Production of methyltin compounds related to possible conditions in the environment

The methylation of heavy-metal compounds (e.g. mercury, lead, tin) in the environment has great significance owing to the much higher toxicity of their methyl derivatives in comparison with inorganic metal species. In this paper abiological methylation of inorganic tin is described. Ethanol, acetic acid and propionic acid abiologically methylated inorganic tin, and the highest yield of methyltin was observed in the reaction between inorganic tin(II) and ethanol. Furthermore, environmental factors for the methylation, such as pH, temperature, added ethanol, concentration of sodium chloride and photoirradiation, were investigated in this reaction. Methyltin production increased at low pH, and decreased at higher concentrations of sodium chloride. Photoirradiation accelerated the reaction rate, and a shorter wavelength showed a higher rate. Inorganic tin(II) was converted rapidly into monomethyltin, and gradually transformed into dimethyltin and trimethyltin with the course time.     

The methylation of inorganic tin by humic materials in an aquatic environment

This paper presents a study of methylation of inorganic tin (SnCl₄·5H₂O) by humic materials (humic and fulvic acids) isolated from the sediment of Tianjin Harbor, Tianjin, China, and the effects of pH, salinity, and the concentration of inorganic tin on the production of methyltin were investigated. These humic materials could methylate inorganic tin, and the methyltin product was mainly monomethyltin. Low molecular weight compounds of the humus fraction (i.e. fulvic acid) were more active in the methylation, which could be facilitated by salinity and affected by pH.     

Methylation of tin(II) by methyl iodide: influences of different environmental factors on the efficiency and reaction kinetics

The methylation reaction of Sn(II) with methyl iodide (MeI) in water has been studied using sensitive GC-QSIL-FPD technology. The pH value, amount of MeI and salinity (S) are the three important factors that influence the methylation reaction in an aquatic environment. In all experiments, monomethyltin (MMT) is the only methylation product of the tin(II) reacting with MeI observed. At the 95% confidence level, the pH, MeI and S are significant for the MMT yield. The concentration of MMT in the reactor increases with increase in pH within the selected pH range of 4–9 because four different species of Sn(II)–Sn²⁺, SnOH⁺, Sn(OH)₂⁰ and Sn(OH)₃⁻–have different reaction activities with MeI. The methylation activity of Sn(II) was found to be highest at a salinity of 0.1 M at three different pH levels: 5, 7 and 9. Higher concentration of Cl⁻ (as a relatively weak nucleophilic ion) will obstruct nucleophilic attack of Sn(II) on MeI. MMT production also increases with rising volume of MeI. Moreover, first-order reaction rates have been calculated at different pH, salinity and MeI, and found to be in the range 0.0018–0.0199 h⁻¹. The reaction rate also varies largely under different reaction conditions. One probable mechanism for the methylation reaction of Sn(II) with MeI is a S_N2 nucleophilic attack on the methyl group of MeI by Sn(II), via a process of oxidative methyl-transfer. Copyright © 2006 John Wiley & Sons, Ltd.     

Model reactions for abiotic mercury(II) methylation: Kinetics of methylation of mercury(II) by mono-, di-, and tri-methyltin in seawater

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.     

Transformations of mercury species in the presence of Elbe river bacteria

The influence of Elbe river bacteria isolated from suspended particulate matter (SPM) on dynamic species transformation of mercury was investigated. Experiments were carried out in the presence of bacteria (batch cultures) and in sterile tapwater as a control. For the methylation of inorganic mercury ions by bacteria several cofactors are under discussion. In this work, methylcobalamin, methyl iodide and S-adenosylmethionine were tested as biogenic methyl donors and trimethyl-lead chloride, trimethyltin chloride and dimethylarsenic acid as abiotic methyl donors. Transmethylation reactions as examples of abiotic methyl transfers have higher effectiveness in the formation of methylmercury (CH₃Hg⁺) than methylation with biogenic compounds. This result was observed in batch cultures as well as in sterile water. SPM-bacteria inhibit methyl transfer to mercury(II) ions. This is not only due to passive adsorption processes of mercury(II) to bacterial cell walls; methylmercury is also decomposed very rapidly by SPM-bacteria and is immobilized as mercury(II) by the cells.     

