5405-58-3Relevant articles and documents
Synthesis, Structure, Reactivity and Catalytic Implications of a Cationic, Acetylide-Bridged Trigold–JohnPhos Species
Grirrane, Abdessamad,álvarez, Eleuterio,García, Hermenegildo,Corma, Avelino
, p. 8810 - 8818 (2020)
The cationic complex [(JohnPhos–Au)3(acetylide)][SbF6] (JohnPhos=(2-biphenyl)di-tert-butylphosphine, L1) has been characterised structurally and features an acetylide–trigold(I)–JohnPhos system; the trinuclear–acetylide unit, coordinated to the monodentate bulk phosphines, adopts an unprecedented μ,η1,η2,η1 coordination mode with an additional interaction between distal phenyl rings and gold centres. Other cationic σ,π-[(gold(I)L1)2] complexes have also been isolated. The reaction of trimethylsilylacetylene with various alcohols (iPrOH, nBuOH, n-HexOH) catalysed by cationic [AuIL1][SbF6] complexes in CH2Cl2 at 50 °C led to the formation of acetaldehyde acetals with a high degree of chemo- and regioselectivity. The reaction mechanism was studied, and several organic and inorganic intermediates have been characterised. A comparative study with the analogous cationic [CuIL1][PF6] complex revealed different behaviour; the copper metal is lost from the coordination sphere leading to the formation of cationic vinylphosphonium and copper nanoparticles. Additionally, a new catalytic approach for the formation of this high-value cationic vinylphosphonium has been established.
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.
