bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reaction and polymerization of methyl α‐chloroacrylate with organozinc compounds
Authors: Tsuruta Teiji , Kawakami Yusuke , Tsushima Rikio 
Published: April 2003

AbstractThe reactions of methyl α‐chloroacrylate (MCA) with organozinc compounds were studied. The elementary reactions of MCA with di‐n‐butylzinc (n‐Bu2Zn) in toluene and tetrahydrofuran (THF) were found to be conjugate addition and carbonyl addition reactions. n‐Butyl(dimethyl malonato)zinc (n‐BuZnDMM), on the other hand, underwent only conjugate addition reaction. Some parts of the conjugate addition products were transformed to cyclopropane derivatives.Methyl α‐chloroacrylate was found to be polymerized in toluene and THF with n‐Bu2Zn and n‐BuZnDMM as initiator. Results of some copolymerization reactions as well as kinetic studies indicated the mechanism of the polymerization in toluene or THF to be radical type. In hexamethylphosphoric triamide (HMPT), however, this monomer was polymerized through anionic mechanism. Any sign of the cyclopropane formation was not detected in HMPT as solvent even in the reaction with an excess of the organozinc compounds.
Vinylpolymerisation durch das system aminosäureester und kupfer(II)ion
Authors: Takemoto Kiichi , Azuma Kouji , Nakamichi Kazuya 
Published: April 2003

AbstractDie Polymerisation von Vinylmonomeren wurde mit dem System Aminosäureester/Kupfer(II)ion in Dimethylsulfoxidlösung bei 50°C untersucht. Es ergab sich, daß die Polymerisation radikalisch verläuft und die Geschwindigkeit der Anfangskonzentration des Monomeren und der Quadratwurzel aus der Initiatorkonzentration proportional ist. Mit dem System Aminosäure/Kupfer(II)ion konnte keine Polymerisation beobachtet werden. Die Aktivierungsenergie der Polymerisation des Methylmethacrylats beträgt ca. 9,5 kcal/Mol. Ferner wurden die Effekte von verschiedenen Kupfersalzen, Monomeren und Lösungsmitteln geprüft.
Strukturuntersuchungen an sternmolekülen mit glykogen als kern
Authors: Burchard W. , Kratz I. , Pfannemüller B. 
Published: April 2003

AbstractDie Struktur von Glykogen und von Sternmolekülen mit aufgepfropften Amyloseketten und Glykogen als Kern wurde durch die Jodaufnahme und durch Lichtstreuungsmessungen an den Tricarbanilaten untersucht.Unter Anwendung der von GOOD und von GORDON entwickelten Theorie der Kaskadenprozesse wurden für vier verschiedene Verzweigungsmodelle, die teilweise auf einer früheren Arbeit von ERLANDER und FRENCH basieren, Strukturberechnungen durchgeführt. Aus einem Vergleich der experimentellen Werte mit diesen vier Modellen konnte die Zahl der aufgepfropften Ketten, ihre Kettenlänge und die Struktur des Glykogenkerns bestimmt werden. Die Ergebnisse lassen auf eine sehr regelmäßige Struktur des Glykogenkerns schließen.Zwischen dem aus der Lichtstreuung bestimmten Gewichtsanteil der aufgepfropften Ketten und dem aus der potentiometrischen Jodtitration ermittelten Wert (Verhältnis der Jodaufnahme der verzweigten Produkte zu Amylose als Bezugssubstanz) besteht bei den hochmolekularen Substanzen eine gute Übereinstimmung; mit abnehmendem Molekulargewicht treten jedoch zunehmend Abweichungen auf.
Darstellung und eigenschaften von linearen oligourethanen mit phenylendgruppen und von cyclischen oligourethanen aus diäthylenglykol und hexamethylendiisocyanat
Authors: Heitz W. , Höcker H. , Kern W. , Ullner H. 
Published: April 2003