Model studies for the thiol-mediated methyl transfer to corrinoids

The thiol-dependent methylation of heptamethyl cob(II)yrinate 8r with methyl iodide and methyl tosylate was explored under a variety of conditions. The interaction of the heptamethyl cob(II)yrinate with a variety of thiols was monitored prior to the addition of the methylating agent, and the formation of the Co(I) complex was only apparent in the reaction with hexane thiol. Nevertheless, thiol-mediated methylation of the Co(II) complex 8r takes place with methyl iodide under most conditions. The Co-methylation with methyl tosylate showed a different reactivity, was inhibited by pyridine or N-methylimidazole, and was strongly dependent on the the acidity of the thiol used. Mechanistic aspects are discussed.     

Extractive spectrophotometric determination of platinum, rhodium and iridium

Platinum, iridium and rhodium in mixtures are determined sequentially, with rubeanic acid, tin(II) chloride and tin(II) iodide respectively. The working ranges (in microg) are: Pt 7-100, Rh 7-70, Ir 7-30.     

A study of methylation of inorganic tin by iodomethane in an aquatic environment with 13C carbon isotope tracer technique

The methylation of tin(II) [Sn(II)] by iodomethane (CH₃I) under environmental conditions has been further demonstrated by a ¹³C carbon isotope tracer method. Methylation products are mainly monomethyltin, and very small amounts of dimethyltin. The reaction of Sn(II) and CH₃I was investigated at pH 2, 4, 6, 8, 10 and salinity (S) 8, 15, 22, 28, 35%; it has been found the reaction was affected by pH and salinity, the tin methylation activity being highest at about pH 6 and S = 28% . The methylation reaction is first-order for both CH₃I and Sn(II), and the rate equation has been obtained as follows: .     

Arsine generation and determination of trace amounts of arsenic by atomic absorption spectrometry

Arsenic can be determined by atomic absorption spectrometry after reduction to arsine with potassium iodide, tin(II) chloride and zinc powder tablet; the arsine generated is carried into an argon-hydrogen flame by means of argon. Accuracy, precision and speed are satisfactory. Serious interferences arise only from nitric acid, lead, chromium and selenium.     

Chemical methylation of germanium(II) in model aqueous solutions

Inorganic germanium(II) in micromolar concentrations was reacted with methyl iodide (CH₃I) and methylcobalamin (CH₃-CoB₁₂) at various pH values and with different salt matrices. In all experiments monomethylgermanium was the only product. The reaction with CH₃-CoB₁₂ at pH 1 yielded approximately 1.3% of the added germanium, whereas no methylation occurred at pH 7. Reaction yields with CH₃I were lowest at pH 1 in 0.1 mol dm^?3 KCl (1.6%) and highest at pH 7.6 in artificial seawater (6%). For the reaction of CH₃?CoB₁₂ with germanium(II) a free-radical mechanism is assumed, whereas methylation by CH₃I is most likely an oxidative addition mechanism.     

Interactions of Tin(IV) and monomethyltin cation in estuarine water–sediment slurries from the great bay estuary,New Hampshire,USA

This study describes experiments on sedimentestuarine water slurries originating from a Spartina alterniflora salt marsh. We investigated the fate of tin(IV) or monomethyltin cation (MeSn³⁺) chlorides after their additon to slurries under anaerobic and aerobic conditions. We did not observe methylation of tin in anaerobic or aerobic slurries with and without added tin(IV). MeSn³⁺-amended samples occasionally formed small amounts of Me₂Sn²⁺ or Me₃Sn⁺ after extended periods of time, particularly when MeSn³⁺ remained in solution. The stability of MeSn³⁺ in slurries demonstrates that the absence of net methylation of tin(IV) is not due to rapid demethylation of MeSn³⁺ or its further methylation. Inorganic tin concentrations in the aqueous phase of anaerobic slurries spiked with MeSn³⁺ and unspiked slurries decreased by about 85% in 21 days and remained relatively constant until the end of the 59-day experiments. In similar anaerobic experiments about 25% of the MeSn³⁺ spike was adsorbed to sediment within 1 h and about 75% was adsorbed within 10 days. The lack of methylation and demethylation reactions in our aerobic and anaerobic slurries, which contrasts with two previous reports, undoubtedly reflects the absence of added nutrients and low concentrations of added tin(IV) in our experiments. We believe that our model experiments more accurately reflect conditions in salt marshes than do previous studies. We conclude that future model studies on methylation of inorganic tin should include. S. alterniflora because it is so prominent in observations of methyltin compounds in the estuary.     

