6863-58-7Relevant academic research and scientific papers
Novel Si(II)+and Ge(II)+Compounds as Efficient Catalysts in Organosilicon Chemistry: Siloxane Coupling Reaction ?
Fritz-Langhals, Elke,Kneissl, Sotirios,Piroutek, Phillip,Werge, Sven
, (2020/09/02)
Novel catalytically active cationic Si(II) and Ge(II) compounds were synthesized and isolated in pure form. The Ge(II)+-based compounds proved to be stable against air and moisture and therefore can be handled very easily. All compounds efficiently catalyze the oxidative coupling of hydrosil(ox)anes with aldehydes and ketones as oxidation reagents and simultaneously the reductive ether coupling at very low amounts of 0.01 mol %. Because the catalysts also catalyze the reversible cyclotrimerization of aldehydes, paraldehyde can be used as a convenient source for acetaldehyde in siloxane coupling. It is shown that the reaction is especially suitable to make siloxane copolymers. Moreover, a new fluorine-free weakly coordinating boronate anion, B(SiCl3)4-, was successfully combined with the Si(II) and Ge(II) cations to give the stable catalytically active ion pairs Cp*Si:+B(SiCl3)4-, Cp*Ge:+B(SiCl3)4-, and [Cp(SiMe3)3Ge:+]B(SiCl3)4-.
Highly Efficient and Selective N-Alkylation of Amines with Alcohols Catalyzed by in Situ Rehydrated Titanium Hydroxide
Khodakov, Andrei Y.,Kusema, Bright T.,Niu, Feng,Ordomsky, Vitaly V.,Wang, Qiyan,Yan, Zhen
, p. 3404 - 3414 (2020/03/23)
Catalytic N-alkylation of amines by alcohols to produce desired amines is an important catalytic reaction in industry. Various noble-metal-based homogeneous and heterogeneous catalysts have been reported for this process. The development of cheap non-noble-metal heterogeneous catalysts for the N-alkylation reaction would be highly desirable. Hereby, we propose the N-alkylation of amines by alcohols over a cheap and efficient heterogeneous catalyst-titanium hydroxide. This catalyst provides a selectivity higher than 90% to secondary amines for functionalized aromatic and aliphatic alcohols and amines with high catalytic activity and stability. Mild Br?nsted acidity formed by the continuous rehydration of Lewis acidity excludes the side reactions and deactivation by adsorbed species. The mechanism of the reaction involves dehydration of alcohols to ethers with subsequent C-O bond cleavage by amine with the formation of secondary amine and recovery of alcohol.
Cobalt-Catalyzed Secondary Alkylation of Arenes and Olefins with Alkyl Ethers through the Cleavage of C(sp2)-H and C(sp3)-O Bonds
Dong, Xunqing,Li, Qun,Li, Guigen,Lu, Hongjian
, p. 13402 - 13413 (2018/11/20)
A novel cobalt-catalyzed C-H alkylation of arenes and olefins is achieved with (pyridin-2-yl)isopropyl amine as an N,N-bidentate directing group. Different linear, branched, and cyclic alkyl ethers were used as practical secondary alkylating reagents through cleavage of C(sp3)-O bond, providing an efficient approach to the synthesis of verstile o-alkylated arylamides and tetrasubstituted acrylamides. Mechanistic studies indicate that cleavage of the inert C(sp3)-O bond involves a cobalt-promoted radical process and that cleavage of the inert C(sp2)-H bond by a cobalt catalyst is a rate-limiting step.
Synthesis of Benzyl Alkyl Ethers by Intermolecular Dehydration of Benzyl Alcohol with Aliphatic Alcohols under the Effect of Copper Containing Catalysts
Bayguzina,Gimaletdinova,Khusnutdinov
, p. 1148 - 1155 (2018/10/24)
Synthesis of benzyl alkyl ethers was performed in high yields by intermolecular dehydration of benzyl and primary, secondary, tertiary alcohols under the effect of copper containing catalysts. The formation of benzyl alkyl ethers occurs with participation of benzyl cation.
