Abdelaziz Nait Ajjou

The hydration of nitriles catalyzed by water-soluble rhodium complexes

Abstract The water-soluble rhodium complex generated in situ from [Rh(COD)Cl] 2 and P(m-C 6 H 4 SO 3 Na) 3 has been found to be a very effective catalyst for the hydration of nitriles, under basic conditions.

Chromium(VI)-catalyzed benzylic oxidations with commercial t-butylhydroperoxide or hydrogen peroxide

Abstract The factors influencing the efficiency of chromium(VI)-catalyzed benzylic oxidations were examined using indane as starting material. An 86% yield of α-indanone was reached in methylene chloride with 0.05 equiv of CrO 3 and 4 equiv of 70% t-BuOOH as oxidant, while Cr(VI)−30% H 2 O 2 led only to low yields.

Effective chromium-mediated oxidation of allylic and benzylic alcohols by sodium percarbonate

Abstract High selectivity to the corresponding ketones and aldehydes has been observed for the title reaction when performed in 1,2-dichloroethane at 80°C in the presence of catalytic amounts of pyridnium dichromate and Adogen 464. The oxidation of unactivated alcohols was less efficient under these conditions.

First example of water-soluble transition-metal catalysts for Oppenauer-type oxidation of secondary alcohols

Abstract The first water-soluble transition-metal catalysts for Oppenauer-type oxidation of secondary alcohols have been developed. The catalytic system composed of [Ir(COD)Cl]2, 2,2′-biquinoline-4,4′-dicarboxylic acid dipotassium salt (BQC) and sodium carbonate is highly efficient for the selective oxidation of benzylic and aliphatic secondary alcohols to the corresponding ketones with catalyst/substrate ratios ranging from 0.4 to 2.5%. The substitution of [Ir(COD)Cl]2 by its rhodium analog [Rh(COD)Cl]2 generates a less active catalytic system. [Ir(COD)Cl]2/BQC was also found to be more active than its water-insoluble analog system [Ir(COD)Cl]2/2,2′-biquinoline (BC).

Cation-exchanged montmorillonite catalyzed hydration of styrene derivatives

Abstract Iron-exchanged Wyoming montmorillonite (Fe 3+ -SWy-1) is quite an effective catalyst for the hydration of styrene derivatives. The yields and selectivities depend on the reaction conditions, with good efficiency attained using THF as solvent at 120°C. Fe 3+ -SWy-1 calcined at 300°C, and pillared clays (PIL.Fe 3+ -SWy-1), either air dried or calcined at 300°C, were inactive for the hydration of styrene. The hydration of styrene was also investigated in the presence of a cation-exchanged Fluka K10 montmorillonite (M n+ -K10). Fe 3+ -K10 was found to be the most effective catalyst. However, it shows less activity, selectivity and reproducibility than Fe 3+ -SWy-1.

Chromium-catalyzed homolytic scission of organic peroxides with t-butyl hydroperoxide and its relation to benzylic oxidation

Abstract In using 9-(t-butylperoxy)-fluorene as test substrate and various chromium compounds, it has been shown that the transformation to fluorenone requires the simultaneous presence of t-BuOOH to be efficient. This transformation is much less effective when using free t-BuO. or t-BuOO. radicals. A mechanism involving the homolytic scission of the peroxidic bond of the substrate is proposed.

Bistriphenylsilanol-Assisted Oxidation Catalyzed by Chromium(VI) Oxide of Activated Trimethylsilyl Ethers with tert-Butyl Hydroperoxide

Abstract Secondary benzylic or allylic trimethylsilyl ethers are oxidized at room temperature to the corresponding ketones in good yields using aqueous 70% t-BuOOH and catalytic amounts of a mixture of Ph3SiOH and CrO3.

Chromium-Assisted Oxidations with Sodium Perborate by Phase Transfer Catalysis

Abstract Oxidation by sodium perborate of selected alcohols and unsaturated compounds to ketones and acids was achieved at 60–80°C in the presence of catalytic amounts of chromium(VI) oxide and methyltridecylammonium chloride.

Highly efficient oxygen transfer from tert-butyl hydroperoxide to benzylic carbons catalyzed by chromium(VI) oxide under high substrate/ hydroperoxide ratios

Abstract Chromium(VI) oxide induces a quasi-quantitative transfer of one oxygen atom from t-BuOOH to a benzylic methylene group when a high ratio of substrate/hydroperoxide is employed, the corresponding carbonyl compound being the major oxidation compound. Hydroxylation and tert-butyl-peroxidation are the main reactions observed for a tertiary benzylic carbon. The interference of free benzylic radicals under these conditions is a minor reactive pathway.

Chromium-Promoted Benzylic Oxidations by tert-Butyl Hydroperoxide: A New Catalyst and a Comparison of the Different Procedures1

Abstract Homogeneous data from literature reports concerning chromium-induced benzylic oxidations by tert-butyl hydroperoxide and from an efficient system using bistriphenylsilyl chromate as catalyst are presented.