5756-43-4Relevant articles and documents
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-.
Conversion of ethanol into linear primary alcohols on gold, nickel, and gold–nickel catalysts
Chistyakov,Zharova,Tsodikov,Nikolaev,Krotova,Ezzhelenko
, p. 803 - 811 (2016/12/07)
The direct conversion of ethanol into the linear primary alcohols CnH2n+1OH (n = 4, 6, and 8) in the presence of the original mono- and bimetallic catalysts Au/Al2O3, Ni/Al2O3, and Au–Ni/Al2O3 was studied. It was established that the rate and selectivity of the reaction performed under the conditions of a supercritical state of ethanol sharply increased in the presence of Au–Ni/Al2O3. The yield of target products on the bimetallic catalyst was higher by a factor of 2–3 than that reached on the monometallic analogs. Differences in the catalytic behaviors of the Au, Ni, and Au–Ni systems were discussed with consideration for their structure peculiarities and reaction mechanisms.
Synthesis of ethyl hexyl ether over acidic ion-exchange resins for cleaner diesel fuel
Guilera,Ramírez,Fité,Tejero,Cunill
, p. 2238 - 2250 (2015/04/14)
The synthesis of ethyl hexyl ether as a suitable diesel additive was investigated using 1-hexanol and diethyl carbonate as reactants and acidic ion-exchange resins as catalysts. Liquid-phase experiments were performed in a batch reactor at the temperature range of 403-463 K and 2.5 MPa. The formation of ethyl hexyl ether proceeded from two routes: thermal decomposition of ethyl hexyl carbonate and intermolecular dehydration of 1-hexanol with ethanol. Both pathways require a previous transesterification reaction between diethyl carbonate and 1-hexanol. It was revealed that this reaction is favoured in polymer zones of 0.4 nm nm-3 polymer density (equivalent to 2.6 nm diameter pores in inorganic materials). Acidic ion-exchange resins containing a significant volume fraction of this polymer density are Dowex 50W×2 and Amberlyst 70. By using this kind of catalyst, reaction rate and selectivity are significantly increased. Finally, it was observed that working at low temperature would favour the selectivity to ethyl hexyl carbonate and hinder the undesired formation of alkenes. This journal is
SYNTHESIS AND PROPERTIES OF TRIETHYLBENZYLAMMONIUM ALKOXIDES. REACTIVITY IN ELIMINATION AND NUCLEOPHILIC SUBSTITUTION REACTIONS
Shavanov, S. S.,Tolstikov, G. A.,Shutenkova, T. V.,Ryabova, N. A.,Filippova, S. A.
, p. 643 - 647 (2007/10/02)
Triethylbenzylammonium alkoxides exhibit high reactivity during the elimination of hydrogen chloride from polychloroalkanes and can also be used in the synthesis of ethers from halogenoalkanes.Quaternary ammonium salts do not form tetraalkylammonium or trialkylbenzylammonium alkoxides under the influence of a concentrated aqueous solution of sodium hydroxide in the presence of alcohols.
FRAGMENTATION OF LINEAR ACETALS IN HOMOLYTIC LIQUID-PHASE TRANSFORMATIONS
Kalashnikov, S. M.,Imashev, U. B.,Zlotskii, S. S.,Rakhmankulov, D. L.
, p. 783 - 786 (2007/10/02)
The kinetics of the accumulation of the products formed by fragmentation of linear acetals in free-radical liquid-phase reactions initiated by thermal decomposition of tert-butyl peroxide were investigated.The products from the transformation of 1,1-dimethoxyethane are methyl acetate and methane, whereas ethanal, pentanal, and 1-ethoxypentane are formed in addition to amyl acetate and pentane in the case of 1,1-dipentyloxyethane, and ethanal, hexanal, and 1-ethoxyethane are formed in addition to hexyl acetate and hexane from 1,1-dihexyloxyethane.The initial formation rate of pentane and hexane was measured for the first time, and it was shown that the sum of the accumlation rate of the alkane and the initiation rate is close to the accumlation rate of the ester.A scheme which takes account of all the products is proposed for the fragmentation of linear acetals.The C1-H bond in the linear acetals is an order of magnitude more reactive than the other C-H bonds.The difference in the activation energies for the cleavage of the active C-H bonds was evaluated, and the lenght of the chains, the activation energies for decomposition of tert-butyl peroxide in the acetals, and the kinetic parameters of the homolytic liquid-phase reactions of the acetals were determined.
