EPR study of free radical in gamma-irradiated bis(cyclopentadienyl)zirconium dichloride single crystal

Bis(cyclopentadienyl)zirconium dichloride (BCZD; zirconocene dichloride) single crystals were exposed to ⁶⁰Co-γ irradiation at room temperature. The irradiated single crystals were investigated between 125 and 470?K by electron paramagnetic resonance spectroscopy. The spectra of the crystals were found to be temperature independent. The paramagnetic center was attributed to the cyclopentadienyl radical. The g values of the radiation damage center observed in BCZD single crystal and the hyperfine structure constants of the free electron with nearby protons were obtained.     

Synthesis of polyamides by nickel-catalyzed coupling polymerization of aryl dichloride containing amide structural units

Four aryl dichlorides containing secondary amide structural units as monomers were synthesized from substituted piperazines and chlorobenzoyl chlorides. Polyamides were prepared by the nickel-catalyzed coupling polymerization of these monomers. Polymerizations were carried out in N-methyl-2-pyrrolidinone (NMP) in the presence of nickel chloride, zinc, triphenylphosphine, and bipyridine, and resulted in polyamides with inherent viscosities up to 0.38 dL/g under mild conditions. The structure of polymer was determined by IR and ¹³C-NMR spectroscopies. The polyamide, poly[4,4′-biphenyldicarbonyl (2,5-dimethylpiperazine)] 6d , was readily soluble in dipolar aprotic solvents and chloroform. Thermogravimetry of polyamides, poly[(4,4′-biphenyldicarbonyl piperazine)]s 6 , showed 10% weight loss at around 425 and 450°C in air and under nitrogen, respectively. © 1992 John Wiley & Sons, Inc.     

Reductive Coupling Cyclization of 1,1—Dicyanoalkenes Promoted by Sm^0／cat.HgCl2 System

The intermolecular reductive coupling cyclization reaction of 1,1-dicyanoalkenes promoted by Sm^0/cat.HgCl2 studied.A possible reaction mechanism was proposed.     

Activity coefficients of hydrocarbons at infinite dilution in di-n-octyltin dichloride. Comparison with results obtained in other alkyltin solvents

The gas chromatographic method was employed to measure the infinite dilution activity coefficients of twenty-eight hydrocarbons of different types in di-n-octyltin dichloride between 50 and 80°C, and of seven branched alkanes in tri-n-octyltin chloride between 40 and 60°C. A comparison is made between the results obtained for all the solutes in both solvents and in tetra-n-octyltin.     

Synthesis of diaryl selenides using the in situ reagent SeCl2

Reactions of in situ prepared SeCl₂ with Grignard reagents (prepared from bromobenzene, o-tolyl bromide, 2,6-dimethyl-4-tert-butyl-1-bromobenzene, and 1-bromo-2-methylnaphthalene) and dilithiated benzamides (prepared from N-phenyl, N-cyclohexyl, and N-isopropyl benzamide) are described.     

Cp2TiCl2催化下Grignard试剂与芳醛反应的研究

Meunier 等曾研究了 Cp_2TiCl_2催化下,格氏试剂对卤代烷和羰基化合物的还原反应,并报道了与芳环或碳-碳双键或碳-碳三键共轭的羰基化合物不被格氏试剂还原。我们却发现,在较低温度下,这些芳醛或与碳-碳重键共轭的羰基化合物也会被还原,特别是在芳环上有吸电子取代基时,还原产物的产率很高。     

Recent developments in manufacturing emulsions and particulate products using membranes

Membrane emulsification (ME) is a relatively new technique for the highly controlled production of particulates. This review focuses on the recent developments in this area, ranging from the production of simple oil-in-water (O/W) or water-in-oil (W/O) emulsions to multiple emulsions of different types, solid-in-oil-in-water (S/O/W) dispersions, coherent solids (silica particles, solid lipid microspheres, solder metal powder) and structured solids (solid lipid microcarriers, gel microbeads, polymeric microspheres, core-shell microcapsules and hollow polymeric microparticles). Other emerging technologies that extend the capabilities into different membrane materials and operation methods (such as rotating membranes, repeated membrane extrusion of coarsely pre-emulsified feeds) are introduced. The results of experimental work carried out by cited researchers in the field together with those of the current authors are presented in a tabular form in a rigorous and systematic manner. These demonstrate a wide range of products that can be manufactured using different membrane approaches. Opportunities for creation of new and novel entities are highlighted for low throughput applications (medical diagnostics, healthcare) and for large-scale productions (consumer and personal products).     

Photochromic dihetarylethenes. 14. Synthesis of symmetrical and unsymmetrical dihetarylcyclobutene-1,2-diones

A procedure was developed for the synthesis of symmetrical and unsymmetrical cyclobutene-1,2-dione derivatives bearing thiophene and thieno[3,2-b]thiophene substituents by the Friedel—Crafts reaction of the corresponding heterocyclic compounds with squaric acid dichloride in the presence of AlCl₃. In addition to the target dihetarylcyclobutenediones, monoacylation products of methyl (2,5-dimethylthiophen-3-yl)acetate and methyl 5-methylthieno[3,2-b]thiophene-2-carboxylate with squaric acid dichloride were isolated and characterized.     

Darstellung intramolekular stabilisierter Diazaphosphorinan-Derivate mit der Trimethylethylendiamin- bzw. der Tetramethylguanidingruppe als Substituent am Phosphor: Studium intramolekularer Me2N → P-Wechselwirkungen

Formation of Intramolecularly Stabilized Diazaphosphorinane Derivatives with the Trimethylethylenediamine and the Tetramethylguanidine Group as Substituents at Phosphorus: Investigation of intramolecular Me₂N → P Interactions In the reaction of trimethylchlorophosphonium chloride 1 with N-trimethylsilyl-N′,N′,N″,N″-tetramethylguanidine 2 the expected guanidine-substituted trimethylphosphonium chloride 3 was formed, presumably via the ammonium chloride 3a which could not be isolated. By contrast, the reaction of the related chloromethyldimethylchlorophosphonium chloride 5 with N-trimethylsilyl-N,N′,N′-trimethylethylenediamine 6 and N-trimethylsilyl-N′,N′-dimethylethylene diamine, 7 , respectively, furnished in an unusual fashion six-membered heterocycles, the ammonium-phosphonium dichlorides 10 and 11 . Their formation involved cleavage of both the P? Cl and the C? Cl bond, followed by intramolecular C←N-acceptor-donor interaction. A similar C←N interaction was not observed in the reaction of 5 with 2 , and the acyclic product 12 was formed. The reaction of chloromethylmethylchlorophosphine 13 with the hydrogen peroxide/urea 1:1-adduct led to chloromethylmethylphosphinic acid 14 . Attempts at the reaction of 14 with 2 or with SOCl₂ were unsuccessful. The reaction products were characterized by ¹H-, ¹³C-, ³¹P- and, in two cases, by ¹⁵N-NMR-spectroscopy.     

1,1—二甲基—3—丁烯基环戊二烯基稀土二氯化物的合成

１，１－二甲基－３－丁烯基环戊二烯基稀土二氯化物的合成林进张萍王昭煜＊（河北师范大学化学系石家庄０５００１６）关键词烯基环戊二烯基，稀土二氯化物，配合物，合成１９９７－０８－０６收稿，１９９７－１２－０５修回河北省自然科学基金资助课题环戊二烯基轻稀土...