Tin Carboxylates Research Articles

An overview of the chemistry of condensation curing silicone sealants and adhesives

Condensation curing silicone sealants and adhesives are materials that are used to connect substrates to each other in various industries, especially where harsh conditions are limiting the use of organic materials. Chemistry of condensation curing silicones is reviewed in this publication through an historical perspective, which provides an insight into the challenges faced by the early formulators. The impact of the formulation ingredients can be very significant on the uncured, curing and/or cured properties of the material. Their main influence is described with a special focus on the main curing systems, i.e., acetoxy, alkoxy, oxime, amine, acetone, and amide. Cure characteristics are summarized and compared across their chemistries. Alkyl tin carboxylates and alkoxy titanium catalysts are the most used condensation catalysts. They are acting through a different mechanism, which is compared briefly. Typical features and principles about one-part and two-part silicones are described and related to their physicochemical properties. Finally, a brief review of the latest developments and trends is depicted.

Synthesis, characterization, and biological evaluation of seven organotin(IV) complexes with a 5-thio-tetrazole carboxylate ligand derived from the Bargellini reaction

The organometallic tin(IV) carboxylates are, in general, well known; however, the corresponding organotin(IV) tetrazole-carboxylates are not known, despite their interest in function of the presence, in these bifunctional ligands, of a rigid tetrazole ring and a flexible carboxylate anion with the possibility of a wide structural diversity and relevant biological activity. In consequence, we report here the synthesis and full characterization of seven new organotin(IV) complexes with a 5-thio-tetrazole carboxylate ligand, the anion of the 2-methyl-2-[(1-phenyl-1H-tetrazol-5-yl)sulfanyl)]-propanoic acid obtained from the Bargellini reaction. The reaction of Bargellini is a source of economical synthesis of compounds in a multi-component reaction with an increase in complexity and functionality; however, its use in the synthesis of ligands for the obtention of new metal complexes is very limited. Therefore, another reason for this study lies in the convenience of broadly showing the usefulness of this reaction in the synthesis of ligands suitable for coordination chemistry. The new complexes were characterized by common spectroscopic techniques, and elemental analysis, and four of the complexes by single-crystal X-ray diffraction, whose structures are discussed, and the complexes were tested for their antibacterial capacities.

Mechanistic Insight into the Precursor Chemistry of Cesium Tin Iodide Perovskite Nanocrystals

Colloidal tin halide perovskite nanocrystals (NCs) are of interest as an alternative to their lead-based counterparts. While some advancements have been achieved in their synthetic development, the reaction mechanism, especially the precursor chemistry, of tin halide perovskite NCs remains poorly understood. Here, using cesium tin iodide (CsSnI3) perovskite NCs as a model system, we report on the mechanistic insight into the precursor chemistry of tin-based perovskite NCs through a combination of infrared, mass spectrometry, and nuclear magnetic resonance spectroscopy. We identify that the active intermediate complexes, polymeric alkanoate iodides that form via the reaction of the iodide source with oligomers present in the tin(II) carboxylates, play a key role in governing the reactivity of the tin iodide precursor, which leads to the variation in the size, size uniformity, and photoluminescence quantum yield of CsSnI3 NCs. Our work underscores the importance of understanding the precursor chemistry as a key parameter to design and synthesize tin halide perovskite NCs, which not only aids in their syntheses by design but also might benefit the fabrication of high-quality polycrystalline tin-based films.

ВЛИЯНИЕ КАРБОКСИЛАТОВ ОЛОВА НА ПРОЦЕСС ОТВЕРЖДЕНИЯ ОЛИГОМЕРНОГО КРЕМНИЙОРГАНИЧЕСКОГО СВЯЗУЮЩЕГО И СВОЙСТВА ТРЕХМЕРНО-АРМИРОВАННОГО МАТЕРИАЛА НА ЕГО ОСНОВЕ

ВЛИЯНИЕ КАРБОКСИЛАТОВ ОЛОВА НА ПРОЦЕСС ОТВЕРЖДЕНИЯ ОЛИГОМЕРНОГО КРЕМНИЙОРГАНИЧЕСКОГО СВЯЗУЮЩЕГО И СВОЙСТВА ТРЕХМЕРНО-АРМИРОВАННОГО МАТЕРИАЛА НА ЕГО ОСНОВЕ

