- Ti-rich TS-1: A highly active catalyst for epoxidation of methallyl chloride to 2-methyl epichlorohydrin
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Ti-rich TS-1 showed high catalytic activity and H2O2 efficiency for epoxidation of methallyl chloride (MAC). Unexpectedly, it was much more active in tert-butyl alcohol (TBA) solvent than in methanol and acetonitrile partially because TBA increased the adsorption amount of MAC in the channel of Ti-rich TS-1, and consequently enhanced the MAC concentration around the Ti sites. By optimizing reaction conditions, the MAC conversion reached 85.4% with epoxide selectivity of 96.7%, which could be maintained by regenerating the catalyst by calcination. Addition of alkali or salt into the reaction system or impregnation of these materials on the Ti-rich TS-1 led to a drastic decrease in activity. In combination with NH3-TPD and diffuse reflectance UV-vis spectroscopy results, it was found that active Ti-OOH (η2) intermediates were formed for framework tetrahedral Ti species with moderately strong Br?nsted acidity. This indicates that an Eley-Rideal-type reaction mechanism probably dominated the MAC epoxidation over Ti-rich TS-1.
- Jiao, Weiyong,He, Yue,Li, Junfen,Wang, Jianguo,Tatsumi, Takashi,Fan, Weibin
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- Substitution effects on the catalytic activity of Mn(III)-porphyrins in epoxidation of alkenes with iodosylbenzene: A comparison between the electron-rich and electron-deficient porphyrins
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Oxidation of different olefins with iodosylbenzene in the presence of Mn(III) complexes of meso-tetra(para-tolyl)porphyrin, meso-tetra(ortho-tolyl) porphyrin, meso-tetra(thien-2-yl)porphyrin and β-hexaboromo-meso- tetra(thien-2-yl)porphyrin as catalyst has been studied. Oxidation of cis- and trans-stilbene in a competitive reaction strongly suggests the involvement of a high valent (porphyrin)MnO as the active oxidant intermediate, in the case of each catalyst. Clear observation of the band relevant to a (porphyrin)Mn(IV)O species in the presence of excess amounts of styrene shows the stability of this moiety towards reaction with olefins. Although, the stability of metalloporphyrins towards oxidative degradation decreases in the order MnT(o-tolyl)P(OAc) > MnT(thien-2-yl)PBr6(OAc) > MnT(p-tolyl)P(OAc) ≥ MnT(thien-2-yl)P(OAc), a complex pattern of catalytic activity and product (epoxide) selectivity has been found for the Mn-porphyrins in oxidation of various alkenes.
- Zakavi, Saeed,Ebrahimi, Leila
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- Optimization of the technological parameters of epoxidation of methallyl chloride by hydrogen peroxide over TS-1 catalyst
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The influence of the technological parameters on the course of epoxidation of methallyl chloride by a 30 wt % hydrogen peroxide over the titanium silicalite TS-1 catalyst has been investigated. The effects of temperature, molar ratio of methallyl chloride to hydrogen peroxide, concentrations of methanol (solvent) and TS-1 catalyst, and reaction time were determined. The optimisation of the technological parameters of methallyl chloride epoxidation was performed by the application of a statistical experimental design method based on a rotatable uniform design. The epoxidation process was described by using the following functions: the selectivity of transformation to 2-methylepichlorohydrin in relation to methallyl chloride consumed, the selectivity of transformation to organic compounds in relation to hydrogen peroxide consumed, the conversions of methallyl chloride and hydrogen peroxide.
- Wroblewska, Agnieszka,Milchert, Eugeniusz
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- Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
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The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.
- Lambert, Tristan H.,Steiniger, Keri A.
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supporting information
p. 8013 - 8017
(2021/10/25)
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- Cationic alkyl glycoside quaternary ammonium salt surfactant and preparation process thereof
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The invention discloses a cationic alkyl glucoside quaternary ammonium salt surfactant and a preparation process thereof. Reaction of 3 - chlorine -2 - methyl propylene with hypochlorous acid is firstly reacted with hypochlorous acid, and then the intermediate 1 is prepared by reaction with N, N - diethylaminopropylmethyldimethoxysilane to prepare the intermediate 2, and the intermediate 2 3 is reacted with the alkylglucoside to form a cationic alkyl glycoside quaternary ammonium salt 3 surfactant which has a quaternary ammonium 4 salt structure and 4 can be efficiently sterilized to play an antibacterial role. In addition, the surfactant has the organic silicon structure, has the characteristics of organic matter and inorganic substance, endows the surfactant with excellent high temperature resistance, and also has the function of organic silicon cationic surfactant, and plays a role in solubilization and emulsification.
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Paragraph 0030-0032; 0038-0040; 0046-0048; 0054-0056; ...
(2021/11/27)
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- SYSTEMS AND METHODS FOR REGIOSELECTIVE CARBONYLATION OF 2,2-DISUBSTITUTED EPOXIDES
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Provided are methods of carbonylating cyclic substrates to produce carbonyl ated cyclic products. The cyclic substrates may be 2, 2-di substituted epoxides and the cyclic products may be β,β-di substituted lactones. The method may be carried out by forming and pressurizing a reaction mixture of the cyclic substrate, a solvent, carbon monoxide, and a [LA+][CO(CO)4-] catalyst, where [LA+] is a Lewis acid capable of coordinating to the cyclic substrate. The method may proceed with a regioselectivity of 90:10 or greater. The resulting carbonylated cyclic products may be converted to ketone aldol products that retain the stereochemistry and enantiomeric ratio of the carbonyl ated cyclic products.
