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71.
Selective oxidation of benzylic,allylic and propargylic alcohols using dirhodium(II) tetraamidinate as catalyst and aqueous tert‐butyl hydroperoxide as oxidant 下载免费PDF全文
We show that the dirhodium(II) tetraamidinate complex Rh2(Msip)4 efficiently catalyzes the oxidation of activated secondary alcohols at only 0.1 mol% loading. In this approach, we oxidized various benzylic, allylic and propargylic alcohols to the corresponding carbonyl compounds under mild aqueous conditions using the inexpensive oxidant T‐HYDRO® (70 wt% aqueous tert‐butyl hydroperoxide). Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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73.
Anatoly N. Nikitin Michael C. Grady Georgios A. Kalfas Robin A. Hutchinson 《大分子反应工程》2008,2(5):422-435
Batch experiments were carried out to investigate the kinetics of catalytic chain transfer copolymerization of methyl methacrylate and n‐butyl methacrylate. The Predici® model developed to represent the system describes the numerous experimental data measured at high concentrations of Co(II ) catalyst, taking into account the chain‐length dependencies of termination, propagation and catalytic chain transfer. The constants for catalytic chain transfer are determined as 2.3 × 104 for both methyl methacrylate and n‐butyl methacrylate from fitting the experimental data. Two inhibition mechanisms are shown to describe the decrease of the polymerization rate in the presence of catalyst equally well, with an unknown impurity dissolved in initiator introduced to explain experimental profiles measured at high initiator concentrations.
74.
Carbon black (N234) and silica (Vulksail N) with a silane coupling agent Si-69 were chosen as reinforcing fillers in butyl rubber (IIR). The rheological behavior of the IIR compounds and the dynamic mechanical properties of IIR vulcanizates were investigated with a rubber processing analyzer and dynamic mechanical analysis (DMA) to examine the filler dispersion in the rubber matrix and the interaction between filler and matrix. The data indicated that the N234 filled IIR compounds had more filler networks than those filled with silica. Filler networks first appeared at 30 phr N234 and 45 phr silica with silane coupling agent Si-69. The interaction between N234 and IIR was far stronger than that between silica and IIR. However, the silica Vulksail N filled IIR had better wet-grip and lower rolling resistance compared to the carbon black-filled IIR should IIR be chosen as a substitute of styrene-butadiene rubber (SBR) in tire tread. The reinforcing factor, R, R (related to the difference in tan d peak height at Tg for the filled and nonfilled rubbers), also demonstrated that the N234-IIR interaction was stronger than for the silica. IIR with 30 phr N234 exhibited the largest tensile strength, 20.1 MPa, for those vulcanizates examined. The tensile and tear strengths of N234 filled IIR were higher than those of IIR with similar amounts of silica. Thus, it was concluded that N234 is a more active reinforcing filler in IIR than silica (Vulksail N) even with a silane coupling agent (Si-69). 相似文献
75.
以二苯基-4-苯硫基代苯基硫鎓盐(DPTS)为光引发剂,研究了乙烯基正丁醚的本体和溶液光聚合。在本体聚合中,聚合速率(Rp)与引发剂浓度成正比;在15~35℃范围内,聚合活化能几乎为零。分别以CHCl3(CH2Cl)2和C6H5Cl作溶剂的溶液聚合,其Rp均比本体聚合者大,同时单体浓度对Rp的影响则表现出复杂的关系。根据普遍接受的硫鎓盐光解机理并假设溶剂和单体均可不同程度地参与引发反应,解释了溶液聚合中单体影响的动力学规律。 相似文献
76.
随着互穿聚合物网络(IPN)的发展,出现了无机/有机杂化IPN,调整两组分或多组分互穿程度控制材料的结构、形态与性能,可使材料具有较宽的适用范围.此类材料具有高模量、高韧性,易成型加工. 相似文献
77.
A calorimetric method was applied at 25 °C to measure the enthalpies of dissolution of cyclohexane, heptane, and decane in
the methanol-n-butanol mixed solvent and hexadecane in mixtures of methanol withn-, iso-, andtert-butyl alcohols. The standard enthalpies of dissolution of alkanes were determined. It was shown that the equation proposed
in the literature for calculation of the enthalpies of dissolution of alkanes in mixtures with nonspecific intermolecular
solvent-solvent interactions describes satisfactorily the enthalpies of dissolution of alkanes in mixtures of methanol withn- andiso-butyl alcohols. It was suggested that there is no preferential solvation of alkanes by one of the mixed solvent components
in the MeOH−BunOH and MeOH−BuiOH mixtures; in the MeOH−ButOH system, the composition of alkane solvation shell differs slightly from the solvent composition in the bulk.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 271–274, February, 1999. 相似文献
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79.
Contributions to the Chemistry of Phosphorus. 244. The First Oxatetraphospholane, (PBut)4O Under suitable conditions, the reaction ot tri‐tertbutylcyclotriphosphane, (PBut)3, with di‐tert‐butylperoxide gives rise to a mixture of 2,3,4,5‐tetra‐tert‐butyl‐1,2,3,4,5‐oxatetraphospholane, (PBut)4O ( 1 ), and 1,2‐di‐tert‐butyl‐1,2‐di‐tert‐butoxidiphosphane, [But(ButO)P]2 ( 2 ). Both compounds have been isolated in the pure state. The oxatetraphospholane 1 is a constitutional isomer of 1,2,3,4‐Tetra‐tert‐butyl‐1‐oxocyclotetraphosphane, which has been reported recently [1]. The corresponding reaction of tetra‐tert‐butylcyclotetraphosphane furnishes only small amounts of 1 because of the kinetic stability of (PBut)4. The diphosphane 2 is presumably a secondary product of primarily formed oxocyclotetraphosphanes (PBut)4O1–4. The NMR parameters of 1 and 2 are reported and discussed. 相似文献
80.
Contributions to the Chemistry of Phosphorus. 243 On the Oxocyclotetraphosphanes (PBut)4O1–4 Under suitable conditions, the reaction of tetra‐tert‐butylcyclotetraphosphane, (PBut)4, with dry atmospheric oxygen gives rise to the corresponding monoxide (PBut)4O ( 1 ) which has been isolated by column chromatography. The reaction with hydrogen peroxide furnishes a mixture of oxocyclotetraphosphanes (PBut)4O1–4 consisting of two constitutionally isomeric dioxides (PBut)4O2 ( 2 a , 2 b ), the trioxide (PBut)4O3 ( 3 ), and the tetraoxide (PBut)4O4 ( 4 ), in addition to 1 . According to the 31P NMR parameters the oxygen atoms are exclusively exocyclically bonded to the phosphorus four‐membered ring. Which of the P atoms are present as λ5‐phosphorus follows from the different low‐field shifts of the individual P nuclei compared with the starting compound. Accordingly, 1 is 1,2,3,4‐Tetra‐tert‐butyl‐1‐oxocyclotetraphosphane, 2 a and 2 b are 1,2,3,4‐Tetra‐tert‐butyl‐1,2‐dioxo‐ and ‐1,3‐dioxocyclotetraphosphane, respectively, 3 is 1,2,3,4‐Tetra‐tert‐butyl‐1,2,3‐trioxocyclotetraphosphane, and 4 is 1,2,3,4‐Tetra‐tert‐butyl‐1,2,3,4‐tetraoxocyclotetraphosphane. When the oxidation reaction proceeds a fission of the P4 ring takes place. 相似文献