Epoxidation of Lower Olefins with Hydrogen Peroxide and Titanium Silicalite

• Published in: Journal of catalysis 1993-03, Vol.140 (1), p.71-83
• Main Authors: Clerici, M.G., Ingallina, P.
• Format: Article
• Language: English
• Subjects: 400201 - Chemical & Physicochemical Properties; ALCOHOLS; ALKENES; AQUEOUS SOLUTIONS; BASES; CATALYSIS; CATALYTIC EFFECTS; Catalytic reactions; CHEMICAL REACTION KINETICS; CHEMICAL REACTION YIELD; CHEMICAL REACTIONS; Chemistry; CHLORINATED ALIPHATIC HYDROCARBONS; DECOMPOSITION; DISPERSIONS; ELEMENTS; ETHANOL; Exact sciences and technology; General and physical chemistry; HALOGENATED ALIPHATIC HYDROCARBONS; HETEROGENEOUS CATALYSIS; HYDROCARBONS; HYDROGEN COMPOUNDS; HYDROGEN PEROXIDE; HYDROXY COMPOUNDS; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; KINETICS; METHANOL; MIXTURES; NONMETALS; ORGANIC CHLORINE COMPOUNDS; ORGANIC COMPOUNDS; ORGANIC HALOGEN COMPOUNDS; OXIDATION; OXYGEN; OXYGEN COMPOUNDS; PEROXIDES; REACTION KINETICS; RETENTION; SILICATES; SILICON COMPOUNDS; SOLUTIONS; SOLVENTS; SOLVOLYSIS; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; TITANIUM COMPOUNDS; TITANIUM SILICATES; TRANSITION ELEMENT COMPOUNDS; YIELDS
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1006/jcat.1993.1069

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 2O 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 < iso-butene < 1-butene < cis 2-butene, 2-methyl-1-butene < 1-pentene, and 3-methyl-1-butene < 2-methyl-1-butene < 2-methyl-2-butene. The epoxidation occurs with retention of configuration. Basic compounds at low concentration do not slow the kinetics, but do improve significantly the yields, up to 97% in the epoxidation of 1-butene. At higher concentrations, TS-1 activity is decreased and eventually inhibited by bases. No effect on kinetics is exerted by tetrapropylammonium hydroxide. Catalytic activity is improved by acids. A heterolytic peracid-like mechanism is envisaged in the oxygen-transfer step. A five-membered cyclic structure, formed by a titanium hydroperoxo moiety Ti-OOH, and a protic molecule ROH at Ti sites, is proposed as the active species.