Search results for "Azo compound"
showing 10 items of 61 documents
Interplay of Chiral Side Chains and Helical Main Chains in Polyisocyanates
1996
Here we describe the synthesis of seven new copolymer series prepared by copolymerization of hexyl isocyanate with seven new chiral azo chromophores with an isocyano functionality. The resulting copolyisocyanates (Nylon 1) possess a helical polymer conformation. In the cases in which the chiral group and polymer chain are linked to the same phenyl ring (copolymer series VI-IX) a transfer of chirality to the polymer chain is possible. I.e. one helical twist sense is preferred in this case. By variation of the chiral center, polymers with preferable right- or left-handed helical conformation are accessible. The photochemical isomerization of the azo chromophore (trans → cis) is possible in hi…
4,4′‐Distyrylazobenzol als Chromophor
1992
4,4′-Distyrylazobenzene as Chromophore 4,4′-Distyrylazobenzenes are prepared from 4,4′-dimethylazobenzene. Whereas the Siegrist method furnishes stereoselectively the (E,E,E) configuration, a Wittig olefination leads to a mixture of (Z,E,Z), (Z,E,E) and (E,E,E) isomers which can be easily separated. Irradiation of the intense absorption at λ ≈ 400 nm causes a selective (E) (Z) isomerization of the N = N bond of all three isomers. The reverse reaction takes part in the photochemical equilibration, moreover, it is a thermal process with a relatively low activation barrier.
Selective and Scalable Electrosynthesis of 2H-2-(Aryl)-benzo[d]-1,2,3-triazoles and Their N-Oxides by Using Leaded Bronze Cathodes.
2020
Abstract Electrosynthesis of 2H‐2‐(aryl)benzo[d]‐1,2,3‐triazoles and their N‐oxides from 2‐nitroazobenzene derivatives is reported. The electrolysis is conducted in a very simple undivided cell under constant current conditions with a leaded bronze cathode and a glassy carbon anode. The product distribution between 2H‐2‐(aryl)benzo[d]‐1,2,3‐triazoles and their N‐oxides can be guided by simply controlling the current density and the amount of the charge applied. The reaction tolerates several sensitive functional groups in reductive electrochemistry. The usefulness and the applicability of the synthetic method is demonstrated by a formal synthesis of an antiviral compound.
Synthesis and characterization of some dibutylbis{5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoato}tin(IV) compounds. Toxicity studies of di- and tri-or…
2003
The preparation and spectroscopic characterization of some complexes of the type Bu2Sn(LH)2 (LH = 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoate) are reported. On the basis of spectroscopic evidence (1H, 13C, 119Sn NMR, IR and 119mSn Mossbauer) the compounds were judged to adopt the usual dicarboxylato structural type with a skew trapezoidal arrangement. This was further confirmed by X-ray crystallography in the case of Bu2Sn(L5H)2 (L5H = 5-[(E)-2-(4-chlorophenyl)-1-diazenyl]-2-hydroxybenzoate). Toxicity studies of the di- and tri-organotin compounds on the second larval instar of Aedes aegypti mosquito larvae are reported. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis and structural studies by infrared and Mössbauer spectroscopy of adducts of tin(IV) and organotin(IV) derivatives with 2,2′-azopyridine
1985
Abstract A number of complexes have been prepared by the reaction between 2,2′-azopyridine(AZP) and tin(IV) halides and organotin(IV) halides, and characterized by elemental analysis and infrared and variable temperature 119Sn Mossbauer spectroscopies. All of the new compounds have 1:1 stoichiometry, with the AZP ligand occupying two coordination sites by bonding through one of the ring and one of the azo group nitrogen atoms, to give rise to distorted octahedral structures. In the diorganotin complexes the two organic groups occupy trans positions. The infrared and Mossbauer spectroscopic data suggest that these compounds are monomeric in the solid state.
Palladium(II)-Stabilized Pyridine-2-Diazotates: Synthesis, Structural Characterization, and Cytotoxicity Studies
2018
Well-defined diazotates are scarce. Here we report the synthesis of unprecedented homoleptic palladium(II) diazotate complexes. The palladium(II)-mediated nitrosylation of 2-aminopyridines with NaNO2 results in the formation of metal-stabilized diazotates, which were found to be cytotoxic to human ovarian cancer cells.
Synthesis and in vitro antimicrobial activities of new (cyano-NNO-azoxy) pyrazole derivatives
2011
The antibacterial and antifungal activity of a series of products, in which the 1,5-dimethyl-4-(cyano- NNO-azoxy)pyrazol-3-yl and 1,3-dimethyl-4-(cyano-NNO-azoxy)pyrazol-5-yl moieties were linked to pyridine, pyrazole, isoxazole, thiophene and the furan ring, were examined. No molecule displayed activity against the Gram-negative bacteria tested. Conversely, some compounds displayed activity against two Staphylococcus aureus strains, including the methicillin resistant strain. All compounds displayed interesting antifungal activity, the most active compound of the series being the thiophene derivative 7a. This compound’s activity against Candida krusei and Candida glabrata (MIC = 0.25 and 0…
Determination of sulphonamides in human urine by azo dye precolumn derivatization and micellar liquid chromatography
1995
Abstract A high-performance liquid chromatographic method for the determination of sulphonamides in urine is reported. The drugs (sulphadiazine, sulphaguanidine, sulphamethizole, sulphamethoxazole, and sulphathiazole) were diazotized with nitrite and coupled with N-(1-naphthyl)ethylenediamine dihydrochloride in a sodium dodecyl sulphate (SDS) micellar medium. Separation of the sulphonamide azo dyes was performed on a C18 column with a 0.05 M SDS-2.4% pentanol mobile phase, which permitted the direct injection of the urine samples. The limits of detection were in the 0.1–0.3 μg/ml range.
Development of a method for the analysis of seven banned azo-dyes in chilli and hot chilli food samples by pressurised liquid extraction and liquid c…
2008
An automated, confirmatory and sensitive procedure has been developed and validated for the determination of Sudan (I-IV), Sudan Orange G, Sudan Red 7B and Para Red in hot chilli food samples. The proposed method includes pressurised liquid extraction (PLE) with acetone, gel permeation chromatography (GPC) clean-up and detection by liquid chromatography (LC) coupled to electrospray ionization in positive mode tandem mass spectrometry (ESI-MS-MS). The main parameters affecting the performance of the different ionization sources and PLE parameters were previously optimised using statistical design of experiments (DOE). The method was in-house validated on chilli powder and chilli meat. Linear…
High-performance micellar liquid chromatography determination of sulphonamides in pharmaceuticals after azodye precolumn derivatization
1995
Abstract A chromatographic procedure with precolumn derivatization to form the N-(1-naphthyl)ethylenediamine dihydrochloride azodyes is proposed for the analysis of several sulphonamides (sodium sulphacetamide, sulphadiazine, sulphaguanidine, sulphamerazine, sulphamethizole, sulphamethoxazole, sulphanilamide and sulphathiazole) in pharmaceutical preparations (tablets, pills, capsules, suspensions and drops). The separation is performed with a 0.05 M sodium dodecyl sulphate/2.4% pentanol eluent at pH 7. The precolumn derivatization improved the resolution in the chromatograms and increased the selectivity in the determination of mixtures of sulphonamides and in preparations where other drugs…