共查询到20条相似文献,搜索用时 0 毫秒
1.
Richard D. Chambers Mandy Parsons Emmanuelle Thomas John S. Moilliet 《Tetrahedron》2006,62(30):7162-7167
Reaction of a series of model hexyl derivatives of the form C6H13-X (X=Cl, Br, I, CO2Me, COMe, CHO) with both elemental fluorine and Selectfluor™ was studied in order to assess the impact of electron withdrawing functional groups upon fluorination of an alkyl chain. Fluorination generally occurs at secondary sites, with a slight preference for those that are furthest removed from the electron withdrawing group, consistent with an electrophilic substitution process, although mixtures of fluorinated products are obtained in most cases. 相似文献
2.
Recent studies at Durham on direct fluorination 总被引:1,自引:0,他引:1
Richard D. Chambers John Hutchinson Graham Sandford 《Journal of fluorine chemistry》1999,100(1-2):63-73
Developments in direct fluorination are described, which changed our perception of the viability of this methodology for selective introduction of carbon–fluorine bonds. Use of acids as solvent media is a valuable technique for electrophilic fluorination, especially with aromatic systems. Fluorinations of 1,3-dicarbonyl compounds proceed well and techniques for promoting reactivity in other carbonyl derivatives are described. ‘In-situ’ formation of other reagents, e.g. by reaction of fluorine with other halogens and with water, provides convenient methodology for halogenation and oxidation. 相似文献
3.
Robert G. Syvret William J. Casteel Jr. Jaidev S. Goudar 《Journal of fluorine chemistry》2004,125(1):33-35
Fluoroaryl 1,2,4-triazolin-5-ones are an important class of herbicidal compounds useful in a variety of crop protection applications, primarily for the control of grassy and broad-leaf plant species. While a number of different synthetic strategies can be used for the step-wise preparation of these complex molecules, it is generally preferred to introduce fluorine later in the synthetic pathway, since the presence of fluorine and other halogens has a dominant effect on all subsequent synthetic steps. We have investigated the reactions that occur between aryl triazolinones and a variety of fluorination agents, including F2/N2, XeF2, (CF3SO2)2NF, Selectfluor®, CF2(OF)2, CF3OF, CH3COOF, and CF3COOF, and have used this knowledge to develop several alternative high-yielding routes to fluoroaryl 1,2,4-triazolin-5-ones. The fluorine introduction strategy and experimental results for a representative example of this important class of compounds are discussed herein. 相似文献
4.
Richard D. Chambers Darren Holling Andrei S. Batsanov 《Journal of fluorine chemistry》2004,125(5):661-671
Direct fluorination of various quinoline derivatives in acidic reaction media gives fluorinated quinoline products arising from electrophilic substitution processes. 相似文献
5.
Takashi Okazoe Kunio Watanabe Masahiro Itoh Daisuke Shirakawa Kengo Kawahara Shin Tatematsu 《Journal of fluorine chemistry》2005,126(4):519-525
A new synthetic procedure for the preparation of perfluorinated carboxylic acid membrane monomers from non-fluorinated compounds has been developed. A key step in the synthetic route is liquid-phase direct fluorination reaction with elemental fluorine. Direct fluorination of a partially fluorinated diester, which was prepared from a hydrocarbon diol and a perfluorinated acyl fluoride, followed by thermal elimination, gave a perfluorinated diacyl fluoride, which is a precursor of a perfluorinated carboxylic acid membrane monomer. 相似文献
6.
Bakenova Zagipa 《Journal of fluorine chemistry》2007,128(10):1168-1173
Anodic fluorination of five-membered nitrogen-containing heterocyclic sulfides like tetrazolyl sulfides was comparatively studied. The anodic fluorination of tetrazolyl sulfides having α-electron-withdrawing groups was successfully carried out to provide α-monofluorinated tetrazolyl derivatives in moderate yields. This is in sharp contrast to the low efficient anodic fluorination of triazolyl sulfides. Thus, it was found that the efficiency of anodic fluorination is greatly affected by the basicity of the heterocyclic groups of the starting heterocyclic sulfides. 相似文献
7.
