Alkyltin halides

Whereas bromine radicals (133) and succinimidyl radicals (134) react by the Sh2 mechanism at the tin center in tetraalkyltins, but not in alkyltin halides, alkoxyl radicals (135) and ketone triplets (136) react with alkyltin halides, but not tetraalkyltins this may reflect the conflicting, electronic demands of the radical reagents which, as electrophilic species, should be more reactive towards tetraalkyltins than alkyltin halides, but which would also tend to make use of a 5d orbital... 

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). 

At equilibrium, the distribution of alkyltin halides may be described by three equilibrium constants, the values (104) of which are given below for the system Sn(CH3)4 vs SnCl4. 

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. 

Various allyl-, benzyl-, and alkyltin halides have been prepared by direct methods compounds have included frmctionaUy substituted dialkyltin dihaUdes X2Sn[(CH2) Y]2 (n = 1 or 2, Y = R2NCO, ROCO, RCO n = 2, Y = NC n = 3, Y = RO). 

Alkyltin halides and isopropoxides similarly exchange their groups readily as illustrated by the following equations (6). 

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. 

Cleavage of an alkyl-tin bond by an Sh2 reaction (see Section 5.3.6) occurs more readily with the alkyltin halides (and carboxylates) than with the tctraalkylslannancs.87 88 These reactions were first identified by ESR spectroscopy in the photolysis of di-t-butyl peroxide in the presence of organotin halides, which provides a very convenient technique for ESR studies of alkyl radicals, for example equations 11-28 and 11-29.89... 

The interaction of sodium perthiocyanate (438) and suitable bifunctional dihalides readily produces polymers (444) which are claimed to be useful catalysts in the production of polyurethane foams. The use of l,4-di(chloro-methyl)benzene in ethanol, for example, gives 444 (R = p-CH2C6H4CH2, terminating in p-CH2C6H4CH2OEt, mol wt 2960) in 90% yield.354 5-Mercapto-3-methylthio-1,2,4-thiadiazole yields the tin-containing derivatives 445 (R = Bu, Ph, or cyclohexyl n = 1-3) on treatment with alkyltin halides in tetrahydrofuran.355... 

In 1959, our laboratories began investigating direct reactions of alkyl halides with tinfoil, as shown in Eq. (2.1), and various halo-alkyltin halides were obtained as products of reactions conducted under many reaction conditions in the presence of catalysts [1 ]. 

I Partial hydrolysis of alkyltin halides, alkoxides or dithiocarbamates with ... 

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