Chemistry of odorants: stereoselective synthesis of octahydronaphthalene-based perfumery Georgywood, (+,−)-1-[(1R,2S)-1,2,3,4,5,6,7,8-octahydro-1,2,8,8-tetramethylnaphthalen-2-yl]ethan-1-one

A straightforward synthesis of octahydronaphthalene-based fragrance, such as Georgywood, is described. The Lewis acid tin (IV) chloride catalyzed efficiently an original one-pot sequential cycloaddition-clyclization process by reaction of myrcene with 3-bromo-but-3-en-2-one, leading directly to the octahydronaphthalene skeleton in very good yields (85%). Then, dehydrohalogenation with DBU gave the key 2,4-dienone intermediate in excellent yield (85%). Regioselective Michael addition gave rise to the formation of the addition product as a trans/cis diastereoisomeric mixture, by reaction either with CH₃Cu·BF₃ (6:1 ratio, 70%) or (CH₃)₂CuLi/TMSCl reagents (3:1 ratio, 80%). The generation of thermodynamically more stable enolate by treatment of the diastereoisomeric mixture with sodium hydride in tetrahydrofuran in the presence of an excess of methyl iodide, allowed stereoselective introduction of the methyl group at C2, leading to the formation of Georgywood in good yield (60%), as the only diastereoisomer, with a trans stereochemistry of the two methyl groups as demonstrated by NMR experiments.     

Tin(II) Chloride Dihydrate Catalyzed Groebke Condensation: An Efficient Protocol for the Synthesis of 3-Aminoimidazo[1,2-a]pyridines

The ability of tin(II) chloride dihydrate as a catalyst to promote the three-component condensation reaction from a diversity of aromatic aldehydes, 2-aminopyridines and isonitriles at room temperature is described. This methodology affords a number of 3-aminoimidazo[1,2-a]pyridines in the presence of tin(II) chloride dihydrate as a new and mild Lewis acid catalyst in the multi-component reaction in reasonable yields and short reaction time without any significant optimization of the reaction conditions.     

羟基磷灰石固载路易斯酸催化三糖转化为乳酸酯

采用浸渍法制备了羟基磷灰石(HAP)负载的路易斯酸SnCl2和SnCl4催化剂.它们在三糖在醇溶液中转化为乳酸酯反应中表现出一定的催化活性.在最佳的反应条件下,SnCl2/HAP催化1,3-二羟丙酮在正丁醇溶液中转化为乳酸正丁酯,收率高达73.5%.     

Influence of humic substances on sorption and methylation processes of inorganic- and organo-tin species

The influence of humic substances on sorption and methylation processes for inorganic- and organotin species is presented. Four sediment samples from different locations of the Rivers Elbe, Mulde and Spittelwasser, Germany, with different organotin and humic contents were selected to extract the humic and fulvic acids. The various fractions—the original sediment, the humic acid, the fulvic acid and the residual sediment—were analysed for their organotin content. The individual buyltin species show quite different distribution patterns. Monobutyltin is found mostly associated with humic acids. Dibutyltin shows a nonunique behaviour. At low total organotin content, dibutyltin is found bonded to humic and fulvic acids, whereas at high organotin content dibutyltin is distributed more with the residual sediment. Most of the tributyltin remains in the sediment unextracted; only small quantities of it are in the fulvic acid fraction. Tetrabutyltin is only in the humic acid fraction when it binds to humic matter; it mostly remains in the sediment. General observations indicate that ionic butyltin species bind to fulvic acids whereas the non-polar tetrabutyltin is not found in the fulvic acid fractions in any of the samples. The appearance of monomethyl- and dimethyl-tin species in the humic and fulvic acid fractions after the alkaline extraction was surprising. There is a correlation between the humic content of the sample and the formation of methyltin species. Evidence is provided by experiments that humic substances act as methylation agents.     

Extractive separation and spectrophotometric determination of palladium and platinum with dithizone in the presence of stannous chloride

The conditions [acid used, presence of chloride and tin(II)] for the extractive separation and spectrophotometric determination of palladium and platinum as the dithizonates Pd(HDz)(2) and Pt(HDz)(2) have been examined. In the absence of stannous chloride platinum does not undergo extraction. Conditions for the separation and determination of these metals in the presence of mercury, gold and copper, which are also extracted with dithizone into carbon tetrachloride or chloroform under the conditions suitable for palladium (1M sulphuric acid/0.1M hydrochloric acid), have been defined. The mercury and gold dithizonates are formed quickly and can be removed before the palladium and platinum compounds have had time to form. They can be decomposed with iodide. Copper dithizonate is decomposed by reduction with tin(II). The proposed procedure has been applied to the determination of palladium in technical platinum metal.     

