56851-51-5Relevant articles and documents
Designed electron-deficient gold nanoparticles for a room-temperature Csp3-Csp3coupling reaction
Yu, Qiu-Ying,Su, Hui,Zhai, Guang-Yao,Zhang, Shi-Nan,Sun, Lu-Han,Chen, Jie-Sheng,Li, Xin-Hao
supporting information, p. 741 - 744 (2021/02/06)
Stille cross-coupling reactions catalysed by an ideal catalyst combining the high activity of homogeneous catalysts and the reusability of heterogeneous catalysts are of great interest for C-C bond formation, which is a widely used reaction in fine chemistry. Despite great effort to increase the utilization ratio of surface metal atoms, the activity of heterogeneous catalysts under mild conditions remains unsatisfactory. Herein, we design a proof-of-concept strategy to trigger the room-temperature activity of heterogeneous Au catalysts by decreasing the electron density at the interface of a rationally designed Schottky heterojunction of Au metals and boron-doped carbons. The electron-deficient Au nanoparticles formed as a result of the rectifying contact with boron-doped carbons facilitate the autocleavage of C-Br bonds for highly efficient C-C coupling reactions of alkylbromides and allylstannanes with a TOF value of 5199 h-1 at room temperature, surpassing that of the state-of-the-art homogeneous catalyst. This journal is
Rhodium-catalyzed allylation of benzyl acetates with allylsilanes
Onodera, Gen,Yamamoto, Eriko,Tonegawa, Shota,Iezumi, Makoto,Takeuchi, Ryo
scheme or table, p. 2013 - 2021 (2011/10/09)
Benzyl acetate reacted with allyltrimethylsilane to give an allylation product in the presence of a catalytic amount of the (cyclooctadiene)rhodium(I) chloride dimer {[Rh(cod)Cl]2}, sodium tetrakis[3,5- bis(trifluoromethyl)phenyl]borate (NaBARF), and triphenyl phosphite [P(OPh) 3] in refluxing 1,2-dichloroethane. Primary, secondary and tertiary benzyl acetates could be used for the reaction. Moreover, allylation of gem-benzyl acetate was possible with [Rh(cod)Cl]2, NaBARF, and P(OPh)3. Monoallylation and diallylation of gem-benzyl acetate could be controlled by altering the reaction conditions. Cationic rhodium species generated in situ act as a Lewis acid catalyst to give a benzyl carbocation by elimination of the acetoxy group from the benzylic carbon. Copyright
Determination of rate constants in the carbocationic polymerization of styrene: Effect of temperature, solvent polarity, and lewis acid
De, Priyadarsi,Faust, Rudolf,Schimmel, Holger,Ofial, Armin R.,Mayr, Herbert
, p. 4422 - 4433 (2007/10/03)
The electrophilicity parameter (E = 9.6) of the 1-phenylethyl cation, 1+, has been determined and combined with the nucleophilicity parameter (N = 0.78, s = 0.95) of styrene (St) to predict diffusion-limited propagation in the cationic polymerization of St by the linear free energy relationship log k = s(N + E). This prediction has been experimentally verified using two different diffusion clock methods, which provided a value of k p± ≈ 2 × 109 L mol-1 s-1, 6 orders of magnitude higher than previously accepted, for the absolute rate constant of propagation of the TiCl4-induced polymerization of St in methyl cyclohexane/methyl chloride 60/40 (v/v) at -80°C. The kp± value remained unchanged in the temperature range -50 to -80°C, indicating that propagation does not have an enthalpic barrier; however, it increased moderately with increasing solvent polarity. The nature of the Lewis acid has little effect on kp ± as similar values have been obtained with TiCl4 or SnCl4. The apparent rate constant of ionization, k iapp, the rate constant of deactivation, k-i, and the apparent equilibrium constant of ionization, Ki app, have also been determined as a function of temperature. The kiapp increases slightly and k-i increases moderately with increasing temperature; therefore, Kiapp and the overall polymerization rate decrease moderately with increasing temperature.
