Epoxidation of lower olefins with hydrogen peroxide and titanium silicalite
- Eniricerche SpA, Milano (Italy)
The epoxidation of lower olefins, catalyzed 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[sub 4]-C[sub 8] linear olefins, allyl chloride, and allyl alcohol show fast reaction rates and high selectivities (72-97% on H[sub 2]O[sub 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[sub n] > n-C[sub n+1], 1-hexene [much gt] 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. 41 refs., 5 figs., 4 tabs.
- OSTI ID:
- 7369081
- Journal Information:
- Journal of Catalysis; (United States), Vol. 140:1; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
Similar Records
The organometallic chemistry of aqueous ruthenium(II) with functionalized olefins: Complex formation, isomerization, and metathesis chain transfer
Catalytic asymmetric epoxidation and kinetic resolution: modified procedures including in situ derivatization
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALKENES
OXIDATION
TITANIUM SILICATES
CATALYTIC EFFECTS
ALCOHOLS
AQUEOUS SOLUTIONS
BASES
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHLORINATED ALIPHATIC HYDROCARBONS
ETHANOL
HETEROGENEOUS CATALYSIS
HYDROGEN PEROXIDE
METHANOL
OXYGEN
RETENTION
SOLVENTS
SOLVOLYSIS
CATALYSIS
CHEMICAL REACTIONS
DECOMPOSITION
DISPERSIONS
ELEMENTS
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
KINETICS
MIXTURES
NONMETALS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXYGEN COMPOUNDS
PEROXIDES
REACTION KINETICS
SILICATES
SILICON COMPOUNDS
SOLUTIONS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
YIELDS
400201* - Chemical & Physicochemical Properties