bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die darstellung nitrierter phenolischer mehrkernverbindungen durch kondensation von nitrophenol und seinen derivaten
Authors: Kämmerer Von Hermann , Böhmer Volker 
Published: April 2003

AbstractEs wurden einige Mehrkernverbindungen dargestellt, die aus Nitrophenoleinheiten bestehen, welche in ortho‐Stellung zur phenolischen OH‐Gruppe über Methylengruppen verbunden sind. Die Nitrierung fertiger phenolischer Mehrkernverbindungen ist hierzu nicht geeignet. Jedoch gelingt die Darstellung durch Kondensation von Nitrophenolen mit Formaldehyd oder durch Kondensation von chlormethylierten Nitrophenolen mit anderen Nitrophenolen. Im ersten Fall ist die Bildung des Benzdioxanringes als Nebenreaktion zu beobachten. All dargestellten Mehrkernverbindungen wurden dünnschichtchromatographisch auf Reinheit geprüft; ihre Struktur wurde in beinahe allen Fällen durch voneinander unabhängige. Synthesewege gesichert.
Polymerisation von acetylenderivaten. IV. Mitt.: Die ionische polymerisation von phenylacetylen
Authors: Simionescu Von Cristofor , Dumitrescu Svetlana 
Published: April 2003

AbstractDie vorliegende Arbeit befaßt sich mit der ionischen Polymerisation von Phenylacetylen in Gegenwart löslicher metallorganischer Katalysatorkomplexe von Typ Al(C2H5)3/Ti(OC4H9)4, Al(C2H5)3/TiCl2(C5H5)2, Al(C2H5)3/VO(C5H7O2)2, Al(C2H5)3/Cr(C5H7O2)3, Al(C2H5)3/Co(C5H7O2)3. Ein Maximum der Katalysatoraktivität wurde bei bestimmten Molverhältnissen gefunden.Die Kinetik des ionischen Mechanismus wurde untersucht, und die erhaltenen Polymeren wurden charakterisiert. Die in Gegenwart von Al(C2H5)3/Ti(OC4H9)4 dargestellten Polymeren wurden hinsichtlich ihrer Polydispersität untersucht.Die Aktivität von Makroionen im Vergleich zu Makroradikalen des Polyphenylacetylens wurde hinsichtlich der Bildung der Ketten diskutiert.
Über die durch benzopersäure initiierte lösungs‐copolymerisation von chloropren und schwefeldioxid
Authors: Lokaj Von Jan , Hrabák František 
Published: April 2003

AbstractDer Verlauf der durch Benzopersäure initiierten Copolymerisation von Chloropren mit SO2 wurde bei −20°C in m‐Kresol, Methyl‐m‐kresyläther, in einem Gemisch aus Ameisensäure und Monochloressigsäure und in Dimethylformamid verfolgt. Es wurden die Reaktionsordnungen in bezug auf die beiden Monomeren, die Benzopersäure und das Lösungsmittel bestimmt; die Gesamtaktivierungsenergie der Copolymerisation wurde berechnet, und die Grenzviskositätszahlen der Polychloroprensulfone wurden gemessen. Auf Grund der ermittelten Daten wird der Mechanismus der untersuchten Reaktion diskutiert.
Equilibrium melting temperature of polyethylene with finite chain length
Authors: Kamide Kenji , Ohno Kunio , Kawai Tōru 
Published: April 2003

AbstractAn attempt is made to determine the equilibrium melting temperature (T) of polyethylenes with finite chain length, using the data on the observed melting temperature (Tm) and the heat of fusion (ΔH) of the samples annealed isothermally. Five fractions with the viscosity‐average molecular weight (M̄v) ranging from 2.8 · 104 to 3.80 · 106 were annealed in a Perkin‐Elmer differential scanning calorimeter at the different temperatures for various periods, and then heated up without cooling. For the fractions of low and moderate molecular weights, the partial melting was very rapid and the change in the DSC thermogram during annealing was mainly attributed to the partial melting followed by the subsequent recrystallization. Thus, T can be evaluated from the plot of Tm against ΔH by the following relation: , where t represents annealing time. Figures obtained for T are 142.0 ± 0.5°C and 139.5 ± 0.5°C for the fractions of M̄v = 2.10·105 and 2.8·104, respectively. These values are in good agreement with those calculated from the BROADHURST equation. On the other hand, the isothermal melting of the higher molecular weight fractions was slow and the recrystallization was not observable, implying that this method is inapplicable to these fractions.
Rolle der amidinverbindungen bei der hydrolytischen bildung von poly‐ε‐capronamid
Authors: Csürös Von Zoltán , Rusznák István , Bertalan György , Körösi Jenö 
Published: April 2003

