1758-32-3Relevant articles and documents
Stereocontrol of the Red Light Induced Photoepoxidation of 2-Butenes by Nitrogren Dioxide in Solide Ar
Nakata, Munetaka,Frei, Heinz
, p. 7670 - 7677 (1989)
Photooxidation of cis-2-butene was initiated in an inerrt gas matrix by exciting cis-2-butene*NO2 pairs at red, yellow, and green wavelengths .Chemical reaction was monitored by FT-IR spectroscopy, and emission from an Ar ion or a tuned CW dye laser was used for photolysis.As in the case of the trans-2-butene + NO2 reaction reported earlier, 2,3-epoxybutane was the only final oxidation product observed upon direct photolysis of reactant pairs.While in the case of the trans-2-butene reaction stereochemical retention was complete, we found in the cis case 85percent of the epoxide with retained configuration when conducting the reaction at low matrix concentration.This fraction decreased with increasing reactant to matrix ratio.Infrared bands of two conformers of a butyl nitrile radical were observed concurrently with the epoxide, one syn, the other anti with respect to conformation (CH3 groups) about the central CC bond.A correlation was found between the syn to anti nitrile radical and the cis to trans epoxide ratios, suggesting a common transient precursor.It is most probably an oxirane biradical, whose conformation determines the stereochemistry of the epoxide product.The photolysis wavelength dependence of the product growth kinetics was studied, and relative reaction efficiencies so obtained are shown to give insight into aspects of the dynamics of the reaction that relate to the observed product and stereospecificity.The two trapped butyl nitrite radical conformers were found to photodissociate under exposure to long-wavelength visible light with complete conformer specificity.The anti conformer gave trans-2-butene oxide and NO at a threshold wavelength of 613 nm, while the syn form was found to decompose to 2-methylpropanal and NO upon 573 nm and shoter wavelength irradiation.
-
Denney,D.B.,Jones,D.H.
, p. 5821 - 5825 (1969)
-
Oxidation of lower alkenes by Α-oxygen (FeIII–O??)Α on the FeZSM-5 surface: The epoxidation or the allylic oxidation?
Starokon, Eugeny V.,Malykhin, Sergei E.,Parfenov, Mikhail V.,Zhidomirov, Georgy M.,Kharitonov, Alexander S.
, p. 43 - 51 (2017/11/15)
Reactions of anion-radical α-oxygen (FeIII–O??)α with propylene and 1-butene on sodium-modified FeZSM-5 zeolites were studied in the temperature range from ?60 to 25 °C. Products were extracted from the zeolite surface and identified. It was found that main reaction pathway was the epoxides formation. Selectivity for epoxides at ?60 °C was 59–64%. Other products were formed as a result of secondary transformations of epoxides on the zeolite surface. According to IR spectroscopy, the oxidation of propylene over the entire temperature range and 1-butene at ?60 °C were not accompanied by the formation of (FeIII–OH)α groups, in distinction to methane oxidation. This testifies that hydrogen abstraction does not occur. In case of 1-butene reaction with α-oxygen at 25 °C, hydrogen abstraction occurred but was insignificant, ca 7%. According to DFT calculation ferraoxetane intermediate formation is preferable over hydrogen abstraction. Following decomposition of this intermediate leads to the propylene oxide (PO) formation. The results may be relevant to the low selectivity problem of the silver catalyst in propylene epoxidation and raise doubts about the presently accepted mechanism explaining an adverse effect of allylic hydrogen.
Gas-phase dehydration of vicinal diols to epoxides: Dehydrative epoxidation over a Cs/SiO2 catalyst
Kim, Tae Yong,Baek, Jayeon,Song, Chyan Kyung,Yun, Yang Sik,Park, Dae Sung,Kim, Wooyoung,Han, Jeong Woo,Yi, Jongheop
, p. 85 - 99 (2015/09/28)
A novel type of dehydration reaction that produces epoxides from vicinal diols (dehydrative epoxidation) using a basic catalyst is reported. Epoxyethane, 1,2-epoxypropane, and 2,3-epoxybutane were produced from the dehydrative epoxidation of ethylene glycol, 1,2-propanediol, and 2,3-butanediol, respectively. Among a number of tested basic catalysts, the Cs/SiO2 catalyst showed outstanding performance for the dehydrative epoxidation of 2,3-butanediol and is considered to be the most promising catalyst for this type of reaction. In order to identify the superiority of the Cs/SiO2 catalyst and a mechanism of the reaction, structure-activity relationships were studied along with density functional theory (DFT) calculations. The following features are found to be responsible for the excellent activity of the Cs/SiO2 catalyst: i) strong basic sites formed by Cs+, ii) low penetration of Cs+ into SiO2 which permits basic sites to be accessible to the reactant, iii) stable basic sites due to the strong interactions between Cs+ and SiO2 surface, and iv) mildly acidic surface of SiO2 which is advantageous for the elimination to H2O. In addition, the dehydrative epoxidation involves an inversion of chirality (e.g. meso-2,3-butanediol (R,S) to trans-2,3-epoxybutane (R,R or S,S)), which is in agreement with DFT results that the reaction follows a stereospecific SN2-like mechanism.
