[1011-95-6] · C12H12Sn · Diphenylstannane · (MW 274.95)
(hydrostannylation of alkenes and alkynes; reduction of aldehydes and ketones; hydride transfer reactions with other organometallic reagents)
Alternate Name: diphenyltin dihydride.
Physical Data: colorless oil; bp 89-93 °C/0.3 mmHg, 74 °C/0.001 mmHg; mp -17 °C; d 1.39 g cm-3; n
Solubility: sol most organic solvents. Many polar aprotic solvents catalyze the decomposition to diphenyltin oligomer and hydrogen (e.g. MeOH, Et2NH, pyridine, morpholine, DMF, DMSO). Diphenylstannane reacts (exothermically) with all protic solvents.
Form Supplied in: not commercially available.
Analysis of Reagent Purity: 119Sn NMR recommended (d -234 ppm, 1J(119Sn-1H) 1928 Hz).4
Handling, Storage, and Precautions: must be stored in the absence of oxygen, moisture, and light (preferably under argon). Use in a fume hood.
All aspects of the preparation, spectroscopic properties, and chemical reactions of diphenylstannane are discussed in the Gmelin Handbuch volume dealing with organotin hydrides (literature covered up to the end of 1974),1a while more general aspects of the preparation and chemistry of organotin hydrides (and deuterides) are reviewed in the Houben-Weyl volume on organotin compounds (literature coverage up to 1977).1b
The hydrostannylation of monoalkenes (e.g. acrylonitrile, methyl acrylate, methyl methacrylate) or monoalkynes affords monomeric products (eq 1).5 Dialkenes (e.g. 1,4-divinylbenzene) or dialkynes (e.g. 1,4-diethynylbenzene), in contrast, yield polymeric materials.6 In some cases (e.g. 1,2-divinylbenzene, 1,2-diethynylbenzene) a mixture of polymeric and monomeric products is formed (eq 2).7
Aldehydes and ketones are reduced by diphenylstannane to primary and secondary alcohols, respectively. This reaction is of preparative interest in the case of a,b-unsaturated ketones, since here only the carbonyl group is normally reduced, the alkenic double bond remaining unaffected (eq 3).8 Some cases are known, however, in which the double bond is reduced while the carbonyl group remains intact.9
Diphenylstannane undergoes reversible exchange reactions with diphenyltin dihalides to afford halodiphenylstannanes,10 which in turn can be used as reducing agents. Many other ligand exchange reactions are known, but these have not so far been shown to be of interest for synthetic organic chemistry.
Virtually no synthetic work has been published since 1974. The reason for this is likely to be the fact that, in general, diphenylstannane has no notable advantage over the dimethyltin or dibutyltin analogs. Its disadvantage lies in the high boiling points of diphenyltin compounds, which make it difficult to remove tin-containing residues completely from reaction products. Its one potential advantage lies in the fact that such compounds are in some cases solids at rt. However, even these generally have a residual solubility in organic compounds. It will indeed not generally be necessary to resort to the use of tin dihydrides in order to carry out chemistry of the nature described above, except when polymeric or cyclic organotin products are required. The monohydrides are chemically very versatile and in addition much more stable (see in
Terence N. Mitchell University of Dortmund, Germany
Terence N. Mitchell
University of Dortmund, Germany