Traveling waves were investigated in the Belousov−Zhabotinsky reaction in which 1,4-cyclohexanedione was the substrate. Isothermal density change (Δρc) and reaction enthalpy were determined. Δρc is positive, while the reaction enthalpy is negative; therefore, double-diffusive convection was expected according to the Pojman−Epstein model. Experiments were carried out in tubes and in spectrophotometric cells. In tubes the effect of the diameter and the orientation of the tube on the wave velocity and on the wave shape was studied; gravitational anisotropy and the expected double-diffusive convection were found. Experiments in cells were compared to the calculations of Wu et al. (Wu, Y.; Vasquez, D. A.; Edwards, B. F.; Wilder, J. W. Phys. Rev. E 1995, 51, 1119−1127). They predicted a critical cell width under which no simple convection should occur. However, because double-diffusive convection was observed, their calculations are not directly applicable.

The effect of FeCl3 in acetonic medium on the structure of Na-bentonite was studied using X-ray diffraction (XRD), 57Fe Mössbauer spectroscopy, X-ray fluorescence spectroscopy and infrared spectroscopy to describe the structure of the bentonite before and after treatment. In the samples treated with FeCl3, an increase in the basal spacing was found by XRD, while a new magnetically split component assigned to Fe3+ incorporated within the interlayer regions of montmorillonite showed up in the low-temperature Mössbauer spectra. The Mössbauer parameters observed were close to those of Fe oxyhydroxides, suggesting the presence of some kind of nanoparticles. These results show that the treatment with acetonic FeCl3 solution is an effective method for introducing Fe into montmorillonite in the form of Fe3+ accommodated in the interlayer region. The treated samples proved to be efficient Lewis catalysts in the acylation of aldehydes (benzaldehyde and 4-OH-benzaldehyde) by acetic acid anhydride.

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57 Fe Mö ssbauer spectroscopy, X-ray diffraction, X-ray fluorescence spectroscopy and infrared spectroscopy were used to study the effect of FeCl 3 and acetone on the structure of a Na-bentonite. XRD indicated the incorporation of Fe 3+ ions into the interlayer space since the basal lattice spacing of montmorillonite increased to 1.6 from 1.24 nm after treatment with FeCl 3 dissolved in acetone. Interlayer Na + ions could be exchanged to Fe 3+ . Magnetically split Mö ssbauer subspectra with internal magnetic fields 41 and 46 T at 74 K, were associated with two main Fe 3+ microenvironments within the interlayer regions. The resultant Femontmorillonite was successfully applied as a catalyst in the preparation of 1,1-diacetates from aromatic aldehydes and acetic acid anhydride.

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