21022-73-1Relevant articles and documents
Method for selectively oxidizing cumene compounds
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Paragraph 0099; 0100, (2019/11/21)
The invention relates to a method for selectively oxidizing cumene compounds, and the method comprises the following steps: placing cumene compounds shown in a formula (I), an iron porphyrin catalyst,an oxidant and a dispersant into a ball milling tank, sealing the ball milling tank, performing ball milling for 3 to 24 hours at a rotating speed of 100 to 800 rpm at room temperature, stopping ballmilling once every 1 to 3 hours in the ball milling process, discharging gases in the ball milling tank, finishing the reaction, and performing post-treatment on a reaction mixture to obtain product2-phenyl-2-propanol compound shown in a formula (II); according to the invention, the oxidation conversion of the cumene and derivatives thereof is realized through solid-phase ball milling, the reaction mode is novel, the operation is convenient, and the energy consumption is low; the method needs no organic solvent, thus effectively avoiding the use of toxic and harmful organic solvents and being green and environment-friendly; has low peroxide content and high safety factor, and high 2-phenyl-2-propanol and derivative selectivity and meets the social requirements of the current green chemical process, environmental compatibility chemical process and biological compatibility chemical process.
ortho-Effect on the acid-catalyzed hydration of 2-substituted α-methylstyrenes
Prusek, Ondrej,Bures, Filip,Pytela, Oldrich
experimental part, p. 85 - 99 (2009/06/06)
α-Methylstyrene and nine ortho-substituted analogs have been synthesized and the kinetics of their acid-catalyzed hydration in aqueous solutions of sulfuric acid at 25°C have been investigated. The kinetic acidity function HS has been constructed from the dependence of the observed rate constants kobs on the sulfuric acid concentration. The catalytic rate constants of the acid-catalyzed hydration kortho have been calculated as well. The identical shape of the kinetic acidity functions for ortho- and para-derivatives confirms what the consistent mechanism A-SE2 of the acid-catalyzed hydration has already proved for the corresponding paraderivatives. The A-SE2 mechanism involves a rate-determining proton transfer of the hydrated proton to the substrate. From the dependence of the catalytic rate constants of the ortho-derivatives on the catalytic rate constants of the para-derivatives, it is seen that the logarithm of the catalytic rate constant for hydrogen as a substituent is markedly out of the range of the other substituents and, simultaneously, that the ortho-derivatives react significantly slower than the corresponding para-derivatives. In correlation with the substitent constants σp+, a reaction constant of ρ+= -1.45 have been found. The constant is, in absolute value, considerably smaller than that for para-derivatives (ρ+ = -3.07). In parallel, the steric effects are enforced more significantly for the monoatomic substituents (slope of the Charton's constants 3.92) than for substituents including more atoms (slope of the Charton's constants 2.09). A small value of the reaction constant ρ+ has been elucidated due to the lower conjugation between the reaction centre and the benzene ring as a consequence of the geometric twist of the reaction centre out of the main aromatic plane accompanied by fading mesomeric interaction between the reaction centre and the substituents attached to the benzene ring. The isopropyl group in the carbocation is twisted less out of the aromatic plane for the monoatomic substituents and, therefore, also a small difference in the bulk of substituents has considerable steric influence on the conjugation between the carbocation and the benzene ring bearing substituents. On the contrary, the isopropyl group in the carbocations with polyatomic substituents is twisted to such a degree that changes in the bulk of substituents affect the resonant stabilization negligibly. Similar conclusions were also deduced from the correlations of the substitution constants σI and σR+.
Palladium-catalyzed arylation of α,α-disubstituted arylmethanols via cleavage of a C-C or a C-H bond to give biaryls
Terao, Yoshito,Wakui, Hiroyuki,Nomoto, Michiyo,Satoh, Tetsuya,Miura, Masahiro,Nomura, Masakatsu
, p. 5236 - 5243 (2007/10/03)
The palladium-catalyzed arylation of α,α-disubstituted arylmethanols with aryl halides proceeds not only via C-H bond cleavage at the ortho-position, but also via cleavage of the sp2-sp3 C-C bond with the liberation of ketones (β-carbon elimination) to give the corresponding biaryls. Both reactions appear to occur through common arylpalladium(II) alcoholate intermediates. The results of systematic studies with respect to which C-C or C-H bond is preferentially cleaved in the arylation are reported. Among the important findings is the selective elimination of ortho-substituted aryl groups even from aryl(diphenyl)methanols due to steric reasons. Thus, various biaryls having ortho-substituents can be produced efficiently by treatment of the corresponding aryl(diphenyl or dimethyl)methanols with aryl bromides and chlorides.
