交联聚苯乙烯-铂铬合物的合成及其催化的硅氢加成反应

首次合成了巯甲基化交联聚苯乙烯-铂络合物,将其用于催化不同结构的碳碳不饱和化合物与甲基二氯硅烷的加成反应,结果表明,该催化剂对乙炔、苯乙烯、苯乙炔、三烷基乙烯基硅烷等化合物具有很高的催化活性,对丙烯酸丁酯的催化活性显著降低,对甲基丙烯酸甲酯则无催化活性,该催化剂用于苯乙烯的硅氢加成反应,可重复使用20次,而且回收再用非常方便。     

Design of latent catalysts and their application to polymer synthesis

Design of latent catalysts such as benzyl sulfonium, benzyl ammonium, benzyl pyridinium, benzyl phosphonium, and hydrazinium salts, and their application to polymer synthesis have been described. They have been demonstrated as excellent thermal or photolatent catalysts for polymerizations of cyclic monomers such as epoxides, bicyclo orthoesters, spiro orthocarbonates, and vinyl monomers such as styrene and vinyl ethers.     

1-Butadienyl Sulfide Polymerization

1-Butadienyl sulfides, mainly cis in configuration, are obtained by the base-catalyzed addition of mercaptans to vinylacetylene. bis-1-Butadienyl sulfides are readily polymerizable using azo catalysts, but mono-1-butadienyl sulfides are not, nor do they copolymerize with styrene or butadiene. They have a high Q-value and copolymerize well with other high Q monomers such as chlorostyrene and chloroprene. bis-1-Butadienyl sulfides were made by reacting a dithiol, such as bis-4-mercaptophenyl ether, with vinylacetylene or by a two-step process using mercaptoethanol followed by treatment of 2-hydroxyethylthiobutadiene with diisocyanate. The polymers were largely of 1,4-trans polydiene structure.     

聚甲基异丙烯基酮和聚异亚丙基丙酮的不对称硅氢化反应

光活性高分子的合成具有重要意义，它在生物活性高分子、用于不对称合成的高分子试剂或催化剂以及不对称选择性色谱柱填料等领域具有潜在的应用价值．研究表明，不对称选择性聚合反应难以获得高光学活性的高分子［１］，而手性过渡金属络合物催化的高分子不对称反应是获得...     

Selective hydrosilylation of styrene using an in situ formed platinum(1,3-dimesityl-dihydroimidazol-2-ylidene) catalyst

A highly active and selective in situ formed platinum(N-heterocyclic carbene) catalyst for the hydrosilylation of styrene with triethylsilane is described, which unlike all other known hydrosilylation catalysts, selectively yields hydrosilylation products, but (almost) no dehydrogenative silylation products.     

The photo-induced degradations of tetraneopentylchromium and trimesitylchromium tetrahydrofuranate: some applications to catalysis

Photo-induced reactions of tetraneopentylchromium (I) and trimesitylchromium tetrahydrofuranate (II) have been investigated. Both I and II upon photolysis in solution function as active catalysts for the polymerization of vinyl monomers such as styrene, methyl acrylate, methyl methacrylate, and vinyl acetate, and also for the polymerization of ethylene under very mild conditions. Irradiation of I in tetrahydrofuran in the presence of carbon monoxide leads to the production of Cr(CO)₆ and Cr(CO)₅(THF), demonstrating that low valent chromium species are formed under these conditions.     

Evidence for a C-H...pi type weak interaction: 1 : 1 complex of styrene with acetylene studied by mass selective high-resolution UV spectroscopy and ab initio calculations

The 1 : 1 complex of styrene with acetylene has been studied by mass selective low- and high-resolution UV resonance-enhanced two-photon ionisation (R2PI) spectroscopy combined with genetic-algorithm-based computer-aided fit of the spectra with partial rotational resolution, and high level ab initio quantum chemistry calculations. Two stable conformeric geometries of the 1 : 1 complex of styrene and acetylene have been theoretically found: one with acetylene binding to styrene as a proton donor, and one with acetylene acting as a proton acceptor. From the analysis of the vibronic structure of the S1<-- S0 spectrum and the fit of the highly resolved spectrum of the 0 origin band of the complex it is shown that the favoured conformation is the one in which acetylene binds to the benzene ring of styrene through formation of a non-conventional hydrogen bond of C-H...pi type with no marked change of the transition moment orientation of styrene. The styrene moiety remains planar and the acetylene molecule is tilted by a small angle of 4 degrees relative to the C6 symmetry axis of the benzene ring, most likely due to the reduced symmetry of the benzene ring pi electrons rather than to a direct interaction with the vinyl group.     

