Search results for "HALO"

Macrocycles as Molecular Units to Build up Electroresponsive Materials: A Comparative Theoretical Investigation of the Electronic and Optical Propert…

1990

Besides their classical and well-known applications as, e.g., dyes, pigments, catalysts, etc. [1], phthalocyanines (Pc’s) have been of particular interest in many fields of basic and applied research concerning solar cells [2], photosensitizers [3], low dimensional metals [4], gas sensors [5], electrochromism [6], Langmuir-Blodgett (LB) films [7], and nonlinear optics [8]. As an example, gas sensors [9], electronic devices [10], laser recording materials [11], and photovoltaic cells [12] can now be built from LB films of phthalocyanines. This great variety of interesting applications results from a number of unique properties that phthalocyanines exhibit On the one hand, they show an except…

Polymere ester von Säuren des phosphors, 5. Ringöffnende polymerisation des 2-phenoxy-1,3,2-dioxaphospholan durch Michaelis-Arbuzov-reaktion

1977

2-Phenoxy-1,3,2-dioxaphospholane (14) was polymerized by benzyl halogenides at temperatures between 120 and 200°C. It was found that the main chain consists predominantly of unexpected ethylene 1,2-ethanediphosphonate units 7; only about 10% of the monomer was incorporated as the expected 2-hydroxyethanephosphonate structure. An insertion mechanism, proposed by Harwood and Patel for the analogous polymerization of 2-phenyl-1,3,2-dioxaphospholane, does not agree with our experimental results. A hypothesis is developed involving a two step addition process, which exclusively occurs at the chain end. Alternating, one monomer molecule is added by a normal Michaelis-Arbuzov-reaction, and then a …

ChemInform Abstract: Electroorganic Synthesis of Nitriles via a Halogen-Free Domino Oxidation-Reduction Sequence.

2016

A direct electroorganic sequence yielding nitriles from oximes in undivided cells is reported. Despite the fact that intermediate nitrile oxides might be formed, the method is viable to prepare benzonitriles without substituents ortho to the aldoxime moiety. This constant current method is easy to perform for a broad scope of substrates and employs common electrodes, such as graphite and lead.

ChemInform Abstract: Elemental Bromine Production by TiO2Photocatalysis and/or Ozonation.

2016

Significant production of elemental bromine (Br2 ) was observed for the first time when treating bromide containing solutions at acidic pH, with TiO2 photocatalyst, ozone, or a combination thereof. Br2 selectivities up to approximately 85 % were obtained and the corresponding bromine mass balance values satisfied. The process is general and may be applied at a laboratory scale for green bromination reactions, or industrially as a cheap, safe, and environmentally sustainable alternative to the currently applied bromine production methods.

ChemInform Abstract: Acid-Mediated Reaction of Bis(pyridine)iodonium(I) Tetrafluoroborate with Aromatic Compounds. A Selective and General Iodination…

2010

Reaction of aromatic compounds with bis(pyridine)iodonium(I) tetrafluoroborate (IPy2BF4) in the presence of HBF4 or CF3SO3H in CH2Cl2 at room temperature furnishes monoiodo derivatives with excellent regioselectivity and yields. Use of either acid gives comparable results with activated aromatics, whereas CF3SO3H is much more effective in the iodination of deactivated aromatics. © 1993 American Chemical Society.

Oxidative halogenation of substituted pyrroles with cu(II). Part I. Bromination of some 3-acetylpyrroles

1990

3-Acetylpyrroles are brominated with copper(II) bromide. The reaction afforded almost quantitatively only nuclear monobromination. Evidence for the structures of final compounds was by mass spectrometry, 1 H-nuclear magnetic resonance, ir, and elemental analysis

Oxidative halogenation of substituted pyrroles with cu(II). Part II. Bromination of some ethyl 3-pyrrolecarboxylates and corresponding acids

1990

Ethyl 3-pyrrolecarboxylates and their corresponding acids are brominated with copper(II) bromide. The reaction afforded at 0°, with high-yield nuclear monobromination.

Preparation, reactivity and tautomeric preferences of novel (1H-quinolin-2-ylidene)propan-2-ones

2006

1,1-Difluoro-3-(1H-quinolin-2-ylidene)propan-2-one 1a, 1,1,1-trifluoro-3-(1H-quinolin-2-ylidene)propan-2-one 1b, 1,1,1-trifluoro-3-(4-chloro-1H-quinolin-2-ylidene)propan-2-one 1c and 1,3-dibromo-1,1-difluoro-3-(2-quinolyl)propan-2-one 2 are prepared and characterized by various spectroscopic techniques. The crystal structure of 1a is determined by X-ray diffraction. Furthermore, a series of previously known non-halogenated (1H-quinolin-2-ylidene)propan-2-ones 1d-1h are oxidized with AgBrO3 in the presence of AlCl3. In all cases, 2-(1-bromo-1-chloromethyl)quinoline 3 is obtained in high yield. The bromination order and sites of 1a are analyzed based on ab initio MP2 and DFT calculations for …

Surface modification of graphite+polymer composite and ITO electrodes by Nafion®+cupromeronic phthalocyanine films

1999

Abstract The surface of indium tin oxide (ITO) and graphite+polymer composite electrodes can be modified by Nafion ® films containing a little amount of dispersed electroactive substances, such as phthalocyanines. This procedure allows the recovery of electroanalytical information on the electroactive deposited substance. The preparation methods for these types of modified electrodes are discussed from the voltammetric results obtained in this work. The Nafion ® net acts as a permeable membrane to the hydrogen ions. Furthermore, the presence of methylviologen within the Nafion ® film makes the electron transport throughout this membrane easy.

HALOGEN AS A READILY CLEAVABLE PROTECTIVE GROUP FOR REACTIVE POSITIONS IN PHENOLS AND PHENOLIC COMPOUNDS

1976