy)tin, respectively catalysed by SnCl4, and they have been easily hydrolysed to coumarin and 6‐methylcoumarin. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
12.
A factorial experimental design determined separate and combined effects of MeCoB12 (methylcobalamin) and Me2Co(N4)+ (a methylcobalamin model) on methylation of Sn(II) and Pb(II) in sediment matrices. Total methyltin yields ranged from 1.4% to 3.2%, and total methyllead yields varied from 0.037% to 0.11%. No methylmetal products occurred in the absence of Me2Co(N4)+. 相似文献
13.
G. Papanastasiou A. Papoutsis M. Tsirtou I. Ziogas 《Journal of solution chemistry》1996,25(2):203-217
The kinetics of the reaction between sodium ethoxide and methyl iodide has been studied at 25°C in various cyclohexane-ethanol solvent mixtures with a cyclohexane content of 10 to 50% per volume. The determination of the rate constants att=0 were carried out by a new iterative method proposed in this investigation. The obtained results show that the reaction rate decreases with the increasing cyclohexane content. This behavior can be attributed to various solute-solvent interactions of electrostatic nature. On the other hand, the variation of ion and ion pairs rate constants with solvent composition permits the various solvation effects to be taken into account. 相似文献
14.
15.
E. V. Kolyakina L. B. Vaganova A. V. Lado A. V. Piskunov V. K. Cherkasov D. F. Grishina 《Russian Chemical Bulletin》2007,56(7):1363-1368
The effect of bis(3,6-di-tert-butylcatecholato)tin(IV) ditetrahydrofuranate (1) on the kinetic parameters of methyl methacrylate polymerization and on the molecular weight characteristics of polymers
prepared was studied. According to EPR data, complex 1 can accept and eliminate the growing macroradicals in monomer media. This allows the lifetimes of the growing polymer chains
to be controlled. The optimal temperature range for accomplishing controlled synthesis of polymer in the presence of complex
1 was determined.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1314–1319, July, 2007. 相似文献
16.
三(邻氟苄基)氯化锡和四(对氟苄基)锡的合成及结构研究 总被引:7,自引:0,他引:7
邻氟苄基氯或对氟苄基氯分别与锡反应合成三(邻氟苄基)氯化锡(1)和四(对氟 苄基)锡(2).经X射线方法测定了新化合物的晶体结构.晶体结构1属单斜晶系,空 间群为P2(1)/n,晶体学参数:a=0.5896(9)nm,b-1.262(2)nm,c=2.634(4)nm, V=1.959(5)nm^3,Z=4,Dx=1.632g/cm^3,μ(Mo Kα)=14.69cm^-1,F(000)=952, R1=0.0541,wR2=0.1280;晶体结构2属单余晶系,空间群为Cc,晶体学参数:α=1. 0778(6)nm,b=2.3312(14)nm,c=1.0888(7)nm,V=2.460(3)nm^3,Z=4,Dx=1. 499g/cm^2,μ(Mo Kα)=10.82cm^-1,F(000)=1112,R1=0.0302,wR2=0.0590.在化合 物1和2中Sn-C键长分别为0.2136-0.2148和0.2138-0.2180nm,Sn-Cl键长为0.2378 (4)nm,中心锡与亚甲基碳(氯)原子构成畸型四面体。 相似文献
17.
Kiyomi Kakiuchi Koichi MinatoKen Tsutsumi Tsumoru MorimotoHideo Kurosawa 《Tetrahedron letters》2003,44(9):1963-1966
Radical ring-opening reactions of bicyclo[4.2.0]octanones, its C6 alkyl derivatives, and tricyclic ketones promoted by SmI2 gave cyclohexanones via fission of the external cyclobutane bond. The CO2Me, CN, and phenyl derivatives led to the production of the eight-membered ring compounds through cleavage of the central cyclobutane bond. Using this regioselective reaction, the synthesis of (±)-acorenone was achieved. 相似文献
18.
The direct synthesis of the two industrially important organotin intermediates, di(n-butyl)tin and di(n-octyl)tin dihalides, has been investigated by reacting the appropriate alkyl halide with metallic tin undervarying conditions. Observations were made on the influences of temperature, pressure, reaction time, nature of the tin metal, organic halide/tin reactant ratios and the presence of catalysts on the extent of tin conversion and yields of the organotin products. The efficacy of the onium halides, notably n-Bu4NI, Me3SI and Ph3MeAsI, either singly or in binary combinations with iodine or inorganic iodine compounds, in catalysing the synthesis of the above dialkyltins as well as higher di(n-alkyl)tin analogues is described. 相似文献
19.
邻溴苄基溴或对溴苄基溴与锡反应合成三(邻溴苄基)溴化锡(1)和四(对溴苄基)锡(2).经X射线方法测定了新化合物的晶体结构.晶体结构1属斜方六面体晶系,空间群为R-3,晶体学参数:a=1.3389(3) nm, b=1.3389(3) nm, c=2.1896(8) nm, V=3.3993(16) nm3, Z=6, Dx=2.077 Mg·m-3, μ(Mo Kα)=81.83 cm-1, F(000)=2004, R1=0.0477, wR2=0.1372;晶体结构2属正交晶系,空间群为Fdd2,晶体学参数:a=2.1027(7) nm, b=2.3034(8) nm, c=1.1431(4) nm, V=5. 536(3) nm3, Z=8, Dx=1.917 Mg·m-3, μ(Mo Kα)=67.11 cm-1, F(000)=3056, R1=0.0358, wR2=0.0659.化合物1中Sn-C键长为0.2160(8) nm, Sn-Br键长为0.2491(3) nm;化合物2中Sn-C键长分别为0.2175和0.2178 nm.中心锡与亚甲基碳(或溴)原子构成畸型四面体. 相似文献
20.
S. Yu. Bylikin S. A. Pogozhikh A. G. Shipov Vad V. Negrebetskii Yu. E. Ovchinnikov Yu. I. Baukov 《Russian Chemical Bulletin》2000,49(4):755-757
A new cation-anionic complex of hypercoordinated tin, {[L2Sn(OH)]+ BF4 ?}2 (L is a bidentate (2-oxopyrrolidino)methyl C,O-chelating ligand), was obtained by the reaction of L2SnCl2 with AgBF4 and structurally characterized by X-ray diffraction analysis. In crystalline form, the BF4 ? anions are bound to the dications through O?H...F hydrogen bonds (the H?F distance is 1.78 Å). The octahedral coordination of the Sn atoms is strongly distorted because of a weak additional interaction with solvate molecules of dioxane (the Sn?O distance is 3.16 Å). 相似文献