859146-54-6Relevant articles and documents
Synthesis, characterization and catalytic performances of benzimidazolin-2-iminato actinide (IV) complexes in the Tishchenko reactions for symmetrical and unsymmetrical esters
Liu, Heng,Khononov, Maxim,Fridman, Natalia,Tamm, Matthias,Eisen, Moris S.
, p. 123 - 137 (2017/10/25)
A new family of benzimdazolin-2-iminato actinide?(IV) complexes [(Bim7-MeDipp/MeN)An(N(SiMe3)2)3] (An = U (3), Th (4)) and [(Bim4-MeDipp/MeN)An(N(SiMe3)2)3] (An = U (5), Th (6)) were synthesized and their solid state structures were established by single-crystal X-ray diffraction analysis. The catalytic performances of complexes 3–6 towards the homo- and cross-coupling of aldehydes (Tishchenko reaction) were studied and the thorium complexes 4 and 6 displayed moderate to high activities for the production of the corresponding symmetric and unsymmetrical esters. Coupling of aldehyde and alcohols, known as the tandem proton-transfer esterification, and the intermolecular coupling reaction between aldehyde and trifluoromethylketones were also investigated by these thorium complexes, indicating a complementary method to obtain unsymmetrical esters selectively. Plausible mechanisms for these reactions are proposed based on stoichiometric studies.
Organoactinides promote the dimerization of aldehydes: Scope, kinetics, thermodynamics, and calculation studies
Sharma, Manab,Andrea, Tamer,Brookes, Nigel J.,Yates, Brian F.,Eisen, Moris S.
experimental part, p. 1341 - 1356 (2011/04/16)
Surprising catalytic activities have been found for the actinide complexes Cp*2ThMe2 (1), Th(NEtMe)4 (2), and Me2SiCp″2Th(C4H9) 2(3) toward oxygenated substrates. During the catalytic dimerization of benzaldehydes to their corresponding esters, complexes 1 and 2 gave 65 and 85% yield in 48 h, respectively, while the geometry-constrained complex 3 gave 96% yield in 24 h. Exploring the effect of substituents on benzaldehyde, it has been found that, in general, electron-withdrawing groups facilitate the reaction. Kinetic study with complexes 1 and 3 reveals that the rate of the reaction is first order in catalyst and substrate, which suggests the rate equation "rate = k[catalyst]1[aldehyde]1". The activation energy of the reaction was found to be 7.16 ± 0.40 and 3.47 ± 0.40 kcal/mol for complexes 1 and 3 respectively, which clearly indicates the advantage of the geometry-constrained complex. Astonishing are the reactivity of the organoactinide complexes with oxygen-containing substrates, and especially the reactivity of complex 3, toward the dimerization of substrates like p-methoxybenzaldehyde, m/p-nitrobenzaldehyde, and furanaldehyde and the reactivity toward the polymerization of terephthalaldehyde. Density functional theory mechanistic study reveals that the catalytic cycle proceeds via an initially four-centered transition state (+6 kcal/mol), followed by the rate-determining six-centered transition state (+13.5 kcal/mol), to yield thermodynamically stable products.
Oxidation of benzylic alcohols with I2/K2CO 3/tert-butanol: Formation of aldehydes or dimeric esters
Tumkevicius,Navickas,Dailide
, p. 1377 - 1383 (2007/10/03)
Oxidation of a series of aromatic and heteroaromatic benzylic alcohols with molecular iodine in tert-butanol in the presence of potassium carbonate has been studied. Oxidation of most benzylic alcohols affords the corresponding aldehydes in reasonable yields. The reaction has been shown to be compatible with amino, formyl, methylthio groups and thiophene ring in the molecule. Oxidation of the electron-poor benzylic alcohols such as nitrobenzyl alcohols and (benzimidazol-2-yl)methanol results in the formation of the corresponding dimeric esters.
