Search

This study investigates the effectiveness of sludge in coagulation-flocculation treatment for suspended solids (SS) removal from landfill leachate using Tin (IV) chloride and Jatropha curcas seed (...

A tin(IV) chloride promoted (3 + 2) annulation of trans-2-aroyl-3-styrylcyclopropane-1,1-dicarboxylates with nitriles is reported. The transformation involves the Lewis acid assisted formation of 1,5-dipolar intermediates from the cyclopropane dicarboxylates and nitriles followed by cyclization. The reactions proceed in a highly diastereoselective manner and afford 5-vinyl-1-pyrroline derivatives in 60–88% yields.

A synthesis of a series of novel fused tricyclic heterocyclic compounds has been achieved in one-pot reaction set up starting from (E)-3-(2-oxo-2-phenylethylidene)indolin-2-one and 1,4-benzoxazinone/quinoxalinone derivatives promoted by tin(IV) chloride. The reaction is supposed to occur via a sequential intermolecular Michael addition of the 1,4-benzoxazinone derivatives to the oxindoles, intramolecular cyclization, and aromatization with the elimination of water. Apart from spectroscopic characterization, the structure of one of the pyrrolo[1,4]benzoxazinone derivative is confirmed by single-crystal X-ray diffraction. Thus, the developed domino protocol provides easy access to multifunctional pyrrolo[1,4]benzoxazines in one-pot with high efficiency.

Landfill leachate is highly polluted and generated as a result of water infiltration through solid waste produced domestically and industrially. This study investigated the applicability of the response surface methodology (RSM) to optimize the removal performances of chemical oxygen demand (COD), color, and suspended solids (SS) from landfill leachate by coagulation process using Tin tetrachloride pentahydrate. The leachate samples were collected from Alor Pongsu Landfill (APLS) in Perak, Malaysia. Before starting the experiments, general characterization was carried out for raw leachate samples to investigate their physical and chemical properties. The effects of the dosage and pH of SnCl4 on the removal performances were evaluated as well. An ideal experimental design was performed based on the central composite design (CCD) by RSM. In addition, this RSM was used to evaluate the effects of process variables and their interaction toward the attainment of their optimum conditions. The statistical design of the experiments and data analysis was resolved using the Design-Expert software. Further, the range of coagulant dosage and pH was selected based on a batch study which was conducted at 13000 mg/L to 17000 mg/L of SnCl4 and pH ranged from 6 to 10. The results showed that the optimum pH and dosage of SnCl4 were 7.17 and 15 g/L, respectively, where the maximum removal efficiency was 67.7% for COD and 100% for color and SS. The results were in agreement with the experimental data with a maximum removal efficiency of 67.84 %, 98.6 %, and 99.3%, for COD, color, and SS, respectively. Overall, this study verified that the RSM method was viable for optimizing the operational condition of the coagulation-flocculation process.

The authors are grateful to the Tunisian Ministry of High Education and Scientific Research and Technology for financial support of this research Bisphosphonates of the types X(P(O)(OEt)2)2 (X = CH2=C (1a), CNCH2CH (1b) and PhCH2NCH2CH (1c)) react with SnCl4 in anhydrous dichloromethane to produce the new tin(IV) adducts [SnCl4(1a)] (2a), [SnCl4(1b)] (2b) and [SnCl4(1c)] (2c) in 72-80% yields. These complexes were characterized using IR, multinuclear (1H, 13C, 31P, 119Sn) NMR spectroscopy, elemental analysis, and in one case by single crystal X-ray diffraction. The NMR data show that the bisphosphonate ligands are coordinated to the tin center in a bidentate fashion forming cis octahedral tin complexes. Furthermore, the X-ray structure of complex 2b reveals that the bisphosphonate ligand is coordinated in a bidentate manner to the metal center in a distorted octahedral arrangement with Sn-O-P bond angles in the range 135.95(16)–137.99(18)°. The P=O and Sn-O bond lengths of 1.495(3)-1.497(3) and 2.134(3)-2.146(2) Å, respectively are in the order expected for phosphonate tin(IV) complexes. The results are discussed and compared with closely related analogues. Postprint

A series of novel 1-(4-amino-6-methyl-1-aryl-1H-pyrazolo[3,4-b]pyridin-5-yl)-ethanones and 6-methyl-1-aryl-1H-pyrazolo[3,4-b]pyridin-4-amines were prepared by the annulation of 5-amino-1-aryl-1H-pyrazole-4-carbonitriles with acetylacetone in the presence of tin(IV) chloride. The results demonstrated that the ethanones are the precursors of second compounds.

