F+:Highly flammable;
78-79-5Relevant articles and documents
Highly efficient synthesis of isoprene from methyl tert-butyl ether and formaldehyde over activated carbon supported silicotungstic acid catalysts
Wang, SaiSai,Chen, Xingkun,Tan, Yuan,Zhao, Ziang,Yang, Wenshao,Huang, Chuanqi,Wang, Xuepeng,Chen, MiaoMiao,Du, Zhongnan,Ding, Yunjie
, (2020)
In this contribution, we reported the liquid single-stage synthesis of isoprene from methyl tert-butyl ether (MTBE) and formaldehyde over activated carbon supported silicotungstic acid (STA/AC) catalysts. In comparison with the corresponding homogeneous STA catalysts, the STA/AC catalysts exhibited much higher activity of the prins condensation reaction under the same conditions. The results could be attributed to the highly dispersed STA, the relative weaker acidity resulting from the strong interaction between STA and AC and the structural collapse of STA. Additionally, the catalyst could be reused at least 3 times with only a slight decrease of activity. The physical and chemical properties of the STA/AC catalysts were characterized by means of DRIFT, HRTEM, HAADF-STEM, NH3-TPD, XRD, XPS and TG techniques. The excellent catalytic reactivity and easy recycling advantages make the STA/AC catalyst to be an attractive candidate of the prins reactions in the future.
Kinetics and mechanism of monomolecular heterolysis of commercial organohalogen compounds: XLII. Effect of aprotic solvent on the rate of 3-methyl-3-chloro-1-butene dehydrochlorination. Correlation analysis of solvation effects
Ponomarev,Zaliznyi,Dvorko
, p. 1517 - 1523 (2005)
The kinetics of 3-methyl-3-chloro-1-butene dehydrochlorination in propylene carbonate, γ-butyrolactone, sulfolane, acetone, MeCN, PhNO2, PhCN, PhCOMe, MeCOEt, cyclohexanone, o-dichlorobenzene, PhCl, PhBr, 1,2-dichloroethane, dioxane, and AcOEt were studied; v = k[C5H 9Cl], E1 mechanism. The reaction rate is satisfactorily described by the parameters of the polarity, electrophilicity, and cohesion of the solvent; the solvent nucleophilicity and polarizability exert no effect on the reaction rate. 2005 Pleiades Publishing, Inc.
The kinetics of transformation of isopentenols in the presence of the Nafion-H catalyst
Ryabova,Osipova,Librovich
, p. 2034 - 2036 (1998)
The kinetics of transformation of 3-methyl-1-buten-3-ol in the presence of the Nafion-H catalyst was studied. A comparison between the data obtained and those for the reaction catalyzed by sulfuric acid showed that under the same conditions, the macroscopic acidic properties of Nafion-H correspond to the catalytic activity of 8-15% sulfuric acid.
Isomerization of 1-Methylcyclobutene by Single Collision Activation at a Surface. Variation of Initial Energy
Arakawa, R.,Rabinovitch, B. S.
, p. 4772 - 4776 (1982)
The reaction probability per collision, Pc, for 1-methylcyclobutene activated at a hot seasoned fused silica surface has been measured under single collision conditions over the reactor temperature range Tr = 480-800 K.The initial thermal vibrational energy population distribution of the cyclobutene molecules was varied from Tc = 273 K to Tc 570 K.The reaction is isomerization to isoprene.Mixed samples of 1-methylcyclobutene and cyclobutene (which had been studied earlier) were used for internal comparison under the same conditions.These experiments provide a test of the relative suitability of various analytical forms for the collisional transition probability matrix P.Stochastic calculations with a Gaussian form provide the best overall fit to the data.The calculated average amount of energy (E0) transferred from the hot molecules in a vibrational down transition from the reaction threshold energy level, E0, declined from 7220 to 3890 cm-1 with increase in surface temperature from 600 to 800 K.The experimental collisional efficiency, β1, declined from 0.39 to 0.035 over the combination temperature range Tr,Tc = 600,500 to 800,293.Strong collider behavior was observed with both 1-methylcyclobutene and cyclobutene for Tr less than 450 K.
Isoprene Synthesis from Formaldehyde and Isobutylene in the Presence of Aluminum- and Niobium-Containing BEA Catalysts
Chistov, D. L.,Drozhzhin, V. R.,Ivanova, I. I.,Kots, P. A.,Ponomareva, O. A.,Rodionova, L. I.
, p. 942 - 949 (2020)
Abstract: A single-stage gas-phase synthesis of isoprene from formaldehyde and isobutylene in the presence of Al–BEA and Nb–BEA zeolite catalysts containing different amounts of aluminum and niobium has been studied. The physicochemical properties of the catalysts have been studied by low-temperature nitrogen adsorption, infrared spectroscopy of adsorbed CO, X-ray fluorescence analysis, and ammonia TPD methods. Catalytic tests have shown that, at similar formaldehyde conversion values, the isoprene selectivity is higher in the presence of the Al-containing BEA catalysts. It has been found that Al–BEA with Si/Al = 12 exhibits the highest activity in isoprene synthesis.
