THE GAS-PHASE THERMOLYSIS AND OXIDATIVE THERMOLYSIS OF SOME HOMOLEPTIC TETRAALKYLSTANNANES - AN FT-IR STUDY

Fourier transform infared spectroscopy has been employed to investigat e the thermal decomposition chemistry of a number of homoleptic tetrao rganostanannes, R(4)Sn (R = Et, Pr-n,Pr-i, (n)Bu, (s)Bu) in the temper ature range 543-573 K. Neat tetraethyltin and tetra-n-butyltin give pr incipally alkene (ethene when R = Et; a mixture of but-1-ene and cis- and trans-but-2-ene when R=(n)Bu) with some of the corresponding alkan e. When the thermolysis reactions are carried out in the presence of o xygen decomposition of all the tetraalkylstannanes studied give alkene and an organic carbonyl compound, together with carbon dioxide and wa ter. In the cases of tetra-n-propyltin, tetra-iso-propyltin and tetra- sec-butyltin, propanal, acetone, and butanone, respectively, are forme d as the tetraorganotin is consumed. Only small amounts of carbonyl co mpounds are formed initially in the thermal decomposition of tetraethy ltin and tetra-n-butyltin in the presence of oxygen, alkenes being the major product, although in the latter case peaks due to butyraldehyde grow in intensity as the reaction mixture is held at 573 K. The decom positions in both the absence and presence of oxygen are considered to proceed by radical mechanisms involving the homolytic fission of the tin-carbon bond to produce alkyl radicals, which react to give the obs erved products.