Tin disulfide thin films were prepared with different molarities of tin species (MSn) at the optimized substrate temperature using the Nebulized Spray pyrolysis technique to obtain better crystallinity with mono phase thin films. The concentration of Tin IV chloride Penta hydrate precursor is varied from 0.05:0.4 to 0.25:0.4 (SnCl4.5H2O: thiourea) to achieve correct stoichiometry and to tune the concentration of Tin ions in the SnS2 thin films. These films were well adherent, uniform, and shiny. Lower concentrations of Tin yields highly textured SnS2 thin films with (001) crystallite orientation. On increasing the concentration, the multi-phases (SnS and Sn2S3) were found to be present along with SnS2 material. The platelet-like grains were observed from SEM analysis in these SnS2 films. Multiple interference effects were predominant in all these thin films in the wavelength region of 600–1100 nm. The direct optical band gap of tin disulfide thin films had decreased from 3.2 eV to 2.75 eV with an increase in MSn from 0.05 to 0.2 M, respectively, and further increased to 3.0 eV for 0.25 M concentration. Using Hall Effect measurement, the type of semiconductor is found to be of n-type. A minimum resistivity value of 2.19 × 103 Ω cm was obtained for the film grown at MSn = 0.2 M.

This paper investigates the third-order nonlinear optical properties of 4α-(4-tert-butylphenoxy) phthalocyaninato dichlorotin(IV) (α-SnOtBpPc) and 4β-(4-tert-butylphenoxy) phthalocyaninato dichlorotin(IV) (β-SnOtBpPc) in different organic solvents. The third-order susceptibilities of α-SnOtBpPc and β-SnOtBpPc are reported in different solvents, using Z-scan techniques with 10 ns laser pulses at 532 nm. Their nonlinear absorption coefficient and absorption cross sections were also determined. The molecular imaginary components of the second-order hyperpolarizability Im[γ] of α-SnOtBpPc and β-SnOtBpPc were found to be 2.60 × 10–31 and 2.94 × 10–31 esu (tetrahydrofuran), 2.12 × 10–31 and 2.54 × 10–31 esu (chloroform), 3.06 × 10–31 and 2.54 × 10–31 esu (dichloromethane), and 1.27 × 10–31 and 1.50 × 10–31 esu (toluene), respectively. This study found that substitution at the α position has an effect of lowering the two-photon (2PA) cross section value for α-SnOtBpPc compared to that for β-SnOtBpPc, with values...

The hydrothermal treatment of pentose-rich corncob under microwave irradiation was performed using SnCl4 as catalyst for furfural production in this study. The influences of the catalyst amount, reaction temperature and reaction time on the compositions of the hydrolysate and solid residue were discussed comparatively. The solid residue obtained was characterized by FTIR, XRD and SEM. The results showed that the cell wall structure of the treated corncob was destroyed to a certain extent under the function of catalysts during the treatment, and most of the hemicelluloses were released from the cell wall and entered the hydrolysate as hemicellulose-derived sugars, followed by the selective dehydration to furfural. When the temperature reached the preset value of 190 °C under microwave irradiation, the highest furfural yield of 9.0 wt% (based on the dry weight of corncob) was achieved from the one-step conversion of corncob under the microwave-assisted hydrothermal treatment with a 1 % amount of SnCl4 (based on the dry weight of corncob) and a solid-to-liquor ratio of 1:20.

A novel SnCl4-promoted tandem reaction toward multisubstituted indenes via a sequential C-O bond cleavage/Nazarov cyclization/nucleophilic addition reaction has been developed to afford a series of multisubstituted indenes with an all-carbon quaternary center in moderate to good yields.

Synopsis Total cross section for electron scattering from SnCl4 molecules has been measured for energies from 0.6 to 300 eV. Obtained results have been compared with total cross sections for electron scattering from other tetrachoride molecules: XCl4 where X=C, Si, Ge.

