696-01-5Relevant articles and documents
Fluoro-substituted and 13C-labeled styrylbenzene derivatives for detecting brain amyloid plaques
Sato, Kumi,Higuchi, Makoto,Iwata, Nobuhisa,Saido, Takaomi C.,Sasamoto, Kazumi
, p. 573 - 578 (2007/10/03)
Two styrylbenzene derivatives, (E,E)-1-fluoro-2,5-bis-(3-hydroxycarbonyl-4- hydroxy)styrylbenzene (FSB) and (E,E)-1-bromo-2,5-bis(3-hydroxycarbonyl-4- hydroxy)styrylbenzene-α,α′-13C2 ([ 13C]BSB), were synthesized for use as a histochemical stain to detect amyloid plaques of Alzheimer's disease (AD) brain sections. An analysis of fluorescence spectra demonstrated that FSB shows approximately twofold fluorescence intensity relative to the conventional styrylbenzene derivative, (E,E)-1-bromo-2,5-bis-(3-hydroxycarbonyl-4-hydroxy)styrylbenzene (BSB). Moreover, FSB was found to stain amyloid plaques and neurofibrillary tangles of AD brains with greater fluorescence intensity and a lower level of background signals compared to BSB. These finding indicate that FSB can be an excellent fluorescent compound to label human amyloid lesions with high sensitivity and specificity. Because of the possession of a nuclide with a quantized angular momentum, both FSB and [13C]BSB are also potential contrast agents for magnetic resonance imaging to locate AD pathologies in vivo.
A product analytical study of the thermal and photolytic decomposition of some arenediazonium salts in solution
Canning, Peter S. J.,Maskill, Howard,McCrudden, Katharine,Sexton, Brian
, p. 789 - 800 (2007/10/03)
Products of thermal and photochemical reactions of eleven arenediazonium tetrafluoroborates in various solvents have been analyzed. All compounds in most solvents undergo unimolecular heterolysis to give singlet aryl cations which are captured by solvent. This mechanism is dominant for arenediazonium ions without electron-withdrawing substituents in all solvents, and the only reaction observed in water. Additionally, appreciable yields of fluoroarenes are obtained by fluoride abstraction by the aryl cation from fluorinated solvents and from tetrafluoroborate in fluorinated solvents. Yields from photochemical processes are very similar to those from thermal reactions indicating that the main reactions proceed through common or very similar intermediates. Aryl cations formed from ion-paired diazonium ions may react with the counterion, but fragmentation of dissociated diazonium ions leads only to solvent-derived product. Some arenediazonium ions in some solvents undergo an alternative radical reaction leading principally to hydrodediazoniation. It is proposed that this reaction involves initial rate-limiting electron transfer from ethanol to the arenediazonium ion followed rapidly by homolysis of the resultant aryldiazenyl radical. Within the same solvent cage, the aryl radical then either abstracts an α-hydrogen from the ethanol radical cation generated in the first step to give the reduction product and protonated acetaldehyde, or combines with it at the oxygen to give a protonated aryl ethyl ether.
First application of ionic liquids in electrophilic fluorination of arenes; Selectfluor (F-TEDA-BF4) for "green" fluorination
Laali, Kenneth K.,Borodkin, Gennady I.
, p. 953 - 957 (2007/10/03)
The NF fluorinating agent F-TEDA-BF4 dication salt (Selectfluor) 1 dissolves in imidazolium-based ionic liquids [emim][OTf] 7, [emim][BF4] 8, [bmim][PF6] 9 and [bmim][BF4] 10 (assisted by sonication), providing a convenient medium for fluorination of arenes under essentially acid-free conditions in a simple set-up (no volatile solvent; simple extraction of the aromatics without aqueous work-up), from which the ionic liquid can be easily recycled and reused. Comparative studies in [emim][OTf] 7 with anisole as substrate show that 1 is superior to NFTh-BF4 (Accufluor) 2 and that the N-fluoropyridinium salt NFPy-B2F7 4 is least effective. The scope of the reaction has been surveyed. Substrate selectivity (k mesitylene: k durene = 10) measured in competitive experiments in 7 is clearly indicative of a conventional polar mechanism. Substrate selectivity measured without the ionic liquid in MeCN solvent is also indicative of a polar mechanism but exhibits lower magnitude (k mesitylene: kdurene = 6). Addition of dicyclohexano-24-crown-8 to the fluorination reaction mixture (1 and anisole) in 7 reduced the conversion but did not change the isomer distribution. AM1 minimization was used to model the complexation of 1 with this crown. With reactive aromatics optimal fluorination yields in ionic liquids (using 1 equivalent of the NF reagent) are around 50% (higher for naphthalene). A key control experiment suggests that the free base (produced upon transfer-fluorination) could complex to unreacted 1 (generating a bulky dimer complex which may be ineffective for fluorine transfer) in competition to N-protonation.