Triorganotin 4-isopropylbenzoates as model transesterification catalysts for triorganotin carboxylates grafted to cross-linked polystyrene

Starting from 4-isopropylbenzoic acid, three new triorganotin carboxylates bearing methyl, butyl and phenyl substituents at tin, respectively, were prepared and fully characterized by spectroscopic and thermal techniques, with particular regard to the coordination number of tin atom, in solution as well as in the solid state. The triorganotin compounds, tested as transesterification catalysts in the reaction between ethyl acetate and primary, secondary or tertiary alcohol, respectively, displayed, as expected, a strong decrease of activity on passing from the primary to the tertiary alcohol reactant. Different activities by the tin carboxylates were also observed in the reaction between primary alcohol and ethyl acetate. The reaction mechanism, as elucidated by Sn NMR, involves coordination of both ester substrate and alcohol reactant to the triorganotin compound, the reaction conversion appearing related not only to the Lewis acidity of the tin atom, but also to the nature of the reactants. Preliminary catalytic tests were also carried out in the reaction between glyceryl tridodecanoate (as a model of natural triglyceride) and ethanol, mimicking the preparation of biodiesel fuel. Although in this case lower conversions were obtained with respect to the reactions on ethyl acetate, the catalytic activity of organotin derivatives appears considerable.

Tin Carboxylates and Phosphates

AbstractFor Abstract see ChemInform Abstract in Full Text.

Polylactones, 52. Tin Carboxylates as Initiators ofɛ-Caprolactone

Eleven different tin carboxylates were used as initiators of the ring-opening polymerization of e-caprolactone. All polymerizations were conducted with 2 M solutions in chlorobenzene at 80°C and time/conversion curves were determined up to 96–99% conversion. The following structure-reactivity relationships were found. Noncyclic initiators, such as Bu2Sn(acetate)2 or Bu2Sn(benzoate)2 are more reactive than cyclic initiators such as Bu2Sn succinate and Bu2Sn phthalate, respectively. Electron withdrawing substituents enhance the reactivity. Bu2Sn(acetate)2 is more reactive than Bu3Sn acetate and Sn(II) bis(2-ethylhexanoate) is more reactive than Bu2Sn(2-ethyl-hexanoate)2. Traces of moisture to play the role of efficient co-initiators. This conclusion is supported by the following observations. The degrees of polymerization (DP) largely exceed the monomer/initiator (M/I) ratios. Furthermore, the DPs increase with the purity of e-CL suggesting that the monomer itself carries traces of moisture. The co-initiation with water and the incorporation of a few acyl endgroups were confirmed by MALDI-TOF mass spectroscopy. CH2OH endgroups were also found in all polyesters by 1H NMR spectroscopy, whereas only traces of acyl endgroups were detectable. Tetrabutyldistannoxane bisacetate is far more reactive than Bu2Sn bisacetate. Addition of an alcohol to a tin carboxylate allows a control of the molecular weight, and, as previously reported by several research groups, accelerates the entire polymerization process.

Synthesis and structural characterization of several tris(2-methyl-2-phenylpropyl)tin carboxylates containing germanium

Thirteen tris(2-methyl-2-phenylpropyl)tin germylpropionates have been synthesized and their structures characterized by elemental analysis, IR, multinuclear NMR ( 1H, 13C, 119Sn) and MS spectroscopies. The structure of (PhC(CH 3) 2CH 2) 3SnO 2CCH 2CH( o-C 6H 4Cl)GePh 3 has been determined by X-ray diffraction study, which indicated that the tin in the compound possess a tetrahedral geometry. Bioassay results have shown that some of the compounds have good acaricidal activity.