Benzyl esters are cleaved upon reaction with SnCl4, resulting in isolation of the corresponding carboxylic acid. Importantly, benzyl ethers, amines, and amides do not undergo debenzylation under these conditions, nor do a variety of other common protecting groups for alcohols, thereby rendering SnCl4 selective amongst Lewis acids. The scope, tolerance, and limitations of the strategy are demonstrated through the analysis of several multifunctional substrates, including those bearing Cbz groups.

Novel pyrrolo[2,3-d]pyrimidines 5a–j, 6a–j and pyrrolo[2,3-b]pyridines 7a–h; incorporating the common vicinal diaryl motif of tumor necrosis factor-α (TNF-α) inhibitors, were synthesized starting from 2-amino-pyrrole-3-carbonitriles 1a–h. The structures of synthesized compounds were elucidated by spectral data (IR, NMR, and MS) and elemental analyses. Representative compounds were evaluated for their ability to inhibit lipopolysaccharide-induced TNF-α production in vivo in rat at 25 mg/kg p.o. Structure activity relationships are described. The pyrrolo[2,3-d]pyrimidines displayed better inhibitory activity than the pyrrolo[2,3-b]pyridines. The most potent among the biologically tested compounds was the pyrrolopyrimidine 5h (N-(4-ethoxyphenyl)-2-(4-oxo-6-phenyl-7-(pyridine-4-yl)-4H-pyrrolo[2,3-d]pyrimidin-3(7H)-yl)acetamide),showing TNF-α inhibitory activity (96 %) comparable to that of dexamethasone (91 %).

A series of novel N-acylsulfonamides derivatives were synthesized via direct condensation of parent sulfonamide with ethyl lactate as an acylating agent in the presence of tin (IV) chloride (SnCl4) as a Lewis acid catalyst. The sulfonamides were prepared, starting from chlorosulfonyl isocyanate (CSI), in three steps (carbamoylation, sulfamoylation, and deprotection) with excellent yields.

The reaction of SnCl4 with β-chlorovinyl aldehydes in anhydrous dichloromethane gave a series of octahedral complexes of the general formula SnCl4·2L (L = aldehyde). The adducts have been characterized in solution using multinuclear (1H, 13C, and 119Sn) NMR and IR spectroscopy. Solution NMR studies show that the complexes undergo rapid ligand dissociation at ambient temperature. Ligand exchange is slowed significantly at low temperature, such that, in most of the complexes, it is possible to identify both the cis and trans isomers with predominance of the cis form. The magnitude of the metal-ligand interaction was estimated on the basis of 119Sn NMR chemical shifts and used to classify the aldehydes studied according to their Lewis basicity.

Leachate production from landfilling contributes crucial pollutants to the environment. This study examined the potential of tin (IV) chloride as coagulant that involved charge neutralization and sweep flocculation mechanisms. The negative charge of leachate is neutralized by adding tin (IV) chloride as cationic coagulant which resulted precipitation and swept most of the colloids and dissolved solids that entrapped in the settling as hydrous oxide floc. Parameters such as suspended solid (SS) content, color, and chemical oxygen demand (COD) were analyzed using standard jar test procedures. The best condition was observed at pH 8, with removal efficiencies of 75.99 %, 99.29 % and 98.36 % for COD, SS, and color, respectively. At optimum dosage, tin (IV) chloride successfully removed 98.40 % for color, 99.54 % for SS and 71.53 % for COD. These results indicated the satisfactory performance of tin (IV) chloride. Hence, tin (IV) chloride is a potential coagulant for the treatment of Alor Pongsu Landfill leachate.

A group of substituted oxiranes were readily transformed to the corresponding β-hydroxyhydroperoxides (HHP) in good yields in ethereal SnCl4–H2O2 system in which SnCl4 acts as catalyst. Alternatively, treating oxiranes with SnCl4 first, followed by addition of ethereal H2O2 solution achieved primary gem-dihydroperoxides (DHP) in moderate yields. In the case of preparing DHP, SnCl4 first promoted the rearrangement of oxiranes to aldehydes, followed by condensation with hydrogen peroxide to provide DHP as final products.

