M. G. Clerici

Bio: M. G. Clerici is an academic researcher. The author has contributed to research in topics: Solvolysis & Cyclohexene. The author has an hindex of 2, co-authored 2 publications receiving 637 citations.

Epoxidation of Lower Olefins with Hydrogen Peroxide and Titanium Silicalite.

Abstract: The epoxidation of lower olefins, catalysed by titanium silicalite (TS-1) under mild conditions, is reported. The reaction may be performed at near room temperature, in dilute alcoholic or aqueous solutions of hydrogen peroxide. In methanol C 4 -C 8 linear olefins, allyl chloride, and allyl alcohol show fast reaction rates and high selectivities (72-97% on H 2 O 2 ). The solvolysis of the oxirane ring and the oxidation of the solvent are the main side reactions. Yields and kinetics are decreased by increasing the chain length or the cross-section of the olefin ( n -C n > n -C n +1 , 1-hexene ⪢ cyclohexene), by electron-withdrawing substituents (1-butene > allyl chloride > allyl alcohol), and by solvents in the order methanol > ethanol > t -butanol. The rate of reaction also depends on the position and steric configuration of the double bond and on the branching, as a result of inductive and shape selectivity effects: trans 2-butene cis 2-butene, 2-methyl-1-butene

Hydrogen Peroxide Synthesis: An Outlook beyond the Anthraquinone Process

Abstract: Hydrogen peroxide (H2O2) is widely used in almost all industrial areas, particularly in the chemical industry and environmental protection. The only degradation product of its use is water, and thus it has played a large role in environmentally friendly methods in the chemical industry. Hydrogen peroxide is produced on an industrial scale by the anthraquinone oxidation (AO) process. However, this process can hardly be considered a green method. It involves the sequential hydrogenation and oxidation of an alkylanthraquinone precursor dissolved in a mixture of organic solvents followed by liquid–liquid extraction to recover H2O2. The AO process is a multistep method that requires significant energy input and generates waste, which has a negative effect on its sustainability and production costs. The transport, storage, and handling of bulk H2O2 involve hazards and escalating expenses. Thus, novel, cleaner methods for the production of H2O2 are being explored. The direct synthesis of H2O2 from O2 and H2 using a variety of catalysts, and the factors influencing the formation and decomposition of H2O2 are examined in detail in this Review.

Lewis acids as catalysts in oxidation reactions: from homogeneous to heterogeneous systems.

Abstract: This review is focused on the use of solid Lewis acids to promote catalytic oxidations. While the concept of using Lewis acids to promote the reaction of organic substrates with oxidizing reagents is widely accepted in homogeneous catalysis, this concept has not become evident and generally used in heterogeneous catalysis until recent days. Certainly the development of new Lewis acid solids active and selective for catalytic oxidations is an urgent need and a challenging scientific target for some substrates especially using environmentally friendly oxidants. Since the replacement of current stoichiometric oxidations for the production of fine chemicals by environmentally benign catalytic oxidations is one of the major tasks in green chemistry, solid Lewis acids are called to play a crucial role to accomplish this goal. In the review, we will see the still important role that stoichiometric oxidations play in our daily life, and how they are being substituted by catalytic oxidations. At this point, three general mechanisms in which Lewis acids are involved will be described, and the material has been organized starting from homogeneous and ending with solid catalysts for heterogeneous oxidations. A bridge between the two will be established by presenting catalytic systems that can fill the gap between the two systems helping to rationalize the nature of the catalytic active sites in solid systems. This review is obviously focused on solid oxidation catalysts, and the core of the review is organized to show the evolution from the simplest strategy for heterogeneizing homogeneous catalysts, i.e., supporting the active species on large surface area solids, to the more elaborate ones in which the active sites are part of the solid structure. Given the importance of metallosilicates, and more specifically titanosilicates, as catalysts in commercial processes, special attention has been paid to these types of materials. Although sufficient references are provided to early seminal work, special emphasis has been given to most recent contributions to this area, particularly of the last 10 years. Patent literature has also been extensively covered in this review. Examples to illustrate the concepts have been selected among recent publications, and an effort has been made to present a series of commercial and near commercial processes based on catalytic oxidations. Finally, two * E-mail: acorma@itq.upv.es. 3837 Chem. Rev. 2002, 102, 3837−3892

Efficient Epoxidation of Olefins with ≥99% Selectivity and Use of Hydrogen Peroxide

Abstract: Epoxides are an important class of industrial chemicals that have been used as chemical intermediates. Catalytic epoxidation of olefins affords an interesting production technology. We found a widely usable green route to the production of epoxides: A silicotungstate compound, [gamma-SiW10O34(H2O)2]4-, is synthesized by protonation of a divacant, lacunary, Keggin-type polyoxometalate of [gamma-SiW10O36]8- and exhibits high catalytic performance for the epoxidation of various olefins, including propylene, with a hydrogen peroxide (H2O2) oxidant at 305 kelvin. The effectiveness of this catalyst is evidenced by >/=99% selectivity to epoxide, >/=99% efficiency of H2O2 utilization, high stereospecificity, and easy recovery of the catalyst from the homogeneous reaction mixture.