Richard D. Chambers Takashi Nakano Graham Sandford 《Journal of fluorine chemistry》2009,130(9):792-1498
Attempts to develop a direct enantioselective fluorination protocol using elemental fluorine and an appropriate Lewis acid and chiral ligand system are described. 相似文献
8.
Selective anodic fluorination of electrophilic alkenes 总被引:1,自引:0,他引:1
Vasile Dinoiu Kazuako Kanno Tsuyoshi Fukuhara Norihiko Yoneda 《Journal of fluorine chemistry》2005,126(5):753-758
Anodic fluorination of some electrophilic alkenes (conjugated with electron-withdrawn groups), ethyl cinnamates, RC6H4CHCHCO2Et (R = H, CH3, CH3O, F and CF3), cinnamonitrile, C6H4CHCHCN, phenyl stryryl ketone, and t-butyl styryl ketone using ammonium fluorides as the fluorine source and supporting electrolyte, in CH2Cl2 as electrolytic solvent yields the expected vicinal difluoro compounds, as mixture of erythro and threo isomers. The anodic fluorination of phenyl 3,5-di-t-butyl-4-hydroxystyryl ketone yields two monofluoro compounds. A possible reaction mechanism is discussed. 相似文献
9.
A series of optically enriched monofluorinated dipeptides incorporating an α-fluoro-α-amino acid were prepared by enantio- and diastereoselective electrophilic fluorination. This previously unsuccessful approach to fluorinated dipeptides can now be achieved with up to 73:27 enantiomeric ratio and high >98:2 diastereomeric ratio. 相似文献
10.
Ana Maria Ferraria 《Journal of fluorine chemistry》2004,125(7):1087-1094
A fluorination reactor was designed and built in the laboratory. The optimal conditions of fluorination within the reactor were selected by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis of fluorinated surfaces of a film and a plaque of pure high-density polyethylene (HDPE). This reactor was used to post-mould fluorinate plaques and films of a range of mixtures of virgin and recycled HDPE with and without (re)introduction of additives. The ability to be fluorinated has shown no dependence on the composition virgin/recycled HDPE.Comparison of in-line and post-mould fluorinated samples showed that fluorine concentration profile in depth is thinner in the in-line fluorinated sample when compared with the post-mould fluorinated sample, though the fluorination degree in the extreme surface is larger in the in-line fluorinated sample. This is attributed to a migration of lower surface energy chain blocks towards the surface in the material at high temperatures, which is the case in the in-line fluorination, hindered in the post-mould fluorination where maximum temperature is below the melting point to keep the macroscopic shape. The additives played a minor role in the ability of the surface to be fluorinated. 相似文献
11.
Robert Musiol Josef Jampilek Barbara Podeszwa Jacek Finster Dominik Tabak Jiri Dohnal Jaroslaw Polanski 《Central European Journal of Chemistry》2009,7(3):586-597
In the present paper we describe results on the synthesis and lipophilicity determination of a series of biologically active
compounds based on their heterocyclic structure. For synthesis of styrylquinoline-based compounds we applied microwave irradiation
and solid phase techniques. The correlation between RP-HPLC retention parameter log k (the logarithm of retention factor k) and log P data calculated in various ways is discussed, as well as, the relationships between the lipophilicity and the chemical structure
of the studied compounds.
相似文献
12.
Richard D. Chambers Takashi Okazoe Emmanuelle Thomas 《Journal of fluorine chemistry》2010,131(9):933-936
Reactions of dialkyl ethers with either fluorine or Selectfluor™ led to the formation of unusual difluorinated polyether products in modest yields. A mechanism involving initial fluorination of the site adjacent to ether oxygen followed by elimination of hydrogen fluoride, reaction of the generated enol system with a further equivalent of fluorinating agent giving an oxonium system which reacts with water during aqueous work-up to lead eventually to the products observed, is suggested. 相似文献
13.
Ji-Chang Xiao 《Journal of fluorine chemistry》2005,126(4):473-476
A microwave-assisted fluorination method for 1,3-dicarbonyl compounds using Selectfluor® has been developed. 2-Monofluorinated products can be obtained in high yield in neutral reaction conditions with addition of 1 eq. of Selectfluor®. Treatment of 1,3-dicarbonyls with 3 eq. of Selectfluor® in the presence of tetrabutylammonium hydroxide (TBAH) as the base results in the formation of 2,2-difluorinated derivatives only. 相似文献
14.