The title compounds are partially condensed products of hydrolysed tri­methyl­tin chloride. In the two structures, short cationic tris­tannatoxanes (C9H29O2Sn3) are bridged by a diformatotri­methyl­tin anion or a chloride anion., The title compounds, [Sn3(CH3)9(OH)2(H2O)2][Sn(CH3)3(CHO2)2] (1) and [Sn3(CH3)9(OH)2]Cl·H2O (2), are partially condensed products of hydrolysed tri­methyl­tin chloride. In the structures of 1 and 2, short cationic tris­tannatoxanes (C9H29O2Sn3) are bridged by a diformatotri­methyl­tin anion or a chloride anion, respectively. Hydrogen bridges are present and supposedly stabilize these structures against further polymerization to the known polymeric tri­methyl­tin hydroxide. Especially noteworthy is that the formate present in this structure was formed from atmospheric CO2.

A novel SnCl4-promoted tandem reaction toward multisubstituted indenes via a sequential C-O bond cleavage/Nazarov cyclization/nucleophilic addition reaction has been developed to afford a series of multisubstituted indenes with an all-carbon quaternary center in moderate to good yields.

Organotin compounds are high toxiferous chemicals and ubiquitous in our environment, which also have high biological activities. Di-n-butyl-(4-chlorobenzohydroxamato)tin (IV) chloride (DBDCT) represents a new paradigm for tin-based antitumor complexes with high activity. The inhibitory effect of DBDCT on cytochrome P450 3A(CYP3A) was studied in this article. The adult male SD rats were randomly divided into five groups with six in each and treated separately with saline, lipopolysaccharide (LPS, 5mg/kg), DBDCT (1.25, 2.5 and 5.0mg/kg, respectively) intraperitoneally for 2 days after induced with dexamethasone (DEX) at a dose of 100mg/kg for 4 days. The cytochrome P450 (CYP450) content was assayed by the method of Omura and Santa after the protein concentration detected by BCA assay kit. The activity of CYP3A was determined by the method of Nash. Western blot analysis was used to detect the expression of CYP3A1/2 at protein level in rat liver microsomes and Buffalo Rat Liver (BRL) cells. The results demonstrated that the activity of CYP450 and CYP3A were inhibited by exposure to DBDCT in rat liver compared with that of the blank control group. The expression of CYP3A1 and CYP3A2 proteins in rats treated with 1.25, 2.5 and 5.0mg/kg DBDCT were down-regulated respectively by 22.8% (p

Thermal behavior of poly (methyl methacrylate) was analyzed in the presence of tin (IV) chloride. Five different proportionspolymer to additivewere selected for casting films from common solvent. TG, DTG and DTA were employed to monitor thermal degradation of the systems. IR and py-GC-MS helped identify the decomposition products. The blends start degrading at a temperature lower than that of the neat polymer and higher than that of the pure additive. Complex formation between tin of additive and carbonyl oxygen (pendent groups of MMA units) was noticed in the films soon after the mixing of the components in the blends. The samples were also heated at three different temperatures to determine the composition of residues left after the expulsion of volatiles. The polymer, blends and additive exhibited a one step, two-step and three-step degradation, respectively. T0 is highest for the polymer, lowest for the additive and is either 60 o C or 70 o C for the blends. The amount of residue increases down the series (moving from blend-1 (minimum additive concentration) to blend-5 (maximum additive concentration)). For blend-1, it is 7% of the original mass whereas it is 16% for blend-5. Tmax also goes up as the concentration of additive in the blends is elevated. The complexation appears to be the cause of observed stabilization. Some new products of degradation were noted apart from those reported earlier. These included methanol, isobutyric acid, acid chloride, etc. Molecular-level mixing of the constituents and "positioning effect" of the additive may have brought about the formation of new compounds. Routes are proposed for the appearance of these substances. Horizontal burning tests were also conducted on polymer and blends and the results are discussed. Activation energies and reaction orders were calculated. Activation energy is highest for the polymer, i.e., 138.9 Kcal/mol while the range for blends is from 51 to 39 Kcal/mol. Stability zones are highlighted for the blends. The interaction between the blended parts seems to be chemical in nature.