AbstractBei der hydrolytischen Polymerisation von ε‐Caprolactam entstehen außer linearen und cyclischen Oligomeren der ε‐Aminocapronsäure auch semicyclische Verbindungen mit endständigen Amidingruppen. Diese sind im Gegensatz zu anderen Amidinverbindungen (z. B. Amidinhydrochloriden) sehr reaktionsfähig und können während der Polymerisation verschiedene Reaktionen eingehen. Auch das erste Glied der polymerhomologen Reihe, die N‐[1‐Aza‐cyclohepten‐(1)‐yl‐(2)]‐ε‐aminocapronsäure, initiiert die Polymerisation des Caprolactams gut; dabei entstehen seine Polymerhomologen. Verbindungen mit −NH‐Endgruppen entstehen nur in Spuren. Daneben kann auch eine Reaktion mit gleichzeitigem Verschwinden der Amidin‐ und Carboxylgruppen auftreten.Bei der hydrolytischen Polymerisation tritt – im Gegensatz zu den Aminsalz‐Initiatoren – auch bei niedriger Initiatorkonzentration kein Wendepunkt in den kinetischen Kurven auf. Dies kann mit der abweichenden Reaktionsfähigkeit der Amidincarbonsäuren erklärt werden.
Sequential homogeneity, a new quantity characterizing sequence distribution in copolymers
Authors: Tosi Camillo , Catinella Giuseppe 
Published: April 2003

AbstractIn order to ground on a quantitative basis the concept of “homogeneity” of copolymers, we introduce a novel quantity, which we propose to call “index of sequential homogeneity” and to denote by the symbol Hs. Its derivation is based on a new approach to the description of the statistical properties of copolymers, consisting in the evaluation of the probability Pn of each of the (n + 1) possible compositions of a sequence of n units picked up at random from an infinite copolymer chain we show that, as n increases, the curve of Pn against composition takes on a GAUSSian shape; hence we can calculate the mean square deviation μ of composition from the average. The limit value of μ/n, when n goes to infinity, is defined as the index of sequential homogeneity of copolymers. The dependence of Hs on the copolymer composition and the product of reactivity ratios is discussed, with particular emphasis to the comparison with informational entropy per monomeric unit. Some examples of experimentally measurable quantities concerning ethylene/propylene copolymers (melting temperature, half‐width of the X‐ray band of amorphous copolymers, ratio of IR‐bands characteristic of methyl rocking vibration), which correlate with sequential homogeneity, are also given.
Vinyl polymerization. 244. Polymerization of methyl and n‐butyl methacrylate and n‐butyl acrylate initiated by the system of cupra‐rayon, water and carbon tetrachloride
Authors: Imoto Minoru , Ueda Kenji , Takemoto Kiichi 
Published: April 2003

AbstractPolymerization of methyl methacrylate was carried out in the presence of cupra‐rayon, water and carbon tetrachloride. It was concluded that the process was of radical mechanism. The effects of the amount of methyl methacrylate, cupra‐rayon, water or carbon tetrachloride on the rate of polymerization were investigated. From the rates of polymerization at 70–90°C, overall activation energy was estimated as 9.7 kcal/mole. n‐Butyl acrylate and methacrylate were also polymerized by the above system. However, styrene and acrylonitrile did not polymerize.
Study of diethylzinc/water catalyst system
Authors: Nakaniwa Mikio , Ozaki Kazuo , Furukawa Junji 
Published: April 2003

