Annie Finiels

Selective isopropylation of naphthalene over zeolites

The isopropylation of naphthalene with isopropylbromide over a series of H mordenites and Y zeolites has been studied. In both cases, a high β-selectivity is observed in the monoalkylation and dialkylation reactions (selective formation of 2-isopropylnaphthalene and a mixture of 2,6- and 2,7-iisopropylnaphthalenes, respectively). Over H mordenites, the β-selectivity is explained as the result of transition-state shape selectivity. Over Y zeolites, the β-selectivity is due to a thermodynamic equilibrium favorable to the formation of 2-isopropylnaphthalene from 1-isopropylnaphthalene. The use of zeolites modified by silanation using chemical vapor deposition leads to an improvement of the β-selectivity by reducing the amount of trialkyl derivatives that are formed on the external surface.

Acylation over cation-exchanged montmorillonite

The Friedel-Crafts acylation of aromatic compounds (benzene, toluene, xylene) with carboxylic acids (CH3(CH2)n COOH, n = 0–14) was performed over cation-exchanged montmorillonites (H+, Al3+, Ni2+, Zr4+, Ce3+, Cu2+, La3+). n nYields in ketones were found to be dependent upon the nature of the interlayer cation and on the acid chain length.

SBA‐15‐Type Organosilica with 4‐Mercapto‐N,N‐bis‐(3‐Si‐propyl)butanamide for Palladium Scavenging and Cross‐Coupling Catalysis

This work describes the synthesis of novel functional silica materials with difunctional thiol-amide substructures and featuring regular architectures on a mesoscopic level. The functional materials were synthesised by both one-pot co-condensation and post-grafting approaches. The thiol groups confined in the matrix were found to be efficient for palladium entrapment, leading to highly active and reusable heterogeneous catalysts for Sonogashira and Suzuki-Miyaura cross-coupling reactions. This work evidences the crucial role of both the thiol precursor and the condensation degree of the silica scaffold in view of the design of stable and reusable tailor-made mesoporous catalytic silica materials.

Photocatalytic degradation of hydroxylated biphenyl compounds

The photocatalytic degradation of three hydroxylated bicyclic aromatic compounds (2,2′-dihydroxybiphenyl, 4,4′-dihydroxybiphenyl and 4-hydroxybiphenyl) in contact with TiO2, in aqueous unbuffered solution was achieved. The main intermediate, in all cases, was 1,2,4-trihydroxybenzene. The photoxidation of this intermediate led to identified compounds: maleic acid, muconic acid and butadiene, resulting from the aromatic ring opening. A complete mineralization scheme for hydroxylated bicyclic aromatic compounds can be proposed.

Liquid-phase acetylation of tetralin with acetyl chloride over zeolites : inhibition of the reaction by the products

HY and H-beta zeolites are efficient catalysts in the acetylation reaction of tetralin with acetyl chloride. Their activity depends largely on the experimental conditions and is restricted by the strong adsorption of organic species, either acetic acid or acetyltetralin formed in the reaction.

Cyclohexylation of naphthalene over unmodified HY zeolites

Cyclohexylation of naphthalene was studied over four commercial unmodified HY zeolites. Approximately equal results were obtained on HY (ZF 515, ZF 520, CBV 720) zeolites. The best results were obtained with cyclohexylbromide as alkylating agent inn-nonane and inn-decane as solvents at boiling point. Conversion of naphthalene was max. 97%, 2,6-selectivity 43% andβ,β-selectivity 77%.

Photocatalytic oxidation of substituted toluenes with irradiated TiO2 semiconductor. Effect of zeolite

Photocatalytic oxidation of substituted toluenes was investigated on irradiated TiO2 and TiO2 combined with HY15 and HY20 zeolites. In all cases the oxidation occurred in the first step exclusively on either one substituent or the other, but never on both simultaneously. In the presence of a zeolite, photooxidation conversion was higher than that obtained without zeolite.

Selective Synthesis of Carbonyl Compounds Using Zeolites

Various typical acid-catalyzed reactions leading to carbonyl compounds were studied using zeolites taking into account their acidic and shape selective properties. Acylation of aromatic compounds by carboxylic acids over Y zeolites leads to quantitative conversion in acylated derivatives with very high para selectivity. On the other hand, the Fries rearrangement of phenylbenzoate gives mainly ortho hydroxybenzophenone. Zeolites are also efficient catalysts in hydration of various aromatic and aliphatic alkynes leading to the corresponding ketones. The epoxide rearrangement of styrene oxide yields phenylacetaldehyde with high conversion. In this latter case, the use of surface-modified zeolites shows that both external and internal acid sites of the zeolite are involved in liquid phase epoxide conversion.

Triple Bond Hydration Using Zeolites as Catalysts

Summary Hydration reactions of alkynes and nitriles were studied over various zeolites in liquid phase, with ethanol as solvent. Alkyne hydration led to expected carbonyl compounds whereas the formation of the amide and of the corresponding ester was observed during nitrile hydration. In the case of alkynes, a linear correlation was found between the activity of the zeolite and the Si/Al ratio. A different behaviour was observed for nitriles, which can be related to the difference in the adsorption of the compounds.