Dunbar P. Birnie, III and Norbert J. Bendzko
Source: Materials Chemistry and Physics, 59,
26-35 (1999)
Abstract: Hydrogen and carbon NMR spectroscopy have been used
to investigate the chemical modification process of titanium isopropoxide
by acetic acid. The spectra confirm the belief that the titanium isopropoxide
exchanges isopropyl groups with modifying acetate groups to form a molecule
with approximate stoichiometry Ti(OiPr)2(OAc)2. This
stoichiometry results even when enough acetic acid is present in solution
to allow for significantly higher isopropyl replacement. In addition, progressive
esterification to form isopropyl acetate results in a gradually increasing
level of condensation and oxo-bridging between the Ti oligomers. Throughout
the condensation process, the remaining Ti-bound acetate and isopropyl
groups maintain an approximate 1:1 ratio, suggesting that oxo-bridge formation
occurs through a transesterification process.