Search results for "Activity"

Saponins as immunoadjuvants and immunostimulants

1999

Saponins are either triterpene or steroid glycosides widely distributed in the plant and animal kingdom and include a large number of biologically active compounds. Most of them have surface-active and cholesterol-binding properties.

TI: Cyclophosphazenes as polymer modifiers

2003

The utilization of cyclophosphazenes as polymer modifiers is reviewed, with particular concern to their exploitation as versatile chain extenders, possibly for recycle problems, crosslinkers, to enhance mechanical properties of polymeric materials, branchers, to selectively introduce ramifications in linear polymers, and compatibilizers, to favor the formation of blends between originally incompatible organic macromolecules. The great versatility of the synthetic methods put forward for these substrates, together with the ease of controlling their modification, functionalization and reactivity are important parameters for the evaluation of which type of use is more feasible for these trimer…

Umsetzungen an polymeren

1968

Umsetzungen an Polymeren konnen mit verschiedenen Zielen ausgefuhrt werden: Darstellung neuer Polymerer oder Modifizierung der Eigenschaften bekannter Polymerer; Strukturaufklarung und Analytik bei Polymeren; Untersuchung chemischer Bestandigkeit und Alterungsprozesse; Einfuhrung spezifischer funktioneller Gruppen und Untersuchung ihrer Reaktivitat; Reaktionskinetik bei Polymeren. Folgende Themen werden an ausgewahlten Beispielen behandelt: Ringschlusreaktionen bei Polymeren; Ringoffnungsreaktionen bei Polymeren; Polymere mit metallorganischen Seitengruppen; Polymere mit ungepaarten Elektronen in den Seitengruppen; photochemische Reaktionen mit Polymeren. There are different aims for studyi…

Polymer ester von sären des phosphors, 7. Polymerisation des 1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.1]heptans

1981

1-Oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.1]heptane is transformed in situ (prepared from trimethyl phosphite and glycerol) at −78°C in the presence of a trace of water into a crosslinked polymer containing constitutional repeating units with 5- and 6-membered rings. The reaction with reagents containing hydroxyl groups (water, acetic acid, alcohol) leads to the degradation of the network with the formation of soluble fragments with Pn = 35–50. This reactivity and the possibility to obtain other derivatives from the fragments make this polymer a carrier for pharmacologically active polymers with the advantage of decomposing only into the innocuous components phosphoric acid and glycerol.

Entzündungshemmende wirkstoffe. XI. Ringschlußreaktion an 5-phenyl-2-thiobiuret

1988

Die Umsetzung von 5-Phenyl-2-thiobiuret (1) mil α-Chlorcarbonylverbindungen 2 fuhrt zu den N-Phenyl-N′-(2-thiazolyl)harnstoffen (3). Unter den neuen Verbindungen finden sich besonders die entzundungshemmende, anthelminthische und trichomonazide Wirksamkeit stark ausgepragt. The reaction of 5-phenyl-2-thiobiuret (1) with α-chlorocarbonyl compounds 2 leads to the structure type of N-phenyl-N1-(thiazolyl)urea (3). The new compounds exhibit particularly antiinflammatory, anthelminthic, and trichomonacidal activity.

Über umsetzungen an poly-p-lithiumstyrol. 4. Mitt. Darstellung carbonylgruppenhaltiger derivate des polystyrols

1961

In Fortsetzung fruherer Arbeiten wird die Reaktivitat von Poly-p-lithiumstyrol gegenuber solchen Agenzien gepruft, die zur Bildung von carbonylgruppenhaltigen Verbindungen fuhren. Wahrend bei der Umsetzung mit Orthoameisensaureester nur vernetzte Polymere entstechen, last sich mit Dimethylformamid ein losliches Derivat des Polystyrols herstellen das p-standige Formylgruppen tragt. Die Reaktion mit Nitrilen liefert polymere Ketone; mit Acetophenon entsteht Poly-p-vinylacetophenon, das mit dem aus dem Monomeren durch Polymerisation erhaltenen Produkt verglichen wird. Mit Benzonitril erhalt man Poly-p-vinylbenzophenon. Die polymeren Ketone konnen in die Oxime ubergefuhrt werden, deren Sticksto…

1972

The determination of reactivity ratios is simplified by using an excess of one monomer (M1) at a time large enough that the copolymers will have a very small content of the other monomer (M2). In this case chain propagation takes place almost exclusively by addition to polymer radicals with a terminal M1-unit (P) and monomer consumption by propagation of P may be neglected. One reactivity ratio (r1) is obtained from monomer conversions by means of a simple integrated equation which is valid up to high conversions. A calculation is proposed in order to account for the neglected propagation via P. The other reactivity ratio (r2) is obtained from copolymerizations with excess M2. As the new me…

WEITERE SELEKTIVITÄTSSTUDIEN AM BEISPIEL EINES ARYLSULFONYLACETYLENS

1984

Abstract With 1-(phenylsulfonyl)propyne-(1) 1 as a model compound, we have investigated the competition reactions with RSH, RNH2 and ROH (R=n-Bu). With RSH and RNH2, the cis-trans-isomeric olefins 2 to 5 are formed. ROH does not react under these conditions. The compounds 6 and 7 are obtained only with ROH as the alcoholate. The reactivity of 1 with nucleophiles is increased in comparison to phenylvinyl sulfone; the selectivity of 1 is, however, decreased. The difference in reactivity of 1 and phenylvinyl sulfone corresponds to ca. 10:1. Mit 1-(Phenylsulfonyl)-propin-(1) 1 als Modellverbindung haben wir die konkurrierenden Umsetzungen mit RSH, RNH2 und ROH (R=n-Bu) studiert. Mit RSH und RNH…

Structure and properties of pharmacologically active polymers

1975

Although the concept of using pharmacologically active macromolecular compounds as drugs is still regarded with much skepticism for both theoretical and practical reasons, interest in this field has grown in recent years because of the opportunity to take advantage of the specific properties of polymeric materials. For low molecular weight drugs, changes in structure often lead to a loss of specific activity. On the other hand, the properties of macromolecular drugs depend on the structure of the polymer used and this can be varied over a wide range by the incorporation of comonomer units, by the application of polymer-analogous reactions, or by related structural changes. A new model is pr…

1992

A series of copolymers are synthesized by repetitive Diels-Alder polyaddition reaction of bifunctional cyclohepta-1,3,5-trienes with bifunctional 1,2,4-triazoline-3,5-diones. The copolymers of different bistriazolinediones with a bisdiene, or of different biscycloheptatrienes with a dienophile, have good solubility in CH2Cl2 and CHCl3, while the homopolymers are poorly soluble. The copolymers were characterized by standard analytical techniques to test the structural regularity of these systems. Due to the kinetic control, it is possible to apply copolymerization statistics to these systems. Based on a model study, it is concluded that alipatic and aromatic bistriazolinediones have the same…