An allylic isoprenoid C5 nucleophile for the synthesis of forskolin
Behnke, Dirk,Hamm, Stefan,Hennig, Lothar,Welzel, Peter
, p. 7059 - 7062 (1997)
InCl3-mediated coupling of δ-alkoxy allylic stannane 9b with aldehydes has been shown to give the α-coupling products in high yield, probably via two S(E)' processes. Most specifically, drimenal (rac-l) has been converted into labdane derivative 17 which is considered to be an important intermediate on the way to forskolin.
Isoprene Synthesis from Formaldehyde and Isobutylene over Zeolite Catalysts
Ponomareva,Chistov,Kots,Ivanova
, p. 711 - 718 (2019)
Abstract: Single-stage gas-phase synthesis of isoprene from formaldehyde and isobutylene in the presence of zeolite catalysts of the MFI, BEA, and FAU(Y) framework types and Al–BEA, Zr–BEA, Sn–BEA, and Nb–BEA catalysts synthesized by isomorphous substitution methods has been studied. Catalytic tests have shown that the isoprene yield increases in the following order: Zr–BEA Sn–BEA Nb–BEA Al–BEA, which is in agreement with the content of Br?nsted acid sites in the samples, whereas the formation of the major byproduct—carbon monoxide resulting from the decomposition of formaldehyde—increases with an increase in the number of Lewis acid sites. Comparison of the catalytic properties of zeolites of the different framework types has shown that the highest isoprene selectivity is exhibited by medium-pore MFI zeolites with a pore diameter of 5.5 ?.
Mechanisms of Methylenecyclobutane Hydrogenation over Supported Metal Catalysts Studied by Parahydrogen-Induced Polarization Technique
Salnikov, Oleg G.,Burueva, Dudari B.,Kovtunova, Larisa M.,Bukhtiyarov, Valerii I.,Kovtunov, Kirill V.,Koptyug, Igor V.
, (2022/03/15)
In this work the mechanism of methylenecyclobutane hydrogenation over titania-supported Rh, Pt and Pd catalysts was investigated using parahydrogen-induced polarization (PHIP) technique. It was found that methylenecyclobutane hydrogenation leads to formation of a mixture of reaction products including cyclic (1-methylcyclobutene, methylcyclobutane), linear (1-pentene, cis-2-pentene, trans-2-pentene, pentane) and branched (isoprene, 2-methyl-1-butene, 2-methyl-2-butene, isopentane) compounds. Generally, at lower temperatures (150–350 °C) the major reaction product was methylcyclobutane while higher temperature of 450 °C favors the formation of branched products isoprene, 2-methyl-1-butene and 2-methyl-2-butene. PHIP effects were detected for all reaction products except methylenecyclobutane isomers 1-methylcyclobutene and isoprene implying that the corresponding compounds can incorporate two atoms from the same parahydrogen molecule in a pairwise manner in the course of the reaction in particular positions. The mechanisms were proposed for the formation of these products based on PHIP results.
A mild method for the replacement of a hydroxyl group by halogen: 3. the dichotomous behavior of α-haloenamines towards allylic and propargylic alcohols
Munyemana, Fran?ois,Patiny, Luc,Ghosez, Léon
, (2021/06/07)
A study of the deoxyhalogenation of allylic and propargylic alcohols with tetramethyl-α-halo-enamines is reported. Primary allylic and primary and secondary propargylic alcohols gave the corresponding halides in high yields. Secondary allylic and propargylic alcohols yielded the corresponding secondary halides but the reaction also produced some rearranged primary halides (I > Br > Cl). The reactions with tertiary allylic and tertiary propargylic alcohols gave several products and was therefore of little synthetic value. However, the addition of triethylamine to the reaction mixture or the use of lithium alkoxide instead of alcohol brought about a major change of the course of the reaction which led to amides carrying an allyl or an allenyl group at C2. This was shown to result from a Claisen-Eschenmoser rearrangement of an intermediate α-allyloxy- or propargyloxy-enamine.
Study on heteropolyacid-based catalysts with high activity and reusability for isoprene synthesis from formaldehyde and isobutene
Wang, Qingxue,Luo, Xu,Liu, Li,Tao, Shenghui,Xu, Shan
, p. 5371 - 5381 (2021/04/06)
Silica-supported heteropolyacid catalysts with different pore structures were synthesizedviaimpregnation method using silicalite-1 with three-dimensional MFI structure, two-dimensional hexagonal SBA-15 and amorphous silica as supports. Moreover, these catalysts were employed for the gas phase one-step synthesis of isoprene from isobutene and formaldehyde. The result showed that the activity of silicotungstic acid supported on silicalite-1 (SiW/S-1) catalysts was significantly better than that on other supports, which indicates that the three-dimensional MFI structure and suitable pore size of silicalite-1 were more conducive to the production of isoprene. Furthermore, the formation rate of isoprene over 20% SiW/S-1 catalyst reached up to 8.5 times that on the bulk silicotungstic acid catalyst, which could be attributed to the highly dispersed silicotungstic acid and the suitable acidity produced by the strong interaction between silicotungstic acid and silicalite-1. In addition, the 20 wt% SiW/S-1 catalyst exhibited excellent reusability and was reused 10 times without obvious loss of activity.