Four octahedral complexes of the type SnCl4.2L [L = (R2N)3P(E): E = Se; R = Me(1), Et(2) and E = S; R = Me(3), Et(4)] have been studied in solution by multinuclear (31P, 77Se, and 119Sn) NMR spectroscopy. 31P and 77Se NMR data were informative of changes associated with complex formation. The solution structure of the complexes was confirmed by their 119Sn NMR spectra that showed two triplet features for each complex, attributed to a mixture of the expected cis and trans isomers. The triplet signal is due to the coupling with two equivalent phosphorus atoms, consistent with an octahedral geometry around the tin center. In addition, density functional theory (DFT)/B3LYP calculations have been carried out to support the interpretations of NMR data. The results are discussed and compared with those reported for related complexes. GRAPHICAL ABSTRACT

Mono-, di- and trisaccharide representing the reducing terminal of the core structure of N-glycans were incorporated into Leu-Lys-Asn-Gly-Gly-Pro hexapeptide that is a partial structure of the Trp-cage mini-protein by linear assembly. These studies provide evidence that the used combination of Fmoc and Boc strategy and mild conditions result in glycopeptides in high purity and reasonable yield.

The surfactant sodium bis(2-ethylhexyl) sulfosuccinate based tin(IV) phosphate (AOT-SnP) fibrous ion exchanger has been synthesized and characterized by using different physico-chemical methods. The characterization of the exchanger was performed by using infrared (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and elemental analysis. The ion exchange property was studied by determining the ion exchange capacity, elution and concentration behavior of the cation exchanger. The thermal behavior of exchanger was studied by performing ion exchange capacity at different temperatures. Adsorption studies on the synthesized material showed that it is highly selective for Cd2+, Zn2+and Hg2+ ions. Therefore, the separation of Cd2+, Zn2+and Hg2+ ions from the synthetic waste water has been performed on its column and observed to be quite effective in presence of acid, alkali, alkaline earth and other transition metals.

A facile synthesis of potential acetylcholinesterase (AChE) inhibitors, the tacrine analogues 3a-p, has been accomplished by direct cyclocondensation of 1-aryl-4-cyano-5-aminopyrazole with β-ketoesters using tin(IV) chloride as catalyst. The structures of all the compounds have been confirmed by IR, ¹H- and ¹³C-NMR.

The title compound was crystallized according to the solid–liquid phase diagram at lower temperatures. It is built-up of SnCl4(H2O)2 octa­hedral units and lattice water mol­ecules. An intricate three-dimensional network of O—H⋯O and O—H⋯Cl hydrogen bonds between the complex molecules and the lattice water molecules is formed in the crystal structure., The title compound, [SnCl4(H2O)2]·6H2O, was crystallized according to the solid–liquid phase diagram at lower temperatures. It is built-up of SnCl4(H2O)2 octa­hedral units (point group symmetry 2) and lattice water mol­ecules. An intricate three-dimensional network of O—H⋯O and O—H⋯Cl hydrogen bonds between the complex molecules and the lattice water molecules is formed in the crystal structure.

Formal [4 + 2] cycloaddition between various 3-ethoxycyclobutanones and allyltrialkylsilanes proceeded to give 3-ethoxy-5-[(trialkylsilyl)methyl]cyclohexan-1-ones by catalysis with tin(VI) chloride. The use of allyl-tert-butyldiphenylsilane induced 1,5-hydride transfer, which gave 2-[3-(tert-butyldiphenylsilyl)propyl]-6-methyltetrahydro-4-pyrones.

Dimethyl(thioacetato)tin chloride (1) was synthesized by the reaction of dimethyltin dichloride with thioacetic acid in the presence of triethylamine. Compound 1 was subjected to hydrolysis under different reaction conditions in order to obtain sulfido/hydrosulfidotin compounds. Except for one case where the product was hexamethyl-1,3,5-trithia-2,4,6-tristannacyclohexane, (Me2SnS)3 (4), all other reactions led to desulfurization, and the products obtained were organostannoxane compounds, dinuclear tetramethyl-oxo-dichloroditin, {Me2SnCl2.Me2SnO} 2 (2), and tetraacetatodioxotetra( dimethyltin), (Me2Sn)4O2(O2CMe)4 (3). These complexes have been characterized by 1H, 13C, 119Sn NMR and FTIR spectroscopy, and compounds 2 - 4 also by X-ray crystallography. Density functional calculations were performed to explain the structure and reactivity of the compounds.