COMMUNICATION: CATALYSIS OF METHYL ACETATE FORMATION FROM METHANOL ALONE BY (η5-C5H5)(PPh3)2RuX (X = Cl,SnCl3, SnF3): HIGH ACTIVITY FOR THE SnF3 COMPLEX

Abstract

We have recently shown^1,2 that the Ru(II)-Sn(II) bimetallic complex can catalyze the unprecedented one-step formation of acetic acid (or methyl acetate) with methanol used as the sole source. It was suggested that the reaction consists of sequential processes of methanol → formaldehyde (methylal) → methyl formate → acetic acid (methyl acetate). While the Ru(II) complexes capable of catalyzing the dehydrogenation of methanol into methyl formate are known,^3–5 this catalyst system is unique because of its extra ability to isomerize methyl formate to acetic acid without a CO atmosphere (usually high pressure) or an iodide promoter (often corrosive to reaction apparatus).⁶ In this communication, we examine the cyclopentadienyl bis(triphenylphosphine) ruthenium(II) auxilliary in view of its well-defined geometry and configurational stability,⁷ and demonstrate that combination with the SnF₃ ^? ligand⁸ gives quite high catalytic ability compared to the conventional⁹ SnCl₃ ^? ligand.     

Arsenic colorimetry with silver diethyldithiocarbamate

The effect of 22 interferences had been studied. Sulfur(II) must be oxidized by nitric acid; germanium, nitric acid, and perchloric acid must be removed by repeated evaporation with hydrochloric acid. Antimony, phosphate, selenium, tellurium, iron, tin, copper, nickel, and many other elements are eliminated by extraction of arsenic(III) chloride in concentrated hydrochloric acid with p-xylene or benzene. Metal ions forming complex or insoluble iodide can be blocked with an excess of potassium iodide. The method enables the determination of 2–30 μg of arsenic with a relative error <10%. It was tested with the materials of copper production.     

Synthesis of oxime bearing cyclophosphazenes and their reactions with alkyl and acyl halides

Two novel cyclophosphazenes containing oxime groups were prepared from the hexakis(4‐formylphenoxy)cyclotriphosphazene ( 2 ) and hexakis‐(4‐acetylphenoxy)cyclotriphosphazene ( 7 ). The reactions of these oximes with acetyl chloride, chloroacetyl chloride, methyl iodide, propyl chloride, mono‐ chloroacetone, and 1,4‐dichlorobutane were studied. Hexasubstituted compounds were obtained from the reactions of hexakis(4‐[(hydroxyimino)methyl]phenoxy)cyclotriphosphazene ( 3 ) with acetyl chloride ( 4 ) and chloroacetyl chloride ( 5 ); however, tetrasubstituted product was obtained from methyl iodide ( 6 ). Tetra‐ and trisubstituted products were obtained from the reactions of hexakis(4‐[(1)‐N‐hydroxyethaneimidoyl]phenoxy)cyclotriphosphazene ( 8 ) with acetyl chloride ( 9 ) and chloroacetyl chloride ( 10 ), respectively. All products were obtained in high yields. Pure and defined product could not be obtained from the reaction of 8 with methyl iodide, and could not be also obtained from the reactions of 3 and 8 with propyl chloride, monochloroacetone, and 1,4‐dichlorobuthane. The structures of the compounds were defined by elemental analysis, IR, ¹H, ¹³C, and ³¹P NMR spectroscopy. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:112–117, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20176     

Dialkyl (Alkylene) Dithiophosphate Adducts of Anhydrous Stannous Chloride: Synthesis,Characterization, and Biological Activities

Abstract

Dialkyl (alkylene) dithiophosphate adducts of stannous chloride were synthesized by the reaction of anhydrous tin(II) chloride (SnCl₂) and dialkyl (alkylene) dithiophosphoric acid in a 1:1 molar ratio, under anhydrous reaction conditions, below 5 °C in a closed vessel. The newly synthesized adducts were characterized by physicochemical and spectroscopic techniques [FT-IR, NMR (¹H, ³¹P, and ¹¹⁹Sn), and mass spectrometry]. Coordination modalities have indicated a donor–acceptor interaction between sulfur and tin(II) moieties, where tin(II) acts as a Lewis acid. The adducts were found to have significant antibacterial activity against Escherichia coli and Pseudomonas aeruginosa, and antifungal activity against Aspergillus niger and Candida albicans.

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.