AbstractThe poor reproducibility of catalytic activity of a diethylzinc/water system for the propylene oxide polymerizations was much improved by removing free diethylzinc by freeze‐drying under a reduced pressure in a nitrogen atmosphere. The catalyst thus obtained (dried catalyst) contains still not only ZnO bonds but also EtZn bonds bound to the catalyst. The catalyst activity is proportional to the content of both ZnO bond and EtZn bond bound to the catalyst. The active species for the formation of high molecular weight propylene oxide is thus not a simple ZnO bond but ZnO bond coexisting with EtZn bond.The further addition of water and oxygen destroys the catalyst activity. A catalyst with an excess of free diethylzinc added corresponding to the undried catalyst favors the formation of oligomers (liquid polymers). The proton magnetic resonance analysis of the dried catalyst indicates the presence of EtZn bonds bound to the catalyst, whereas that of the undried catalyst possesses EtZn bonds both bound as well as free.
True and apparent graft
Authors: Sakurada I. , Ikada Y. , Horii F. 
Published: April 2003

AbstractWhen a grafting reaction of a monomer Y is carried out onto a polymer X, and the product is thoroughly extracted with a solvent for the polymer Y, the residue is conventionally called a graft; the weight increase in percent of the polymer X due to the unextractable polymer Y is regarded to be percent graft. However, it is possible that a part of polymer Y which is formed in the matrix of polymer X is unextractable only due to entanglement with polymer X. When we determine the amount of polymer Y which is insolubilized by the entanglement, we know the true value of the percent graft.The grafting of methyl methacrylate (MMA) was carried out onto dry or water‐swollen films of poly(vinyl alcohol) (PVA) in the presence of methanol mainly by mutual irradiation technique and the true and an apparent percent graft were compared.It was found that the difference between an apparent percent graft (A) and the true one (B) was considerably large, the fraction of true graft (B/A) ranging from 0.02 to 0.57. The true percent graft and the branch length were also discussed in dependence on the methanol content of the monomer mixture and the degree of swelling of water‐swollen film.
The hydrodynamic behaviour of amylose tricarbanilate in dilute solution. IV. A comparison of experimental and calculated coil dimensions for amylose tricarbanilate in a pyridine/water theta‐solvent
Authors: Banks W. , Greenwood C. T. , Sloss J. 
Published: April 2003

AbstractHydrodynamic measurements on amylose tricarbanilate fractions in a pyridine/water theta‐mixture have been used to provide a test of theoretical treatments of limiting viscosity number and frictional coefficient which have been developed on the basis of the partial free‐draining model. Coil dimensions have been calculated using the theories of BRINKMAN‐DEBYE‐BUECHE, KIRKWOOD‐RISEMAN, KUHN‐KUHN‐SILBERBERG, and of PETERLIN, and these have been compared with the experimental values. Only the treatment of KUHN‐KUHN‐SILBERBERG gives reasonable agreement between the experimental parameters and those calculated from both viscosity and sedimentation data.
Die kationische polymerisation von monomerem formaldehyd in lösung. 39. Mitt. über polyoxymethylene
Authors: Kern Von W. , Eberius E. , Jaacks V. 
Published: April 2003

