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The purpose of this work was to study the composition of cluster ions in samples containing sodium stannate and tin(II) chloride. It has been shown that the composition of mass spectra is influenced by such parameters as the laser radiation energy and the substance content in the sample being studied. Conditions for preparing samples and recording mass spectra using these parameters were optimized. Presumptive identification of peaks in the recorded mass spectra was carried out. It has been shown that many of the ion peaks observed in the mass spectra may correspond to clusters containing tin. In the mass spectra of sodium stannate, ions of the general composition SnxOyNazHm were detected, in which the number of tin atoms reaches eight, and the maximum ion mass-to-charge ratio (m/z) is 1100. In the mass spectra of tin(II) chloride, there are ions of the general composition SnxOyHmClp and SnxCly, where the number of tin atoms reaches 4, and the highest m/z value is 1000. [ABSTRACT FROM AUTHOR]

The use of tin(II) chloride in amount above its required mole ratio as reducing agent can lead to instability of peptide-based radiopharmaceuticals. In this work, we optimize the radiolabeling conditions, especially tin(II) chloride amount for 99mTc-labeling of one 6-hydrazinonicotinamide (HYNIC) conjugated peptide in the presence of tricine and nicotinic acid (NA). Implementation of this procedure leads to 99mTc-labeling of this HYNIC-conjugated peptide in high radiochemical yield (>95%). By comparison, our experimental results can provide an efficacious strategy for 99mTc-labeling of HYNIC-conjugated biomolecules in the presence of tricine/NA. The resulting 99mTc-labeled peptide, without the need for any chemical modification and pretreatment, shows good stability in saline and human serum. This work can provide a new perspective for 99mTc-labeling of HYNIC-conjugated biomolecules. [ABSTRACT FROM AUTHOR]

The syntheses of novel 1-acyloxyindole compounds 1 and the investigations on reaction pathways are presented. Nitro ketoester substrate 2, obtained in a two-step synthetic process, underwent reduction, intramolecular addition, nucleophilic 1,5-addition, and acylation to afford 1-acyloxyindoles 1 in one pot. Based on the systematic studies, we established the optimized reaction conditions for 1 focusing on the final acylation step of the intermediate 1-hydroxyindole 8. With the optimized conditions, we succeeded in synthesizing 21 examples of new 1-acyloxyindole derivatives 1 in modest yields (Y = 24 − 35%). Among the 1-acyloxyindole compounds, 1-acetoxyindole compounds 1x were generally unstable, and their yields were relatively lower than the other 1-acyloxyindoles. We expect that a bulkier alkyl or aromatic group on R2 could stabilize the 1-acyloxyindole compounds. Significantly, one-pot reactions of a four-step sequence successfully generated compounds 1 that are all new and might be difficult to be synthesized otherwise. [ABSTRACT FROM AUTHOR]

The reduction of 7-nitro-N(9)-substituted 2,3-dihydroimidazo[1,2-a]benzimidazoles with SnCl2 in conc. HCl forms a mixture of the previously unknown 7-amino and 7-amino-6-chloro derivatives in a ratio depending on the nature of the substituent at position 9. This result gave grounds to assume that not the final heteroarylamine, but the intermediate heteroarylhydroxylamine formed by a mechanism similar to the acid-induced Bamberger rearrangement of arylhydroxylamines, is subjected to chlorination. [ABSTRACT FROM AUTHOR]

Extrapure-grade (99.9985 wt % pure) SnCl2 has been prepared from commercially pure metallic tin and hydrogen chloride gas. Purifying the synthesized tin(II) chloride in a fractional distillation column under normal conditions, we obtained extrapure-grade SnCl2 containing under 1 ppm impurities. The samples thus prepared were characterized by inductively coupled plasma mass spectrometry, IR and Raman spectroscopies, and X-ray diffraction. [ABSTRACT FROM AUTHOR]