AbstractEs wurden lineare Oligourethane mit Phenylendgruppen und cyclische Oligourethane aus Diäthylenglykol und Hexamethylendiisocyanat dargestellt. Der größte bisher isolierte Ring enthält je sieben Grundbausteine und besitzt 119 Ringglieder bei einem Molekulargewicht von 1920.Eine gute Trennung der Oligomeren wurde durch Adsorptionssäulenchromatographie erzielt. Hierbei wurde ein Elutionsmittel mit Lösungsmittelgradient verwendet. Schmelzpunkte, Umwandlungserscheinungen, Langperioden und Weitwinkeldiagramme der Oligomeren werden im Hinblick auf ihre Struktur diskutiert.
Organometallic compound with lewis base I. Polymerization of vinyl‐compounds by organometallic compound/lewis base complex
Authors: Ikeda Masanori , Hirano Tsuneo , Tsuruta Teiji 
Published: April 2003

AbstractAlEt3/α.α′‐dipyridyl (dip) and AlEt3/triphenylphosphine (PPh3) polymerized methyl methacrylate (MMA) and acrylonitrile (AN), and InEt3 dip, InEt3/PPh3, ZnEt2/dip and ZnEt2/PPh3 polymerized AN, while AlEt3, InEt3, and ZnEt2 by themselves did not polymerize MMA and AN. Styrene could not be polymerized by any of these organometallic compounds alone or together with a LEWIS base.The results from the copolymerization of AN with MMA by AlEt3/LEWIS base indicate that these polymerizations occur by an anionic mechanism. The coordination of the LEWIS base to the central metal ion of the aluminum complex reduces the electronegativity of the metal ion and increases the ionic character of the metal‐carbon bond which in turn induces the polymerization of polar vinyl compounds such as AN and MMA. The tacticity of the poly(MMA) obtained by AlEt3/LEWIS base catalysts obeys the statistics of BOVEY'S single parameter σ, although the propagating end is not a free anion nor solvent separated ion‐pair. A tentative explanation is presented.
Cationic copolymerization of dioxolan and tetroxan
Authors: Yamashita Yuya , Inoue Toshihide , Hattori Genjiro , Ito Koichi 
Published: April 2003

AbstractThe cationic copolymerization of dioxolan (DOL) and tetroxan (TEX) at a mole‐ratio of 9/1 with BF3OEt2 in toluene was studied by gas chromatography and NMR. The very reactive TEX was consumed at an early stage, whereas DOL was consumed slowly until an equilibrium conversion was reached. Correspondingly, the fraction of formal units in the copolymers decreased gradually with conversion. Therefore TEX is both kinetically and thermodynamically more reactive than DOL. As a by‐product, a significant amount of trioxepan was found, which indicates a rather facile back‐biting reaction.
The polycation polymers of integral type obtained from the reaction of p‐xylylenedichloride and α.ωtert‐diamines
Authors: Tsuchida Eishun , Sanada Kei , Moribe Kazuhiko 
Published: April 2003

AbstractWhen p‐xylylenedichloride (XDC) and α.ω‐tert‐diamines are present in equimolar amounts in dimethylformamide (DMF), fairly fast polymerization occurs to form the polycation polymers of integral type owing to the structural characteristic of XDC to stabilize the transition state with delocalization. The reactivities based on the structures of monomers are as follows:
Diamines:

equation image

Dihalogren compounds:

equation image

The reactivity of XDC is remarkable.The reaction of TED and XDC proceeds by nucleophilic bimolecular substitution (SN2), thus the rate Eq. is, v = k · [XDC][TED]. The fact that this polymerization is considerably faster than the normal MENSCHUTKIN reaction may be attributed to the structure of XDC above mentioned and the solvent effect of DMF that solvates cations only. The activation energy and log of the frequency factor of this polymerization are 9.6 and 5.61 kcal/mole, respectively.
Studies on homologous series of oligomeric antioxidants derived from p‐cresol/formaldehyde condensates. I. Synthesis and characterisation
Authors: Huglin M. B. , Knight G. J. , Wright W. W. 
Published: April 2003

Abstractmagnified image
have been prepared and their structure confirmed by elemental, infrared and mass spectrometric analysis. In view of their proposed use as antioxidants, solubilities in toluene were measured, and all the compounds were subjected to thermogravimetric analysis in atmospheres of air and nitrogen. The higher mol. wt. novolak materials undergo some form of condensation reaction at moderately elevated temperatures. This reaction could have some relevance to their properties as antioxidants and is also of interest with respect to the behaviour of novolak materials in the hardening of phenolic resins.
Zur kenntnis der anionischen polymerisation von maleinsäureanhydrid
Authors: Zweifel Hans , Löliger Jürg , Völker Theodor 
Published: April 2003