Polymers having bis(cyclopentadienyl)titanacyclopentadiene units in the main chain were prepared by the polymerization of a low-valent bis(cyclopentadienyl)-titanium(II) complex, generated in situ from bis(cyclopentadienyl)titanium dichloride (Cp2TiCl2) and n-butyllithium (2 equiv), with internal diynes such as 1,4-bis(1-hexynyl)-benzene and 4,4′-bis(1-hexynyl)biphenyl. The bis(cyclopentadienyl)titanacyclopentadiene-containing polymers were subjected to the reaction with tin(IV) chloride, followed by the treatment with methyllithium to give 1,1-dimethylstannole-containing organometallic polymers in moderate yields. The stannole containing polymers are soluble in organic solvents, whose number-average molecular weight was estimated to be 2,700–2,800 by GPC. Optical and electrochemical properties of the resulting stannole-containing polymers were studied by their UV-vis spectra and cyclic voltammetric analyses, from which they were supposed to have low LUMO energy levels.

The stereochemistry of four octahedral complexes SnCl 4 ·2(O)PCl(NR 2 ) 2 (R = Me ( 1 ); R = Et ( 2 )) and SnCl 4 ·2(O)PCl 2 NR 2 (R = Me ( 3 ); R = Et ( 4 )) was studied by both multinuclear ( 1 H, 31 P and 119 Sn) NMR spectroscopy in solution and density functional theory (DFT) calculation. The NMR data suggest the presence in dichloromethane solutions of a mixture of cis and trans isomers for 1 and 2 , whereas only the cis isomer is observed for 3 and 4 . Moreover, the latter complexes showed partial ligand dissociation in solution. The assignment of the cis and trans isomers was based on the NMR chemical shifts and particularly on the magnitude of the 2 J ( 31 P– 119 Sn) coupling constant obtained in both solution NMR and DFT studies. In addition, the stereochemistry observed was shown to be highly dependent on the steric hinderance and/or the Lewis basicity of the phosphine oxide ligand. DFT/B3LYP calculations which compared favourably with the experimental data provided further insight into the coordination at the tin atom. The results obtained for both complexes are compared with those of the hexamethylphosphoramide complex.

The reaction of meso -tetraarylporphyrins (H 2 T(X)PP) with SnCl 4 affords green intermediate sitting-atop (i-SAT) complexes, [(H 2 T(X)PP)SnCl 4 ]. UV–Vis, 1 H NMR and 13 C NMR spectral data show that the porphyrin core of the complexes is distorted, thus two nitrogen atoms of the pyrrolenine groups on one side of the porphyrin plane act as electron donors to the tin center of SnCl 4 . The intermediate sitting-atop (i-SAT) complex is formed each time during the incorporation of the metal center, where in the intermediate state the pyrrolic protons still remain on the porphyrin.

The two octahedral complexes SnCl4 · 2(O)P(NR2)2OCH2CF3 (R = Me (1) or Et (2)) have been prepared from SnCl4 and the ligands (R2N)2P(O)OCH2CF3 in chloroform solution. Both adducts have been characterised by (31P and 119Sn) NMR, IR spectroscopy and elemental analysis. The NMR data show that the complexes exist as mixtures of cis and trans isomers in solution with the latter isomer being the predominant species. The structure of 1 has been determined by X-ray crystallography. Accordingly, the structure is centrosymmetric and the two ligands are bound trans to each other in the octahedral tin complex. DFT/B3LYP calculations show that trans configuration does indeed lead to the lowest energy species. Comparison of the structural, NMR and theoretical data of both complexes with those related to SnCl4 · 2L (L = (Me2N)3P(O) and (Me2N)2P(O)F) further supports the important effects of the nature of the substituents in the ligand on the stereochemistry of the complex formed.

The rate of thermal decomposition of azobisisobutyronitrile (AIBN) dissolved in xylene was investigated alone and in the presence of tin(IV) chloride over the temperature range of 90-107 o C. It was found that the decomposition rate of AIBN increases linearly with increasing concentration of tin(IV) chloride, which suggests the formation of an activated complex between AIBN and tin(IV) chloride. A parallel reaction mechanism is proposed to describe the kinetic behavior. The Arrhenius relationships of rate constants were also obtained

The three isostructural compounds butyl­ammonium hexa­chlorido­tin(IV), pentyl­ammonium hexa­chlorido­tin(IV) and hexyl­ammonium hexa­chlorido­tin(IV), (CnH2n+1NH3)2[SnCl6], with n = 4, 5 and 6, respectively, crystallize as inorganic–organic hybrids. As such, the structures consist of layers of [SnCl6]2− octa­hedra, separated by hydro­carbon layers of inter­digitated butyl­ammonium, pentyl­ammonium or hexyl­ammonium cations. Corrugated layers of cations alternate with tin(IV) chloride layers. The asymmetric unit in each compound consists of an anionic component comprising one Sn and two Cl atoms on a mirror plane, and two Cl atoms in general positions; the two cations lie on another mirror plane. Application of the mirror symmetry generates octa­hedral coordination around the Sn atom. All compounds exhibit bifurcated and simple hydrogen-bonding inter­actions between the ammonium groups and the Cl atoms, with little variation in the hydrogen-bonding geometries.