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Paragraph 0146; 0151
(2020/06/05)
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- Ti-rich TS-1: A highly active catalyst for epoxidation of methallyl chloride to 2-methyl epichlorohydrin
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Ti-rich TS-1 showed high catalytic activity and H2O2 efficiency for epoxidation of methallyl chloride (MAC). Unexpectedly, it was much more active in tert-butyl alcohol (TBA) solvent than in methanol and acetonitrile partially because TBA increased the adsorption amount of MAC in the channel of Ti-rich TS-1, and consequently enhanced the MAC concentration around the Ti sites. By optimizing reaction conditions, the MAC conversion reached 85.4% with epoxide selectivity of 96.7%, which could be maintained by regenerating the catalyst by calcination. Addition of alkali or salt into the reaction system or impregnation of these materials on the Ti-rich TS-1 led to a drastic decrease in activity. In combination with NH3-TPD and diffuse reflectance UV-vis spectroscopy results, it was found that active Ti-OOH (η2) intermediates were formed for framework tetrahedral Ti species with moderately strong Br?nsted acidity. This indicates that an Eley-Rideal-type reaction mechanism probably dominated the MAC epoxidation over Ti-rich TS-1.
- Jiao, Weiyong,He, Yue,Li, Junfen,Wang, Jianguo,Tatsumi, Takashi,Fan, Weibin
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- Compositions for dyeing keratinic fibres, containing paraphenylenediamine derivatives with an azetidinyl group
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The invention relates to novel compositions for the oxidation dyeing of keratin fibers, comprising at least one para-phenylenediamine derivative containing an azetidinyl group as oxidation base, to the dyeing process and to the dyeing kit using this composition, and also to novel para-phenylenediamines containing an azetidinyl group.
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- Reactions of 2-substituted epichlorohydrins
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2-Substituted epichlorohydrins have been synthesized by starting with 1,2-dichloro acetone and various alkyl and aryl halides via dichlorohydrins followed by cyclization. The reactive 2-substituted epichlorohydrins were subjected to nucleophilic attacking of azide and cyanide ions to afford corresponding β-azido alcohols and α,β-unsaturated nitriles.
- Tanyeli,Demir,Akhmedov,Ozgul,Kandemir
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p. 2967 - 2980
(2007/10/03)
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- Quaternary Ammonium Tetrakis(diperoxotungsto)phosphates(3-) as a New Class of Catalysts for Efficient Alkene Epoxidation with Hydrogen Peroxide
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The use of quaternary ammonium tetrakis(diperoxotungsto)phosphates(3-) in conjuction with hydrogen peroxide as the primary oxidant in an aqueous/organic biphase system provides an efficient, versatile, and synthetically valuable catalytic method for olefin epoxidation.By this method, a variety of water-insoluble unactivated alkenes, internal or terminal, open-chain or cyclic, isolated or carrying diversified functionalities, were epoxidized in high yields under mild conditions and after relatively short reaction times.
- Venturello, Carlo,D'Aloiso, Rino
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p. 1553 - 1557
(2007/10/02)
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- Synthesis and Alkali-Metal Complexing Abilities of Crown Ether Tertiary Alcohols
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Twenty-three crown ethers with a hydroxyl and an alkyl or aryl group linked directly to the central carbon of a three-carbon bridge were synthesized in one-step reactions of glycol and bisphenol dianions with substituted 2-(chloromethyl)oxiranes.Crown ether tertiary alcohols with methyl, n-decyl, n-tetradecyl, phenyl, and p-(n-decyl)phenyl substituents and four ring sizes are prepared.The effect of substituent on Na+ and K+ complexation is assessed by the picrate extraction method for closely related tertiary crown ether alcohols with 16-crown-5 and 15-crown-5-rings.
- Pugia, Michael,Knudsen, Brian E.,Cason, C. Victor,Bartsch, Richard A.
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p. 541 - 547
(2007/10/02)
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- Synthesis and pharmacological study of aryloxypropanolamines substituted on carbon 2
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In a series of aryloxypropanolamines, substitution on carbon 2 by alkyl, aryl or aralkyl groups lowers the β-blocking activity. This effect increases with the size of the substituent.
- Galons,Combet Farnoux,Miocque,et al.
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- PREPARATION OF 3-CHLORO-2-METHYL-1-SELENOPHENYLPROPENE, A NEW EQUIVALENT OF METHACROLEIN. APPLICATION TO THE REGIOSPECIFIC SYNTHESIS OF A MODEL OF THE SELAGINE RING SYSTEM.
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We report herein the preparation of a new selenium reagent and illustrate one important aspect of its potential usefulness in organic synthesis.
- Gravel, Denis,Deziel, Robert,Bordeleau, Luc
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p. 699 - 702
(2007/10/02)
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