摘要:

AbstractDie Derivatisierung von α‐(2‐Hydroxyäthyl)‐ω‐hydroxypoly(oxyäthylen) (1) (Polyäthylenglykol) und Polyvinylalkohol (3) mit aromatischen Amino‐, Thiophosphorsäureester‐und 2‐Hydroxyäthylphenylthioäther‐Gruppen wird beschrieben. Von den verschiedenen Polymerderivaten eignen sich für die „Liquid‐phase”︁‐Synthese von Oligonucleotiden besonders Thiophosphorsäureester und Hydroxyäthyl‐phenylthioäther des Polyäthylenglykols als polymere Phosphatschutzgruppen. Diese Derivate sind in hohen Ausbeuten zugänglich und fast quantitativ mit Nucleinsäurebausteinen beladbar. Einführung und Abspaltung der polymeren Phosphatschutzgruppen werden am Beispiel der Derivatisierung von Desoxythymidin und 5′‐Desoxythymidylsäure beschrieben. Die hydrolytische Abspaltung der polymeren Phosphatschutzgruppen ist unter Erhalt von Schutzgruppen der Nucleobasenreste möglich und füh

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760801

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractBei der Knoevenagel‐Kondensation von 2,6‐Dimethylthiazolo[4,5‐f] benzthiazol (1) mit Mono‐ und Dialdehyden der Benzol‐ und Thiophenreihe wurden einige Poly(thiazolo[4,5‐f]benzthiazol‐2,6‐ylenvinylenarylenvinylen)e (7a–c) und einige ihrer Oligomeren (3a–e) erhalten. Die Knoevenagel‐Kondensation von 2‐Methylbenzthiazol (4) mit Dialdehyden ergab eine weitere Reihe von Oligomeren (6a–c). Die Struktur der erhaltenen Verbindungen wurde durch Elementaranalyse, IR‐Spektren und Elektronenspektren, die der Oligomeren zusätzlich durch Massenspektren und – soweit es die Löslichkeit der Verbindungen zuließ – auch durch1H‐NMR‐Spektren bestätigt. Außerdem wurde die elektrische Leitfähigkeit bei allen Verbindungen und der therm

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760802

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractDer Mechanismus der spontanen Polymerisation von 1,2‐Dimethyl‐5‐vinylpyridiniumbromid in Wasser wurde untersucht. Die Reaktion wird durch Licht initiiert, doch findet auch in der Dunkelheit eine langsame Polymerisation statt, die durch den thermischen Zerfall eines angenommenen Peroxid‐Initiators erklärt wer

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760803

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractThe homogeneous polymerization of acrylamide initiated by the new redox system permanganate‐malic acid was investigated in aqueous media under nitrogen at 35±0,2°C. Over a wide range of concentration (2,5 to 30 mmol dm−3) of the activator (malic acid), (4), the polymerization rate remains unaffected. Addition of sulfuric acid (0,1 to 5 mmol dm−3) increases the rate but decreases the maximum conversion. The value 0,53 of the catalyst exponent confirms a bimolecular termination mechanism. The variation of the rate at a low monomer concentration is linear. The initial rate and the conversion increase with increasing temperature. The activation energy is found to be 82,20 kJ/mol (19,74 kcal/mol) in the temperature range of 25 to 50°C. Neutral salts, water miscible organic solvents, and ethylenediaminetetraacetic acid all suppress both the limiting conversion and the rate of polymerization. The addition of more catalyst at intermediate stages as well as the addition of MnSO4raise the initial rate and the conversion. Sodium fluoride enhances the rate but lowers the limiting co

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760804

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractChelate formation of vinylamine/vinyl alcohol copolymers with copper(II) was studied both by the spectrophotometric and by titrimetric methods. For comparison, polyvinylamine/poly(vinyl alcohol) mixtures were also taken up for measurements. In the case of the copolymer systems, copper(II) ions were found to be coordinated exclusively by nitrogen atoms of the copolymer ligand. The complexation constants of the chelates were determined by applying the modified Bjerrum method, in neglect of the acid dissociation of hydroxy groups in the copolymers. It was found that the copolymer/Cu(II) chelates tend to be unstable with decreasing contents of NH2groups in the copolymers. In the homopolymer mixture systems, copper(II) ions are not coordinated by the oxygen atoms of poly(vinyl alcohol), but only by the nitrogen atoms of polyvinylamine.