The syntheses of novel 1-acyloxyindole compounds 1 and the investigations on reaction pathways are presented. Nitro ketoester substrate 2, obtained in a two-step synthetic process, underwent reduction, intramolecular addition, nucleophilic 1,5-addition, and acylation to afford 1-acyloxyindoles 1 in one pot. Based on the systematic studies, we established the optimized reaction conditions for 1 focusing on the final acylation step of the intermediate 1-hydroxyindole 8. With the optimized conditions, we succeeded in synthesizing 21 examples of new 1-acyloxyindole derivatives 1 in modest yields (Y = 24 − 35%). Among the 1-acyloxyindole compounds, 1-acetoxyindole compounds 1x were generally unstable, and their yields were relatively lower than the other 1-acyloxyindoles. We expect that a bulkier alkyl or aromatic group on R2 could stabilize the 1-acyloxyindole compounds. Significantly, one-pot reactions of a four-step sequence successfully generated compounds 1 that are all new and might be difficult to be synthesized otherwise.

Methyl vinyl glycolate (methyl 2-hydroxybut-3-enoate, MVG) has recently become obtainable from Sn catalysed cascade reactions of mono- and disaccharides. The chemical structure of MVG present several options for chemical transformations and has great potential as a renewable platform chemical for industrial added-value compounds within e.g. polymer chemistry. Herein, we report a catalytic benign transesterification method for the synthesis of MVG ester derivatives of trimethylolpropane (TMP) and pentaerythritol (PE). The secondary alcohol group of MVG greatly complicates the reaction and requires a highly selective catalyst to direct the reaction towards high conversion while avoiding polymerization. Thus, a range of different catalytic systems, e.g. Candida Antarctica Lipase B (CALB), Brønsted bases/acids, salicylic aldehyde as well as Lewis acids were evaluated for the reaction. Despite the challenges this leads to unique derivatives of TMP and PE with an additional chemical handle compared to classic derivatives like the methacrylate and mercaptopropionate. [ABSTRACT FROM AUTHOR]

The application of heterogeneous solid acid catalysts in biodiesel production has become popular and gained significant attention over the last few years. It is since these types of catalysts hold the benefits in terms of easy separation from the product, reusability of the catalyst, high selectivity of the reaction. They are also considered sustainable and powerful particularly in organic synthesis. This work studied the use of tin(II) chloride as solid Lewis acid catalyst to promote the esterification reaction of high Free Fatty Acid (FFA) jatropha oil in continuous reactive distillation column. To obtain the optimum condition, the influences of reaction time, molar ratio of the reactant, and catalyst were investigated. It was revealed that the optimum condition was achieved at the molar ratio of methanol to FFA at 1:60, catalyst concentration of 5%, and reaction temperature of 60°C with the reaction conversion of 90%. This result was significantly superior to the identical reaction performed using batch reactor. The esterification of high FFA jatropha oil using reactive distillation in the presence of tin(II) chloride provided higher conversion than that of Amberlyst-15 heterogeneous catalyst and was comparable to that of homogenous sulfuric acid catalyst, which showed 30 and 94.71% conversion, respectively. The esterification reaction of high FFA jatropha oil was subsequently followed by transesterification reaction for the completion of the biodiesel production. Transesterification was carried out at 60 °C, molar ratio of methanol to oil of 1:6, NaOH catalyst of 1%, and reaction time of one hour. The jatropha biodiesel product resulted from this two steps process could satisfy the ASTM and Indonesian biodiesel standard in terms of ester content (97.79 %), density, and viscosity.

