Detail of "2497-21-4"

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Evaluation of acidity of strong acid catalysts

Evaluation of acidity of strong acid catalysts. II. The strength of boron trifluoride-water systems. Farcasiu, Dan; Ghenciu, Anca (Dep.In this study， 141-79-7 and 2497-21-4 are also used. Chem. Eng., Univ. Pittsburgh, Pittsburgh, PA 15261, USA). J. Catal., 134(1), 126-33 (English) 1992. CODEN: JCTLA5. ISSN: 0021-9517. DOCUMENT TYPE: Journal CA Section: 67 (Catalysis, Reaction Kinetics, and Inorganic Reaction Mechanisms) Section cross-reference(s): 77 The method of detg. a thermodn. acidity function from the chem. shift changes of 1C signals of unsatd. ketones at infinite diln. in the investigated acid established by the authors (1992) was applied to the system boron trifluoride-water (III) ranging from the monohydrate (BF3.H￥O) to the trihydrate (BF3.3H2O). The indicators used were mesityl oxide and 4-hexen-3-one. III is significantly stronger than indicated by earlier measurements conducted by the classical Hammett method based on UV-visible spectroscopy. The mixts. with ~1.25 mol of water per mol BF3 or less are stronger than pure H￥SO4 and are therefore superacidic. The stronger acidity of III can be understood because BF3 is a much stronger Lewis acid than SO3; therefore the complex with a hydroxyl anion of the former (hydroxytrifluoroborate anion) should have a lower affinity for a hydron than the corresponding complex of sulfuric anhydride (bisulfate anion). Preliminary expts. indicate that the 13C NMR method can be applied successfully to working catalysts based on III, which are colored and contain dissolved org. materials. .