AbstractIn Gegenwart von Pyridinbasen, von Triphenylphosphin oder Tributylphosphin polymerisiert Maleinsäureanhydrid spontan. Anhand eines Reaktionsmodelles wird die Bildung der beiden charakteristischen Strukturelemente in diesen Maleinsäureanhydridpolymerisaten erklärt. Die Strukturelemente der Polymeren wurden durch die analytischen Daten (IR‐, NMR‐, ESR‐Spektroskopie, Titrationen) belegt. Zum Teil wurden die Abbauprodukte isoliert und identifiziert.
Reaction of formaldehyde with wool. Effects of formalisation on the solubility of wool
Authors: Reddie R. N. , Nicholls C. H. 
Published: April 2003

AbstractSamples of Merino wool were treated with aqueous solutions of formaldehyde, and the effectiveness of the formalisation on reducing the amount of wool dissolving in four solutions (sodium hydroxide; urea/sodium metabisulphite; thioglycollic acid; potassium thioglycollate/potassium carbonate) was determined. The formaldehyde content of the wool was estimated by a radiochemical technique. Complete insolubilisation was found for urea/sodium metabisulphite and potassium thioglycollate/potassium carbonate solutions, and a limiting value of about 80% reduction in alkali solubility was approached when the concentration of the formaldehyde was increased to about 0.2 M. The thioglycollic acid solubility was more dependent on the formaldehyde content of the wool than were the solubilities in the other three solvents; there was found to be a strong dependence of thioglycollic acid solubility on the formalisation conditions as well as on the formaldehyde content of the wool. The results are discussed in terms of the concept of crosslinkage formation, and they do support this concept.
Ylide als polymerisationsinitiatoren. I. Salzhaltige und salzfreie phosphoniumylide
Authors: Klippert H. , Ringsdorf H. 
Published: April 2003

AbstractPhosphorylide, R3PCHX und R3PCH2·LiBr, können eine anionische Polymerisation von Vinylmonomeren starten. Dabei werden im Falle des Methacrylnitrils und des Methylmethacrylats die Ylide als Endgruppen in die Polymeren eingebaut. Bei den salzfreien Yliden hängt die Startwirksamkeit von der Basizität des Ylidcarbanions ab, die Struktur dieser Ylide hat aber keinen meßbaren Einfluß auf das Molekulargewicht und die Taktizität der entstehenden Polymeren. Im Gegensatz dazu wird bei der Initiierung mit den salzhaltigen Yliden auch die Taktizität der Polymeren von den Substituenten der Phosphorylide beeinflußt.
Conformation of polymer analogs in solution. X‐ray scattering from ethylene oxide oligomers carrying iodine atoms at the chain ends
Authors: Li Hsueh‐Ming , Post Benjamin , Morawetz Herbert 
Published: April 2003

AbstractThe angular dependence of X‐ray scattering intensities of solutions of diiodobenzenes was compared with that of iodobenzene solutions containing the same concentration of iodine atoms. The data yielded interiodine distances of 3.6, 5.9, and 6.9 Å for the ortho, meta, and para isomers, respectively, in good agreement with the known values of 3.52, 5.92, and 6.84 Å. The same method was applied to a study of inter‐iodine separations in ICH2CH2(OCH2CH2)nI (n = 1, 2, 3) using CH3CH2OCH2CH2I as the monoiodo analog. Experimental limitations preclude detailed interpretation of the data in terms of a probability distribution of the end‐to‐end distances of these model compounds. The intramolecular inter‐iodine distances were characterized by the first minimum and the first maximum of the scattering function i(s) = ΔĪcorr/f, where ΔĪ is the difference in the scattering intensity from solutions of the diiodo and monoiodo compounds corrected for polarization, fI is the form factor of iodine and s = 4π sin Θ/λ, 2Θ is the scattering angle and λ the wavelength of the X‐rays. The molecular chains of all three oligomers were significantly more expanded in m‐xylene than in ethanol, the difference increasing with increasing chain length. A conformational analysis was carried out for ICH2CH2OCH2CH2I choosing the energies for conformational transition so as to yield a conformational distribution with the observed average square dipole moment and scattering function in non‐polar media. The contraction of the molecule in ethanol is much larger than can be accounted for by the reduction in the COULOMBic energy of dipole interaction in a medium of higher dielectric constant.
Anionic polymerization of unsaturated aldehydes initiated by anion‐radicals of aromatic carbonyl compounds
Authors: Panayotov Ivan M. , Rashkov Ilya B. 
Published: April 2003