AbstractDie kationische Polymerisation (Fällungspolymerisation) von monomerem Formaldehyd wird in verschiedenen organischen Lösungsmitteln bei −78 bis −30°C untersucht; sie ist bezüglich der Initiator‐ und Monomerkonzentration jeweils erster Ordnung. Die Wirksamkeit der Initiatoren für die Polymerisation in Toluol bei −78°C nimmt in der Reihenfolge ab: SnCl4 > CH3COClO4 > HClO4 > AlBr3 > BF3 ċ O(C2H5)2 > TiCl4 > FeCl3 > SbCl5 > H2SO4 > Cl3CCOOH > HCOOH > Jod. Die Bruttoaktivierungsenergien betragen 1,0 bis 10 kcal/Mol. Die Polymerisationsgrade (Viskositätsmittel Pv) steigen meist etwa proportional mit der Monomerkonzentration und dem Umsatz an und erreichen Werte bis Pv ∼ 15000. Bei Variation des Lösungsmittels fallen die Pv‐Werte in der Reihenfolge n‐Pentan, Toluol, Diäthyläther, Nitroäthan, Methylenchlorid, Tetrahydrofuran, Aceton stark ab, während die Polymerisationsgeschwindigkeiten in etwa dieser Reihenfolge ansteigen. In Aceton und in Tetrahydrofuran wurde starke Kettenübertragung gefunden.Zusätze von Wasser, Methanol, Ameisensäure, Aceton oder Acetanhydrid erhöhen in kleinen Konzentrationen die Polymerisationsgeschwindigkeit und wirken anscheinend als Cokatalysatoren; in höheren Konzentrationen retardieren sie hingegen.Oft tritt schon nach geringem Umsatz eine starke Abnahme der Bruttopolymerisationsgeschwindigkeit oder sogar völliger Stillstand der Reaktion ein. Durch die obengenannten polaren Zusätze, durch Verwendung stark polarer Lösungsmittel oder durch Erhöhung der Polymerisationstemperatur kann die Abnahme der Polymerisationsgeschwindigkeit vermindert oder verzögert werden.Um den Grund für die Abnahme festzustellen, wurde die Konzentration der aktiven kationischen Zentren durch Abbruch der Wachstumsreaktion mit einem großen Überschuß an Amylalkohol und analytische Bestimmung der dabei entstehenden Pentoxyl‐Endgruppen ermittelt. Die Analyse erfogte durch saure Hydrolyse des gereinigten Polymeren und gaschromatographische Bestimmung des aus den Endgruppen gebildeten Amylalkohols. Diese Methode führt in vielen Fällen zu dem Schluß, daß die Startreaktion schnell und vollständig ist, während die Wachstumsreaktion durch behinderte Diffusion des Monomeren in die feste Polymerphase in ihrem Ablauf zunehmend gehemmt wird. Hinweise auf einen echten Abbruch wachsender Ketten ergaben sich nicht.
The identification and semi ‐ quantitative investigation of some dipeptide sequences of cysteic acid in a partial hydrolysate of α‐keratose
Authors: Asquith Raymond Smith , Parkinson David 
Published: April 2003

Abstractα‐Keratose, an alkali‐soluble fraction of peracetic acid oxidised wool of low sulphur content has been partially hydrolysed under controlled conditions with acid. The mixture of low molecular weight peptides has been fractionated into two fractions. The cysteic acid rich fraction has been studied in as quantitative a manner as possible. It has been shown to contain 63% of the cysteic acid (Cya) content of α‐keratose bound in peptides. This material has been further fractionated and the structures of a number of cysteic acid peptides present have been deduced. The amounts of each present in α‐keratose have been calculated. The most common two‐residue sequences of cysteic acid identified in α‐keratose are (in descending order) Ser‐Cya, Cya‐Cya, Cya‐Gly, Cya‐Pro, Cya‐Val, Cya‐Glu, Gly‐Cya. The results have been compared with previous findings for the high sulphur fraction (γ‐keratose). Whilst the environment of half cystine in α‐keratose is more varied than in γ‐keratose, it is still predominantly non‐helical.
Production of organometallic polymers by the interfacial technique. XIX. Effect of leaving group in the synthesis of poly(stannylalkylenediamines)
Authors: Carraher Charles E. , Winter Duane O. 
Published: April 2003

AbstractA study has been made of the function of X and R on the interfacial synthesis of poly(stannylalkylenediamines) of the below form:
magnified imageMolecular weight and yield are constant as X is varied. The molecular weight of the polymer increases as the steric hindrance of R decreases. Possible reaction mechanisms are discussed.
Formation of Macrozwitterions in the polymerization of β‐propiolactone initiated by betaine. 4th Communication on Macrozwitterions
Authors: Mathes N. , Jaacks V. 
Published: April 2003

