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Abstract

An apparatus is constructed to study the products of decomposition of a range of inorganic and organometallic tin compounds. The apparatus incorporates gas, liquid and solid sample collection and separates the decomposition products into gaseous, volatile and non-volatile fractions. The products of pyrolysis can be collected in sufficient quantities to permit full analyses using techniques such as: Gas Chromatography- Mass Spectroscopy, i.r. spectroscopy, uv spectroscopy, elemental analysis, X-ray diffraction, TLC, titrimetric analysis, and nmr spectroscopy.

A pyrolysis head attachment for a mass spectrometer was also constructed to permit gas chromatographic -mass spectroscopic identification of the gaseous products of pyrolysis.

The inorganic compounds studied were tin(ii) carboxylate derivatives including complex tin(ii) formates, acetates, oxalates and malonates. For the complex tin(ii) formates , the transition metal was seen to affect the order of cleavage of the metal-formate bonds, (ie. Sn or M-formate bond broken in first pyrolysis reaction), and to have different catalytic effects on the volatile products formed. The Na, K, and Ca tin(ii) acetates followed similar decomposition pathways with formation of Sn0 and metal acetate in the first pyrolysis step, with subsequent breakdown of the metal acetate to give the carbonate in the final decomposition stage. For the NH4+ derivative, the ammonium acetate portion of the complex decomposed initially, rapidly followed by decomposition of the stannous acetate. The metal carbonates were also the final decomposition product of pyrolysis of the oxalates and malonates although as with-the formates, the different metals are seen to have different catalytic effects on the volatile gaseous products.

The organotin compounds' studied included triphenyltin hydroxide, dialkyltin oxide polymers, dialkyl and diaryltin nitrates, dialkyl and diaryltin sulphates, and organotin(iv) carboxylates. For the majority of compounds full decomposition pathways are presented. The oxides and hydroxide show quite complex pyrolysis pathways involving partial reduction of Sn(iv) to Sn(ii) in the final decomposition stage to give solid residues comprising both Sn(ii) and Sn(iv) oxides. Both the nitrates absorb moisture initially to form hydroxides which breakdown to give Sn02 as the final solid residue. Complicated partial decomposition pathways were followed for the carboxylates, which incorporated several pyrolysis steps.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > Q Science (General) Q Science > QD Chemistry T Technology > T Technology (General)
Departments:	School of Science & Technology School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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