AbstractThe capacity of anion‐radicals of aromatic ketones to initiate polymerization of acrolein, methacrolein and crotonic aldehyde is studied. It is established with the aid of spectral and chemical methods that the polymerization is initiated mainly by electron transfer to the monomer.
A double‐bridged zinc(II) phosphinate polymer. The zinc(II) bis‐(1‐methyl‐butyl)‐phosphinate
Authors: Giancotti Vincenzo , Giordano Federico , Ripamonti Alberto 
Published: April 2003

AbstractThe coordination polymer of zinc(II) with the diastereoisomeric mixture of bis‐(1‐methyl‐butyl)‐phosphinic acid, (Zn{[(CH3)(n‐C3H7)CH]2PO2}2)n, has been prepared and its chain structure has been investigated by X‐ray diffraction. The identity period along the fibre axis determined from the X‐ray diffraction photographs of drawn fibres is 9.16 Å. The reflections can be indexed on the basis of a hexagonal packing of chains.Comparison between observed intensities and the calculated intensity distribution on the layer lines of the X‐ray pattern shows that zinc(II) bis‐(1‐methyl‐butyl)‐phosphinate, has a backbone structure with double phosphinate bridges between tetrahedral metal atoms instead of a structure with alternating single and triple phosphinate bridges as found when the organic side chains are phenyl or linear alkyl groups. This is accounted for by restrictions on the formation of the triple bridged cages due to the steric interactions between the branched alkyl groups.
Notes on light scattering from dilute poly(vinyl chloride) solutions in a binary theta‐solvent, tetrahydrofuran/water
Authors: Kratochvíl Pavel , Straková Dagmar 
Published: April 2003

AbstractTetrahydrofuran (THF) with 8–9 vol.‐% of water (depending on the polymer tacticity) is at 25°C a Θ‐solvent for poly(vinyl chloride). The refractive index increment (dn/dc)μ (i.e. measured after dialysis) for this system is 0.1085 and 0.112 ml/g for λ0 = 546 and 436 nm, respectively. The light scattering measurements yield correct molecular weights of the polymer. The measurements, however, require special care. Evaporation of THF and polymer aggregation in solvents with even slightly negative second virial coefficients are the major source of error.
Crystallization under stress of gaussian networks‐polyoxyethylene
Authors: De Candia F. , Vittoria V. 
Published: April 2003

AbstractThe melting behavior of stretched polyoxyethylene networks was examined. Polyoxyethylene networks were prepared by reacting the chain ends of fractions of polyoxyethylene having a molecular weight of 15,000. The apparent melting temperatures are given by stress‐temperature plots, following a modified version of a method described by GENT. True thermodynamic temperatures were determined using the HOFFMAN and WEEKS method; the experimental data were analyzed following the FLORY and ROE‐KRIGBAUM treatments.
Kinetics of the polymerization of aromatic amines by ferric chelates in aqueous solutions
Authors: Tsuchida Eishun , Kaneko Masao , Takahashi Hiroshi 
Published: April 2003