A novel approach to soluble polystyrenes functionalized by tri-n-butyltin carboxylates

The methyl esters (5 a and 5 b) of two ω-(para styryl)alkanoic acids, 3-p-styryl propionic and 5-p-styryl pentanoic acid, were respectively synthesized from 3-phenyl propionic acid and 5-phenyl pentanoic acid in four reaction steps. These esters have been submitted to radical copolymerization with styrene affording the corresponding copolymers. The methyl ester functions were subsequently converted into the tri-n-butyltin carboxylates using bis(tributyltin) oxide. This approach by-passes complications of radical polymerization inhibition due to the presence of tin in the monomers. It also avoids undesired, uncontrolled early stage polymerization of styryl moieties during the hydrolysis of the methyl esters into the corresponding carboxylic acid precursors of the monomeric tin carboxylates. Finally, it reduces significantly the polymerization time. Characterizations of the tin functionalized polymers in solution and solid state by NMR, IR and thermal techniques allow us to conclude that the tin atoms are tetracoordinated.

Kinetics and catalysis of consecutive isocyanate reactions. Formation of carbamates, allophanates and isocyanurates

Organic isocyanates (I) react with alcohols and phenols (HX) in a sequence of reactions to give Carbamates, allophanates and Isocyanurates. Rate and equilibrium constants of the individual steps have been determined. The partitioning of the reaction products predominantly depends on the I : HX ratio and the nature of the catalyst applied. At equimolar I : HX ratios, the carbamate is the dominating product in the absence and in the presence of catalysts like tin carboxylates and common tertiary amines including 1,4-diazabicyclo[2.2.2]octane (DABCO). In these cases, the rate constant of carbamate formation (k1) is larger than those of allophanate and isocyanurate formation (k2 and k3). With catalysts such as aminals, aminoalcohols, amidines and carboxylate, phenolate and alkoxide anions, however, the isocyanurate is mainly formed. With these catalysts the ratio of rate constants is k1 < k2≈k3. For base catalysts, the k1 : k2 : k3 ratios depend on the mechanism of catalysis. Tertiary amines react in the alcohol-isocyanate reaction by a concerted termolecular mechanism, whereas the anionic catalysts react by a stepwise mechanism via alcoholate anions. In the reactions of the Isocyanate with phenols, Carbamates and allophanates, all base catalysts react by the stepwise anionic mechanism, but the anionic ones are more efficient because their conjugate acids form hydrogen-bonded homoassociate complexes in higher extend.At high I : HX ratios, the isocyanurate is the only final product formed via the carbamate and allophanate as detectable intermediates. The kinetics of cyclotrimerisation is mainly governed by the k1 : k2 : k3 ratios and the magnitude of the equilibrium constants K1, K2 and K3. The kinetic order with respect to Isocyanate may vary from 1 to 3.

Syntheses and bioactivities of mixed butyl/cyclohexyl tin carboxylates

AbstractEight novel compounds have been synthesized and they are two series of mixed tri(butyl/cyclohexyl) tin carboxylates: BunCy3‐n SnO2CR (n = 1, 2; R = n‐C3H7, C6H5, 4‐ClC6H4, 4‐NO2C4H4). In addition to the studies of their structures with IR, 119Sn and 13C NMR, we tested their fungicidal, insecticidal and acaricidal activities. The percentage of inhibition to the aforementioned phytopathogen is about 80—100% at 50 ppm in glasshouse and 100% for T. Uriticae at 500 ppm. Those findings indicate that this kind of compounds have both fungicidal and acaricidal activities and may have a good prospect for applications.

Biodegradable polymers. 6th comm. Polymerization of ϵ‐caprolactone

AbstractThe ring‐opening polymerization of ϵ‐caprolactone was investigated in dependence on the most important reaction parameters. It was found that the monomer conversion is above all determined by polymerization temperature just as type and concentration of initiator. High yields of polymer can be obtained by initiation with tin(II) carboxylates, tin(II, IV) halogenides and titanium alkylates. The molecular weight of the polymer depends in a complex manner on the reaction conditions because the primary ring‐opening reaction is accompanied by consecutive reactions. The values of molecular weight pass through a maximum.

