78681-13-7Relevant articles and documents
Chemistry at Rigid Surfaces, 6. - Photochemically Induced Reactions with Surface-bound Sensitizers
Horner, Leopold,Klaus, Joachim
, p. 792 - 810 (2007/10/02)
AerosilR reacts with 3-triethoxysilylpropylamine to give Aminoaerosil (1) which can be converted into aerosils 2a - f by means of sensitizers containing carboxyl groups.The density of the functional groups on the surface which was determined by several methods clearly effects the reaction.On irradiation in 2-propanol, acetone was produced as well as the surface-bound pinacol, e. g. 4, which could be reoxidized by lead tetraacetate to give 2b.Hydrodimerization on the surface of 2b proceeds three times more slowly than with the homogeneous analogues.The photoreduction of 2b with a minor surface density, gave - in addition to 4 - the carbinol 8 and the mixed pinacol 9. - The aerosil with surface-bound p-acetylbenzoic acid (modified aerosil 2b) is investigated in comparison to the homogeneous system: experiments were made in (S)-p-menth-3-yl lactate and (R,S)-p-menth-3-yl-lactate.In both cases the surface-bound pinacol 4 was formed, and in the latter case a decrease in the optical activity of the lactate was observed. - With surface-bound sensitizers the following photochemically induced reactions were studied: a) the photosensitized addition of 2-propanol to maleic acid and diethyl maleate to give terebinic acid (12a) or its methyl ester, respectively; b) the sensitized cis/trans isomerization of maleic acid or diethyl fumarate; c) the sensitized cis/trans isomerization of 1,2-diphenylcyclopropane; d) the sensitized autoxidation of 2,5-dimethylfuran. - All four reactions, although slower, yield the same products as in the analogous homogeneous system.In reaction b), c), and d) the efficiency factor WF (ratio of reaction rates in homo- and heterogeneous system) and the reutilization factor SF (ratio of co nversions after a given time in the first and second experiment) was determined for the heterogeneous sensitizer.