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.

Two octahedral complexes of the general formula SnCl 4 · 2(O)PF 2 NR 2 (R = Me ( 1 ) or Et ( 2 )) have been synthesised from SnCl 4 and the ligand R 2 NP(O)F 2 in anhydrous CHCl 3 . The new adducts have been characterised by multinuclear ( 119 Sn, 31 P, 19 F and 1 H) NMR, IR spectroscopy and elemental analysis. When compared with previously described hexamethylphosphoramide (HMPA) and trimethylphosphate (TMPA) analogues, the NMR data of the two complexes prepared suggest the presence of only the cis isomer in solution. Steric factors and the Lewis basicity of the ligand may explain the stereochemistry observed. Low temperature 31 P and 119 Sn NMR spectra show that the compounds partially dissociate in dichloromethane. Additionally, DFT/B3LYP calculations on complex 1 and its ligand have been carried out to support the interpretations of NMR data.

The compound bis(acetylacetonato)dichlorotin(IV) [Sn(acac)2Cl2] forms a distorted octahedral structure involving both oxygen atoms of the acetylacetone group. The two chlorides occupy the cis position, with Sn-Cl distances of Sn1-Cl1 = 2.380(2) A, Sn1-O1 = 2.043(2) A and Sn1-O2 = 2.093(2) A. We report here a new and simple method for the synthesis of Sn(acac)2Cl2, its spectroscopic characterization and, for the first time, we report its crystal structure.

We have developed a new method of N-nitrosation of various secondary and tertiary amines, amides and ureas using a mixture oftin(IV) chloride and sodium nitrate. This method leads to a selective, high-yielding and mild heterogeneous N-nitrosation by in situ generation of nitrosyl chloride (NOCl). The reaction can be carried out in several different solvents such as chloroform, dichloromethane, ethers, ethyl acetate and alcohols, at room temperature.

Trimethyltin(IV)trithiophosphates [(RO)P(S)S2][Sn(Me)3]2 and tributyl tin(IV)trithiophosphates [(RO)P(S)S2][Sn(Bu)3]2 (R=CH3, –C2H5, –C3H7, –C3H7 iso –C4Hn 9, –C4H9 iso, –C4H5 scc, –C5H11 iso C6H11, –C6H5) were prepared in methanolic solution of R3SnCl and dipotassium salt of trithiophosphates in 2:1 molar ratio. These newly synthesised derivatives have been characterized by elemental analysis, molecular weight measurements, IR, 13C, 31P, and 119Sn,NMR spectral studies. Coordination number of four suggested for tin(IV) in these derivatives.

The synthesis of the polysubstituted 8-oxa-1-azaphenalene lactone 4, which embodies the ABCring system of stephaoxocani dine, a tetracyclic isoquinoline alkaloid recently isolated from the tubers of Stephania cepharantha Hayata, is reported. Elaboration of 4 was carried out by means of the camphorsulfonic acid-assisted lactonization of 9, coupled to a titanium(IV) chloridemediated acetal cyclization of the resulting lactone 10 to form the tricyclic intermediate 12, followed by the base-promoted aromatization of the latter to 13 and final benzylic bromination. Lactone 4 constitutes an advanced key intermediate for the total synthesis of stephaoxocanidine, the simplest stephaoxocane.

