Search results for "Organic Chemicals"
showing 8 items of 728 documents
New simple hydrophobic proline derivatives as highly active and stereoselective catalysts for the direct asymmetric aldol reaction in aqueous medium
2008
New 4-substituted acyloxyproline derivatives with different hydrophobic properties of the acyl group were easily synthesized and used as catalysts in the direct asymmetric aldol reaction between cyclic ketones (cyclohexanone and cyclopentanone) and several substituted benzaldehydes. Reactions were carried out using water, this being the best reaction medium examined. Screening of these catalysts showed that compounds bearing the most hydrophobic acyl chains [4-phenylbutanoate and 4-(pyren-1-yl)butanoate] provided better results. The latter catalysts were successfully used in only 2 mol% at room temperature without additives to give aldol products in excellent stereoselectivities. These resu…
Covalent Protein Binding of Vinyl Chloride Metabolites During Co-Incubation of Freshly Isolated Hepatocytes and Hepatic Sinusoidal Cells of Rats
1983
Proteins of isolated rat hepatic sinusoidal cells incubated with 14C-vinyl chloride, rat liver microsomes and an NADPH-regenerating system were alkylated by vinyl chloride metabolites formed by microsomes. This suggests that reactive vinyl chloride metabolites can penetrate sinusoidal cells. Protein alkylation in isolated hepatic sinusoidal cells was higher when these were co-incubated with isolated hepatocytes, indicating that reactive vinyl chloride metabolites formed by hepatocytes are stable enough to diffuse out of hepatocytes into sinusoidal cells. Glutathione added to the incubation medium inhibited the covalent protein binding of vinyl chloride metabolites in sinusoidal cells as wel…
Synthesis, Structure and Solvatochromism of the Emission of Cyano-Substituted Oligo(phenylenevinylene)s
2001
Strongly luminescent and highly soluble oligo(phenylenevinylene)s with five benzene rings and cyano groups in different positions of the terminal styrene units were prepared by means of Horner and Knoevenagel reactions. The substitution pattern − cyanide moieties on the vinyl or on the aromatic regions, together with the effect of auxochromic groups − has distinct influences on the electronic spectra, particularly on the fluorescence. Polar solvents induce red shifts and strongly reduce the fluorescence intensity of the vinyl-substituted oligomers. Cyano substitution increases the electron affinity of the oligomers; this effect is more pronounced for molecules with vinyl cyanides and can be…
Fluorine-containing functionalized cyclopentene scaffolds through ring contraction and deoxofluorination of various substituted cyclohexenes
2018
The fluorination of some highly‐functionalized cyclopentene derivatives, obtained from various substituted cyclohexenes through a ring‐opening/ring‐contraction procedure, has been investigated. The transformations were found to be highly substrate dependent, and led to the formation of various functionalized alicyclic compounds or heterocycles containing allyl difluoride or vinyl fluoride moieties. peerReviewed
Design, Synthesis and Evaluation of Fluorescent Analogues of Abscisic Acid
2020
A fluorescent analogue of abscisic acid has been prepared by combining (S)‐abscisic acid (ABA) with nitrobenzoxadiazole (NBD) fluorophore using ethanol amine as a linker. Isomerization of the double bond at the side chain of abscisic acid happened during the synthesis. The resulting fluorophore analogues derived from both isomeric compounds entered cells suggesting a wide applicability of the ABA‐NBD conjugates as fluorescent probes to study ABA mechanism of action. The functional properties of the isomeric ABA‐NBD conjugates were tested in vitro, by measuring TNFα expression and nitrite concentration in LPS‐stimulated macrophages and compared with their non‐fluorescent ABA isomers. Rationa…
Estudio DS 103-282: Relajante Muscular en Lumbalgia Aguda o Lumbago : (estudio doble ciego de Tizanidina + Paracetamol V s Placebo + Paracetamol)
1989
The clinic efficiency and tolerance of tizanidina + paracetamol was compared with placebo+ paracetamol in an estadistical study and in with were treated 50 patients diagnosed of acote back pain or lumbago. Dif'ferent clinical parámeters was dimished in the group ofthe group of tizanidina + paracetamol.
UV filters: From sunscreens to human body and the environment
2007
Recognition of the harmful effects of ultraviolet (UV) radiation on the skin has triggered development of organic chemicals (commonly referred as UV filters) that can absorb UV radiation and attenuate the negative effects of sunlight exposure. Depending on the properties and the intended degree of protection, a wide array of combinations is being marketed as delivering protection against most kinds of UV-induced skin damage. However, some UV filters have dermatological implications, so maximum applicable concentrations have been established. To monitor to what extent commercial products comply with the mandatory limits, several analytical methods have been used for their determination in co…
Carotenoids under the spotlight: from diet to the retina
2016
Revue; Carotenoids under the spotlight: from diet to the retina. 12. congress of the international society for the study of fatty acids and lipids