Organotin peroxides

The two principal routes to the organotin peroxides involve substitution by a peroxide nucleophile at a tin centre (equations 14-69 and 14-70), or (pericyclic) reaction of an allyltin compound with singlet oxygen (equation 14-71). Distannyl peroxides have also been prepared by the (homolytic) reaction of distannanes with triplet oxygen (equation 14-72). 

Some examples of stannyl hydroperoxides and peroxides are included in Table 14-7. 

Stannyl hydroperoxides and distannyl peroxides are probably formed in homolytic chain reactions when triplet oxygen reacts with tin hydrides or distannanes, respectively, but the peroxide products are rapidly reduced by the reactants and these reactions are not useful preparatively. 

If dialkyltin dialkoxides are treated with 98% hydrogen peroxide in ether, insoluble cyclic or linear dialkyltin peroxides (R2SnOO) are formed. These are thermally more stable than the bistrialkyltin peroxides, R3SnOOSnR3, and lose about half their peroxide content in one month at room temperature. If the reactions are carried out in the presence of an aldehyde, l,2,4-trioxa-3-stannolanes are formed, together perhaps with some oligomeric material.132 

Bu2Sn(OMe)2 + 4-N02C6H4CH=0 + H202 10oc 83o/ Bu2Sn CHC6H4N02 (14-76) 

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The organotin peroxides and hydroperoxides in Table 171 are prepared by methods from the following scheme. 

Organotin(IV) compounds could be involved in other biological processes occurring in cells, specifically in peroxide oxidation of lipids. The latter process is very important from the viewpoint of physiology, and it follows a radical chain mechanism. ... 

Petrosyan et studied peroxide oxidation of oleic[(Z)-octadecenoic] acid in the presence of complexes derived from R SnCl4 and phosphatidylcholine [0P(0)(0H)0CH2CH2-N(Me)3, PChol] which is a short-chain analog of phospholipids, and also compared the effects of the complexes (R3SnCl)2-PChol (R = Me, Ph), R2SnCl2-PChol (R = Me, Bu), and RSnCls-PChol (R = Me, Ph) with that produced by the organotin parents. ... 

The stannylenes from either source will insert into the Sn- Sn, Sn-R, or Sn-H bonds of organotin compounds, and react with alkyl halides, disulfides, or peroxides as shown in the reaction scheme below, but only the stannylenes that are generated photolytically will react with carbonyl compounds, and it appears that the stannylenes may exist in two forms, perhaps related as singlet and triplet, or a com-plexed and uncomplexed species. 

Crompton [21] has reviewed the use of electrochemical methods in the determination of phenolic and amine antioxidants, organic peroxides, organotin heat stabilisers, metallic stearates and some inorganic anions (such as bromide, iodide and thiocyanate) in the 1950s/1960s (Table 8.75). The electrochemical detector is generally operated in tandem with a universal, nonselective detector, so that a more general sample analysis can be obtained than is possible with the electrochemical detector alone. 

Use of mild conditions was crucial and the development of diimide reduction of singlet oxygenates, silver-salt-assisted displacement of halide by peroxide nucleophiles, peroxymercuration and demercuration, peroxide transfer from organotin to alkyl triflates, and oxygen trapping of azoalkane-derived diradicals have all played a part in providing the rich harvest of new bicyclic peroxides described herein. 

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... 

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