摘要:

AbstractThree novel metal catalyzed cross‐coupling polymerization reactions which result in carbon‐carbon bond formation are described and discussed in context with other metal catalyzed cross‐coupling polymerization reactions. Diarylacetylene monomers and dimers are prepared by the phase transfer Pd(0)/Cu(I) catalyzed coupling of aryl halides with 2‐methyl‐3‐butyn‐2‐ol. Aryl‐alkyl bond forming polymerization reactions are achieved by the phase transfer Pd(0) catalyzed coupling of B‐alkyl‐9‐borabicyclo[3.3.1]nonane derivatives with aryl halides. Soluble polyphenylenes are prepared by the Ni(0) catalyzed homocoupling of substituted phenylenebistriflates

ISSN:0258-0322    

DOI:10.1002/masy.19920540113

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThis article reviews our current work on the palladium‐ and nickel‐catalyzed polycondensations for the synthesis of various types of condensation polymers. We succeeded for the first time in the synthesis of carbon‐carbon coupling polymers, that is polycinnamamides, by the palladium‐catalyzed cross‐coupling polycondensation of aromatic diiodides with divinylic compounds. We further developed a new promising method of the synthesis of aramids and related condensation polymers by the palladium‐catalyzed carbonylation polycondensation starting from aromatic dibromides, bifunctional nucleophilic monomers such as aromatic diamines, and carb

ISSN:0258-0322    

DOI:10.1002/masy.19920540114

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractSeveral polyimides were prepared by the palladium catalyzed carbonylation and condensation of tetraiodoaromatic compounds and diamines. This new reaction for preparing polyimides was found in model compound work to be an efficient, high yield route to cyclic imides. Since fully imidized groups are formed during the polymerization, it was necessary to limit the diamines to those that would impart solubility to the polymer. In contrast to the model compound work, the polymerization reaction yielded an appreciable concentration of amide functional groups due to incomplete cyclization and/or branching reactions. Mixed haloaromatic compounds were also examined as monomers in this reaction. Model reactions betweeno‐bromoiodobenzene and aniline indicated that amide formation through the iodide was preferred and that imide formation through the bromide occurred later. Extension of this chemistry to dibromodiiodobenzene and diaminophenylindane DPI, gave low molecular weight oligomers at low phosphine levels and branched material at higher level

ISSN:0258-0322    

DOI:10.1002/masy.19920540115

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPlatinum complexes together with compounds containing silicon‐hydrogen bonds comprise a novel class of initiators for the ring‐opening polymerization of a wide variety of heterocyclic compounds including; epoxides, oxetanes and 1,3,5‐trioxane. This paper reports on a preliminary survey of the scope and limitations of these new initiator systems with special emphasis on the ring‐opening polymerization of epoxides. Considerable effort has been directed towards the elucidation of the mechanism of the polymerizations initiated by these systems. The best current evidence suggests that polymerization proceeds by a cationic mechanism. Data is also presented which suggests that platinum metal colloids may function as the active initiating

ISSN:0258-0322    

DOI:10.1002/masy.19920540116

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractOrganometallic rhodium complexes were found to be catalysts for the ring‐opening polymerization of epoxides and other heterocyclic compounds. A cocatalyst, consisting of a compound or polymer containing silicon‐hydrogen bonds is also required. These same catalyst‐cocatalyst mixtures are also highly active for hydrosilation reactions. Rhodium phosphine complexes have been discovered which, while active for hydrosilation, are not catalysts for epoxide polymerizations. These rhodium phosphine complexes permit the synthesis of epoxy‐functional silanes and siloxanes in high yields without competing ring‐opening polym

