Polymerization of cyclohexene oxide with Al(acac)3- silanol catalyst

The polymerization of cyclohexene oxide was investigated with a new catalyst system of Al(acac)₃- silanol compounds. Catalyst activity varied with the ratio of silanol/Al(acac)₃ and the structure of silanol compounds. Catalyst deactivation appeared to be caused by self-condensation of silanol and the addition of silanol to the epoxy ring. Polymer structure was investigated by ¹³C-NMR spectroscopy and x-ray diffraction. The mechanism of the polymerization appears to be cationic.     

Polymerization of methyl methacrylate by Ziegler-Natta type catalyst systems: Fe(acac)3-AlEt2Br and Fe(acac)3-ZnEt2

The polymerization of methyl methacrylate was carried out with the following Ziegler-Natta type initiating systems: Fe(AcAc)₃-AlEt₂Br, Fe(AcAc)₃-ZnEt₂ (acac = acetyl acetonate). Both the catalyst systems are active under homogeneous conditions in benzene at 40°C for methyl methacrylate polymerization. The polymerization kinetics suggests that the average rate of polymerization was first order with respect to [monomer] for both the catalyst systems, and the overall activation energies were found to be 14.0 and 12.8 kcal mol ^?1.     

Polymerization of cyclohexene oxide with aluminum complex-silanol catalyst. IV. Photopolymerization with Ph3SiCOPh-Al complex-alcohol catalyst system

A new catalyst system (Ph₃SiCOPh-aluminum complex-alcohol) was investigated for photopolymerization of cyclohexene oxide. Polymer conversion and molecular weight increased with polymerization time. When a Ph₃SiCOPh-Al (n-Praa)₃-alcohol catalyst system was used the catalyst activity decreased, depending on the alcohol: i-PrOH > n-PrOH > i-BuOH > MeOH > t-BuOH > H₂O. When the Ph₃SiCOPh-Al complex-i-PrOH catalyst system was used the catalyst activity decreased, depending on the ligand of the Al complex: ß-ketoester > orthocarbonyl phenol > ß-diketone. Benzophenone derivatives were effective for catalyst activation as a photosensitizer.     

Ln（acac）3—BuMgCl催化甲基丙烯酸甲酯聚合

开发了催化甲基丙烯酸甲酯聚合的一类新型催化剂，由稀土乙酰基丙酮配合物Ｌｎ（ａｃａｃ）３和格氏试剂ＢｕＭｇＣｌ组成．研究了不同稀土元素、催化剂陈化时间和温度、溶剂、ＣＣｌ４添加剂、聚合时间和温度的影响．结果表明，在石油醚中单体聚合转化率和聚合物相对分子质量高于芳烃和其它极性溶剂，过量ＢｕＭｇＣｌ可能起链转移作用，降低温度可提高聚合物的间同含量．     

Polymerization of cyclohexene oxide with aluminum complex/silanol catalyst. VI. Oligomer and polymer effects

The activity of an aluminum complex/polysilanol polymerization catalyst was examined in order to confirm the dependence of catalytic activation on silanol chain length. Tris (acetylacetonato)–aluminum/silanol increased when silanols with an intramolecular hydrogen bond such as the trimer of diphenylsilanediol, polydiphenyl(4-vinylphenyl)silanol, and polymeric silanol of silicone were used. However, when tris(ethylacetoacetato)aluminum or tris(salicylaldehydato)aluminum was used, the product obtained from the reaction of a part of the aluminum complex with the polysilanols had to be considered in any explanation of the catalytic activation. The active catalyst with such aluminum complexes was obtained when the silanols that had intramolecular hydrogen bonds and gave the appropriate ratio of the reaction between the aluminum complex and silanol were used.     

Investigations on the kinetics of copolymerization of vinyl acetate with acrylonitrile by Co(acac)3–Al(C2H5)3 catalyst system

Vinyl acetate and acrylonitrile were copolymerized with Co(acac)₃-Al(C₂H₅)₃ catalyst system in benzene at 40°C. The rate of copolymerization is linearly proportional to monomer concentration and catalyst concentrations up to a certain value. The overall activation energy was found to be 11.3 kcal/mole. The effect of hydroquinone on the rate of copolymerization indicates the presence of free radicals in this system. The possibility of simultaneous formation of coordinate anionic and free radical active sites has been proposed.     

Oligomerisation of phenyl acetylene over titanium oxide supported on silica - alumina catalyst

Titanium oxide on silica-alumina support is found to be effective for oligomerisation of phenyl acetylene. Cyclic trimerisation of the acetylene leading to trisubstituted benzene was also found to occur during the oligomerisation, in addition to the formation of small quantities of a ketone by the reaction of phenyl acetylene with moisture over the catalyst surface.     

聚4-乙烯基吡啶/SiO~2纳米杂化材料负载茂钛催化剂的制备 及苯乙烯聚合

以聚4-乙烯基吡啶(PVP)为有机组分,正硅酸乙酯(TEOS)为无机组分,利用sol-gel方法制得PVP/SiO~2纳米杂化材料,以此为载体制备了杂化材料负载单茂钛催化剂。利用XPS和IR分析了载体与CpTiCl~3的结合方式,确认对苯乙烯聚合有两种活性中心,苯乙烯聚合结果表明在50℃左右间规度达到最大;在70℃,n(Al)/n(Ti)=1500时活性最高可达1.09×10^6gPS/(molTi·h),GPC结果表明产物分子量分布呈双峰分布。     

Copolymerization of styrene and butadiene with Ni(acac)2-methylaluminoxane catalyst