Biodiesel is one of the promising energy alternatives to fossil fuel. Among the economical feedstocks of biodiesel is high free fatty acid (FFA) vegetable oil. Production of biodiesel from high FFA oils needs esterification reaction as the pre-treatment step. In this work, esterification reaction of high FFA non-edible oil mixture (used cooking oil, jatropha oil, and nyamplung seed oil) was conducted in reactive distillation (RD) column in the presence of solid acid tin(II) chloride catalyst. RD has potential to be applied at industrial scale. For this purpose, an accurate model is required to scale up the process, predict the RD performance and optimise the process. Experimental work, simulation study and validation were carried out in this work to determine the accurate model and simulation. In experimental work, esterification reaction was conducted by varying the reaction temperature and catalyst concentration. The simulation was performed using ASPEN PLUS V8.8 and validated with the experimental data. Based on the experiment, the optimum FFA conversion was 78.33%, obtained at temperature of 60°C and catalyst concentration of 5% (w/w). The FFA conversion achieved from the simulation was 75.8%. The proximity between the simulation and experimental data demonstrated that this simulation has accurately predicted the conversion of FFA with less than 5% error. [ABSTRACT FROM AUTHOR]

The influence of tin (II) chloride additives on sorption of Rh(III) on the Purolite S920 ion exchange resin with isothiouronium groups, the Purolite S985 weak base anion exchange resin, and the Purolite A500 strong base anion exchange resin is investigated. It is established that the introduction of SnCl leads to a substantial increase in selectivity of all tested ion exchange resins to Rh(III) and in the sorption rate of Rh(III) on S985 and S920 ion exchange resins. The optimal dosage of SnCl (0.01 mol/L) at which the distribution coefficients of Rh(III) during sorption for all tested ion exchange resins reach maximal values is determined. It is shown that almost quantitative recovery of Rh(III) is attained when passing the multicomponent chloride solution of the composition (g/L) 0.2 Rh(III), 72.9 HCl, 53.5 NHCl, 2.7 Al(III), 1.23 Fe(III) and 5.9 Sn(IV) with the SnCl additive through the Purolite S920 ion exchange resin with isothiouronium groups. Desorption of Rh(III) from the Purolite S920 saturated ionite with the acidified thiourea solution is incomplete, no greater than 60%. [ABSTRACT FROM AUTHOR]

The application of heterogeneous solid acid catalysts in biodiesel production has become popular and gained significant attention over the last few years. It is since these types of catalysts hold the benefits in terms of easy separation from the product, reusability of the catalyst, high selectivity of the reaction. They are also considered sustainable and powerful particularly in organic synthesis. This work studied the use of tin(II) chloride as solid Lewis acid catalyst to promote the esterification reaction of high Free Fatty Acid (FFA) jatropha oil in continuous reactive distillation column. To obtain the optimum condition, the influences of reaction time, molar ratio of the reactant, and catalyst were investigated. It was revealed that the optimum condition was achieved at the molar ratio of methanol to FFA at 1:60, catalyst concentration of 5%, and reaction temperature of 60°C with the reaction conversion of 90%. This result was significantly superior to the identical reaction performed using batch reactor. The esterification of high FFA jatropha oil using reactive distillation in the presence of tin(II) chloride provided higher conversion than that of Amberlyst-15 heterogeneous catalyst and was comparable to that of homogenous sulfuric acid catalyst, which showed 30 and 94.71% conversion, respectively. The esterification reaction of high FFA jatropha oil was subsequently followed by transesterification reaction for the completion of the biodiesel production. Transesterification was carried out at 60 °C, molar ratio of methanol to oil of 1:6, NaOH catalyst of 1%, and reaction time of one hour. The jatropha biodiesel product resulted from this two steps process could satisfy the ASTM and Indonesian biodiesel standard in terms of ester content (97.79 %), density, and viscosity. [ABSTRACT FROM AUTHOR]

Sn(II) is a well-known reductant used in the formation of phosphomolybdenum blue for the determination of dissolved reactive phosphorus (DRP) in waters because it provides rapid and quantitative reduction. However, in saline waters, this method suffers from a salt error which causes a significant decrease in sensitivity. This phenomenon has never been adequately explained in the literature. The Murphy and Riley method, which uses Sb(III) and ascorbic acid for the reduction step, is preferred for DRP determination in saline waters because it is unaffected by salinity, but it exhibits a sensitivity approximately 30% lower than that when Sn(II) is used as the reductant without Cl − interference. This study investigates the processes causing the salt error and possible ways of minimizing it, so that the benefits of Sn(II) reduction on the molybdenum blue reaction rate and sensitivity may be exploited in the determination of low levels of DRP in marine and estuarine waters. It has been established that the salt error is caused by the formation of Sn(IV) chloro-complexes which compete with the formation of Sn(IV)-substituted phosphomolybdenum blue, forcing the reaction to proceed via the much slower, less favourable process of direct reduction that occurs in methods using organic reductants such as ascorbic acid. [ABSTRACT FROM AUTHOR]

