1,721,043 research outputs found
GAS-LIQUID-CHROMATOGRAPHY TOGETHER WITH C-13 NUCLEAR MAGNETIC-RESONANCE SPECTROMETRY IN THE ANALYSIS OF DIASTEREOMERIC MIXTURES OF ALCOHOLS AND DIOLS
No full textA proposal for a new mechanism of interaction of trialkyltin (TAT) compounds with mitochondria
No full textThe interactions of trialkyltin (TAT) compounds with the mitochondria were largely studied The current view of this phenomenon is that these compounds, by exploiting the Cl- and OH- gradient in energised mitochondria, behave as electroneutral OH-/Cl- exchangers. Experiments performed with triethyltin-, tripropyltin-, and tributyltin-chloride, allow as to propose an alternative mechanism. The crucial point of this new mechanism is that TATs enter the mitochondria as lipophilic cations (alkyl)(3)Sn+ and not as electroneutral compounds. The influx is followed by extrusion of the trialkyltin compounds as electroneutral hydroxi compounds (alkyl)(3)Sn-OH. Measurements of membrane potential show that the uptake of the TAT cation (alkyl)(3)Sn+ is followed by membrane depolarisation measured as the release of the trimethylphenylphosphonium probe. The depolarization occurs in the order: (Et)(3)Sn-Cl < (Pro)(3)Sn-Cl < (Bu)(3)Sn-Cl in agreement with the increasing lipophilicity of the tested compounds from ethyltin toward butyltin derivative. The uptake of TAT induces the opening of a selective anionic channel which could explain the swelling of mitochondria observed in a chloride mediu
A STUDY OF THE DISPROPORTIONATION EQUILIBRIUM FOR ALLYLDIBUTYLTIN(IV) CHLORIDE AS AN APPROACH TO UNDERSTANDING THE ROLE OF ORGANOTINS IN THE AQUATIC ENVIRONMENT
No full textThe equilibrium:
2 Bu(2)(CH2=CHCH2)SnCl
reversible arrow Bu(2)Sn(CH2=CHCH2)(2)+Bu(2)SnCl(2)
takes place when the allyltin chloride is stirred in water. This has been chosen as a model to understand the extent as well as the mechanistic pathways of the disproportionation reactions 2 R(3)SnX reversible arrow R(4)Sn+R(2)SnX(2) which are thought to occur in the aquatic environment. The behaviour of Bu(2)(CH2=CHCH2)SnCl has been studied in various media: water, water-acetone, water-ethanol and water-hexane. It has also been ascertained that Bu(2)(CH2=CHCH2)SnCl is a product arising at room temperature from the scrambling of Bu(2)Sn(CH2=CHCH2)(2) and Bu(2)SnCl(2) either neat, in organic solvents or also in the presence of water. Equilibrium [1] has been interpreted as arising from a bimolecular interaction between the electrophilic aquo-cation [Bu(2)(CH2=CHCH2)Sn(H2O)(n)](+) and the nucleophilic molecule Bu(2)(CH2=CHCH2)SnCl. Kinetic studies on R(3)SnMe/Me(2)SnX(2) (X=Cl, NO3) systems in alcoholic solvents (R=Me, Et, n-Pr, i-Pr, n-Bu) support the assumption that, in dissociating media, redistribution processes can be promoted by ionic electrophilic specie
ORGANOTINS AS ETHERIFICATION CATALYSTS .1. CATALYTIC CONVERSION OF 1,4-BUTANE-DIOL AND 1,5-PENTANE-DIOL TO TETRAHYDROFURAN (THF) AND TETRAHYDROPYRAN (THP) BY BUTYLTIN TRICHLORIDE
No full text
New Simple Route to Allylstannanes by Zinc-Mediated Coupling of Allyl Bromides with Bu3SnCl and Bu2SnCl2 in an H2O(NH4Cl) Medium
No full textA new zinc-mediated coupling reaction of allyl and allyl-like bromides with Bu3SnCl (1) or Bu2SnCl2 (2), performed in H2O (NH4Cl)/THF medium, represents an easy route to the following organostannanes: Bu3SnCH2CH=CH2 (3) and Bu2Sn(CH2CH=CH2)2 (4), Bu3Sn(C4H7) (5) and Bu2Sn(C4H7)2 (6) (where C4H7 stands for trans-crotyl, cis-crotyl, or alpha-methylallyl), and Bu3SnCH=C=CH2 (7). This striking one-pot procedure successfully improves the already general routes where Grignard or other conventional organometallic reagents are use
ALLYLSTANNATION .12. NEW APPROACH TO ALKENYL-N-ALKYL AND ALKYNYL-N-ALKYL CARBAMATES BASED ON THE SELECTIVE INSERTION OF ALDEHYDES INTO THE ALKENYL-N-ALKYL AND ALKYNYL-TIN BONDS
No full textCrystal Structure of Trivinyltinacetate (A), C8H12O2Sn2, and Trivinyltinmonochloroacetate (B), C8H12O2Sn2
No full textThe reported data predicted some structural features of the title compounds: (i) th dipendence of the dissymetry of the two bridging Sn-O bonds on the pKa of the various chloroacetic ligands and (ii) a conservative geometry of coordination about the tin atom. In order to cnfirm these predictions we have detrmined the crystal structure of the two title compounds
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