Copolymerization of styrene (St) and butadiene (Bd) with nickel(II) acetylacetonate [Ni(acac)₂]-methylaluminoxane (MAO) catalyst was investigated. Among the metal acetylacetonates [Mt(acac)_x] examined, Ni(acac)₂ showed a high activity for the copolymerization of St and Bd giving copolymers having high cis-1,4-microstructure in Bd units in the copolymer. The effect of alkylaluminum as a cocatalyst on the copolymerization of St and Bd with the Ni(acac)₂-MAO catalyst was observed, and MAO was found to be the most effective cocatalyst for the copolymerization. The monomer reactivity ratios for the copolymerization of St and Bd with the Ni(acac)₂-MAO catalyst were determined to be r_St = 0.07 and r_Bd = 3.6. Based on the obtained results, it was presumed that the random copolymers with high cis-1,4-microstructure in Bd units could be synthesized with the Ni(acac)₂-MAO catalyst without formation of each homopolymer. The polymerization mechanism with the Ni(acac)₂-MAO catalyst was also discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3838–3844, 1999     

Hydrogen transfer hydrogenation of nitrobenzene to aniline with Ru(acac)3 as the catalyst

Tris(acetylacetonato)ruthenium(III)(Ru(acac)₃) was synthesized with RuCl₃·nH₂O and acetylacetone as raw materials. The structure of Ru(acac)₃ was identified by FI-IR, ¹H NMR, ¹³C NMR, and elemental analysis. It was used in the catalytic hydrogen transfer hydrogenation of nitrobenzene with sodium formate as hydrogen donor. The effects of reaction conditions on the process, such as temperature, time, dosage of catalyst, and kinds of hydrogen donor, were investigated. The optimal reaction parameters were determined as follows: 80 °C, 4.0 h, the substrate nitrobenzene 20 mL, sodium formate 27.20 g, Ru(acac)₃ 0.96 g, the conversion of nitrobenzene is 100.0 %, the yield of aniline and the selectivity to aniline are 96.65 %. The reaction mechanism is proposed and analyzed. It exhibited excellent catalytic properties in the hydrogen transfer hydrogenation of nitrobenzene to aniline.     

Copolymerization of styrene and isoprene with Ni(acac)2-methylalumoxane catalyst

Copolymerization of styrene (St) and isoprene (IP) with nickel(II) acetylacetonate [Ni(acac)₂] and methylalumoxane (MAO) catalyst was investigated. It was found that the Ni(acac)₂-MAO catalyst is effective for the copolymerization of St and IP. From the copolymerization of St (M₁) and IP (M₂) and IP (M₂) with the Ni(acac)₂-methylalumoxane catalyst, the monomer-reactivity ratios were determined to be r₁ = 1,18 and r₂ = 0,88, i.e., ideal copolymerization was found to proceed to give perfectly random copolymers without formation of any homopolymer. The microstructure of IP units in the copolymers exhibits high cis-1,4 contents.     

Structural Study of Al(acac)3 Catalyzed CH3SiO3/2 Gel

A transparent CH3SiO3/2 gel and an opaque one have been prepared from methyltriethoxysilane. Al(acac)3 is added to obtain the transparency. The two gels are studied by XRD, NMR and infrared spectroscopy. Some amount of silanols remains in the form of T2(CH3SiO(OH)) in the transparent gel, but few in the opaque gel. There is a diffraction peak reflecting intermolecular correlation in the XRD curves, which appears broader at a lower angle in the transparent gel than in the opaque gel. These results are discussed by assuming a larger hindrance in polymerization of silanols in the transparent gel.     

端羟基聚环氧环己烷的合成

端羟基聚环氧环己烷的合成;端羟基聚环氧环己烷;环氧环己烷;阳离子聚合     

Ln（acac）_3／BuMgCl催化聚合甲基丙烯酸甲酯、环氧丙烷和ε－己内酯

Ｌｎ（ａｃａｃ）_３／ＢｕＭｇＣｌ催化聚合甲基丙烯酸甲酯、环氧丙烷和ε－己内酯孙俊全（浙江大学高分子科学与工程系杭州３１００２７）关键词甲基丙烯酸甲酯，环氧丙烷，ε－己内酯，稀土化合物，格氏试剂，配位催化剂，聚合反应在开拓稀土配位聚合反应的研究中，已?..     

Polymerization of ethylene by using zirconocene catalyst anchored on silica with trisiloxane and pentamethylene spacers

New supported catalysts on the basis of cyclopentadienylindenylzirconium dichloride (CpIndZrCl₂) anchored on silica with a trisiloxane spacer (ZATS) and a pentamethylene spacer (ZAPM) were prepared and used for ethylene polymerization with modified methylaluminoxane (MAO) as cocatalyst. ZATS and ZAPM produce polyethylene with lower molecular weight but show higher activity than silica-supported CpIndZrCl₂ which was prepared by reacting zirconocene directly with silica, i.e., the activity of silica-supported CpIndZrCl₂ is enhanced by introducing a spacer between silica surface and metallocene species.     

Chemically induced dynamic nuclear polarization and reaction of Et3Al with CCl4 catalyzed by Ni(acac)2

The influence of Ni(acac)₂ added in catalytic amounts on the chemically induced dynamic nuclear polarization (CIDNP) effects, the mechanism of interaction, and the products of reaction between Et₃Al and CCl₄ were studied. The radical intermediates were identified and the routes for their transformations were proposed. The thermal reaction of Et₃Al with CCl₄ occurs by a radical mechanism. However, in the presence of Ni(acac)₂, the reaction proceeds mainlyvia a nonradical route and gives large amounts of ethylene and ethane. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1580–1583, August, 1998.