Synthesis and Characterization of Tri(organotin)Substituted Heteropolytungstates

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Improved synthesis of α-Methylene-γ-lactones via organotin reagents

The products of the reaction between aldehydes and the organotin reagent (1) have been converted to the corresponding α-methylene-γ-lactones in excellent yield under extremely mild conditions.     

Negative ion mass spectrometry of organotin compounds—an aid to environmental monitoring?

Positive-ion mass spectra of organotin compounds include a large number of different ions and therefore the absolute detection level is reduced. Negative-ion mass spectra are usually less complex and detection levels may therefore be improved. The negative-ion mass spectra of selected organotin compounds of the type R₄Sn, R₃SnCI, R₂SnCI₂ and RSnCl₃ were investigated using conventional electron impact ionization conditions. Simplified mass spectra, suitable for compound speciation, were obtained for R₃SnCI₂ and R₂SnCI₂ materials but the same fragmentation product SnCI was obtained from all the RSnCI₃ samples. R₄Sn compounds produced no negative-ion data in these studies. No significant gains in detection levels were noted but some interesting re-arrangement reactions leading to the formation of compounds consisting of substituents from the original tin atom were identified. These reactions may be of synthetic importance.     

Influence of intermolecular interactions on the Mössbauer quadrupole splitting of organotin(IV) compounds as studied by DFT calculations

The influence of intermolecular interactions on the M?ssbauer quadrupole splitting (Delta) of 119Sn was investigated in detail by density functional theory (DFT) calculations. Six organotin(IV) complexes [Me2Sn(acac)2 (1), Ph3SnCl (2), Me3Sn-succinimide (3), Me3Sn-phthalimide (4), Me3SnCl (5), and cHex3SnCl (6)] of known solid-state structures and quadrupole splittings were selected. Theoretical Delta values were calculated for both fully optimized geometries and experimental solid-state structures of different size, and the results were compared to the experimental Delta values. Compared to a synthetic procedure described in the literature for compound 4, a more convenient synthesis is reported here. The experimental Delta of this compound has also been redetermined at 80 K. For compounds with negligible intermolecular interactions in the solid state, calculated Delta values obtained did not vary significantly. In contrast, the calculated Delta values turned out to be very sensitive to the size of the supramolecular moiety considered in the crystal lattice. The crystal structure of compound 2 shows no significant intermolecular interactions; however, the calculated and the experimental Delta values remained very different, even when the supramolecular moiety considered was extended. Distortion of the coordination sphere of tin in the molecule of 2 toward a trigonal bipyramidal geometry was considered, and a possible weak intermolecular Sn...Cl interaction was included in the model. Steps of the distortion followed the new structure correlation function, which was found for the R3SnCl (R=alkyl, aryl) compounds. The experimental Delta value could be approached by this method. These results suggest that compound 2 is involved in some unexpected intermolecular interaction at 80 K.     

O-phosphorylation of Oligopeptides with Phosphoramidite

Phosphoproteinsplayimportantrolesinbiologicalsignallingcascades,bywhichchemicalsignalsarepassedacrossthecellmembraneandfurthertothecellnucleusl.Forthestudythisprocess,structurallywell-definedpeptidescontainingthecharacteristiclinkageregionofthepeptidebackbonewiththephosphoricacidestercanusedwithmanyadvantages.Ingeneral,estersofoligopeptideswerephosphorylatedwithphosphorylchlorideorwithdialkylordiarylphosphorochloridates'.Butaminogroupsinoligopeptidesshouldbeprotectedwhenhydroxylgroupswerephosp…     

Copolymerization of N-Phenylmaleimide with Cyclohexene

MalebodeanditSderivatvesarewell-bowntopolyInrizetogivethermallystablepolyTnersandthecopolymeriZationwithvariousvinylmonomershasbeenexaminedtohaProvethethermalpropeniesofthepolymers[';-'].HoweverlessworkhasbeendoneonthecopolyInerizationofN-phenylmaletride(PHMI)withcyclohexene(CH).Inthisletter,wesynthesizedanewcopolymerfromthepolymerizahonofPHMIwithCH.ThemonomerPHMIwaspreparedfrommaleicanhydrideandedlineaccordingtoT.OkadaI41.2,2'-Azobisisobutyronitrile(AIBN)wasrecrystallizedtWicefro…     

On study of chemoselectivity of reaction of trialkylalanes with alkenes, catalyzed with Zr π-complexes

