3266-23-7Relevant articles and documents
2,3-Butanediol dehydration catalyzed by silica-supported alkali phosphates
Kim, Wooyoung,Shin, Wookyun,Lee, Kyoung Jun,Cho, YongSeok,Kim, Hyung Soon,Filimonov, Igor N.
, p. 148 - 163 (2018/11/26)
Characterization of acid-base centers and catalytic dehydration of 2,3-butanediol (BDO) was performed over a wide range of silica-supported alkali phosphates (M_P/SiO2; M = Na, K, Cs; M:P = 0.5–3 mol:mol). Selectivity to 1,3-butadiene (BD) and 3-butene-2-ol (3B2OL) formed by elimination correlates with the densities of conjugated acid-base pairs and increases in the order Na ??M+ moieties. Isolated Br?nsted acid centers are probably silica grafted phosphoric acid molecules at low M/P and –PO(OH)2 end groups of oligophosphates at M/P > 1.5. Deactivation rate increases with the increase of M/P ratio in order Na K Cs. Deactivation patterns imply that sites responsible for elimination are active in dehydrative epoxidation. Dehydration of 3B2OL smoothly proceeds to BD, but the catalysts deactivate faster compared to BDO dehydration.
A method for preparing epoxy butane
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Paragraph 0019; 0020, (2017/03/08)
The invention relates to a method for preparing epoxy butane, which comprises the following step: in an isopropyl benzene solution containing 25 wt% of cumene hydroperoxide solute, preparing epoxy butane from butylene oxide by using the cumene hydroperoxide solute as an oxidizer and a titanium-silicon molecular sieve with three-dimensional pore canal structure as a catalyst, wherein the fixed bed reaction conditions are as follows: the mole ratio of butylene to the cumene hydroperoxide solute is (5.0-12.0):1, the weight hourly space velocity of the cumene hydroperoxide is 1.0-5.0 h, the reaction pressure is 1.0-6.0 MPa, and the temperature is 60.0-120.0 DEG C. The catalyst is the titanium-silicon molecular sieve with three-dimensional pore canal structure; the molecular sieve has hysteresis loop on the low-temperature nitrogen adsorption and desorption isotherm; the average pore size is 2.0-8.0nm, and the specific area is 650.0-1100.0 m/g; and the catalyst has the advantages of favorable activity and high epoxy butane selectivity, and can be widely popularized and applied to industrial production of epoxy butane by butylene epoxidation.
A comprehensive test set of epoxidation rate constants for iron(IV)-oxo porphyrin cation radical complexes
Sainna, Mala A.,Kumar, Suresh,Kumar, Devesh,Fornarini, Simonetta,Crestoni, Maria Elisa,De Visser, Sam P.
, p. 1516 - 1529 (2015/03/04)
Cytochrome P450 enzymes are heme based monoxygenases that catalyse a range of oxygen atom transfer reactions with various substrates, including aliphatic and aromatic hydroxylation as well as epoxidation reactions. The active species is short-lived and difficult to trap and characterize experimentally, moreover, it reacts in a regioselective manner with substrates leading to aliphatic hydroxylation and epoxidation products, but the origin of this regioselectivity is poorly understood. We have synthesized a model complex and studied it with low-pressure Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry (MS). A novel approach was devised using the reaction of [FeIII(TPFPP)]+ (TPFPP = meso-tetrakis(pentafluorophenyl)porphinato dianion) with iodosylbenzene as a terminal oxidant which leads to the production of ions corresponding to [FeIV(O)(TPFPP+a?￠)]+. This species was isolated in the gas-phase and studied in its reactivity with a variety of olefins. Product patterns and rate constants under Ideal Gas conditions were determined by FT-ICR MS. All substrates react with [FeIV(O)(TPFPP+a?￠)]+ by a more or less efficient oxygen atom transfer process. In addition, substrates with low ionization energies react by a charge-transfer channel, which enabled us to determine the electron affinity of [FeIV(O)(TPFPP+a?￠)]+ for the first time. Interestingly, no hydrogen atom abstraction pathways are observed for the reaction of [FeIV(O)(TPFPP+a?￠)]+ with prototypical olefins such as propene, cyclohexene and cyclohexadiene and also no kinetic isotope effect in the reaction rate is found, which suggests that the competition between epoxidation and hydroxylation - in the gas-phase - is in favour of substrate epoxidation. This notion further implies that P450 enzymes will need to adapt their substrate binding pocket, in order to enable favourable aliphatic hydroxylation over double bond epoxidation pathways. The MS studies yield a large test-set of experimental reaction rates of iron(iv)-oxo porphyrin cation radical complexes, so far unprecedented in the gas-phase, providing a benchmark for calibration studies using computational techniques. Preliminary computational results presented here confirm the observed trends excellently and rationalize the reactivities within the framework of thermochemical considerations and valence bond schemes.