Novel process for generating useful electrophiles from common anions using Selectfluor fluorination agent
Syvret, Robert G.,Butt, Kathleen M.,Nguyen, Tung P.,Bulleck, Victoria L.,Rieth, Ryan D.
, p. 4487 - 4493 (2007/10/03)
In the present work, the electrophile equivalents C1+, Br+, SCN+, and NO2+ are generated from their respective sodium, potassium, and in some cases ammonium salts (M+X-) by reaction with Selectfluor electrophilic fluorination agent in acetonitrile solution at room temperature. These generated electrophilic species subsequently react in situ with a variety of aromatic substrates containing one or more substituent groups including H, F, C1, CH3, COOH, C(O)CH3, NO2, and OR′ and NR′R″ where R′ and R″ are H or CH3. The resulting substitution products are, in most cases, isolable as pure compounds in high yield. Variations in the process include the use of other anions, electrophilic fluorination agents, and solvents.
Preparation process of fluorine substituted aromatic compound
-
, (2008/06/13)
A preparation process of a fluorine substituted aromatic compound comprising reacting an alkali metal or alkali earth metal salt of an aromatic compound having a hydroxy group with an organic fluorinating agent is disclosed. As a representative fluorinating agent, a bis-dialkylamino-difluoromethane compound, for example, 2,2′-difluoro-1,3-dimethylimidazolidine, is exemplified. According to the process, an industrially useful fluorinated aromatic compound, for example, a fluorobenzene, a fluorine substituted benzophenone, a fluorine substituted diarylsulfone can be prepared with ease in economy without specific equipment.
Process for the preparation of fluoro compounds from the corresponding amines
-
, (2008/06/13)
Compounds containing a primary amino group are converted into compounds containing a fluorine atom in place of the amino group by reaction of the amino compound with hydrogen fluoride and a nitrosating reagent under the influence of ultrasound or microwaves.
Aryl fluoride syntheses involving reactions of aryllead triacetates with boron trifluoride-diethyl ether complex
De Meio,Morgan,Pinhey
, p. 8129 - 8138 (2007/10/02)
Aryllead(IV) triacetates react at room temperature with BF3.Et2O to give the corresponding aryl fluoride in moderate to good yields; triarylboroxines, electron rich aryltrimethylsilanes and some arenes, which yield aryllead triacetates in acid catalysed reactions with lead tetraacetate, are converted directly into aryl fluorides when stirred with lead tetraacetate in BF3.Et2O. An investigation of the mechanism of the fluoro-deplumbation reaction indicates that it probably proceeds by acid catalysed heterolytic cleavage of the C-Pb bond to produce an aryl cation.
SYNTHESIS OF FLUOROMETHOXYTHRIN AND ITS INSECTICIDAL ACTIVITY
Xinzhuo Zou,Keqan Gu
, p. 507 - 513 (2007/10/02)
Fluoromethoxythrin is a kind of pyrethroid.It was synthesized by an eight-step synthesis.The biological activity tests indicated that it has higher insectizidal activity against mosquitoes (larvae), houseflies and German cockroaches than the corresponding methoxythrin.
Elementary Reactions of Fluorine Atoms with Benzene, Toluene, p-Xylene and Etylbenzene
Ebrecht, J.,Hack, W.,Wagner, H. Gg.
, p. 619 - 626 (2007/10/02)
The rate constants of the reactions of fluorine atoms with benzene, toluene, p-xylene and ethylbenzene were studied in a discharge flow reactor at room temperature and low pressure. - The aromatic compounds R were followed under pseudo first order conditions (0 ) by mass spectrometry (MS).The rate constants: F + C6H6 k1(296 K) = (3.0 +/- 0.7) * 1E13 cm3/mol*s (1), F + C6H5CH3 k2(296 K) = (4.0 +/- 0.8) * 1E13 cm3/mol*s (2), F + C6H4(CH3)2 k3(296 K) = (4.2 +/- 0.6) * 1E13 cm3/mol*s (3), F + C6H5C2H5 k4(296 K) = (4.5 +/- 0.6) * 1E13 cm3/mol*s (4) were obtained. - The products of reaction (1) were C6H5F (80percent) and HF ( 8percent) and those of reaction (2) were C7H7F (50percent), C6H5F (20percent) and HF (20percent).For reaction (3) the exchange mechanism is dominant, C7H7F, C8H9F (65percent), and the abstraction contributes 35percent (HF).In reaction (4) the abstraction is dominant (HF (50percent)) with an exchange pathway of 50percent C6H5F and C8H9F. - Keywords: Chemical Kinetics / Elementary Reactions / Mass Spectrometry