AbstractThe anionic polymerization of β‐propiolactone at 25°C in ethanol initiated by the betain \documentclass{article}\pagestyle{empty}\begin{document}${\rm (CH}_3 )_3 \mathop {\rm N}\limits^ \oplus - {\rm CH}_{\rm 2} {\rm COO}^ \ominus $\end{document} was investigated. Macrozwitterions of the structure

were produced, n being intentionally as low as ca. 11. The structure of the product was proven by the nitrogen content of the reprecipiated polymer, by IR and NMR spectroscopy and by titration of the carboxylate endgroups. Some carboxylic acid endgroups were formed by chain transfer with the solvent ethanol. The positive charge at the polymer chain was proven by electrophoresis of polymer after esterification of the carboxylate chain end. Furthermore the dielectric constant of dilute solutions of the polymer in CHCl3 was determined and is discussed.The kinetics of the polymerization process were investigated by IR‐spectroscopy. The initiation reaction between monomer and betain is about 5 times slower than the consecutive propagation by addition of monomer to the anionic chain end.
Kinetics and mechanism of cyclic acetal polymerizations initiated by stable carbonium salts. I. 1.3‐Dioxolan interaction with Ph3C⊕ SbCl6⊖ and SbCl5
Authors: Kubisa Przemysĺw , Penczek Stanisĺw 
Published: April 2003

Abstract1.3‐Dioxolan (DiOX) reacts with SbCl5 giving 1.3‐dioxolenium hexachloroantimonate (Dn), HCl and SbCl3. Dn decomposes in solution, forming β‐chloroethylformate and reproducing SbCl5.
magnified image

magnified image

When DiOX is reacted with Ph3C⊕ SbCl6⊖ Dn and PhCH are formed according to MEERWEIN's reaction in spite of SbCl5 being in equilibrium with the trityl salt. Although neither HCl alone ner HCl + SbCl3 (HSbCl4) initiate the polymerization of DiOX, HCl readily reacts with DiOX, giving ethylene glycol monochloromethylether according to expectations. The polymerization can thus be initiated when this ether reacts further with SbCl5 or when H⊕ SbCl6⊖ (HCl + SbCl5) reacts directly with DiOX. As an alternative PLESCH's ring expansion mechanism, involving a protonated monomer, should be considered.When a model compound, ethoxycarboxonium hexachloroantimonate (CH3CH2OCH2⊕ SbCl6⊖), is reacted with DiOX some of the SbCl6⊖ disappears and instead SbCl3 is formed, indicating the interaction between SbCl5 and DiOX also in this case. If however, prior to this reaction, the ethoxycarboxonium hexachloroantimonate, is “stabilized” by addition of a linear acetal (e.g. CH3OCH2OCH3) and formation of the corresponding tertiary oxonium ion:
magnified image
then its reaction with DiOX is not accompanied by any hydride transfer reaction and [SbCl6⊖] is fully preserved.A detailed UV study of the reaction mixture and all the components involved enabled us to determine λmax and εmax for the majority of intermediate compounds formed in the course of initiation, i.e., when the initiator precursor (Ph3C⊕ SbCl6⊖ or SbCl5) is transformed into the true initiator.
Über die Umwandlungen der primären Produkte bei der Reaktion von Diacylperoxiden mit N.N‐dialkylaromatischen Aminen
Authors: Hrabák F. , Čoupek J. 
Published: April 2003

AbstractDie zeitliche Änderung der Konzentrationen der Ausgangskomponenten und der p‐Nitrobenzoesäure sowie des N‐Methyl‐p‐toluidins (oder N‐Methylmesidin) wurde bei der Umsetzung des p.p′‐Dinitrobenzoylperoxids mit N.N‐Dimethyl‐p‐toluidin (oder N.N‐Dimethylmesidin) verfolgt. In den Produkten der Reaktion von Dibenzoylperoxid mit N.N‐Dimethylanilin, N.N‐Dimethyl‐p‐toluidin oder N.N‐Dimethylmesidin wurde der Gehalt an Ausgangsamin, Benzoesäure, Formaldehyd und sekundären Aminen bestimmt.Die gefundenen Ergebnisse unterbauen die Annahme, daß die primären Produkte der Reaktionen des Dibenzoylperoxids mit tertiären Aminen (C6H5N(R′)CH(R)OCOC6H5) entweder mit dem Ausgangs‐Amin oder miteinander kondensieren können und dabei Benzoesäure und dehydrierte Oligomere des Ausgangs‐Amins bilden.Durch gelchromatographische Analyse der Reaktionsprodukte von Dibenzoylperoxid mit N.N‐Dimethylanilin wurde die Anwesenheit der Oligomeren der Ausgangs‐Amine im Reaktionsgemisch nachgewiesen.
Conformation “ségrégée” et conformation “statistique” dans les copolymères à trois séquences PMM‐PS‐PMM en solution diluée I. Etude viscosimétrique
Authors: Dondos Anastasios 
Published: April 2003