AbstractIt was found that the oxidative polymerization of aromatic amines in the presence of oxygen with ferric chelate in aqueous solutions proceeds via a mechanism similar to that of the MICHAELIS‐MENTEN reaction, the steady state being maintained during the polymerization. On the basis of this mechanism, a kinetic analysis was carried out.The rate constant of the polymerization of p‐phenylenediamine (p‐PD) with Fe(III)EDTA (ferric ethylendiaminetetraacetic acid) (k2) reaches its maximum at pH 7–8, but K1 (the reciprocal of the MICHAELIS constant (Km)) exhibits a minimum in this pH region. From the fact that the rate constant of the oxidation reaction of Fe(II)EDTA alone with oxygen (k0) is very small compared with k2, it was assumed that oxygen is part of the activated radical complex composed of the iron chelate and the monomer. When different ferric chelates are used, the k2 values vary in this order: Nitrilotriacetic acid (NTA) < N‐hydroxyethylethylenediamine‐N.N′.N′‐triacetic acid (HEDTA) < ethylenediaminetetraacetic acid (EDTA) > diethylenetriaminepentaacetic acid (DTPA) > cyclohexylenediaminetetraacetic acid (CyDTA), but K1 decreases in the following order: NTA > HEDTA ≈ EDTA > CyDTA > DTPA. The order of the K1 values for different amines is in accordance with their basicity. Comparing with ferric and cupric chelates, both k2 and K1 exhibit this order: Fe(III)EDTA > Cu(II)EDTA. The above results suggest k2 to be separated into an electron‐transfer step (ke) and a dissociation step of the activated monomer (kd), and that the k2 value is close to that of kd, the latter being the rate‐determining step.
Aufbaureaktionen des Äthylens an methyltitanverbindungen
Authors: Kühlein Klaus , Clauss Karl 
Published: April 2003

AbstractÄthylen reagiert bereits bei −70°C mit den Methyltitan(IV)‐verbindungen CH3TiCl3, CH3Ti(O‐iso‐C3H7)Cl2 und CH3Ti(O‐tert‐C4H9)Cl2 zu Alkyltitan(IV)‐verbindungen mit Alkylresten von C3 bis C33. Beim CH3TiCl3 ist diese Aufbaureaktion noch von einer Verdrängungsreaktion begleitet, die α‐Olefine liefert.Systeme mit Methyltitan(III)‐verbindungen (durch Reduktion der entsprechenden Titan(IV)‐verbindungen mit Hg[Si(CH3)3]2 erstmalig erhalten) polymerisieren Äthylen dagegen unter den gleichen Bedingungen, selbst in kleinen Katalysatorkonzentrationen, rasch zu hochmolekularen Polyäthylenen.
Vinyl polymerization. 276. Polymerization of methyl methacrylate initiated by 9‐diazofluorene
Authors: Nakaya Tadao , Tanaka Mamoru , Imoto Minoru 
Published: April 2003

AbstractBy using 9‐diazofluorene (DF) as an initiator, the polymerization of methyl methacrylate (MMA) in benzene solution was carried out at 75°C. The rate of polymerization was found to be proportional to the square root of the initial concentration of DF and to the initial concentration of MMA. The polymerization proceeded according to a radical mechanism. The overall activation energy for the polymerization was estimated to be 21.9 kcal·mole−1. The rate of decomposition of DF was also measured and the following rate equation was obtained: kd = 3.17·1014 exp (−33.8 kcal/RT) sec−1 (for 80–93°C). From these results and from the product analysis of the reaction between MMA and DF, the initiation mechanism of the polymerization is briefly discussed.
Diethylzine/Nitromethane system as a catalyst for polymerization of olefin oxides
Authors: Nakaniwa Mikio , Kameoka Iwao , Ozaki Kazuo , Kawabata Nariyoshi , Furukawa Junji 
Published: April 2003

AbstractNitro‐compounds were found to be suitable as cocatalysts for the polymerization of alkylene oxides, such as ethylene oxide, propylene oxide, styrene oxide, allylglycidyl ether, and phenylglycidyl ether when they were used with dialkylzinc or trialkylaluminum catalysts. The nitromethane/diethylzine system exhibits a high catalytic activity to give a polymer of extraordinary high intrinsic viscosity as high as 32 dl/g for ethylene oxide. The system requires heat‐treatment at 100°C for activation, but the resulting catalyst is heat‐stable. During heat‐treatment nitromethane reacts with dialkylzine evolving ethane gas to give a zinc‐oxygen linkage together with zinc methazonate. Gas analysis, IR, and NMR studies confirm that the catalyst contains a zinc‐oxygen linkage in addition to the ethyl‐zinc bond responsible for catalyst activity. The catalyst resembles the diethylzinc/water system, but the catalyst is more heat‐stable and has a longer life‐time in the polymerization due to the lack of mobile hydrogen in the cocatalyst.
Polymerization of propylene oxide by the dialkylzine/tertiary alcohol system
Authors: Nakaniwa Mikio , Kameoka Iwao , Hirai Ryuichi , Furukawa Junji 
Published: April 2003