A series of new pyrazolo[5,4-fa]quinoline derivatives were synthesized in good yields by tin(II) chloride dihydrate catalyzed cyclocondensation of 5-amino-3-(arylamino)-1H-pyrazole-4-carbonitriles with cyclohexane-1,3-dione or dimedone. The synthetic procedure can be carried out by means of simple operations under convenient solventfree conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Regioselectivity for either the 3- or the 2-hydroxyl group of a manno-pyranoside. [•] Catalyst concentration dependence of selectivity. [•] Different diaryldiazomethanes give different regioselectivity. [Copyright &y& Elsevier]

• Activation parameters for ROP of ε -caprolactone can be rapidly obtained from DSC. • Reactivity of SnCl 2 is higher than ZnCl 2 in the polymerization of ε -caprolactone. • SnCl 2 produces very high molecular weight PCL in a short time. • Effectiveness of ZnCl 2 in PCL synthesis can be improved by increasing temperature. The kinetics of the ring-opening polymerization (ROP) of ε -caprolactone (ε -CL) initiated by 1.0 mol% of tin(II) chloride (SnCl 2) and zinc(II) chloride (ZnCl 2) was completely investigated by the differential scanning calorimetry (DSC) technique. The fast method to determine the activation parameters such as activation enthalpy (∆ H ≠) and activation entropy (∆ S ≠) was successfully developed basing on the transition state theory and isoconversional method. From Friedman isoconversional method, the values of activation energy (E a) for the ROP of ε -CL initiated by SnCl 2 (36.2 ± 1.5 to 40.8 ± 1.5 kJ/mol) were lower than ZnCl 2 (51.9 ± 2.8 to 62.3 ± 2.8 kJ/mol). From Starink isoconversional method, the E a values for the ROP of ε-CL initiated by SnCl 2 (32.3 ± 1.1 to 35.8 ± 1.1 kJ/mol) were also lower than ZnCl 2 (59.2 ± 0.8 to 62.1 ± 0.8 kJ/mol). By using the compensation parameters, the reconstructed monomer conversion function (f (α)) was fitted with the Avrami-Erofeev nucleation model (A2, f (α) = 2(1- α)[- ln (1- α)]1/2). The values of frequency factor (A) for the ROP of ε -CL with SnCl 2 and ZnCl 2 were 4.3 × 103to 1.6 × 104 min−1 and 2.1 × 105 to 5.3 × 105 min−1, respectively. From the developed rate equation, the values of ∆ H ≠ and ∆ S ≠ could be conveniently determined from dynamic heating. The obtained ∆ H ≠ values for the ROP of ε -CL initiated by SnCl 2 and ZnCl 2 were similar to the E a values. The ∆ S ≠ values for the transition state of the ROP of ε -CL initiated by SnCl 2 (-152.0 to -161.7 J/mol.K) were lower than ZnCl 2 (-129.6 to -153.1 J/mol.K). The kinetics and the stability of transition state information demonstrated that the reactivity of SnCl 2 in the ROP of ε -CL was higher than ZnCl 2. The mechanism of the ROP of ε -CL with SnCl 2 and ZnCl 2 was proposed through a classical coordination-insertion mechanism. From poly(ε -caprolactone) (PCL) synthesis via solvent-free polymerization, SnCl 2 acted as the highly effective initiator than ZnCl 2. The highest number average molecular weight (M n) of PCLs obtained from the SnCl 2 and ZnCl 2 initiator were 1.8 × 105 g/mol and 3.6 × 104 g/mol, respectively. The effectiveness of the slow ZnCl 2 initiator in the production of high molecular weight and %yield of PCL could be improved by increasing the synthesis temperature. These SnCl 2 and ZnCl 2 compounds acted as a powerful initiator for the synthesis of PCL. The obtained results from this work were useful for understanding the transition state formulation in the ROP of other cyclic esters with various initiating systems that still in our attention and would be described in our future work. [Display omitted] [ABSTRACT FROM AUTHOR]

