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1.
Benjamin Falk Santiago M. Vallinas James V. Crivello 《Journal of polymer science. Part A, Polymer chemistry》2003,41(4):579-596
This article describes the development of optical pyrometry (OP) as a new analytical technique for the continuous monitoring of the progress of both free‐radical and cationic photopolymerizations. The method is rapid, reproducible, and very easy to implement. A temperature profile of a photopolymerization can be obtained. Preliminary studies have shown that the temperatures of some polymerizing monomers can easily reach temperatures in excess of 250 °C. The effects of the mass and reactivity of the monomer, light intensity, structures, and concentrations of the photoinitiators and monomers as well as the presence or absence of oxygen on various free‐radical and cationic photopolymerizations were examined with this method. Coupling of real‐time infrared spectroscopy with OP provides a convenient method for simultaneously monitoring both the chemical conversion and the temperature of a photopolymerization. This combined technique affords new insights into the effects of temperature‐induced autoacceleration on the course of photopolymerizations. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 579–596, 2003 相似文献
2.
Prof. Dr. Heinz Falk Alfred Leodolter Georg Schade 《Monatshefte für Chemie / Chemical Monthly》1978,109(1):183-192
The electrochemical oxidation of arylmethylene-pyrrolinones, pyrromethenones and pyrromethenes as representative bile pigment partial structure models was investigated by means of a rotating disc platinum electrode using acetonitrile as the solvent. Two different oxidation reactions were found. The first reaction being a reversible one-electron oxidation with compounds of the arylmethylene-pyrrolinone series and pyrromethenones which are unsubstituted in position 5 of the pyrrole ring. A two step reaction (the first one reversible, the second irreversible) on the other hand was found to be typical for pyrromethenones bearing a methyl group in this position.Through protonation the first step is at a higher potential, whereas the second one is lowered and becomes reversible. The resulting oxidation pattern can be interpreted analogous to the oxidation of hydroquinones in aprotic solvents.The geometrical isomers of a pyrromethenone were oxidized at appr. the same potential, but there is a strong dependence of the potential of the first oxidation step on the substitution: a higher degree of alkylation favours oxidation by lowering the oxidation potential.
Mit 1 Abbildung 相似文献
Mit 1 Abbildung 相似文献
3.
By spectrophotometric measurements in the systemDMSO/H2O/Me
4NOH pK
a-values for several model compounds representing bile pigment partial structures were established. The acidic protons of pyrrole and lactame type nitrogen atoms are removed by bases governed by the electronic properties of the substituents on these ring systems. The pK
a-values for both types lie in the same region. In the pyrromethenones the lower one corresponds to the lactame type NH as was deduced by comparison with specifically methylated derivatives.The complexation of these ligands is determined by the possibility of removing an acidic proton and achieving a chelate structure by means of an adjacent pyrrolinone type nitrogen atom. Complexes are favoured in the series pyrromethenes > lactim ethers > pyrromethenones. With the latter there are two possibilities: one observed with BF2-chelation where the lactime form becomes stabilized, the other one with zink where both acidic centers are involved in the bonding.
19. Mitt.:H. Falk, A. Leodolter undG. Schade, Mh. Chem.109, 183 (1978). 相似文献
19. Mitt.:H. Falk, A. Leodolter undG. Schade, Mh. Chem.109, 183 (1978). 相似文献
4.
Heinz Falk Thomas Schlederer Peter Wolschann 《Monatshefte für Chemie / Chemical Monthly》1981,112(2):199-207
The long standing problem of solvent dependent absorption spectra of certain bile pigments such as bilirubindimethylester has been solved by measurement of molecular masses by means of vapour pressure osmometry. Using this method and the investigation of the concentration and temperature dependence of the absorption spectra on several model compounds an association equilibrium for pigments of the rubinoid structural type could be confirmed. Moreover the optical properties of the coexisting species and the corresponding equilibrium constants could be deduced by spectroscopic techniques. Verdinoid pigments lacking free carboxylic functions on the other hand tend to be monomeric in solution. A heteroassociated species involving equimolar amounts of a verdinoid and a rubinoid pigment could be verified existing on adsorbents like silicagel.
37. Mitt.:Falk, H., Thirring, K., Tetrahedron, im Druck. 相似文献
5.
6.
7.
Beiträge zur Chemie der Pyrrolpigmente, 70. Mitt.: Zum aktiven Transport mit tripyrrinoiden Liganden
The tripyrrin carboxylic acid6 exhibits a pronounced efficiency for carrier mediated proton driven secondary active transport (counter transport) for a series of toxic or valuable cations in a bulk chloroform membrane. In case of Zn++ ions the mechanism including complete concentration profiles forNerst diffusion layers and bulk phase have been established. This compound might be used for detoxification or enrichment of precious metals using membrane separation systems.
Herrn Prof. Dr.A. Neckel mit den besten Wünschen zum 60. Geburtstag gewidmet. 相似文献
8.
The procedure ofBrewster was employed in the calculation of the molecular rotation of optically active derivatives of 1,2-tetramethylene-ferrocene, which (in addition to ferrocene asymmetry) contain asymmetric (chiral) centers in the cyclohexene part of the molecule. Satisfactory agreement between the calculated and observed values for the rotations was obtained throughout. In one case, the calculation of the absolute configuration of the planarasymmetric part was successful; it was found to be in agreement with the results of an independent (experimental) method employed earlier. The absolute conformation of some of the ferrocene derivatives is discussed with the aid of optical circular dichroism. 相似文献
9.
Doz. Dr. H. Falk K. Grubmayr O. Hofer 《Monatshefte für Chemie / Chemical Monthly》1975,106(1):301-312
The condensation of 3.4-dimethyl-3-pyrrolin-2-one with p-methyl-, p-chloro-benzaldehyde and ferrocenealdehyde yields theZ-andE-isomers of the corresponding condensates. Due to kinetic control theZ-isomers are obtained almost exclusively in this reaction. TheE-isomers of the two firstmentioned products can be produced by photochemical isomerization. The structures (tautomeric forms) and configurations of the isomers were established by the Lanthanide-induced-shift-technique and by evaluating the Nuclear-Overhauser-Effect. 相似文献
10.
Helmut Marko Norbert Müller Heinz Falk 《Monatshefte für Chemie / Chemical Monthly》1989,120(2):163-168
Summary The intermolecular complex formation of bilirubin and biliverdin with two proteins (basic pancreatic trypsin inhibitor and lysozyme) were studied by optical and chiroptical methods. Evidence for specific intermolecular interactions of biliverdin with both proteins was found. Bilirubin forms a soluble complex only with lysozyme.
UV-VIS und CD-spektroskopische Untersuchungen intermolekularer Wechselwirkungen von Gallenpigmenten mit kleinen Proteinen
Zusammenfassung Die intermolekulare Komplexbildung von Bilirubin und Biliverdin mit zwei Proteinen (basischer pankreatischer Trypsininhibitor und Lysozym) wurden mittels optischer und chiroptischer Spektroskopie untersucht. Für Biliverdin konnten intermolekulare Wechselwirkungen mit beiden Proteinen nachgewiesen werden. Bilirubin bildet nur mit Lysozym einen löslichen Komplex.相似文献