bluuebunny/crossref_metadata_2025_split huggingface dataset:
Einige Diels‐Alder‐Additionen des Benzvalens
Authors: Christl Manfred , Lüddeke Hans‐Joachim , Nagyrevi‐Neppel Anton , Freitag Gertrud 
Published: June 2007

AbstractZwei 1,2,4,5‐Tetrazine, ein 4,5‐Dihydropyridazin, zwei ortho‐Benzochinone und Hexachlorcyclopentadien liefern als elektronenarme Diene glatt mit der elektronenreichen Doppelbindung des Benzvalens die erwarteten Addukte (5a, b, 7, 9a, b, 16a). Die Umwandlung von 9b und 16a macht das neue C10H10‐Isomere Tetracyclo 4.4.0.02,4.03,5]deca‐7,9‐dien (11b) bzw. das neue C11H12‐Isomere Pentacyclo[6.2.1.02,7.03,5.04,6]undec‐9‐en (16b) bequem zugänglich. Die Konstitutionen der neuen Verbindungen werden anhand ihrer 13C‐NMR‐Spektren gesichert, die ein eindeutiges Kriterium für die Analyse derartiger, das Bicyclo[1.1.0]butan‐System enthaltender Polycyclen bieten.
Thiocarbonyl‐Ylide des 1,3‐Diazacyclopentadiens und des Cyclopentadiens
Authors: Gronski Peter , Hartke Klaus 
Published: June 2007

AbstractDie Thioharnstoffe 10 reagieren mit 4,5‐Dicyan‐2‐diazo‐2H‐imidazol (11) unter Stickstoff‐Eliminierung zu den Isothiuronium‐S‐4,5‐dicyan‐2‐imidazoliden 8. Bei 0°C läßt sich die labile Reaktionszwischenstufe in Form der Isothiuronium‐S‐azo(4,5‐dicyan‐2‐imidazolide) 12 abfangen. In analoger Weise setzen sich die Thioharnstoffe 10 mit den Phenyliodonium‐tricyancyclopentadieniden 17 und 19 zu den Isothiuronium‐S‐tricyancyclopentadieniden 18 und 20 um. Auf Grund der spektroskopischen Daten sind die thermisch sehr stabilen Thiocarbonyl‐Ylide 8, 18 und 20 als Betaine zu formulieren.
Zum Substituenteneinfluß der Guanidino‐ und der Guanidiniumgruppe, Teil I: Der Effekt auf die 19F‐NMR‐Spektren von Fluorbenzolen und auf die aromatische Substitution
Authors: Heesing Albert , Schmaldt Wilhelm 
Published: June 2007

AbstractAus den 19F‐NMR‐Spektren von N‐(Fluorphenyl)guanidinen und ihren Salzen werden die Taftschen σ1‐ und σR‐Werte errechnet. Die Umlagerung des N‐Nitro‐N′‐phenylguanidins (1) in starker Säure verläuft intermolekular als Nitrierung eines N‐Phenylguanidinium‐Ions durch NO. Es entstehen o‐ und p‐Nitroderivate mit relativ zu Benzol nur geringfügig reduzierter Geschwindigkeit. ‐– Zusammen mit 35Cl‐NQR‐Messungen (1) und der Beeinflussung von Redoxpotentialen bei Guanidinochinonen(2) zeigen diese Befunde, daß die Guanidinogruppe als mesomerer Elektronendonator wirkt. — Neben dem erwarteten — I‐Effekt zeigt die Guanidiniumgruppe trotz ihrer positiven Ladung und der Einschränkung der Mesomerie im Guanidinsystem einen deutlichen + M‐Effekt.
Eine flexible und regioselektive Acronycin‐Synthese
Authors: Blechert Siegfried , Fichter Karl‐Ernst , Winterfeldt Ekkehard 
Published: June 2007

AbstractEs wird eine regioselektive Synthese des Acronycins (1) mitgeteilt, die über Zwischenstufen verläuft, deren Konstitution auch Wege zu den Acronycin‐Metaboliten eröffnen sollte.
Beiträge zur Chemie des Phosphors, 78: 1,2,3‐Triphenyltriphosphan
Authors: Baudler Marianne , Koch Dieter , Carlsohn Burkhard 
Published: June 2007

Contributions to the Chemistry of Phosphorus, 78: 1,2,3‐TriphenyltriphosphaneAmong the disproportionation products of 1,2‐diphenyldiphosphane (1), 1,2,3‐triphenyltriphosphane (2) could be enriched up to the maximum concentration of ≈︁50% with respect to the total phosphorus. 2 was identified by the 31P{1H} NMR spectrum that exhibits, in the region of openchain triphosphanes, two A2B and one ABC spin system for the three diastereomers, of which the NMR parameters are reported. Contrary to results given in the literature, 2 is not stable at room temperature, but disproportionates to give lower and higher homologues of the series H(PPh)nH as well as cyclic phenylphosphanes, especially (PPh)5.
Synthese des 6‐Desoxycryptosporins und verwandter Verbindungen
Authors: Krohn Karsten , Brückner Gabriele , Tietjen Hans‐Peter 
Published: June 2007

AbstractDie cis‐Hydroxylierung des Naphthopyrans 5 liefert als Hauptprodukt das Ketol 9. Daneben können das epimere Ketol 11 und die hydroxylierten Chinone 2 und 13 isoliert werden. Das Syntheseprodukt 2 ist die 6‐Desoxy‐Verbindung des Naturstoffs Cryptosporin (1). Über die Stereochemie der katalytischen Hydrierung des Ketols 9 und die Reduktion mit Natriumborhydrid und Diisobutylaluminiumhydrid wird berichtet.
Herstellung und synthetische Verwendung von metallierten Dimethylhydrazonen Regio‐ und stereoselektive Alkylierung von Carbonylverbindungen
Authors: Corey Elias J. , Enders Dieter 
Published: June 2007

AbstractDimethylhydrazone (DMH's) 6–10 von enolisierbaren Aldehyden und Ketonen können mit n‐Butyllithium und/oder Lithium‐diisopropylamid in Tetrahydrofuran quantitativ in α‐Stellung metalliert werden. Die so erhaltenen Lithiumderivate 11–14 sind hochreaktive Kohlenstoffnucleophile. Ihre Verwendung als Enolatäquivalente wird über die Sequenz Carbonylverbindung, DMH‐Derivat. Metallierung, Reaktion mit Alkylhalogeniden (→ 16, 18, 19) und Spaltung zur α‐substituierten Carbonylverbindung (17) an einer Anzahl von Beispielen demonstriert. Die Alkylierungen erfolgen, von Spezialfällen abgesehen, regiospezifisch am weniger substituierten Kohlenstoffatom. Cyclohexanonderivate werden stereoselektiv axial alkyliert, was zur Darstellung von trans‐disubstituierten Cyclohexanonen ausgenutzt wird. Zur quantitativen Spaltung der Dimethylhydrazone zurück zu den Carbonylverbindungen unter milden Bedingungen (pH 7, Raumtemperatur) wurde eine neue oxidative Hydrolyse entwickelt. Die Vorteile der Methode werden kurz diskutiert.
Alkyl‐ und Arylfluorphosphine als Liganden in Übergangsmetallkomplexen mit Metallen in positiver Oxidationsstufe, IV: Ligandenaustausch‐ und Redoxreaktionen an Eisen‐, Cobalt‐ und Nickelhalogenid‐Komplexen
Authors: Bartsch Rainer , Hausard Marcel , Stelzer Othmar 
Published: June 2007

AbstractDie Cobalt(II)‐ und Nickel(II)‐halogenid‐Komplexe CoX2(PhPF2)3 und NiX2(PhPF2)3 (X = Br, I) werden durch überschüssiges Difluorphenylphosphin zu Cobalt(I)‐ bzw. Nickel(0)‐Komplexen CoX(PhPF2)4 (X = Br, I) bzw. Ni(PhPF2)4 reduziert. Diese Komplexe entstehen auch, wenn anstelle der Komplexe des PhPF2 die des Di‐tert‐butylfluorphosphins, MX2(tBu2PF)2 (M = Co, Ni; X = Cl, Br, I), bzw. Tributylphosphins, NiBr2(Bu3P)2, eingesetzt werden. Die Reduktion der Komplexe CoX2(PhPF2)3 (X = Br, I) mit Zink/Quecksilber liefert überraschenderweise den vollständig substituierten Komplex Hg[Co(PhPF2)4]2. Wird der kationische Eisen(II)‐Komplex [FeCl(PhPF2)5][FeCl4] mit Zink/Quecksilber reduziert, erhält man den Eisen(0)‐Komplex Fe(PhPF2)5, während mit Eisenpulver die Eisen(II)‐Verbindung cis‐FeCl2(PhPF2)4 gebildet wird. Oxidation von Fe(PhPF2)5 mit Brom oder Iod führt zu cis‐FeX2(PhPF2)4 (X = Br, I). Die Komplexe Hg[Co(PhPF2)4]2, Ni(RPF2)4 (R = tBu, Ph), CoI(PhPF2)4, Fe(PhPF2)5 und cis‐FeCl2(PhPF2)4 können auch direkt durch Einwirkung der überschüssigen Difluorphosphine auf die entsprechenden Übergangsmetallhalogenide in Gegenwart geeigneter Reduktionsmittel erhalten werden.
Natürlich vorkommende Terpen‐Derivate, 121: Atisiren‐Derivate aus Garuleum sonchifolium (DC) T. Norl.
Authors: Bohlmann Ferdinand , Grenz Michael 
Published: June 2007

AbstractDie Untersuchung der südafrikanischen Composite ergibt neben bekannten Verbindungen drei neue Diterpene mit dem Kohlenstoffskelett des Atisirens (9, 13 und 17). Die Konstitutionen werden durch die spektroskopischen Daten und einige chemische Umwandlungen geklärt. Die biogenetischen Beziehungen werden diskutiert.
Neue heteroanellierte Benzo[b]thiophen‐1,1‐dioxide
Authors: Ried Walter , Mavunkal Joseph B. 
Published: June 2007

Abstract2‐Benzoyl‐3‐chlorbenzo[b]thiophen‐1,1‐dioxid (1a) reagiert mit Semicarbazid, 4‐Methylbenz‐amidrazon, 1,8‐Diaminonaphthalin zu 1c–e, mit KSCN zu dem Senföl 1g: durch Hydrolyse von 1g erhält man 1h, zu dem man auch durch Umsetzung von 1a mit Ammoniak gelangt. 1a reagiert mit Natriumazid zu 2b, mit Hydrazin zu 2a. Saure Hydrolyse von 1d führt zur Verbindung 3. 3‐Aminocrotonsäure‐ethylester kondensiert mit 1a zum Pyridinderivat 4: mit Guanidin, Benzamidin und Acetamidin erhält man die Pyrimidinabkömmlinge 6a–c. 1g reagiert mit Anilin zu 5, 1a mit o‐Phenylendiamin, Ethylendiamin und N‐Methylethylendiamin zu Diazepinverbindungen 8a–c, mit o‐Aminothiophenol zum Benzothiazol 9.
Umsetzungen mit Monohydrazonen von Dicarbonylverbindungen, VI: Synthesen von 4‐Oxocarbonsäuren und deren Estern mit Hilfe von α‐Hydrazonoaldehyden
Authors: Severin Theodor , Poehlmann Hans 
Published: June 2007

Abstractα‐Hydrazonoaldehyde (11) sind aus Ketonhydrazonen 14 durch Selendioxid‐Oxidation oder durch Kupplung von Enaminen 12 mit Diazoniumsalzen 13 darstellbar. Mit (Ethoxycarbonylmethylen)triphenylphosphoran (15) oder mit Estern 17 in Gegenwart von Basen lassen sich α‐Hydrazonoaldehyde 8, 11 zu Hydrazonen ungesättigter 4‐Oxocarbonester (16) umsetzen. Durch Hydrolyse oder reduktive Hydrolyse erhält man ungesättigte bzw. gesättigte 4‐Oxocarbonester (18 bzw. 19). Hydrazonoethyliden‐Derivate von Ketonen ergeben bei der Hydrolyse 4‐Oxocarbonsäuren (28 → 29).
Sulfide Pyrolysis, I: Many Membered Hydrocarbon Cycles via Thermal Extrusion of Sulfide Sulfur
Authors: Bieber Wolfgang , Vögtle Fritz 
Published: June 2007