Furan-2(5H)-one derivatives have been synthesized by a simple, efficient, one-pot, three-component condensation of anilines, dimethylacetylenedicarboxylate, and aromatic aldehydes in the presence of a catalytic amount of tin(II) chloride in excellent yields. [ABSTRACT FROM PUBLISHER]

Reaction of tin(II) chloride and dimethyltin dichloride with Schiff bases derived from S-benzyldithiocarbazate leads to the formation of a new series of tin(II) and organotin(IV) complexes of general formula SnCl2.L and Me2SnCl2.L (where L = Schiff bases are derived from the condensation of S-benzyldithiocarbazate with heterocyclic aldehydes). An attempt has been made to prove the structures of the resulting complexes on the basis of elemental analysis, conductance measurements, molecular weight determinations, infrared, and multinuclear magnetic resonance (1H, 13C, and 119Sn NMR) spectral studies. A few representative ligands and their tin complexes have also been screened for their antibacterial and antifungal activities and found to be quite active in this respect. [ABSTRACT FROM AUTHOR]

A new, simple, rapid, and selective procedure for the flow injection analysis (FIA) spectrophotometric determination of platement (Pt) is described. The method is based on the color reaction of Pt(IV) with SnCl 2 in the HCl medium. The mixed surfactants, i.e., cetylpyridinium chloride (CPC)+triton X-100 (TX-100) are used to enhance sensitivity of the method. The value of apparent molar absorptivity in the term of Pt is (3.00)×10 3 L mol -1 cm -1 at absorption maximum, 405 nm. The detection limit (causing absorbance greater than 3×std. dev.) of the method is 150 ng/mL -1 . The optimum concentration range for the determination of Pt is 0.5–18 µg/mL -1 with slope, intercept and correlation coefficient 0.0086, -0.001, and +0.99, respectively. The sample throughput of the method is 120 samples/h -1 at the flow rate of 3.7 mL/min -1 . The composition of the complex, and the reaction mechanism involved are discussed. The effect of FIA and analytical variables on the determination of the metal is optimized. The method has been tested for the analysis of Pt to the catalytic materials. [ABSTRACT FROM AUTHOR]

Identification and monitoring of gaseous species released during thermal decomposition of title compound 1, Sn2(tu)5Cl4·2H2O (tu stands for thiourea (NH2)2CS)) in flowing air atmosphere have been carried out up to 600°C by both online coupled TG-EGA-FTIR and simultaneous TG/DTA-EGA-MS apparatuses. The first gaseous products of the dehydrated 1, evolved around 190°C, are carbonyl sulphide (COS), carbon disulfide (CS2), and cyanamide (NH2CN). At 240°C isothiocyanic acid, HNCS becomes the main product, accompanied by CS2, ammonia (NH3), a small amount of hydrogen cyanide (HCN) and traces of hydrogen chloride (HCl), according to EGA-FTIR spectroscopic analysis. At 250°C formation of sulphur dioxide (SO2) has been observed by EGA-mass spectrometry. SO2 as air oxidation product of tin sulphides, formed in the previous stages, occurs also around 430°C, while gaseous oxidation products of the organic residues, such as CO2 and NH2CN are released at 515°C. Both oxidation processes are accompanied by an exothermic heat effect. All species identified by FTIR gas cell are also confirmed by mass spectrometry, except HNCS. [Copyright &y& Elsevier]

