Search results for "Reaction condition"
showing 10 items of 70 documents
PHOSPHORORGANISCHE VERBINDUNGEN 115 WEGE ZUM ANALYTISCHEN NACHWEIS VON VERBINDUNGEN MIT DER P(O)F- UND P(O)SR-GRUPPE
1984
Abstract Acridine-9-hydroxamicacid 5 is suitable for the analytical detection of the model phosphorylfluorides 7 by fluorescence. The model compounds are rearranged according to Lossen and degradated to the fluorescent 9-aminoacridine 6 using defined reaction conditions. Thiophospho-S-esters (with diethyl-thiophosphinicacid-S-butylester 8 as a model compound) are cleaved to the corresponding phosphoryl-fluorides (a) and mercaptanes (b) by fluorolysis. (a) is identified qualitatively with acridine-9-hydroxamicacid 5, (b) by the Ellman-reaction. Zum Fluoreszenznachweis der Modellphosphorylfluoride 7 ist Acridin-9-hydroxamsaure 5 geeignet. Die Modellverbindungen 7 werden unter Einhaltung defin…
First Fluorous Synthesis of Fluorinated Uracils
2006
This paper describes a novel fluorous synthesis of fluorinated uracils 4. In this new protocol, fluorous alcohols 1, which are used as fluorous tags, are acetylated to yield acetates 2, which in turn are treated with a base to form their enolates. These are then reacted with fluorinated nitriles to furnish tagged β-enamino esters 3. Although this condensation step had been performed easily in previous solution and solid-phase syntheses, it proved to be very elusive in the fluorous version. Meticulous control of the reaction conditions was thus essential in order to achieve satisfactory yields of β-enamino esters 3. The final treatment of compounds 3 with isocyanates or isothiocyanates effic…
Efficient flow injection and sequential injection methods for spectrophotometric determination of oxybenzone in sunscreens based on reaction with Ni(…
2001
Spectrophotometric determination of a widely used UV-filter, such as oxybenzone, is proposed. The method is based on the complexation reaction between oxybenzone and Ni(II) in ammoniacal medium. The stoichiometry of the reaction, established by the Job method, was 1:1. Reaction conditions were studied and the experimental parameters were optimized, for both flow injection (FI) and sequential injection (SI) determinations, with comparative purposes. Sunscreen formulations containing oxybenzone were analyzed by the proposed methods and results compared with those obtained by HPLC. Data show that both FI and SI procedures provide accurate and precise results. The ruggedness, sensitivity and LO…
Understanding phenolic acids inhibition of α-amylase and α-glucosidase and influence of reaction conditions
2022
Phenolic acids are involved in modulating the activity of starch digestive enzymes but remains unclear if their interaction with enzymes or starch is governing the inhibition. The potential inhibition of nine phenolic acids against α-amylase and α-glucosidase was studied applying different methodologies to understand interactions between phenolic acids and either enzymes or substrates. Vanillic and syringic acids were prone to interact with α-amylase requiring low half-maximum inhibitory concentration (IC50) to inhibit starch hydrolysis. Nevertheless, the initial interaction of phenolic acids with starch somewhat obstructed their interaction with starch, requiring 10 times higher IC50, with…
Initiierte autoxydation von isotaktischem und ataktischem polybuten-1 in lösung
1968
Isotaktisches und ataktisches Polybuten-1 (PB) wurden bei 70,6°C in brombenzolischer Losung mit Azoisobuttersauredinitril als Initiator mit Sauerstoff oxydiert. Die oxydierten Proben wurden isoliert, und der Gehalt an Hydroperoxidgruppen wurde mit Hilfe von Triphenylphosphin bestimint. Cyclische Peroxide, die bei oxydiertem isotaktischem Polybuten 1 moglich sind, konnen nicht mit Triphenylphosphin bestimmt werden, da sie zerfallen, bevor sie mit dem Phosphin reagieren. Dies wurde an niedermolekularen Modellverbindungen uberpruft. Unter den Reaktionsbedingungen war die kinetische Kettenlange so klein (1 bis 2), das deutliche Unterschiede der Oxydation von isotaktischem und ataktischem Polybu…
Surface Modification of Nanoparticles and Nanovesicles via Click-Chemistry
2019
Surface modification of nanocarriers offers the possibility of targeted drug delivery, which is of major interest in modern pharmaceutical science. Click-chemistry affords an easy and fast way to modify the surface with targeting structures under mild reaction conditions. Here we describe our current method for the post-preparational surface modification of multifunctional sterically stabilized (stealth) liposomes via copper-catalyzed azide-alkyne cycloaddition (CuAAC) and inverse electron demand Diels-Alder norbornene-tetrazine cycloaddition (IEDDA). We emphasize the use of these in a one-pot orthogonal reaction for deep investigation on stability and targeting of nanocarriers. As the prod…
Dry synthesis of B-MFI, MTN- and MTW-type materials
1997
Abstract B-MFI and MTN-type materials were synthesized via the fluoride route from dry powders in the complete absence of a solution phase. Amorphous precursors obtained by drying SiO 2 · Al 2 O 3 gels at 700°C were transformed into MTN-type material in the presence of dried NH 4 F and TMACl. Amorphous precursors obtained by drying SiO 2 gels at 700°C were transformed into B-MFI in the presence of dried NH 4 F, B 2 O 3 and TPABr. Water is formed as a reaction product. However, the water vapor pressure is appreciably below the water vapor saturation pressure under the given reaction conditions. In addition, syntheses using seed crystals were carried out successfully.
A new polyphosphate calcium material with morphogenetic activity
2015
Abstract Polyphosphate [polyP] has been proven to elicit morphogenetic activity on bone cells. By applying mild reaction conditions, a Ca-polyP material that displays a hardness of ≈1.3 GPa has been fabricated. The Ca-polyP granules are prone to hydrolytic degradation during in vitro incubation of the cells, suggesting that this property is associated with the observed bioactivity.
Shape-Dependence of Pd Nanocrystal Carburization during Acetylene Hydrogenation
2015
This interdisciplinary work combines the use of shape- and size-defined Pd nanocrystals (cubes of 10 and 18 nm, and octahedra of 37 nm) with in situ techniques and DFT calculations to unravel the dynamic phenomena with respect to Pd reconstruction taking place during acetylene hydrogenation. Notably, it was found that the reacting Pd surface evolved at a different pace depending on the shape of the Pd nanocrystals, due to their specific propensity to form carbides under reaction conditions. Indeed, Pd cubes (Pd(100)) reacted with acetylene to form a PdC0.13 phase at a rate roughly 6-fold higher than that of octahedra (Pd(111)), resulting in nanocrystals with different degrees of carburizati…
Thermal characterisation of Bio Based Building Materials
2006
This paper describes how the characterization of indigenous renewable biomass sources that are applicable for making bio-based building (BBB) materials is crucial as it can significantly affect the cost of production and the quality of material. Nowadays, in any specific area, wide ranges of biomass sources are usually available but only a few sources may be suitable for making BBB material. Therefore the suited sources should be determined. In this paper, the use of BBB materials is focused on Insulation Materials which are widely used in the buildings. Compared with currently used materials, these materials are bio-degradable. Insulation material with a good energy-adsorbing property and …