The compounds [SnCl4(L)n] (where L is pyridine (py), 4-methylpyridine (γ-pico), 3-methylpyridine (β-pico), piperidine (pipd), morpholine (morph), piperazine (pipz), 3-cyanopyridine (3-cyanopy), 4-cyanopyridine (4-cyanopy), quinoline (quin) or 2,2′-bipyridine (bipy) and n=2, 1 or 3/2) were synthesized and characterized by elemental analysis, melting points, thermal studies and IR spectroscopy. The enthalpies of dissolution of adducts, tin(IV) chloride and ligands in 1,2-dichloroethane or 25% (v/v) aqueous HCl 1.2 M in methanol were measured and, by using thermochemical cycles, the following thermochemical parameters for the adducts have been determined: the standard enthalpies for the Lewis acid/base reaction (ΔrH°), the standard enthalpies of formation (ΔfH°), the standard enthalpies of decomposition (ΔDH°), the lattice standard enthalpies (ΔMH°) and the standard enthalpies for the Lewis acid/base reaction in the gaseous phase (ΔrH°). The mean standard enthalpies of the tin–nitrogen bonds ( D ( Sn – N ) ) have been estimated. Based on these last values, the basicity orders: pipd>morph>γ-pico=β-pico>py>4-cyanopy>3-cyanopy and pipz>quin are obtained.

In the presence of SnCl 4 .5H 2 O, a mixture of thiols and tetraallyltin underwent 1,4- and 1,2-addition, respectively, with the imines derived from 3-alkynals to give (Z)-1-sulfenyl-1,5-alkadien-3-ols in good yields, wherethe hydrolysis of the intermediary imino species was found to be crucial.

trans-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates when reacted with nitriles in the presence of tin(IV) chloride afford 2,4,5-trisubstituted oxazoles in good to excellent yields. The reactions take place through in situ generation of aroylmethylidene malonates from the cyclopropanes, followed by conjugate addition of nitriles to the malonates to form nitrilium ion intermediates and subsequent cyclisation.

Tin(IV) chloride selectively promotes the nucleophilic attack of methyl acetoacetate to the cyano instead of the olefinic carbon atom of α,β-unsaturated nitriles to give enaminoketoesters. In the presence of an excess of ketoester a second C–C bond formation occurs followed by cyclisation affording substituted pyridines in a selective cascade sequence.

The reaction of benzil with phenol at 180°C in the presence of SnCl4·5H2O produces a benzofuran, a benzofuranol, a benzodifuran, and a benzofuranone. Anhydrous tin(IV) chloride also gives a benzofuranofuranone. Other phenols and their methyl ethers yield related products. The good yields of the benzo- and naphtho-furanones make the method an attractive alternative to the benzilic acid route to such compounds.

2,3,5-Tri- O -benzoyl-β- d -ribofuranosyl cyanide reacts with methyl acetoacetate and diethyl malonate in the presence of stoichiometric amounts of SnCl 4 to give a β- d -ribofuranosyl-enaminoketoester and a β- d -ribofuranosyl-enaminodiester, respectively. The β- d -ribofuranosyl-enaminoketoester was debenzoylated, treated with 2,2-dimethoxypropane and tert -butyl-dimethylsilyl chloride to give the methyl 3-amino-3-(5′- O - tert -butyldimethylsilyl-2′,3′- O -isopropylidene-β- d -ribofuranosyl)-2-acetyl propanoate obtained in good yield together with small amounts of its α-anomer. The reactions of the β-anomer with hydrazine, methyl- and phenylhydrazine, carried out under controlled experimental conditions, afforded the pyrazole C-nucleosides in good yields as β-anomers.

trans-2-Aryl-3-nitro-cyclopropane-1,1-dicarboxylates when reacted with nitriles in the presence of tin(IV) chloride afford 2,4,5-trisubstituted oxazoles in good to excellent yields. The reactions take place through in situ generation of aroylmethylidene malonates from the cyclopropanes, followed by conjugate addition of nitriles to the malonates to form nitrilium ion intermediates and subsequent cyclisation.

The reaction of 1,4-dilithiotetraphenylbutadiene with germanium(IV) chloride and tin(IV) chloride affords heterocycles Ph4C4GeCl2, I and Ph4C4SnCl2, II. Compounds I and II, which feature a planar tetraphenylbutadiene backbone, were characterized by elemental analyses, 1H and 13C NMR spectroscopy and single crystal X-ray diffraction. The coordination environments for germanium and tin are distorted tetrahedra with bond angles spanning 35.35° for I and 24.86° for II. The Ge[sbnd]Cl and bond distances are 2.134 A and 2.143 A in I, while the Sn[sbnd]Cl and bond distances are 2.313 A and 2.312 A in II.