Accession Number : ADA282789

Title :   Hydrolysis and Condensation of Tin (IV) Alkoxide Compounds: The Control of Structural Evolution.

Descriptive Note : Annual rept. Apr 93-Jun 94,

Corporate Author : NEW MEXICO UNIV ALBUQUERQUE DEPT OF CHEMISTRY

Personal Author(s) : Hampden-Smith, M. J.

Report Date : 03 JUN 1994

Pagination or Media Count : 19

Abstract : We are investigating the mechanism of ester elimination reactions between metal alkoxide compounds and metal carboxylate compounds as a method to form metal-oxo clusters in a controlled fashion. We anticipate that the fundamental insight gained will result in a better understanding of methods to control the evolution of microstructure in metal oxide ceramics. Two parts of our preliminary experiments are reported here. Part 1 describes a series of proton (1H) NMR magnetization transfer experiments utilized to measure the kinetic parameters of alcohol interchange between the homoleptic metal alkoxide, Sn(O-t-Bu)4, and t-butanol, its parent alcohol. These data suggest that the metal center, even in sterically encumbered metal alkoxide compounds such as Sn(O-t-Bu)4, are sufficiently coordinately and electronically unsaturated to react with bulky alcohols. These observations must be taken into account when conducting sol-gel type hydrolysis and condensation reactions. In part 2, the alkoxide Sn(O-t-Bu)4 and carboxylate Me3Si(OAc) are used in a detailed study of the ester elimination process. We report time dependent 170 NMR spectra of the ester elimination reaction of the two from which a plausible associative transition state can be described. Microstructure, Porosity, Tin oxide.

Descriptors :   *ALCOHOLS, *BUTANOLS, *CONDENSATION REACTIONS, *HYDROLYSIS, *KINETICS, *METALS, *STRUCTURES, *TIN, CONTROL, ELIMINATION REACTIONS, ESTERS, MAGNETIZATION, MICROSTRUCTURE, OXIDES, POROSITY, PROTONS, SPECTRA, CERAMIC MATERIALS, EVOLUTION(GENERAL), TIME, TRANSFER, TRANSITIONS.

Subject Categories : Physical Chemistry
      Inorganic Chemistry
      Organic Chemistry
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE