摘要:

AbstractThe 50 per cent adduct of benzenesulfenyl chloride (1b) tocis‐1,4‐polybutadiene shows a two‐phase morphology as has been observed in the corresponding adduct ofp‐toluenesulfenyl chloride (1a). These adducts appear to contain blocky structures which may form if the sulfur atom on a reacted monomeric unit can activate the olefinic bond of an adjacent, unreacted monomeric unit. Kinetic and model compound studies on the additions of1aand1bto polybutadiene support this explanation. The activating mechanism does not operate during addition of 2‐nitrobenzenesulfenyl chloride (1c) and 2,4‐dinitrobenzenesulfenyl chloride (1d), which, therefore, yield adducts with a single‐pha

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790601

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractThe chromatographically pure products, gained on the suppression of polymerisation ofp‐tolyl or 4‐cyclohexylphenyl methacrylates (1, 2) by a great excess of 2‐cyano‐2‐propyl radicals, could be isolated in a total yield of 95 to 100%. The structure of these products was established by1H NMR and mass spectroscopy. There arep‐tolyl or 4‐cyclohexylphenyl 4‐cyano‐2‐(2‐cyano‐2‐propyl)‐2,4‐dimethylvalerate (1a, 2a),p‐tolyl or 4‐cyclohexylphenyl 2‐(2‐cyano‐2‐methylpropyl)acrylate (1b, 2b),p‐tolyl or 4‐cyclohexylphenyl 4‐cyano‐4‐methyl‐2‐(2‐cyano‐2‐methylpropyl)valerate (1c, 2c),p‐tolyl or 4‐cyclohexylphenyl 4‐cyano‐2,4‐dimethylvalerate (1d, 2d), andp‐tolyl or 4‐cyclohexylphenyl 4‐cyano‐2,4‐dimethyl‐2‐pentenoate (1e, 2e(2f)). It is po

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790602

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractDiethylamination of 1,4‐divinylbenzene catalyzed by lithium diethylamide gave rise to 1‐(2‐diethylaminoethyl)‐4‐vinylbenzene (3), quantitatively. Subsequent quaternization of3with ethyl bromide gave a cationic monomer, 4‐vinylphenethyltriethylammonium bromide (7). High molecular weight polymers, poly[1‐{4‐[2‐(diethylamino)ethyl]phenyl}ethylene](5) and poly[1‐{4‐[2‐(triethylammonio)ethyl]phenyl}ethylene bromide](8), were prepared from3and7, respectively, by using radical initiators, especially with redox‐type ones. Anionic polymerization of3was also carried out. The relationship between the polymerization condition and the stereoregularity of the polymer was studied by Carbon‐13 NMR spectroscopy. A polyion complex (10) was prepared from8in combination with poly(sodium 4‐vinylbenzenesulfonate) (9) to evaluate its prop

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790603

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractPendant‐type poly(4‐vinylpyridine) (PVP)‐Cr(III) complexes (1) and ‐Co(III) complexes (2) with various degrees of coordination (x) were prepared, and the structures and properties of the polymer complexes are discussed. The magnetic susceptibility of1showed that1is paramagnetic and that the Cr(III) ions do not interact with each other, although they were coordinated along the PVP chain at high concentration. The far‐infrared absorption bands, assigned to the stretching of the coordinative bond between Co and the pyridine‐unit of PVP shifted to lower wave numbers in2, as compared with the corresponding pyridine complex4. It is thus considered that the coordinative bond in2is weaker than in the monomeric pyridine complex4, owing to the steric hindrance of PVP; the Co(III) chelates coordinated at high concentration. This consideration is supported by the ESR parameters of1. The dissociation temperature of the coordinative bond between Co and PVP increased withx. It is presumed that the PVP complex2has a rigid structure such that more energy is required to break the coordi

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790604

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractA series ofN‐ andC‐protectedL‐norleucine homo‐oligomers from dimer to heptamer was prepared by the dicyclohexylcarbodiimide and acyl azide coupling methods. In the course of the synthetic approachtert‐butyloxycarbonyl as theN‐protecting and methoxy as theC‐protecting end groups were employed. The monodisperse oligomers synthesized in this manner were characterized and found to be chemically pure. A polarimetric investigation in a structure disrupting solvent also indicated that all reactions proceeded with complete retention of the configuration. By UV absorption and far‐UV CD it was shown that these peptides may exist in predominantly β‐form, statistical coil, or partially folded conformation depending upon molecular weight and

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790605

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractCross‐linking of amylose with 1‐chloro‐2,3‐epoxypropane (epichlorohydrin) was studied in aqueous 1M NaOH solution in dependence of the amylose concentration, the mole ratio of anhydroglucose to epichlorohydrin, and the degree of polymerization of the primary chains. Structural changes which occur during the pre‐gel phase were followed by chemical analysis, by viscosity and light scattering measurements, and by the optical properties of the iodine complex. The results indicate in the early stage of the process that the introduced glycerol diether groups are mainly present as intermolecular cross‐links as seen from a rapid increase in the molecular weight. With further progress of the reaction a decrease of particle density may be derived from the unusual dependence of intrinsic viscosity and mean square radii of gyration on molecular weight. The results are discussed being due to association of amylose segments by hydrogen bonds in the weakly cross‐linked products and a solubilizing effect of monoether substituents introd

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790606

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractA series of amylose gels prepared by reaction of amylose solutions in 1 M aqueous NaOH with 1‐chloro‐2,3‐epoxypropane (epichlorohydrin) at different concentrations were characterized by several methods: (a) The density of cross‐links was estimated by equilibrium swelling of the gels in water at room temperature. The molecular weight of the segments between the cross‐links (Mc) derived from the Flory equation decreased exponentially with the epichlorohydrin concentration used for gelation. The results obtained for weakly cross‐linked gels are in the same order as the values determined previously by analytical methods. (b) Further differentiation of the gels and the corresponding sol fractions was achieved by enzymes specific for amylose. The size of the fragments resistent to α‐amylase was found to increase linearly with epichlorohydrin concentration. Only minor attack by the exo‐enzyme β‐amylase was found, indicating lack of longer unsubstituted pendant branches. The presence of some short branches is deduced from their priming activity in phosphorolytic synthesis. The grafted amylose chains are located solely at the surface of the gels. The weakly cross‐linked gels give characteristic colours with iodine indicating slightly longer free amylose segments in the gel than in the corresponding sol. The nature of iodine binding by cross‐linked amyl

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790607

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractAryldihydroxyboranes (2,10) condense with α,ω‐alkanediols HO(CH2)xOH (6), which leads to an equilibrium of oligomeric rings (7) of different size due to a ligand exchange at the boron atom. With low diols (6, x = 2,3) the rate of establishing the equilibrium of the exchange reaction is slow enough for isolating the five‐ and six‐membered heterocycles (7, n = 1). Diols with x≥5, however, lead to the equilibrium mixture of oligomeric heterocycles in a somewhat analogous way to olef

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790608

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractTemperature dependent measurements of13C spin lattice relaxation times and of nuclear Overhauser enhancement factors were carried out for atactic and isotactic polystyrene in tetrahydrofuran and for atactic polystyrene in 1,4‐dioxane. The analysis of the relaxation data by means of a Cole‐Cole distribution of correlation times confirms the additivity of intramolecular and solvent viscosity dependent activation energies. For atactic and isotactic polystyrene the same intramolecular activation energy of 21 ± 5kJ/mol is obtained for the segmental motion. A comparison with13C relaxation measurements of other authors shows that the intramolecular activation energies and the anisotropy of the segmental motion are increasing simultaneously by changing the solvent from toluene over pentachloroethane to tetrahydrofuran. Based on the experimental findings the chain motions in polystyrene are interpreted as diffusion controlled processes in the hindering potential of the CC bonds of the chain backbone which is modified by conformation dependent interactions between phenyl groups and solvent mol

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790609

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY

摘要:

AbstractThe13C NMR relaxation functions are calculated for the case of restricted rotational diffusion of a CH dipole pair about an internal rotational axis. The model is applied to the interpretation of recent13C experiments of polystyrene in a region where the relaxation of all C atoms of the phenyl ring exhibits the same temperature coefficient. It is concluded that the velocity of the phenyl group motion may be overestimated if complete rotation is assumed. By means of the model of restricted internal rotation one findsD/D0<0,1 for the ratio of internal and mean segmental rotational diffusion constant

ISSN:0025-116X    

DOI:10.1002/macp.1978.021790610

出版商:Hüthig&Wepf Verlag    

年代:1978

数据来源: WILEY