Polymerizability of unsaturated monomers capable of forming stable radicals

Some unsaturated monomers bearing hindered phenol and arylamine groups capable of forming stable radicals were prepared. Radical polymerizations of vinyl monomers having such groups were investigated with the use of azobisisobutyronitrile, benzoyl peroxide, cumene hydroperoxide, and tetraethylthiuram disulfide as initiator. Polymerizations of these monomers went normally only when azobisisobutyronitrile was used as initiator. The other initiators inhibited polymerizations remarkably or completely. The results suggest that radicals resulting from benzoyl peroxide and cumene hydroperoxide or tetraethylthiuram disulfide abstract hydrogen of the phenol or the amine to produce the stable radicals, thereby inhibiting the polymerization. Meanwhile, carbon radicals resulting from azobisisobutyronitrile add selectively to the vinyl double bonds of the monomers to initiate the polymerizations. The vinyl derivatives as well as allyl derivatives and cinnamic acid derivatives copolymerize easily with conventional monomers such as styrene, maleic anhydride, and butadiene, again, only when azobisisobutyronitrile was used as initiator. Antioxidative properties for styrene copolymers and butadiene-styrene copolymers incorporating the hindered phenol monomers were investigated.     

Synthesis of functional polyolefins using cationic bisphosphine monoxide-palladium complexes

The copolymerization of ethylene with polar vinyl monomers, such as vinyl acetate, acrylonitrile, vinyl ethers, and allyl monomers, was accomplished using cationic palladium complexes ligated by a bisphosphine monoxide (BPMO). The copolymers formed by these catalysts have highly linear microstructures and a random distribution of polar functional groups throughout the polymer chain. Our data demonstrate that cationic palladium complexes can exhibit good activity for polymerizations of polar monomers, in contrast to cationic α-diimine palladium complexes (Brookhart-type) that are not applicable to industrially relevant polar monomers beyond acrylates. Additionally, the studies reported here point out that phosphine-sulfonate ligated palladium complexes are no longer the singular family of catalysts that can promote the reaction of ethylene with many polar vinyl monomers to form linear functional polyolefins.     

60Co-initiated copolymerization of styrene with vinyl acetate

The kinetic behavior of the ⁶⁰Co-initiated copolymerization at 25°C of styrene with vinyl acetate at 1100 and 2000 rad/hr was studied. As in the case of thermal and photochemical copolymerizations of these monomers, the growing chains are particularly rich in styrene units, and the overall rate is affected by a diluent effect due to the vinyl acetate monomer. However, in the case of the radiation copolymerization, this effect is partially counterbalanced by an increase of the initiation rate with the vinyl acetate concentration; the polymerization rate curve shows a maximum at a vinyl acetate molar fraction of 0.25. This effect is due to the very different free radical yields of these two monomers. The experimental results may be understood on the basis of a kinetic scheme which involves an energy transfer process from the excited vinyl acetate molecules to the styrene monomer and a termination reaction of the growing chains by very short styrene radicals when the mixture is rich in vinyl acetate.     

C60正丙胺铂,铑配合物的合成及其催化硅氢化性能

Ｃ６０与正丙胺反应,然后分别与氯亚铂酸钾或三氯化铑配合,制得出含配位氮原子的富勒烯铂,铑 配合物,它们均能有效地催化烯烃与三乙氧基硅烷硅氢加成,铂配合物还对苯乙烯有独特的催化性能,以近１００％的区域选择性得到α－加成产物,对催化机理进行了初步的探讨。     

Synthesis of new telechelic oligomers and macro-monomers by “constructive degradation”

Telechelic acrylic oligomers possessing terminal carboxylic acid, ketone, aldehyde or hydroxy groups can be synthesised in good yields by the ozonolysis of free radical copolymers of the appropriate acrylic monomer with a small amount of a 1,3-diene, such as butadiene, 2,3-dimethyl-butadiene or 2,3-diphenyl-butadiene. The oligomers so-prepared have high end-functionalities (>98%), controllable average molecular weights, relatively narrow molecular weight distributions, and can be chain extended by a variety of means to give back high molecular weight polymers. Oligomers with perfect α-phenyl ketone-ω-carboxylic acid functionality can be prepared by ozonolysing copolymers containing low concentrations of units derived from phenyl acetylene. Photolysis of copolymers of an alkyl vinyl ketone with monomers such as styrene yield, directly, oligomers with polymerisable unsaturated end-groups, i.e. macromonomers.     

Copolymerization and homopolymerization reactions in systems containing electron-donor monomer,electron-acceptor monomer,and lewis acid

Investigations of the copolymerization of acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, acrylic acid, acryloyl chloride, methyl vinyl ketone, and acrolein with styrene, and of acrylonitrile with acenaphthylene and 1,3-cyclopentadiene in the presence of Lewis acids as catalysts have been carried out. It was found that the free-radical alternating copolymerization and ionic copolymerization or homopolymerization reactions can proceed in these systems. The yield of the competitive free-radical and ionic reactions was related to the type of monomers and strength of the Lewis acid. The mechanism of the catalytic effect of Lewis acids in the reactions studied is discussed.     

