Alkyltin derivatives

Table 9.3 Slope of plot of log /cobs vs. log A obs for series of related electron-transfer reactions. The asterisks in the first column indicate electronically excited states of the complexes. HAs is the ascorbate anion, PTZ is the N-alkylphenothiazine derivative, SnR4 is the tetra-alkyltin derivative, is the bipyridinium derivative, and ArNR is an aromatic amine. The solvent is water, except for the last two entries, where it is acetonitrile. Data from Ref. [14]...

As discussed in section 2, the alkyltin component of organotin compounds is relatively stable to environmental degradation processes such as hydrolysis, compared with the association with the relative ligand (such as an isooctyl mercaptoacetate group). Thus, in water, most of the derivatives are reported to dissociate to the constituent alkyltin (usually as the chloride or the oxide) and the relevant anion (KemI, 2000). 

SnCl2 reacts with triphenylethenyllithium Li(CPh=CPh2) in Et20-w-hexane-THF to yield an alkenyltin(II) derivative which, subsequently treated with butyl bromide, yields a mixed alkyltin halide362 ... 

Two frequently used methods for preparing stannylthiazoles involve either direct metalation or halogen-metal exchange followed by treatment with alkyltin chloride. Dondoni et al. described a preparation of 2-, 4- and 5-trimethylstannylthiazoles in 1986 [28], For instance, 2-trimethylstannylthiazole was readily obtained by quenching 2-lithiothiazole, derived from direct metalation of thiazole, with trimethyltin chloride. 

The most toxic of the organotin compounds are the trialkyltins, followed by the dialkyltins and monoalkyltins. The tetraalkyltins are metabolized to their tri-alkyltin homologs their effects are those of the trialkyltins, with severity of effects dependent on the rate of metabolic conversion, hr each major organotin group, the ethyl derivative is the most toxic. ... 

The basic metal salts and soaps tend to be less cosdy than the alkyltin stabilizers for example, in the United States, the market price in 1993 for calcium stearate was about 1.30— 1.60, zinc stearate was 1.70— 2.00, and barium stearate was 2.40— 2.80/kg. Not all of the coadditives are necessary in every PVC compound. Typically, commercial mixed metal stabilizers contain most of the necessary coadditives and usually an epoxy compound and a phosphite are the only additional products that may be added by the processor. The required costabilizers, however, significandy add to the stabilization costs. Typical phosphites, used in most flexible PVC formulations, are sold for 4.00— 7.50/kg. Typical antioxidants are bisphenol A, selling at 2.00/kg -nonylphenol at 1.25/kg and BHT at 3.50/kg, respectively. Pricing for ESO is about 2.00— 2.50/kg. Polyols, such as pentaerythritol, used with the barium—cadmium systems, sells at 2.00, whereas the derivative dipentaerythritol costs over three times as much. The p-diketones and specialized dihydropyridines, which are powerful costabilizers for calcium—zinc and barium—zinc systems, are very cosdy. These additives are 10.00 and 20.00/kg, respectively, contributing significandy to the overall stabilizer costs. Hydrotalcites are sold for about 5.00— 7.00/kg. 

Alkyltin compounds carrying a leaving group at the y-position undergo 1,3-elimination to produce cyclopropanes9. y,<5-Epoxyalkyltin derivatives are converted to cyclopropyl-methyl alcohols under catalysis of a Lewis acid (equation 5)10. y-Hydroxyalkyl selenides... 

Mercaptides are unchallenged as the ligand of choice for the other entities bonded to the tin, but carboxylates can also be used. Whereas a variety of mercaptans are used, the thioglycolic acid derivatives remain the laigest single mercaptan. Dibutyltin bis(isooctyl thioglycolate) [25168-24-5] and butyltin tris(isooctyl thioglycolate) [25852-704] are two common examples. These materials are produced by the reaction of the appropriate alkyltin chloride or oxide, and the mercaptan. 

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

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... 

Most tetraalkylstannanes similarly usually react by Sh2 at a hydrogen centre, but alkyltin halides and similar derivatives react by an Sh2 process at the tin centre, for example reaction 3-3. These reactions are useful for generating specific alkyl radicals for ESR and similar studies,2 and are discussed in Section 5.3.6 and 11.4. Photoexcited carbonyl compounds react in the same way. 

The organotin methoxides cannot readily be prepared from methanol by reaction 14-2 because its boiling point is too low, and it does not form an azeotrope with water. The methoxides and alkoxides derived from other volatile alcohols can, however, readily be prepared by heating together the bis(trialkyltin) oxide and dialkyl carbonate the exchange reaction between the tin oxide and carbonate gives the tin alkoxide and the alkyltin carbonate (reaction 14-13), which readily decarboxylates to give more alkoxide (reaction 14-14)4... 

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