AbstractSeveral well defined alkylzine monoalkoxide of tertiary carbinols, viz. ethylzine triphenylmethoxide (EtZnTPC), ethylzinc diphenylmethylmethoxide (EtZnDPC), ethylzinc dimethylphenylmethoxide (EtZnMPC), (+)‐2‐methylbutylzine triphenylmethoxide (AmZnTPC), (+)‐2‐methylbutylzinc diphenylmethylmethoxide (AmZnDPC), and (+)‐2‐methylbutylzinc dimethylphenylmethoxide (AmZnMPC) were prepared and were found to be active in the polymerization of propylene oxide.The catalytic activity of these ethylzinc monoalkoxides was strongly influenced by the polar nature of the corresponding tertiary alkyl group. The order of catalytic activity is EtZnMPC < EtZnDPC < EtZnTPC, which runs parallel to the increasing order of acid strength estimated by HAMMETT indicator method. This also holds in the relation among LEWIS acidity and decreasing order of aggregation degree which in turn are linearly correlated with the polar substituent constant, σ*‐constant, of tertiary alkyl group as well as the H1‐chemical shift of the α‐methylene group of the ethyl group bonded to zinc of the respective ethylzinc monoalkoxide.The alkylzinc monoalkoxides with asymmetric alkyl groups induced an asymmetric‐selection polymerization of DL‐propylene oxide and were found to transform one of the enantiomers into an optical active poly(propylene oxide) leaving behind the antipode monomer. It was also found that the increasing order of asymmetric‐selection efficiency of these catalysts is AmZnMPC < AmZnDPC < AmZnTPC and this order runs parallel to the increasing order of σ*‐constant. Consequently, the bond between the optically active alkyl group and the zinc atom is believed to participate in the asymmetric polymerization.
Kinetik der radikalischen copolymerisation α‐substituierter styrole mit styrol. 2. Teil. Copolymerisation von styrol mit 1.1‐diphenyläthylen
Authors: Fischer J. P. 
Published: April 2003

AbstractFür die Copolymerisation von Styrol (M1) mit 1.1‐Diphenyläthylen (M2) bei 110°C zeigte sich, daß die konventionelle Copolymerisationsgleichung mit den Parametern r1 = 0,34 ± 0,04 und r2 = 0 zutrifft, wobei der r1‐Wert wie für andere sterisch ungehinderte Comonomere des 1.1‐Diphenyläthylens das Q‐e‐Schema mit Q2 = 2,3 und e2 = −0,35 erfüllt.1.1‐Diphenyläthylen verursacht eine starke Retardierung, jedoch keine Inhibierung der Styrolpolymerisation. Aus der Retardierung der Styrolpolymerisation bei geringem 1.1‐Diphenyläthylengehalt ergibt sich, daß die Geschwindigkeitskonstanten k12 und k21 für die Alternierungsschritte sich um wenigstens zwei Größenordnungen unterscheiden, derart, daß der niedrige k21‐Wert sowohl für die starke Retardierung als auch hauptsächlich für die geringen Molekulargewichte der Copolymeren verantwortlich ist.
Kinetik der radikalischen copolymerisation α‐substituierter styrole mit styrol. 3. Teil. Das zusammenwirken von copolymerisation, retardierung und kettenübertragung in abhängigkeit von der chemischen struktur
Authors: Fischer J. P. , Lüders W. 
Published: April 2003

AbstractThe copolymerization of styrene with a series of ten α‐substituted styrenes, partially synthesized for the first time, was investigated by kinetic measurements. All compounds react with styrene according to the mechanism of copolymerization. The extent of the observed retardation or chain transfer reaction depends on the chemical nature of the α‐substituent.Some α‐alkylstyrenes scarcely show chain transfer, yet the more bulky the α‐substituent is, the more retardation could be observed. On the other hand α‐arylalkylstyrenes of the type of 4‐substituted 2.4‐diphenyl‐1‐butene‐derivates cause an evident chain transfer as can be seen from the chain transfer constants of 0,29 and 0,26 from 4‐methyl‐2.4‐diphenyl‐1‐pentene and 2.4.4‐triphenyl‐1‐pentene, respectively.The single rate constants of chain propagation and chain transfer are calculated or estimated.