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760805

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractThe polymerization of acrylonitrile (AN) and of methyl methacrylate (MMA) initiated by various copper(II) chelates was studied in the presence of carbon tetrachloride. Several vinylamine (VAm)/vinyl alcohol (VA) copolymers with different contents of NH2and OH bearing monomeric units were chosen as polymer ligands as well as polyvinylamine (PVAm)/poly(vinyl alcohol) (PVA) mixtures (of equal NH2and OH group contents as the corresponding copolymers), PVAm, and PVA. The activity of the used polymer chelates to initiate the AN and the MMA polymerization was compared at various pH values of the reaction systems. For the polymerization of MMA, the VAm/VA copolymer systems showed a higher activity than the PVAm chelate containing the same amount of NH2groups, contrary to the case of the polymerization of AN, where the polymerization activity showed a reverse behavior. The initiation mechanism is discussed.

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760806

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractThe reversible oxygenation of a synthetic polymeric pyridine‐hemochrome was studied in aqueous solution at room temperature. The polymeric hemochrome was synthesized by coordination of partially quaternized poly(4‐vinylpyridine), (QPVP), to the axial site of protoheme in water. The equilibrium constants of hemichrome and hemochrome were 2,60.102and 2,77.104dm3mol−1, respectively, and the coordination number of axial ligands (pyridine groups) both in the complexation of heme and hemin was approximately 1,0.The kinetics of the elementary processes of oxygenation, i.e. “adsorption of O2” and “irreversible oxidation of the resulting oxygen complex”, were studied as a function of the local field around heme. The rate of the irreversible oxidation process of the heme oxygen complex was greatly lowered as a result of situating the active site of heme inside the hydrophobic environment formed by shrinking QPVP with adding a salt {sodium chloride, sodium dodecylsulfate, and poly[1‐(sodium sulfonatophenyl)‐ethylene]} or by complexing QPVP with poly(methacrylic acid). The redox potential of the central metal ion of heme was lowered by increasing the hydrophobicity around heme. On the other hand, the rate of the adsorption process was approximately constant, regardless of the microenvironmental c

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760807

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractThe rate of thermolysis of various 1,1,4,4‐tetraalkyl‐2‐tetrazenes was measured in ethanol by means of UV‐spectroscopy. The rate measurements were carried out over a temperature interval from 90 to 115°C. The activation parameters were calculated from the temperature dependence of the rate constants. On the basis of the kinetic data, the influence of substituents on the thermolysis of 2‐tetrazene is discussed. In this connection the substituent effect on the rate of polymerization of acrylonitrile initiated by 2‐tetrazene derivatives was a

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760808

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractThe general procedures which were developed for the study of the polymerization and copolymerization of isobutene, initiated by novel syncatalytic systems based on dialkyl aluminium halides and halogens or interhalogen compounds, are described. The results of preliminary experiments on polymerization and copolymerization carried out with the goal of identifying the most promising catalytic systems from the point of view of efficiency and of polymer molecular weight are described briefly. The best results were obtained with the systems (C2H5)2AlCl+Cl2, (C2H5)2AlCl + ICl, and (C2H5)2AlI + I2.

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760809

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY

摘要:

AbstractIn the course of studies on polymerizations of isobutene (1) by syncatalysts consisting of ethylaluminium halides and halogens, it became necessary to study the separate reactions between the components of the reaction mixtures. The results showed: (a) that in general alkyl chlorides do not react with halogens in the dark at −35°C and below, but do react in the light; (b) that at low temperatures1and its dimers react with chlorine more easily by substitution than by addition; (c) that ethylaluminium halides react with halogens by forming aluminium halides, ethyl halides and ethylene.The findings of the present study enabled us to design polymerization conditions and procedures which minimize undesirable side‐reactions in the polymerization of1with syncatalysts.The experiments with the dimer of1(i.e. 2,4,4‐trimethyl‐1‐pentene), which is a non‐polymerizable model compound for1, supported our view that initiation occurs by a

ISSN:0025-116X    

DOI:10.1002/macp.1975.021760810

出版商:Hüthig&Wepf Verlag    

年代:1975

数据来源: WILEY