Tin oxide surfaces. Part 21.—Infrared study of the chemisorption of 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoropropan-2-ol, 1,1,1-trifluoropropan-2-one, 1,1,1,3,3,3-hexafluoropropan-2-one and trifluoroacetic acid on tin(IV) oxide gel

Abstract

The adsorption of trifluoroacetic acid, 1,1,1,3,3,3-hexafluoropropan-2-one, 1,l ,l-trifluoropropan-2-one, 2,2,2-trifluoroethanol and 1,1,1,3,3,3-hexafluoropropan-2-ol on tin(iv) oxide gel has been studied by infrared spectroscopy. Trifluoroacetic acid is adsorbed as both hydrogen-bonded molecular trifluoroacetic acid and surface trifluoroacetate, the former being totally converted into the latter by 533 K. The surface trifluoroacetate decarboxylates by 673 K to give surface trifluoromethoxide. Both of the ketones 1,1,1,3,3,3-hexafluoropropan-2-one and 1,1,1-trifluoropropan-2-one are chemisorbed as surface hemiacetal species by interaction with a surface hydroxyl group. These undergo subsequent thermal decomposition to give, respectively, surface trifluoroacetate and a mixture of surface trifluoroacetate and surface acetate. The two alcohols 2,2,2-trifluoroethanol and 1,1,1,3, 3,3-hexafluoropropan-2-ol are chemisorbed as surface alkoxy species which thermally decompose to surface formate and surface trifluoromethoxide in the case of the former and additionally in the case of the latter, surface trifluoroacetate. The thermal stability of the surface carboxylates is in the order: surface acetate > surface trifluoroacetate > surface formate.

Effects of Trifluoroacetic Acid Modification on the Surface Microstructures and Photocatalytic Activity of Mesoporous TiO2 Thin Films

“…These include doping with fluoride and metal ions, ,, coupling the films with metal oxide, modifying the substrates, , and treating the films with acid. , Liao et al reported the adsorption and photoreactions of acetic acid on TiO 2 powders . The chemisorption of trifluoroacetic acid (TFA), an acid with strong electron-withdrawing groups, has also been reported . However, the substrate used in that particular study was tin(IV) oxide gel.…”

In situ Formation of TiO2 in Electrospun Poly(methyl methacrylate) Nanohybrids

“…This result suggests that a small quantity of water contained in the solvent would initiate the hydrolysis of TBT, in view of the fact that TBT is a highly hydrolyzable material. Besides this, the residual solvent TFA is observed by the CF 3 stretching vibration peak detected at 1197 and 1146 cm –1 . Moreover, the C–C and C–H stretching vibration bands and Ti–O–C band are undetectable in the hydrolyzed precursor.…”

“…Besides this, the residual solvent TFA is observed by the CF 3 stretching vibration peak detected at 1197 and 1146 cm À1 . 31 Moreover, the CÀC and CÀH stretching vibration bands and TiÀOÀC band are undetectable in the hydrolyzed precursor. These results demonstrate that the Ti-OR had completely transformed into TiÀOH via the hydrolysis reaction under acid catalysis.…”

Adsorption and Reaction Behavior of Perfluoro-n-alkanes on Al2O3

“…In the end, some remarks are necessary regarding the described changes in the carboxylate infrared bands during stepwise heating. Simultaneous appearance of more than two of those absorptions is usually ascribed to the existence of carboxylate species interacting in different ways with the solid surfaces (e.g., (11,12)). In the case of unidentate species, two absorptions appear with a large separation due to the essentially single-and double-bond character of the two carbonoxygen bonds.…”