The influence of the organoaluminium compound nature, Zr π-ligand environment, solvent type and reagent ratio on the chemoselectivity of reactions of trialkylalanes (AlMe₃, AlEt₃) with alkenes, catalyzed with L₂ZrCl₂ [L = Cp, Cp′ (Cp′-η⁵-C₅H₄CH₃), Cp^∗ (Cp^∗-η⁵-C₅(CH₃)₅), Ind (indenyl), Flu (fluorenyl)] has been studied. It is shown that in the case of AlMe₃, the hydro- and carboalumination products, and alkene dimers are formed. The catalytic reaction of AlEt₃ with the olefins yields aluminacyclopentanes altogether with the hydro- and carboalumination products, and the dimers. A probable reaction mechanism has been proposed.     

Cyclopropanation of Diazoacetate with Olefins

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Production of Superoxide Ion with Carbon Gas-Diffusion-Electrode And Reaction of Superoxide Ion with Aromatic Halide

Superoxide ion O~-_2 is prepared in aprotic media by carbon gas-diffusion-electrode for the first time. The experimental results indicate that this electrode is superior to carbon plane-electrode in the reaction of O~-_2 with p-bromonitrobenzene. When the gas-diffussion-electrode is used, the yield of the product nitrophenol increases by 20%, and the selectivity of the reaction is nearly doubled as compared with the plane-electrode.     

Reactions of α-halonitrosoalkanes with resorcinol

-Halonitrosoalkanes react with resorcinol as nitrosylating agents to form 3-hydroxy-N-(2,4-dihydroxyphenyl)-1,4-quinone imine.Translated fromIzvestiya Akademioi Nauk. Seriya Khimicheskaya, No. 3, pp.773–774, March, 1996.     

The reaction of Tanshinones with Amines

The reaction of cryptotanshinone and tanshinone IIA with several biogenic amine metabolites involved in the pathogenic pathways of HE were investigated and eight 1,2,3,4-tetrahydrophenanthrene derivatives,2-6 and 8-10,were obtained.The probable mechanism on reaction was discussed.     

Copolymerization of Isobutylene with α-Pinene

The copolymerization of isobutylene with α-pinene has been investigated by using EtA1Cb in ethyl chloride diluent at ca. -105°C. The copolymerizations proceeded readily and gave random copolymers of reasonably high molecular weights. Copolymer homogeneity, composition and structure was investigated by GPC, solubility behavior, PMR (60 and 300 MHz), CMR, reactivity ratio determination, and vulcanization behavior.     

Reactions of α-nitroacrylates with thiophenols

Reactions of α-nitroacrylates with aromatic thiols like 4-methyl- and 4-chlorothiophenols afford a series of new 3-arylsulfanyl-2-nitropropanoates. The latter were isolated as diastereomerically pure substances or mixtures of two diastereomers. Structures of the obtained S-adducts were confirmed by IR, ¹H and ¹³C-{¹H} NMR spectroscopy using HMQC and HMBC experiments.     

Mechanism of Dealumination of NaY Zeolite with Oxalic Acid

RemovalofalundnumfromNaYzeolitewithacidisanimportantprocessinthemodificationofzeolite.ItisdifficulttoremovealundnumfromNaYzeolitedirectlywithacidwhilekeepinghighcrystallinity.Intheworkreportedhere,alundnumisremoveddirectlyfromNaYwithoxalicacidandthemodifiedzeolitekeepshighcrystallinity.Reactionconditions:CSBlreflux,acidaddedin3ondn,allowedtoreactfor3OAnn.CSB2reflux,acidaddedrapidly,allowedtoreactfor3Owhn.CS2525-C,acidaddedraPidly,allowedtoreactfor3Omin.CSA25"C,acidaddedin3omin,a1lowe…     

Condensation of p-Benzoquinone with Anilides of β-Aminocrotonic Acid

Benzofuranone derivatives have been synthesized by the condensation of p-benzoquinone with anilides of -aminocrotonic acids under the conditions of the Nenitzescu reaction.     

Synthesis of Indomethacin Conjugates with D-Glucosamine

Two series of indomethacin conjugates with D-glucosamine were prepared with the objectives of reducing ulcerogenic potency, increasing the bioavailability of indomethacin and exerting the coordinative effects on osteoarthritis. The structures of the conjugates were identified by ^1H NMR and ^13C NMR. The ester conjugates inhibited edema as potent as indomethacin.