Polymerization photoinitiated by carbonyl compounds. VI. Mechanism of benzil photoinitiation

The mechanism of the photoinitiation of the vinyl polymerization sensitized by benzil and 4,4′-dimethoxybenzil was studied. The monomers considered were methacrylic acid esters and styrene derivatives. All these monomers are efficient quenchers of the excited triplet benzil. However, the initiation efficiency of the benzil is important only when styrene derivatives are employed as monomers. The main polymerization process follows a simple free radical mechanism. The initiation step is a consequence of the interaction (triplet benzil–monomer double bond) through a charge transfer complex.     

Crown Ether As The Phase-Transfer Catalyst for Free Radical Polymerization of Hydrophobic Vinyl Monomers

Various crown ethers were used as phase-transfer catalysts for free radical polymerizations of some water-insoluble vinyl monomers such as acrylonitrile, methylmethacrylate and styrene with persulfate as initiator. The catalytic abilities of these crown ethers for free radical polymerization of acrylonitrile with S₂O₈^2?ion as an initiator were in the order: 18-crown-6 > 15-crown-4 > 12-crown-4 > benzo-15-crown-5 > dibenzo-18-crown-6. Among various persulfates such as Na₂S₂O₈ K₂S₂O₈ and (NH₄)₂S₂O₈, ammonium persulfate was the optimum initiator for the polymerization of acrylonitrile catalyzed by 18-crown-6 or 15-crown-5. Among the organic solvents used, chloroform seems to be the best solvent for the catalytic polymerization of acrylonitrile. An apparent activation energy of 72.9 kJ mol^?1 was observed for the polymerization of acrylonitrile. The catalytic reaction rates of free radical polymerization for these hydrophobic vinyl monomers were in the order: acrylonitrile > methylmethacrylate > styrene > isoprene. Effects of concentrations of crown ether, initiator, and nitrogen on the polymerization of these vinyl monomers were investigated.     

4,4′-二(硬脂酰胺基)二苯甲烷在乙烯基类单体中的分子组装及其结构形态研究

4,4′-二(硬脂酰胺基)二苯甲烷(BSDM)能在乙烯基类单体中进行聚集、自组装,并可使苯乙烯、丙烯酸丁酯、甲基丙烯酸甲酯、甲基丙烯酸-2-羟基乙酯等凝胶化,形成相应的分子凝胶.凝胶/溶胶相变温度(TGS)与BSDM浓度有关,BSDM质量分数越大,凝胶体系中分子间氢键和π-π键越多,要破坏它们所需要的能量越高,TGS因而也就越高.透射电镜表明,BSDM在各种可聚合溶剂中通过分子间相互作用形成类似纤维状的聚集体结构.BSDM在可聚合溶剂聚合前后的偏光显微照片表明,BSDM在体系中的晶型结构是球晶.     

Insoluble polystyrenes containing amide moieties and N-alkylated nylon-66 as phase transfer catalysts

Insoluble polystrenes containing formamide and acetamide moieties were prepared by free radical terpolymerization of the corresponding vinyl monomers, styrene, and divinylbenzene. These polymers served as phase transfer catalysts for the reaction of n-octyl bromide with potassium thiocyanate in toluene–water system. The activity of these catalysts was affected by some factors such as stirring speed particle size, and degree of crosslinking. The activity also depended strongly on the structure of active site, copolymer composition, and spacer length which cause the difference in the adsorption of potassium ion and in the microenvironment around the active site. Furthermore, nylon-66 was found to display the activity for phase transfer reactions, and the activity was remarkably increased by replacing the amide hydrogen with an alkyl group.     

Phase-Transfer Reactions Catalyzed by Polymer-Supported Imidazoles

Abstract

Polymer-supported imidazoles were prepared by copolymerization of vinyl monomers containing imidazole moiety, styrene, and divinylbenzene with AIBN. The resulting polymers accelerated the reaction of octyl bromide with potassium thiocyanate, and the alkylation of an active methylene compound, benzyl cyanide, under phase-transfer conditions. The latter catalytic reaction afforded monoalkylated compound exclusively, although dialkylated compound was also obtained in monomeric alkylimidazole catalyzed reaction. Further, these polymers served as phase-transfer catalysts for the reduction of acetophenone by sodium borohydride. The relationship between the structure and catalytic activity, and the factors governing these catalytic reactions were examined.     

双官能度自由基引发剂应用研究的进展

双官能度引发剂在自由基聚合中的应用不断受到重视，本文介绍了常用的双官能度引发剂，并综述了其在制备嵌段共聚物及引发乙烯类单体（如苯乙烯、氯乙烯、丙烯酰胺等）聚合的研究进展。