The electron beam curing of dialkyltin diacrylates

Dibutyltin diacrylate, di-2-methylpropyltin diacrylate and dioctyltin diacrylate cure to give tack-free films at much lower doses than the commonly used diluents hexanediol diacrylate, trimethylolpropane, triacrylate etc. Their reactivity is ascribed to their greater stopping power due to the presence of the tin atom and to the homolysis of the weak tin-carbon bond which leads to the production of initiating radicals. Film formation is also aided by the tin carboxylates being able to form an intermolecularly associated structure. The tin acrylates can be used in conjunction with prepolymers, e.g. an epoxidized soya bean oil (Synocure 3111) and a urethane acrylate (Synocure 3134). The tin acrylates are less effective than tripropyleneglycol diacrylate (TPGDA) in reducing the viscosity of the prepolymers. Electron beam curing of mixtures of the tin acrylates and prepolymers gave films possessing greater solvent resistance than those obtained from corresponding mixtures of TPGDA and the prepolymers.

Studies of tris[(phenyldimethylsilyl)methylene]‐tin carboxylates

AbstractTwenty‐six derivatives of tris[(phenyldimethylsilyl)methylene]tin carboxylates have been prepared. All compounds are new and characterized through elemental analysis IR spectra, and 1H, 13C, 110Sn NMR spectral studies. The spectral results showed that all compounds are four coordinated organotin compounds. The Δv (=υ−υ) of them are over 300 cm−1. The chemical shifts (δ) of 119Sn of ArCO2Sn(CH2SiMe2Ph)3 and ArOCH2CO2Sn(CH2SiMe2Ph)3 give good straight‐line correlation with para‐substituent constants. These compounds have good acaricide activity, but their action on the mite are slower than that of Torque.

IR and 13C, 17O, and 119Sn NMR spectra of some bis(1-butyl)tin(IV) carboxylates of dicarboxylic acids

Infrared spectroscopy and multinuclear (13C, 17O, and 119Sn NMR spectroscopy have been used to study the structure of bis(1-butyl)tin(IV) carboxylates of dicarboxylic acids (1-C4H9)2. Sn(X(COO)2), where X = (CH2)n (n = 0-8), CH=CH (cis and trans) and C6H4 (ortho and para).The crystalline compounds are formed by linear or cyclic oligomers or polymers whose basic building units represent a grouping composed of the central tin atom substituted by two 1-butyl groups and coordinated with both oxygen atoms of two anisobidentate carboxylic groups derived from different molecules of a dicarboxylic acid. The environment of the tin atom has a shape of a trapezoidal bipyramid. When dissolvet in non-coordinating solvents, the compounds retain the oligomeric character with unchanged structure of environment of the central tin atom. In the media of coordinating solvents the bis(1-butyl)tin(IV) carboxylates of dicarboxylic acids form complexes whose central hexacoordinated tin atom binds two molecules of the solvent trough their donor atoms. Carboxylic groups form monodenate linkages in these complexes.

To bridge or not to bridge: the formation of μ-oxo and hydroxo complexes by diphenyl tin carboxylates

To bridge or not to bridge: the formation of μ-oxo and hydroxo complexes by diphenyl tin carboxylates

ChemInform Abstract: Studies on the Preparation and Characterisation of Bis‐p‐biphenyltin(IV) Carboxylates.

AbstractThe bis(biphenyl)‐tin carboxylates (III) are prepared by reacting the dichloride (I) with the sodium carboxylates (II).

ChemInform Abstract: Reaction of Dialkylchlorotin Carboxylates with Acetylenes.

AbstractA selective reaction of the title compounds (I) and (II) in the presence of diethylamine, producing the acetylenic tin carboxylates (III), is reported.

FACILE SYNTHESIS OF TIN(IV) CARBOXYLATES

Abstract Tin powders (Sn) or tin(II) chloride (SnCl2) reacted readily with copper(II) carboxylates [Cu(O2CR)2] in an organic solvent to give the corresponding tin(IV) carboxylates [Sn(O2CR)4] in exellent yields.

Preparation and characterization of mixed-oxidation-state tin carboxylates and related tin(IV) carboxylates

Preparation and characterization of mixed-oxidation-state tin carboxylates and related tin(IV) carboxylates