Influence of butanol isomers on the reactivity of cellulose towards the synthesis of butyl levulinates catalyzed by liquid and solid acid catalysts
Démolis, Alexandre,Eternot, Marion,Essayem, Nadine,Rataboul, Franck
, p. 3747 - 3754 (2016/05/09)
Butyl esters of levulinic acid form an interesting class of bio-based compounds that can be used, for example, as fuel additives. Their preparation mainly proceeds through the esterification of levulinic acid while the few reported studies on their direct synthesis from cellulose give limited information. In the present work, we studied for the first time in detail the influence of butanol isomers on the non-catalyzed cellulose liquefaction and the acid catalyzed formation of butyl levulinates from cellulose. In the absence of catalysts there was no influence of the alcohol class on liquefaction which reached 70-85% after 2 hours at 300 °C. In the presence of catalysts, we showed that the class of the alcohol had a significant influence on the butyl levulinate yield. With primary alcohols yields of 50% were obtained in the presence of H2SO4 (200 °C, 30 min). This level of yield can be considered as very interesting for these kinds of one-pot transformations involving cellulose. With secondary alcohols, yields less than 20% were obtained while no butyl levulinate was formed with tertiary alcohols. We also report for the first time this transformation in the presence of solid acids. Insoluble Cs2HPW12O40 or sulfated zirconia catalyzed the reaction heterogeneously despite deactivation leading to limited yields of 13% (200 °C, 1 hour). We finally show that water in butanol had an ambivalent role in enhancing the cellulose reactivity but limiting the esterification step and found that 5-7 wt%/butanol of water was the optimum amount.
A catalytic symmetrical etherification
Bagnell, Laurence,Cablewski, Teresa,Strauss, Christopher R.
, p. 283 - 284 (2007/10/03)
A novel, catalytic, thermal etherification produces minimal waste and can be carried out under almost neutral conditions.
Alcohol Dehydration: Mechanism of Ether Formation Using an Alumina Catalyst
Shi, Buchang,Davis, Burtron H.
, p. 359 - 367 (2007/10/03)
Ether formation during the dehydration of secondary alcohols, namely, 2-butanol, 3-pentanol, and 1-cyclopentylethanol, was investigated.Using the proper reaction conditions, the yield of di-2-butyl ether during the dehydration of 2-butanol on alumina can be as high as 40percent.That ether is formed by adding an alcohol to the alkene is ruled out by the results from deuterium tracer studies.Results from experiments using S(+)-2-butanol suggest that the formation of di-2-butyl ether occurs by a SN2-type mechanism.
Hydrocarbonylation of linear and branched aliphatic C2-C4 alcohols catalyzed by cobalt-ruthenium systems. A comparative study.
Jenner, Gerard
, p. 237 - 252 (2007/10/02)
In an extension of studies of the hydrocarbonylation of C2-C4 alcohols in the presence of a bimetallic catalyst system at high Syngas pressures to yield the next higher homologue, the effect of the catalytic system based on cobalt and ruthenium compounds promoted by iodine or iodides has been examined.For the optimal Co/Ru ratio the selectivity for the higher alcohol is highest because of a large decrease in the extent of hydrocarbon and ether formation.Neither this ratio nor the optimal pressure depends on the structure of the alcohol.It is suggested that the synergism observed in Co-Ru-catalyzed hydrocarbonylation of alcohols is due to a cocatalytic effect of the Ru catalyst involving reaction of ruthenium hydrides with acyl-cobalt complexes.The mechanism is consistent with the suggestion that there is an intermediate olefin that undergoes hydroformylation in a subsequent step.
HIGH-PRESSURE CATALYTIC HYDRATION OF OLEFINS OVER VARIOUS PROTON-EXCHANGED ZEOLITES
Eguchi, Koichi,Tokiai, Takeo,Kimura, Yoshio,Arai, Hiromichi
, p. 567 - 570 (2007/10/02)
Catalytic hydration of ethylene, propylene, and 1-butene to alcohol was investigated at high pressures using proton-exchanged zeolites.All the zeolites more or less exhibited the hydration activities.Pentasil- and ferrierite-type zeolites were the most active among the zeolite catalysts.The activities of zeolite catalysts are correlated with the amount of adsorbed water, indicating that hydrophobic acid sites are effective for olefin hydration.
Chemical Conversions using Sheet Silicates: Novel Intermolecular Dehydrations of Alcohols to Ethers and Polymers
Ballantine, James A.,Davies, Mary,Purnell, Howard,Rayanakorn, Mongkon,Thomas, John M.,Williams, Kevin J.
, p. 427 - 428 (2007/10/02)
Aliphatic primary alcohols, when intercalated in certain ion-exchanged montmorillonites, react preferentially via an intermolecular nucleophilic displacement of water to give high yields of di-(alk-1-yl) ethers, rather than the competitive intramolecular dehydration to alkenes; an essentially similar process yields polymeric material, poly(phenylenemethylene), from benzyl alcohol, but aliphatic secondary and tertiary alcohols, in contrast, yield alkenes almost exclusively.