AbstractThe intrinsic viscosity of a triblock copolymer of styrene and methylmethacrylate prepared anionically was investigated in several solvents — chloroform, benzene, dioxane, tetrahydrofurane, and p‐xylene — as a function of temperature. In all cases a rather sharp break in the viscosity curve was observed, at a temperature depending upon the solvent. It can be assumed that at low temperature the triblock copolymer exhibits a “segregated” conformation in which no heterocontacts can be observed. A proof of this structure is that the viscosimetric expansion factor is identical with the weighted average between the corresponding homopolymers of identical molecular weight.At higher temperature, heterocontact interactions are rendered possible as the incompatibility between the corresponding homopolymers becomes less important. This happens at the transition temperature and the conformation becomes increasingly “gaussian”, as the number of heterocontacts increases with rising temperature.
Radical copolymerization behavior of ethyl vinyl sulfoxide
Authors: Inoue Hiroshi , Umeda Itsuki , Otsu Takayuki 
Published: April 2003

AbstractThe radical copolymerizations of ethyl vinyl sulfoxide (EVSO) with various vinyl monomers were investigated. The copolymerizations of EVSO with styrene, methyl methacrylate and acrylonitrile gave copolymers having minor amounts of EVSO. Vinyl chloride and vinyl acetate, however, did not give any homopolymer and copolymer. From the copolymerization with styrene, EVSO was evaluated as an electron‐accepting and non‐conjugative monomer: Q = 0.13 and e = 0.61.The effects of LEWIS acids (LiCl, ZnCl2) and proton donors (phenols, alcohols) on the monomer reactivity of EVSO were also investigated. These additives were found to enhance the monomer reactivity of EVSO. From the spectroscopic studies, it was concluded that the rate enhancement in monomer reactivity was attributable to the formation of a complex or to a hydrogen bond formation between the EVSO monomer and these additives.
Characterization of the styrene/methyl methacrylate and styrene/butadiene copolymers by the light scattering from their solutions in mixed solvents
Authors: Kratochvíl Pavel , Sedláček Blahoslav , Straková Dagmer , Tuzar Zdeněk 
Published: April 2003

AbstractButanone/α‐bromonaphthalene or cyclohexane/α‐bromonaphthalene mixtures are solvent systems suitable for characterization and determination of the heterogeneity of chemical composition of the styrene/methyl methacrylate or styrene/butadiene copolymers by light scattering. The composition heterogeneities thus established were generally low, in contrast with a large number of literature data. Some styrene/butadiene block copolymers contain microgel particles which consist prevailingly of polybutadiene. A mixture of a homogeneous copolymer and a homopolymer is taken as an example to discuss the sensitivity of the light scattering method in the determination of heterogeneity of the copolymer composition.
Microtacticity of poly(methacrylic esters) obtained by radical polymerization
Authors: Niezette Joseph , Desreux Victor 
Published: April 2003

AbstractThe microtacticity of polymethacrylates prepared by radical initiated polymerization of monomers with side groups of increasing bulkiness is determined by high resolution nuclear magnetic resonance of the corresponding poly(methyl methacrylates).The syndiotacticity decreases systematically from poly(methyl methacrylate) to poly(triethylmethyl methacrylate) in the series of the saturated polymers.The aromatic polymethacrylates have a lower syndiotacticity than the corresponding saturated polymers and poly(trityl methacrylate) is the extreme case.The microtacticity of the polymers is undoubtedly determined by the bulkiness and the polarisability of the ester group as well as by specific interaction between the aromatic rings.