Dialkyltin dichlorides

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. 

Sodium dicyanoethylenedithiolate reacts with trimethyl- or triphenyl-tin chloride to give anionic trialkylstannadithiacyclopentenes, but dialkyltin dichlorides undergo dealkylation (231). 

The dialkyltin dichloride formed by reaction of the dialkyltin stabilizer with the polymer, or with the hydrogen chloride liberated, is itself... 

Thoonen S, Deelman BJ, van Koten G (2001) Platinum- and palladium-catalysed Kocheshkov redistribution of dialkyltin dichlorides or tetraalkyltins with tin tetrachloride. Chemical Communications, 18 1840-1841. 

Next, some special methods for preparing organotinhalides are presented. 1,2-Dichlorotetraalkyldistannanes ClR2SnSnR2Cl (R = Me, Et, Bu) have been prepared by the electrolysis of acetonitrile solutions of the appropriate dialkyltin dichloride using... 

The triorganotin chloride adducts readily exchange with base or with other adducts. The diorganotin dichlorides form only 1 1 adducts with tributylphosphine, even at high base to acid ratios. The lower dialkyltin dichlorides prefer to form 1 1 adducts (at 1 1 mole ratios) with tributylphosphine rather than tributylphosphine oxide (TBPO), whereas... 

Of course, the problems of hydrolysis can be obviated by using non-aqueous solvents, and pseudo-metal ions have the necessary solubilities. For example, spectrophotometric studies (18) of complex formation equilibria between 2,2 -bipyridine (bipy) and dialkyltin dichloride have been reported. The log K values for complexes R2SnCl2-bipy are 3.19 (R, n-C4H9), 3.36 (R, CH3), and 6.7 (R, Cl) in acetonitrile. There is surprisingly little difference between the constants for dimethyl- and the dibutyltin dichloride complexes. The equilibrium constant for the dibutyl-tin dichloride complex increases with increasing dielectric constant of an alcohol solvent. 

Dialkyltin dichloride reacts with alkali metal carbonates in water to give oxycarbon-ates (R2Sn)20C03 (13-14). The Mossbauer spectra (QS 3.0-3.33 mm s-1) indicate that the tin is 5-coordinate, probably through coordination by both the SnOSn and C=0 oxygens.44... 

Dialkyltin dichlorides, R2SnCl2 (R = Me, Et, or C6H13), react with samarium iodide or with magnesium or calcium vapour to give polystannanes with M u/ > 103 and a narrow molecular weight distribution (e.g. equation 18-48). 

Second, they scavenge the HCI which is eliminated, to give the dialkyltin dichloride and thiol, which do not catalyse further elimination. 

The two possible reactions of organotin mercaptide stabilizers, both ending in the formation of dialkyltin dichloride, are shown in Schemes 3.3.1 and 3.3.2. 

The formation of dialkyltin dichloride may thus be considered, as a first approximation, to be a measure of the total stabilizer conversion. Accordingly the diagram in Figure 3.3.6 shows the correlation between the stabilizer conversion and the time of heat treatment at 180 °C. 

The solid-state spectrum of the grafted dialkyltin dichloride (Figure 6.1.3a) displays a single, albeit broad, Sn resonance at its isotropic chemical shift, identical within experimental error to its chemical shift in the Sn hr-MAS spectrum (Figure 6.1.3b), indicating that the tin atom has the same... 

The Ligand Exchange Reaction of Some Dialkyltin Dimercaptides and Dicarboxylates with Dialkyltin Dichlorides... 

The existence of a ligand exchange reaction between dialkyltin dimercaptides and dicarboxylates (typical poly(vinyl chloride) stabilizers) and dialkyltin dichlorides is demonstrated by 1H and 13C NMR. Dibenzyl- and dibutyltin dimercaptides undergo the reaction instantaneously and quantitatively at 25° C to yield dialkylchlorotin mercaptides. Dialkyltin dicarboxylates and dimethyltin dimercaptides appear to participate in an equilibrium exchange reaction with dialkyltin dichlorides in which the individual components are not identifiable by NMR at 25°C. These results are discussed as they pertain to poly(vinyl chloride) stabilization. 

Dialkyltin Compounds. All of the dialkyltin dimercaptides and dicarboxylates were prepared by reaction of the appropriate dialkyltin oxide (Alfa Inorganics) with the desired mercaptan or carboxylic acid. The reactions were carried out in refluxing benzene or toluene using a Dean-Stark water separator. The yields are quantitative and products require no purification (purity confirmed by H and 13C NMR). The dialkyltin dichlorides were obtained commercially (Alfa Inorganics) and used as received ... 

The halide bridging still persists in dialkyltin dichlorides and dibromides, but is somewhat weaker and is of an asymmetric nature, either as in (20) or (21). Diphenyltin dichloride and methylphenyltin dichloride have weak tetrameric associated structures the two terminal tin atoms are tetracoordinate, with the middle two tin atoms being hexacoordinate. Dicy-clohexyltin dichloride has essentially a one-dimensional polymeric structure with a live-coordinate tin atom, but with an additional weak tin chlorine interaction (22). Both bis(2-biphenylyl)tin dichloride and 5,5-dichloro-10,ll-dihydrodibenzo[fc,/]stannepin (23) are monomeric in the solid state. 

Dialkyltin dichlorides couple via the Wurtz reaction (see Section 2.3) to yield long-chain polystannanes, as shown below, along with cychc byproducts. 

Good samples of dialkyltin dichlorides were isolated by this method from mixtures of tin stabilisers with diisooctyl phthalate and tritolyl phosphate the dialkyltin groups have been identified in dibutyl tin dinonylmaleate, dioctyltin dilaurate, dibutyltin dinonylthioglycollate and dioctyltin thioglycollate. 

Freireich et al. " described the synthesis of poly(organotin phosphonates) from the reaction of dialkyltin dichlorides, tetralkyldichlorodistannoxanes, or hexaalkydichlorotristannoxanes with the disodium salt of phenylphosphonic acid, 65. 

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