ISSN:0258-0322    

DOI:10.1002/masy.19920540117

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA new method for the formation of high molecular weight aromatic biphenylene polymers via the nickel coupling of aromatic dichlorides is described. Aromatic biphenylene polymers display a number of highly attractive features which are discussed. The novel reaction is performed in a dry aprotic solvent (e.g., in DMAC) using catalytic amounts of zero‐valent nickel, triphenylphosphine ligand and excess zinc metal. The reactions must be performed under an inert atmosphere and in the absence of water. In order to obtain high polymer, one must use low amounts of nickel, high triphenylphosphine/nickel ratios, excess zinc metal, and moderate temperatures (70 °C). Variables such as the choice of ligand or co‐ligand, salt addition, ligand and zinc concentration, etc … allow for optimization of the reaction efficiency. The method is general and allows for the preparation of an almost infinite variety of polymers. Polymerizations and copolymerizations involving aryl dichlorides possessing dissimilar chloro‐moieties are particularly intriguing since a number of sequence distributions are possible. The two prerequisites for a successful preparation of high molecular weight product are solubility of the monomer, and more particularly of the obtained polymer, in the reaction medium; and the necessity that any functional groups present in the monomer(s) (and in the resulting polymer) be inert toward the zinc/nickel system.Critical features of the polymerization mechanism are also

ISSN:0258-0322    

DOI:10.1002/masy.19920540118

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractNovel polymerization reactions utilizing a divalent germanium or tin species, germylene or stannylene, have been developed. Copolymers having a germanium(IV) or tin(IV) unit in the main chain have been prepared by the reaction of oxidant monomers (Mox) and reductant monomers (Mred, germylene or stannylene). Oxidant monomers employed are p‐benzoquinones, N‐phenyl‐p‐quinoneimines, cyclic α, β‐ unsaturated ketones, and cyclic sulfides. A new aspect of these divalent chemical species as an initiator for vinyl monomers has also been i

ISSN:0258-0322    

DOI:10.1002/masy.19920540119

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPreparation of poly(phenylene sulfide) (PPS) by the new and novel melt phase reaction of p‐diiodobenzene and sulfur is reported. This new, unique polymerization process can be carried out either entirely in the melt or by a combination of melt and solid state polymerization. Elemental iodine was the reaction by‐product. This process produced very high melt viscosity PPS with degrees of polymerization of several hundred or more. A more Newtonian viscosity over a range of shear rates indicated more linearity of the PPS chains than commercial materials. IR analysis of meta‐ and ortho‐copolymers showed a very high reaction specificity for ipso substitution. Disulfide linkages present in the polymer appeared to be involved in rapid chain equilibration of melt‐mixed samples but did not appear to adversely affect overall stability of the final polymer. Disulfides also appeared to be a reactive species for chain buildup, and an initial mechanism based on this is proposed. Crystallization rates can be tailored from moderate to very fast. Although only PPS has been addressed in this report, extensions to other poly(arylene sulfide)s ar

ISSN:0258-0322    

DOI:10.1002/masy.19920540120

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThermolysis of diphenyl disulfide in the presence of iodoarenes yielded the corresponding unsymmetric diaryl sulfides. This new reaction has been utilized for the synthesis of high molecular weight poly(phenylene sulfide) and poly(naphthylene sulfide)s, starting from bis(4‐iodophenyl) disulfide and bis(iodonaphthyl) disulfides. Poly(phenylene sulfide) with a melting temperature above 250 °C was also obtained from bis(4‐bromophenyl) disulfide in the presence of a suitable reducing agent (e.g. potassium iodide). Heating bis(4‐chlorophenyl) disulfide afforded only a low molecular weight polymer. Bis(4‐fluorophenyl) disulfide remained stable under the same thermolysis co

ISSN:0258-0322    

DOI:10.1002/masy.19920540121

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe mechanism of formation of poly(1,4‐phenylene sulfide) (PPS) by solution polymerisation of copper(I) 4‐bromobenzenethiolate (CBT) at 200 °C in quinoline under nitrogen at atmospheric pressure has been investigated. The polymerisation has been monitored as a function of reaction time by electron spin resonance (ESR) spectroscopy and by evaluating the yield and molar mass of the PPS formed. The ESR spectra provided direct evidence for the operation of a mechanism involving single electron transfer processes. The results are discussed in terms of possible mechanisms for polymerisation of CBT, leading to the conclusion that a SRN1‐type mechanism predominates and that a free‐radical mechanism also may be

ISSN:0258-0322    

DOI:10.1002/masy.19920540122

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY