Showing papers in "ChemInform in 1986"
411 citations
TL;DR: One of the challenges for enzyme mimics is to duplicate not only the mechanism by which the enzyme operates but also the very large rate of the process.
Abstract: Enzyme mimics and artificial enzymes have been designed to imitate several different aspects of enzyme catalysis. For instance, mimics have been constructed to imitate an enzymatic mechanism, using the same catalytic groups which the enzyme uses and examining the question of whether a proposed mechanism for the enzymatic process is reasonable or duplicable. Another common goal of enzyme mimics is the imitation of the velocity of enzyme catalyzed reactions. Enzymes can increase the rates of ordinary reactions by factors as large as 1012 using very ordinary catalytic groups to do so. One of the challenges for enzyme mimics is to duplicate not only the mechanism by which the enzyme operates but also the very large rate of the process. The third area of interest is to imitate the selectivity of enzyme-catalyzed reactions.
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TL;DR: In this article, the authors present a list of methyl-4 heptanol-3, brevicomine, eldanolide, decanediol-5,6, methyl-6 undecanediol -5,7 et amino-6 decanol-5
Abstract: Synthese en particulier du methyl-4 heptanol-3, brevicomine, eldanolide, decanediol-5,6, methyl-6 undecanediol-5,7 et amino-6 decanol-5
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TL;DR: The structure of the title compound (I) was elucidated by IR, UV and 1H- and 13C-NMR spectroscopy as mentioned in this paper, and the structure of I was shown to have a 2.
Abstract: The structure of the title compound (I) is elucidated by IR, UV and 1H- and 13C-NMR spectroscopy.
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TL;DR: In this paper, the quadrupole interaction parameters or quadrupolar shifts were reported for various aluminosilicatm (MAS NMR experiments) using the 1.27A! chemical shifts.
Abstract: 27A! chemical shifts and the quadrupole interaction parameters or quadrupolar shifts are reported for various aluminosilicatm (MAS NMR experiments).
TL;DR: Chitin can be regarded as a new type of polymeric material having greater possibilities than cellulose in many respects as discussed by the authors, since it is an amino polysaccharide, it is capable of undergoing many additional modification reactions.
Abstract: Although chitin may be less advanced than cellulose with regard to research and utilization, it has recently begun to attract much attention in both basic and applied research fields, including not only biology and biochemistry but also organic and polymer chemistry, pharmacology, and medicine. The number of reports and patents is increasing at a remarkable rate. Besides basic research, many attempts have been made to find new applications for chitin. Further basic studies, however, seem to be necessary to realize its full potential. One possible breakthrough in chitin chemistry and technology is the development of chemical modifications of chitin which are being studied more and more actively to explore highly sophisticated functions. Chitin can be regarded as a new type of polymeric material having greater possibilities than cellulose in many respects. Since it is an amino polysaccharide, chitin is capable of undergoing many additional modification reactions. It is anticipated that widespread applications will be found in the near future.
TL;DR: In this article, voltammetrie cyclique du comportement electrochimique des composes amphoteres Ru[bpy] 2 [bpy(CO 2 ] 2 avec bpy= bipyridyle-2,2', en presence d'une electrode d'oxyde d'etain modifiee par le systeme RuO 2 -hectorite sodee
Abstract: Etudes par voltammetrie cyclique du comportement electrochimique des composes amphoteres Ru[bpy] 2 [bpy(CO 2 ] 2 avec bpy= bipyridyle-2,2', en presence d'une electrode d'oxyde d'etain modifiee par le systeme RuO 2 -hectorite sodee
TL;DR: In this paper, a laboratory-scale cell was constructed to test the performance of V(II)/V(III) and V(IV/V(V) half-cells in an all-vanadium redox battery.
Abstract: A laboratory-scale cell was constructed to test the performance of V(II)/V(III) and V(IV)/V(V) half-cells in an all-vanadium redox battery. Graphite plates were used as electrodes, and the membrane was manufactured from a sulfonated polyehylene anion-selective material. The average charging efficiency of the cell was over 90 percent. Stability tests on the reduced and oxidized electrolytes, measured over the temperature range of -5 C to 60 C, showed no accelerated decomposition at high temperatures and no crystallization at the lower temperatures. After prolonged usage, however, a slow deterioration of the positive electrode and the membrane was observed. 9 references.
TL;DR: The ring-strain theory was formulated by Adolf von Baeyer over one hundred years ago as discussed by the authors, and it has repeatedly stimulated experimental and theoretical chemists to investigate the structure, energy and reactivity of organic compounds.
Abstract: “Die Ringschliesung ist offenbar diejenige Erscheinung, welche am meisten uber die raumliche Anordnung der Atome Auskunft geben kann. Wenn eine Kette von 5 und 6 Gliedern sich leicht, eine von weniger oder mehr Gliedern sich schwierig oder auch gar nicht schliesen last, so mussen dafur offenbar raumliche Grunde vorhanden sein.… Die vier Valenzen des Kohlenstoffatoms wirken in den Richtungen, welche den Mittelpunkt der Kugel mit den Tetraederecken verbinden, und welche miteinander einen Winkel von 109°28′ machen. Die Richtung der Anziehung kann eine Ablenkung erfahren, die jedoch eine mit der Grose der Letzteren wachsende Spannung zur Folge hat,”[ ] This is the quintessence of the “ring-strain theory” formulated by Adolf von Baeyer over one hundred years ago. Although it is today only one facet of the many aspects of strain theory, it has repeatedly stimulated experimental and theoretical chemists. Among the most spectacular of the recent successes in synthetic chemistry are the syntheses of tetra-tert-butyltetrahedrane and [1.1.1]propellane. The reasons for the great stability of these two highly strained compounds are completely different. The experimental findings as well as the results of theoretical analysis by means of molecular mechanics and ab initio calculations have contributed decisively to our present state of knowledge of the structure, energy, and reactivity of organic compounds.
TL;DR: A great variety of methods are available for the synthesis of cyclobutane derivatives as discussed by the authors, which generally allow regioselective as well as stereo-selective synthesis of extensively substituted four-membered ring carbocycles.
Abstract: A great variety of methods are available for the synthesis of cyclobutane derivatives. These methods generally allow regioselective as well as stereoselective synthesis of extensively substituted four-membered ring carbocycles. Although possessing intense ring strain, cyclobutanes are normally stable at room temperature, hence can be handled easily in laboratories. Nevertheless, four-membered ring compounds can undergo ring cleavage with extreme ease under several reaction conditions such as acidic condition, basic condition, nucleophilic attack, thermolysis, photolysis, oxidizing as well as reducing conditions. When the cyclobutane ring under investigation is appropriately designed to link to other functional groups, ring opening can be usually followed by skeletal rearrangement. These intriguing reactions would yield compounds with very complex structures. Therefore, the combined effect of all these special properties enables cyclobutane derivatives to become very versatile and useful starting materials for organic synthesis.
TL;DR: Isocoumarins have been isolated from a wide variety of microbial, plant and insect sources and have been shown to possess an impressive array of biological activities as mentioned in this paper, which is largely due to improvements in isolation procedures and structural analysis.
Abstract: Isocoumarins have been isolated from a wide variety of microbial, plant and insect sources and have been shown to possess an impressive array of biological activities. Since the review by Barry in 1963 (24), the number of known naturally occurring isocoumarins has increased dramatically. This increase is largely due to improvements in isolation procedures and structural analysis. Previous reviews have concentrated on fungal isocoumarins (293, 294) and mycotoxic isocoumarins (301). This review lists over 160 naturally occurring isocoumarins. Leading references on isolation, structure elucidation, biosynthesis and synthesis are given in the accompanying Tables.
TL;DR: The structure elucidation of iridoid compounds has been studied in the literature since the late 1950s as mentioned in this paper. But it was only in the late 1970s that the structures of the compounds of this series began to be elucidated.
Abstract: Research on iridoids began with the discovery of asperuloside (1) (an iridoid glucoside) in 1848 and gentiopicroside (2) (a secoiridoid glucoside) in 1862. However, it was only in the late 1950’s that the structures of the compounds of this series began to be elucidated. Thus structure elucidation of the non-glycosidic iridoids iridomyrmecin (3) (1, 2, 2a) isoiridomyrmecin (4) (3, 3a, 4) and nepetalactone (5) (5) and that of the iridoid glucoside plumieride (6) (6) gradually led to the unravelling of the structures of other then unknown iridoids. Since then, large numbers of diverse new iridoids have been found and their structures have been elucidated as time progressed.