Tin organo

The cross-linking stage is facilitated by the use of a cross-linking catalyst, which is typically an organo-tin compound. A number of variations of this process exist and in one of these compounding, grafting and extmsion onto wire are carried out in the same extruder. 

There has been a revival of interest in recent years in antimony mercaptides as alternatives to the organo-tin stabilisers. This stems from the low level of toxicity and the strong synergism with calcium stearate. However, compared to the... 

In recent years there has been some substitution of TDI by MDI derivatives. One-shot polyether processes became feasible with the advent of sufficiently powerful catalysts. For many years tertiary amines had been used with both polyesters and the newer polyethers. Examples included alkyl morpholines and triethylamine. Catalysts such as triethylenediamine ( Dabco ) and 4-dimethyla-minopyridine were rather more powerful but not satisfactory on their own. In the late 1950s organo-tin catalysts such as dibutyl tin dilaurate and stannous octoate were found to be powerful catalysts for the chain extension reactions. It was found that by use of varying combinations of a tin catayst with a tertiary amine... 

Formulations for one-shot polyether systems are similar to those used for flexible foams and contain polyether, isocyanate, catalyst, surfactant and water. Trichloroethyl phosphate is also often used as a flame retardant. As with polyesters, diphenylmethane di-isocyanate is usually preferred to TDI because of its lower volatility. Tertiary amines and organo-tin catalysts are used as with the flexible foams but not necessarily in combination. Silicone oil surfactants are again found to be good foam stabilisers. Volatile liquids such as trichlorofluoro-methane have been widely used as supplementary blowing agents and give products of low density and of very low thermal conductivity. 

Silicone fluids containing Si—H groups are also used for paper treatment. The paper is immersed in a solution or dilute emulsion of the polymer containing either a zinc salt or organo-tin compound. The paper is then air-dried and heated for two minutes at 80°C to cure the resin. The treated paper has a measure of water repellency and in addition some anti-adhesive properties. 

Two-part room temperature condensation cure. Silicone can be formulated into two-part systems [3,12,14,33] that prevent the reactive groups from coming into contact before they are needed. The reactions in these systems are based on the condensation of a silanol group with an alkoxy silane group, catalyzed by organo-tin compounds (Scheme 9). 

Scheme 4.21 Proposed mechanisms for organo-tin catalyzation of the NCO/OH reaction.

Organotin compounds such as monobutyltin oxide, the main substance used, accounting for 70% of consumption, dibutyltin oxide, monooctyltin oxide, and dioctyltin oxide are used in certain esterification and transesterification reactions, at concentrations between 0.001% and 0.5% by weight. They are used in the production of substances such as phthalates, polyesters, alkyd resins, fatty acid esters, and adipates and in trans-esterifications. These substances are in turn used as plasticizers, synthetic lubricants, and coatings. Organo-tins are used as catalysts to reduce the formation of unwanted by-products and also provide the required colour properties (ETICA, 2002). 

Organo- tin Photodegradation constant (cm / molecule per second at 25 °C) Half-life (days)... 

Walsh GE, McLaughlin LL, Lores EM (1985) Effects of organo-tins on growth and survival of 2 marine diatoms, Skeletonema costatum and Thalassiosira pseudonana. Chemosphere, 14(3-4) 383-392. 

The Diels-Alder adduct of 1,5-cyclooctadiene with hexachlorocyclo-pentadiene was homopolymerized or copolymerized (113) with cyclic olefins using tungsten halide salts with either organoaluminum or organo-tin cocatalyst to give thermally stable flame- and oil-resistant polymers. 

For mono-organo tin, five- and six-coordination are often found234. Five-coordinate geometry verging on the square pyramid is sometimes observed as in various RSnL2 compounds235 for L a bidentate S ligand. Seven-coordination is also represented, usually... 

Figure 2.14 Schematic representation of the various stages of the grafting of a surface organo-tin complex on a platinum particle (as demonstrated by EXAFS, NMR, chemical analysis, IR). From left to right starting platinum particle with the surface organometallic fragment [(Pts)3(Tl -snBu]i adatoms of Sn, [(Pt4(ri -Sn]) surface PtSn alloy [sphere color-code orange (Pt), blue (H), white (C), green (Sn)].

The organo-tin compounds are formed upon the three types Bn"Cl Sa", 01, and SaCl,—the first resembling the sincic... 

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