Sufid‐Pyrolyse, I: CC‐Bindungsknüpfung durch thermische Sulfidschwefel‐ExtrusionDas Sulfid 1 konnte durch unkatalysierte Thermolyse bei 650°C unter Austritt des Schwefelatoms bei gleichzeitiger Rekombination der benzylischen C‐Atome in den cyclischen Kohlenwasserstoff 2 übergeführt werden.
3‐Diazoindazole: Photochemie, Thermochemie, Cycloadditionen
Authors: Dürr Heinz , Schmitz Heribert 
Published: June 2007

AbstractDie Photolyse oder Thermolyse des 3‐Diazoindazols 1 a liefert unter Stickstoffabspaltung das Carben 2, das sich über eine Nitrenzwischenstufe 3 unter Bildung der Azoverbindung 6 stabilisiert. Weiterhin stellen die 3‐Diazoindazole 1 Dipole mit inversem Elektronenbedarf dar, die mit elektronenreichen Alkinen bzw. Olefinen in einer neuen Reaktion die Triazino‐indazole 9 liefern.
Koaxialrührwerk zum Rühren hochviskoser und nicht‐Newtonscher Medien
Authors: Heiser M. , Ritter J. , Sperling R. , Kraume M. 
Published: June 2007

AbstractVorgestellt werden Ergebnisse aus experimentellen und numerischen Untersuchungen bezüglich des Leistungseintrages einer koaxialen Anordnung aus Schrauben‐ und Wendelrührer. Diese Kombination ist für den Einsatz in komplexen Anwendungen bei höherer Viskosität und bei Vorliegen von strukturviskosem Verhalten geeignet.
Fluiddynamik eines Flüssigkeitsfilms an einem vertikalen Draht
Authors: Grünig J. , Kraume M. , Shilkin A. 
Published: June 2007

AbstractEinem vertikalen Draht wird kontinuierlich Flüssigkeit zugeführt, die als Film herabläuft. Ein Gasstrom wird im Gegenstrom geführt, der die Strömung der Flüssigkeit beeinflusst. In der vorliegenden Untersuchung werden die lokale Filmdicke sowie die Belastungsgrenzen experimentell bestimmt. Als Stoffsysteme werden Luft/Wasser und Luft/Ethanol eingesetzt. In beiden Fällen bildet sich eine Strömungsstruktur aus, bei der ein dünner Basisfilm von einzelnen „Flüssigkeitsperlen”︁ überlaufen wird. Im Stoffsystem Luft/Wasser bildet sich dabei ein dünnerer Basisfilm aus, und die Perlen weisen eine größere Dicke auf. Mit zunehmender Gasbelastung bilden sich größere Perlen und ein dünnerer Basisfilm, wodurch der Transport der Flüssigkeit hauptsächlich durch die Perlen erfolgt. Es lassen sich sehr hohe Gasbelastungen erzielen, der maximale F‐Faktor am Flutpunkt für das Stoffsystem Luft/Wasser beträgt 8,1 Pa1/2.
Whiteness‐blackness and brightness response in a nonlinear color‐appearance model
Authors: Nayatani Yoshinobu , Hashimoto Kenjiro , Takahama Kotaro , Sobagaki Hiroaki 
Published: June 2007

AbstractThe achromatic response of the nonlinear color‐appearance model is developed to predict the perceptions of whiteness‐blackness, brightness, and lightness of object colors. The distinction between whiteness‐blackness and brightness perceptions of achromatic colors is especially important in an adapting condition with nonuniform illumination or in a haploscopic match between different adapting fields. In the whiteness–blackness response, the reference gray is introduced from the viewpoint of opponency of achromatic response, and the whiteness–blackness response is divided into whiteness–grayness and grayness–blackness responses. By giving different weights for the whiteness–grayness and grayness–blackness responses, the metric lightness in the nonlinear color‐appearance model agrees very closely with the CIE 1976 L* function without any alteration to the model formulation.
Simplified equations to calculate mie‐theory parameters for use in many‐flux calculations for predicting the reflectance of paint films
Authors: Mehta K. T. , Shah H. S. 
Published: June 2007

AbstractThe reflectances of paint films can be predicted from the scattering and absorption characteristics of their pigments using the Kubelka‐Munk (K‐M) equations. The K‐M theory has several limitations. To overcome these, the number of fluxes inside the paint film has been increased from two to four in various proposed mathematical models. A more recent theoretical advancement in the subject was made by Mudgett and Richards by the introduction of the many‐flux theory. This theory eliminates several limitations of the K‐M theory. The application of this theory is highly complicated as it requires the use of Mie‐theory parameters like the single scattering and absorption coefficients and the phase function. In our previous publications, we have proposed simple equation to simulate the Mie‐theory phase function. In this article, we give simplified equations to estimate the scattering and absorption coefficients of colorants. The utility of these simplified equations has been established by computing the reflectances of paint films, using the M‐F technique for selected particle sizes up to a range of X = 5 ( = 2 π/λ) and refractive indices m̄ = m – ik, where m varies from 1.10 to 2.00 and k = 0.001 to 0.10. (The imaginary part of the refractive index k should not be confused with the single‐scattering absorption coefficient.) The results are compared with those obtained by using rigorous Mie‐theory equations. The reflectances predicted by the two sets of equations agree well.
Empirical colorant mixture models
Authors: Alman David H. , Pfeifer Charles G. 
Published: June 2007

AbstractThe color behavior of unconventional colorant systems and certain other mixtures cannot be described adequately by available theory. In such cases alternative approaches to formulation and shading need to be developed. In this article we investigate empirical models using Scheffé polynomials to describe color response surfaces for three‐ and four‐component olorant mixtures. We describe experimental designs that allow the efficient estimation of the coefficients of high‐order polynomial models over the full mixture‐design space and that also allow estimation of lower‐order models over subspace mixture regions. The experimental designs are applied to real colorant systems, and the accuracy of color response prediction from linear, quadratic, cubic, and quartic polynomial models is compared to that of theoretical models. The color response surfaces are visualized by preparing contour plots that depict color variation over a compositional region. These maps allow one to observe the relationship between color and composition, to assess the color gamut available with a given colorant set, and to estimate the formula or adjustments required to match a given color position. The effective use of model predictions to perform a sensitivity analysis on the compositional variables is also demonstrated in the context of manufacturing process control.
A new method for the conversion of CIE colorimetric data to munsell notations
Authors: Simon Frederick T. , Frost Judith A. 
Published: June 2007

AbstractAn algorithm for the determination of Munsell Hue Value/Chroma notation from CIE x, y, Y data has been developed. A search‐and‐interpolation routine is utilized that allows for the calculation of accurate Munsell notations. This method achieves the speed of less accurate transforms without sacrificing precision or accuracy. Thus the virtues that have made the Munsell system invaluable in color‐communication applications are made available through conversion of colorimetric data. This algorithm should prove to be quite useful when good accuracy is necessary for the description of colored materials.
Amalgamation of the wright and guild color‐mixture data
Authors: Fry Glenn A. 
Published: June 2007

AbstractThe mixture data for the CIE 1931 standard observer were created by amalgamating two separate sets of mixture data provided by Wright and Guild. Both sets of data were expressed in terms of the NPL system and amalgamated. It is possible to express all three sets of data in terms of Wright's system and show in terms of that system that the CIE data represent an acceptable amalgamation of the Wright and Guild data. This avoids the use of a third system for amalgamating the two sets of data. The properties of the new set of data can be defined by giving the trichromatic coefficients (chromaticity coordinates) of the spectral colors and the luminosity coefficients of the three primaries. This new amalgamated set of data can be used in connection with the V(λ) curve to derive the standard 1931 XYZ diagram and the set of x̄, ȳ, and z̄ values for use in photometry and colorimetry.
Field trials on color appearance and brightness of chromatic object colors under different adapting‐illuminance levels
Authors: Nayatani Yoshinobu , Hashimoto Kenjiro , Takahama Kotaro , Sobagaki Hiroaki 
Published: June 2007

AbstractField trials of the nonlinear color‐appearance model were done by using chromatic object colors under different illuminance levels. Color‐appearance match and brightness match were made for Munsell color pairs by using haploscopic matching. Each color pair was only different in Munsell Chroma. The color‐appearance and the brightness match were realized by adjusting the illuminance of one of the two haploscopic fields. Observed illuminances were significantly different between the color‐appearance and the brightness matches for the same color pairs. The model accurately predicted the illuminances of color‐appearance matches by using the metrics of lightness and chroma Q, T, P of the model, and those of brightness matches by using the metric brightness of the chromatic color Bc. In addition, the estimated contribution of colorfulness to brightness of chromatic colors was generally consistent with that predicted by the formula of Ware and Cowan. To test metric brightness Bc further, an additional experiment on haploscopic matching was done using illuminants with different Ra values. In the experiment, the same samples were used in both fields. Again, matching illuminances in this case were well predicted by using the same contribution factor of colorfulness to brightness already estimated.
Talking about color…
Authors: Newport Linda E. , Wright W. D. 
Published: June 2007

