ALKYLTIN ALKYL

New York City, 2nd-6th May 1999, p.3569-73. 012 MECHANISM OF ORGANOTIN STABILISATION OF POLYVINYL CHLORIDE. IV. PVC STABILISATION BY ALKYLTIN ALKYL MERCAPTOPROPIONATES Fisch M H Bacaloglu R Dooley T Witco Technical Center (SPE)... 

III. STRUCTURE AND EQUILIBRIA OF ALKYLTIN ALKYL MERCAPTOPROPIONATES AND THEIR COMPATIBILITY WITH PVC... 

Brecker, L.R. Mechanism of organotin stabilization of poly(vinyl chloride). 1. The structure and equilibria of alkyltin alkyl mercaptopropionates and their compatibility with PVC. In Plastics Plastics on My Mind, Proceedings Antec 1998 Brookfield, Society of Plastic Engineering Vol. 3, 33291. 

Alkylphenols Alkyl polyglycosides N-Alkylpyrroles Alkyl thiophenes Alkyltins Alkynes... 

Alkyltin Intermedia.tes, For the most part, organotin stabilizers are produced commercially from the respective alkyl tin chloride intermediates. There are several processes used to manufacture these intermediates. The desired ratio of monoalkyl tin trichloride to dialkyltin dichloride is generally achieved by a redistribution reaction involving a second-step reaction with stannic chloride (tin(IV) chloride). By far, the most easily synthesized alkyltin chloride intermediates are the methyltin chlorides because methyl chloride reacts directiy with tin metal in the presence of a catalyst to form dimethyl tin dichloride cleanly in high yields (21). Coaddition of stannic chloride to the reactor leads directiy to almost any desired mixture of mono- and dimethyl tin chloride intermediates ... 

The other commercially important routes to alkyltin chloride intermediates utilize an indirect method having a tetraalkjitin intermediate. Tetraalkyltins are made by transmetaHation of stannic chloride with a metal alkyl where the metal is typicaHy magnesium or aluminum. Subsequent redistribution reactions with additional stannic chloride yield the desired mixture of monoalkyl tin trichloride and dialkyltin dichloride. Both / -butjitin and / -octjitin intermediates are manufactured by one of these schemes. 

Particular drawbacks of using alkylsiHcon and alkyltin haHdes with AlCl for the cationic polymerization of terpenes are low yields and the fact that they require rigorously dried feeds (<50 ppm H2O) to be effective. Increased water content results in lower yields and lower softening points (85). Catalyst systems comprised of AlCl with antimony haHdes in the presence or absence of a lower alkyl, alkenyl, or aralkyl haHde are particularly effective in systems containing up to 300 ppm H2O (89,90). Use of 2—12 wt % of a system composed of 2—3 parts AlCl, 0.7—0.9 parts SbCl, and 0—0.2 parts of an organic... 

Acidolysis of the alkyl-tin bond provides a useful route from tetraal-kyltins to alkyltin carboxylates, and is discussed in Section II,C. 

The relative reactivities of alkyltin compounds towards tert-butoxyl radicals, ketone triplets, and succinimidyl radicals are dominated by the steric effect of the alkyl ligands (R" > R"), but that towards bromine atoms follows the reverse sequence (R" < R ). 

Alkylhalotin hydrides are prepared by reaction of an alkyltin hydride with either an alkyltin halide with the same alkyl groups232 or with hydrogen halides233, e.g. ... 

Redistribution reactions are considered as quite important for the preparation of alkyltin halides having mainly identical alkyl groups. Actually, the redistribution reactions are halogenation reactions of organotin halides by SnX4 (X = F, Cl, Br, I). 

Compounds of the type CpSnX3 (X = alkyl, Cp, Cl) are very photosensitive compared with alkyltin compounds, and on irradiation show strong E.S.R. spectra of the Cp-radical54. The equivalent silicon and germanium compounds do not show this reactivity (reaction 34). 

Tin is comparable in its toxicological behavior to lead. Trialkyl species are the most toxic in both cases. While the toxicity of alkyltin species declines with alkyl chain length, that of alky Head species increases with alkyl chain length. 

Hattori [77] extracted alkyl and alkyltin compounds from sediments with methanoic hydrochloric acid and then, following mixture with sodium chloride and water, the mixture was extracted with benzene and converted to hydrides with sodium borohydride and analysed by gas chromatography using an electron capture detector. Down to 0.02mg kg 1 organotin compounds in sediments could be determined with a recovery of 70-95%. 

Data for the analogous ethyl (220) compounds indicate that the equilibrium constants of the type of Eqs. (129)—(131) are very small for this system also. Consequently, it may be concluded that, in redistribution equilibria involving alkyl groups and halogens on tin, the mixed alkyltin halides are preferred. Mixtures having an overall composition corresponding to one of the mixed alkyltin halides contain this species in major amounts. 

Activation of alkyl groups on tin is one of the subjects which are paid attention. There are a number of reports that demonstrate that highly coordinated alkyltin... 

Enantioselective radical conjugate addition of an alkyl group to 587 was promoted by alkyltin hydride in the presence of chiral bis-isoxazoline derivatives <2002JA984>. 

Fig. 1. Dependence of the biological activity of tri-n-alkyltin acetates on the nature of the alkyl group for different species.

Grignards have often been used for the synthesis of many alkyl and aryl organotin compounds. However, certain derivatives, such as the perfluorinated alkyltins, cannot be... 

Organotin-Hg salt reactions follow the same trends with phenyltin bonds being more easily cleaved than simple alkyl or even some functionally substituted alkyltin bonds, e.g. ... 

Cosolvents and Tri-n-butyltin Fluoride. Dunn and Oldfield (15) first reported the ability of tri-n-butyltin fluoride to dramatically increase the viscosity of a relatively light alkane, namely hexane. Tri-n-butyltin fluoride exists in the form of a penta co-ordinate species, and is thereby able to form linear polymer chains by weak dipole-dipole interactions between the fluorine and tin of adjacent molecules. The fluid in which the tri-alkyltin fluoride is dissolved must have no dipole moment in order not to disrupt the transient associations which form the long chain polymer. As stated earlier, this compound was only very slightly soluble in CO2 (less than two weight percent) and no viscosity increase was observed. Heller et at. (2, 7) have conducted extensive research on these tri-alkyltin fluorides varying the alkyl groups in an attempt to enhance their solubility in 002 ... 

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