Identification and monitoring of gaseous species released during thermal decomposition of title compound 1, dichloro(thiourea) tin(II), Sn(tu)Cl2, [thiourea (tu), (NH2)2C&z.dbnd6;S] in flowing air atmosphere have been carried out by both online coupled TG–FTIR and simultaneous TG/DTA–MS evolved gas analysis (EGA) instruments. The first gaseous products of 1, evolved from 170 °C, are cyanamide (NH2CN), carbonyl sulphide (COS), carbon disulfide (CS2) and water (H2O). At 240 °C isothiocyanic acid (HNCS) becomes the main product, accompanied by CS2, hydrogen cyanide (HCN) and traces of hydrogen chloride (HCl) according to EGA–FTIR analysis. Ammonia (NH3) occurs first only above 250 °C, while sulfur dioxide (SO2) formation is not observed till 400 °C. Air oxidation products of tin sulphides and organic residues, such as SO2, carbon dioxide (CO2) and NH2CN, occur suddenly at 425 °C together with a very sharp exothermic heat effect. All species identified by FTIR gas cells are confirmed by mass spectrometry, except HNCS. Evolution of H2S has not been observed at any stage of the degradation of 1 by either of the EGA methods. [Copyright &y& Elsevier]

A new, simple, and selective method for rapid spectrophotometric determination of Pt is described. It is based on extraction of Pt(II)–SnCl3− complex with chloroform (CF) solution of amide, i.e., N‐alkylacetamide (alkyl = butyl to octyl). The value of apparent molar absorptivity of the complex (with four N‐alkylacetamides) lie in the range of (3.40–3.50) × 104 L mol−1 cm−1 at λmax 400–405 nm. The most sensitive compound, i.e., N‐butylacetamide (BAA) has been selected for the detailed studies. The detection limit (absorbance 0.007 more than thrice of standard deviation of the method) of the method is 40 ppb Pt. The types of the halide and amide in the extraction as well as spectral characteristics of the complex are discussed. The reaction mechanism involved in the extraction of the metal is described. The optimization of analytical variables for the determination of Pt is carried out. The method has been applied for the determination of Pt in the catalytic materials. #E‐mail: dg7j@hrz.tu-darmstadt.de. [ABSTRACT FROM AUTHOR]

The paper reports the tin(II) chloride catalyzed reactions of diazodiphenylmethane with the cis- and trans-1,2-cyclohexanediols and R,S-1,2-propanediol in 1,2-dimethoxyethane and the identification of the monodiphenylmethyl ethers formed. The catalyst is shown to work for both the cis- and trans-cyclohexanediols, but the catalyst is unstable at high reagent concentrations, especially in the case of the trans-isomer. Conditions where catalyst destruction is negligible show that the rate of the reaction with the trans-isomer is larger than with the cis-isomer. The reactions with 1,2-propanediol show small difference between the selectivity for the primary and secondary hydroxyl groups. This is in contrast with the tin(II) chloride catalyzed reactions of diazomethane and diazophenylmethane in methanol with carbohydrates, glycerol and ribonucleosides, where the primary hydroxyl group does not react. [Copyright &y& Elsevier]

The hydration products of Portland cement pastes cured using water containing tin(II) chloride have been compared with those using distilled water. In the latter case, the expected products—portlandite, ettringite and calcite—were observed. The X-ray diffraction patterns of the cement pastes cured in the presence of tin(II) chloride showed several additional peaks that have been attributed to the formation of calcium hydroxo-stannate, CaSn(OH)6, and Friedel''s salt (tetracalcium aluminate dichloride-10-hydrate), Ca3Al2O6·CaCl2·10H2O. The amount of portlandite formed was reduced in the presence of tin(II) chloride. Calcium hydroxo-stannate contains tin in the +IV oxidation state and equations are presented to account for the oxidation of Sn(II) to Sn(IV) preceding the formation of CaSn(OH)6 and Friedel''s salt. [Copyright &y& Elsevier]