An Isolable Radical Anion of an Organosilicon Cluster Containing Only σ Bonds

The radical anion of octa‐tert‐butyloctasilacubane was generated and isolated. The EPR spectrum showed the satellites due to the tertiary ¹³C nuclei of the eight tert‐butyl groups. The X‐ray crystallographic analysis showed that the Si? Si bonds are shortened and the Si? C bonds are elongated compared with those of octa‐tert‐butyloctasilacubane. These results are well explained by the distribution of an unpaired electron in the singly occupied molecular orbital (SOMO).     

Salt‐Free Reduction of Nonprecious Transition‐Metal Compounds: Generation of Amorphous Ni Nanoparticles for Catalytic C–C Bond Formation

A salt‐free procedure for the generation of a wide variety of metal(0) particles, including Fe, Co, Ni, and Cu, was achieved using 2,3,5,6‐tetramethyl‐1,4‐bis(trimethylsilyl)‐1,4‐diaza‐2,5‐cyclohexadiene ( 1 ), which reduced the corresponding metal precursors under mild conditions. Notably, Ni particles formed in situ from the treatment of Ni(acac)₂ (acac=acetylacetonate) with 1 in toluene exhibited significant catalytic activity for reductive C? C bond‐forming reactions of aryl halides in the presence of excess amounts of 1 . By examination of high‐magnification transmission electron microscopy images and electron diffraction patterns, we concluded that amorphous Ni nanoparticles (Ni aNPs) were essential for the high catalytic activity.     

协效剂对膨胀阻燃聚丙烯基木塑复合材料的阻燃增效研究

赋予木塑复合材料(WPC)的阻燃性能成为近年来该领域国内外的研究热点之一。本文通过两轮正交试验,研究8种常见的协效剂对膨胀型阻燃剂(IFRs,m(聚磷酸铵,APP)∶m(季戊四醇,PER)=2∶1)的阻燃增效作用,筛选出具有显著协效作用的协效剂组MgO/EG(可膨胀石墨)/SiO_2,其组成为m(MgO)∶m(EG)∶m(SiO_2)=1∶5∶5,其与IFRs的最佳配比为m(IFRs)∶m(MgO/EG/SiO_2)=1∶0.18,得到性能良好的阻燃型聚丙烯基木塑复合材料。通过热重分析(TGA)和锥形量热分析(CONE)评价IFRs及协效剂组对聚丙烯(PP)基木塑复合材料(WPC)热稳定性能和阻燃性能的影响。结果表明,IFRs及MgO/EG/SiO_2的加入可以有效提高WPC的热稳定性,WPC/IFRs/MgO/EG/SiO_2600℃的残炭率达到22.42%。WPC/IFRs的热释放速率峰(PHRR)、总热释放量(THR)和总烟释放量(TSP)相比于WPC分别降低了21.9%、8.7%和22%。MgO/EG/SiO_2的加入可以进一步提高IFRs的阻燃效率,WPC/IFRs/MgO/EG/SiO_2的PHRR和THR相比于WPC分别降低了33.0%和13.8%。     

Silyl‐ and Disilanyl‐BODIPYs: Synthesis via Catalytic Dehalosilylation and Spectroscopic Properties

We describe herein the first synthesis of silyl‐ and disilanyl‐BODIPYs through transition‐metal‐catalyzed dehalosilylation of iodo‐BODIPYs using a Pd(P(t Bu)₃)₂/Et₃N/toluene system. Various mono‐ and bis‐silyl‐BODIPYs, mono‐ and bis‐disilanyl‐BODIPYs and bis‐BODIPYs linked by silylene and SiOSi groups were synthesized by using this straightforward method. Silyl‐ and disilanyl‐substitution significantly modifies the spectroscopic properties of the BODIPY, in which the fluorescence quantum yields of the silyl‐BODIPYs are remarkably increased, whereas the emission spectra of disilanyl‐BODIPYs are red‐shifted due to effective σ(SiSi)–π(BODIPY) conjugation.     

The Synthesis of Fluorine Containing Polysiloxanes. Part 1. The Synthesis of Fluorine Containing Cyclosiloxanes

A new facile preparative method for the synthesis of semifluorinated organocyclosiloxanes is reported. Ring closure of the dichlorosilanes with NaHCO₃ and pyridine gave a mixture of semifluorinated organocyclosiloxanes with cyclotrisiloxane as the main product in yields 95–98% with yield of cyclotrisiloxanes up to 80%.     

A tribute to professor Robert West,on the occasion of his 90th birthday

Abstract

This is for Bob, and for his vast number of friends and colleagues who wish to celebrate his 90^th birthday. On this occasion we express our admiration, friendship, and appreciation for the wonderful adventures that he has shared with so many of us. While we are limited to providing a personal account of our experience of Bob, we believe that what we describe will in some way resonant with those who know him. Not surprisingly, the life of a great person is dedicated to all possible kinds of movement (mentally and physically) always curious and ready to find out what future brings rather than looking back upon the past. Needless to say – Bob moves quickly. Very quickly. So we will not pretend that we, or anyone else, could capture the essence of the man. As much as he immerses himself in the moment, it seems a losing proposition to try to identify something singular and unchanging about him. As Heraclitus says “we can never step into the same river twice,” so has been our experience, and delight, with Bob. It is our hope that many other accounts of Bob will be told and retold during the events celebrating his 90^th birthday.     

含硅功能化聚烯烃:合成及应用

聚烯烃功能化改性是获得高性价比新材料的有效途径。含硅功能化聚烯烃(SFPO)是聚烯烃分子结构中含有机硅功能基团或有机硅聚合物链段的一类功能化聚烯烃的统称。由于有机硅功能基团及有机硅聚合物特殊的理化性质,SFPO通常具有丰富反应性或优异性能,成为一类有代表性的功能化聚烯烃。SFPO可以作为反应性中间体,用于制备具有复杂拓扑结构的功能化聚烯烃(如星型聚合物、梳型聚合物、接枝共聚物)或聚烯烃共价键接枝改性纳米材料;SFPO还可作为功能性添加剂(如增容剂、加工助剂,表面改性剂),用于开发聚烯烃新材料。近年来,研究人员在含硅功能化聚烯烃研究领域取得了系列进展,本文旨在对相关工作进行系统总结,以期引起同行注意并促进相关研究深入发展。     

Highly selective synthesis of novel (E)-styrylsilatranes via ruthenium-catalyzed trans-silylation

Protocols for the synthesis of cage-substituted 1-vinylsilatranes have been developed and updated. The 1-vinylsilatranes with organic substituents attached to silatrane cage were functionalized in ruthenium-catalyzed trans-silylation with olefins, leading to novel styrylsilatranes in high yields.     

Synthesis of Novel Organosilicon Compounds Possessing Fully Substituted Imidazole Nucleus Sonocatalyzed by Fe-Cu/ZSM-5 Bimetallic Oxides

An efficient four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles is described by one-step condensation of an aldehyde, benzil, ammonium acetate, and primary aromatic amine with nanostructure Fe-Cu/ZSM-5 bimetallic oxides in water under ultrasonic irradiation. The short reaction time, good yields, environmental friendly procedure, mild reaction conditions, and convenient operation are important advantage of this protocol. The products generated during the study have been utilized as substrates for synthesis of organosilicon-containing imidazoles. Synthesis of tris(triorganosilyl)methylimidazole derivatives were carried out using organolithium reagent (Me₃Si)₃CLi, prepared via metalation of (Me₃Si)₃CH with methyllithium in tetrahydrofuran, in excellent yields.