Organotin compounds I. The synthesis of dibutyltin dihalides

The direct reaction between butyl iodide and tin to give dibutyltin diiodide was investigated. It was found that extremely active catalysts for this reaction are provided by combinations of metal halides and oxygenated solvents. Either component alone has little or no catalytic effect but combination gives high yields of dibutyltin diiodide. The metal halide can be added as such, or alternatively a metal or salt which can readily be converted to a halide under the conditions of reaction may be used. Of the metals investigated, lithium appears to be the most active. The results suggest that all oxygen-containing solvents are effective co-catalysts with the metal halides, and that the oxygen-containing co-catalysts may have greater activity if they contain more than one oxygen atom in the molecule.