AbstractLast August I devoted one of these columns to the subject of defective color vision and suggested that it would be very instructive to hear from persons who have a color‐vision defect about the difficulties they experience and also from parents who have a son or daughter with a color defect about the difficulties that arise at school.It transpired that Professor R. J. Fletcher, the present Chairman of our British Colour Group, had been thinking along the same lines, and this led him to organise a very interesting meeting of the Group at The City University in London on 2nd March, 1988, when several speakers described the nature of their color defects and how they managed to cope with them. I seized the opportunity to enroll two of the speakers to contribute to this column, one of them, Mrs. L. Newport, being a school teacher. She herself has normal color vision but her 15‐year‐old son Philip has a protan defect. She is, therefore, well placed to advise both school teachers and parents on how to assist children with color defects.The other contributor, Mr. S. C. Abery, is an optometrist; here he uses his knowledge as a visual specialist to describe the problems he has had as a result of his color defect, which was first established when he was four. His account begins.I hope these two contributions will set teachers and parents talking about color and working out ways of easing the lot of color‐defective youngsters. Our journal, too, can play its part by publicising the problem. I once suggested2 that it might be no bad thing if a Dalton Society were established at which those with color defects could compare notes and perhaps make recommendations on alternative methods of identification in place of color codes. How about it, Mr. Abery?Finally, I must mention that there is a very active International Research Group on Colour Vision Deficiencies which meets every two years, and the secretary of the Group, Dr. Verriest, publishes a Newsletter under the title Daltoniana!3
Reduction in visual science: A philosopher's View
Authors: Hardin C. L. 
Published: June 2007

AbstractSuppose that we had a complete, utopian understanding of the workings of the nervous system. Would we thereby know all that there is to know about subjective sensory experience? It has been maintained that we would not, and that although sensory experiences are caused by brain events, they cannot be identical with these events. We shall consider three arguments that purport to lead to this conclusion, and discover that each of them is defective. It will then be argued that the question of whether sensory experiences are identical with brain events is an empirical one, to be settled by future science. An affirmative answer will require that the phenomenology be properly regimented, and shown to be isomorphic with an appropriate subset of neural processes. Although the realization of these conditions must be regarded as utopian, contemporary visual science has made progress in this direction.
Classification of colors through fuzzy statistical experiment
Authors: Hsu Jyh‐Ping , Wei Tsao‐Hung 
Published: June 2007

AbstractThe membership function describing the degree of association of a color sample to a specified color name is estimated experimentally through fuzzy statistical experiment. Here, we are interested in the surface color of opaque materials including red, orange, yellow, green, blue, purple, white, gray, and black. The characteristics of the membership function for these colors are found to be affected appreciably by the light source used.
Color scaling of chromatic increments on achromatic backgrounds: Implications for hue signals from individual classes of cones
Authors: Drum Bruce 
Published: June 2007

AbstractThe hues of foveal monochromatic increments on concentric white backgrounds were measured as a function of the background retinal illuminance. For each background illuminance tested, the illuminance of the test spot was set 0.6 log unit above its increment threshold, and relative percentages of redness, yellowness, greenness, and blueness were estimated. The percentage of whiteness was also estimated in a separate judgement. At low background illuminances, the spectrum is dominated by blue at short and middle wavelengths and by red at long wavelengths. Higher background illuminances are marked by dramatic growth of yellow and green at middle wavelengths and red at short wavelengths. At still higher photopic levels, the pattern reverts back toward that seen at low background illuminances. The hue patterns at low and high adapting levels are characteristic of tritanopic vision, and are attributable to selective sensitivity losses in chromatic neural pathways that process short‐wavelength‐sensitive (S) cone responses. These results reinforce previous evidence that S cone activity produces a reddish purple hue at short wavelengths and (indirectly) a yellow hue at middle and long wavelengths, and that middle‐wavelength‐sensitive cone activity produces a slightly greenish blue.