亲电氟化反应的新进展 总被引:2,自引:0,他引:2
介绍了自八十年代以来亲电氟化反应的最新进展, 其中包括众多的N-F类电氟化试剂的制备, 它们和各种底物的反应以及此类亲电氟化反应可能的机理。 相似文献
15.
A. A. A. Boraei 《Monatshefte für Chemie / Chemical Monthly》1994,125(8-9):869-876
Summary The deprotonation and acid ionization constants of some quinoline derivatives in aqueous organic solvents were determined. The organic solvents used include methanol and ethanol as amphiprotic solvents andDMF andDMSO as dipolar aprotic solvents. The obtainedpK
1 andpK
2 values are discussed with respect to the nature and the amount of the organic component. The high stabilization of the non-protonated form by dispersion forces and of the proton by its interaction with the solvent are the main factors responsible for the increase in the ionization constants of the protonated forms of the quinolines under investigation. On the other hand, H-bonding interactions (in addition to the electrostatic effect) seem to play the major role in determining the second acid-base equilibrium of 8-hydroxyquinoline. The deprotonation constants of the examined quinolines are correlated with their experimentally determined lone-pair ionization potential values.
Lösungsmitteleffekte auf die Ionisationskonstanten einiger Chinolinderivate
Zusammenfassung Die Deprotonierungs- und Ionisationskonstanten einiger Chinolinderivate wurden in wäßrigen organischen Medien, darunter Methanol und Ethanol als amphiprotische undDMF undDMSO als dipolare aprotische Lösungsmittel, bestimmt. Die gemessenenpK 1- undpK 2-Werte werden im Hinblick auf die Art und Menge der organische Komponente diskutiert. Die hohe Stabilisierung der nichtprotonierten Form durch Dispersionskräfte und des Protons durch Wechselwirkungen mit dem Lösungsmittel sind die wesentlichen Faktoren, die für den Anstieg der Ionisationskonstanten der protonierten Formen der untersuchten Chinoline verantwortlich sind. Andererseits scheinen Wasserstoffbrückenbindungen — zusätzlich zum elektrostatischen Effekt — das zweite Säure-Basen-Gleichgewicht von 8-Hydroxychinolin entscheidend zu beeinflussen. Die Deprotonierungskonstanten aller untersuchten Chinoline werden mit ihren experimentell bestimmtenlone-pair-Ionisationspotentialen korreliert.相似文献
16.
Alain Tressaud Etienne Durand Christine Labrugère 《Journal of fluorine chemistry》2004,125(11):1639-1648
Due to their extreme reactivity, fluorine and fluorinated gases may be used to modify the surface properties of numerous materials. In the following, the surface fluorination of some carbon-based compounds (graphite, graphitised carbon fibres, carbon blacks and elastomers) using CF4 rf plasma technique and direct F2-gas fluorination is proposed. From XPS studies, the different types of CF bonding obtained in the materials after treatment have been correlated either to the physico-chemical characteristics of the pristine material or to the experimental parameters of the fluorination. Reaction mechanisms are proposed. 相似文献
17.
Yi Cao 《Tetrahedron》2005,61(28):6854-6859
Various 2-oxazolidinones were galvanostatically electrooxidized in the presence of various fluoride salts. It was found that a fluorine atom was introduced to the α-position of the nitrogen atom of N-acyl- and N-alkoxycarbonyl-2-oxazolidinones to provide the corresponding α-fluorinated products in moderate to good yields. In the case of N-phenoxycarbonyl derivative, fluorination took place on the phenyl group selectively. 相似文献
18.
19.
Nguyen Quang VuDanielle Grée René GréeEric Brown Gilles Dujardin 《Tetrahedron letters》2003,44(34):6425-6428
Reaction of polysubstituted 2-hydroxyalkyldihydropyrans with DAST led regiospecifically to fluorination at the exocyclic position, except for primary alcohols. Difluorination of carbonylated analogues with deoxo-fluor™ occurred also regioselectively. The unexpected stability and synthetic potential of these new allylic fluorides are discussed. 相似文献
20.
The outstanding characteristics of fluorine gas, e.g., extreme reactivity and oxidizing power, and the utmost electronegativity of F− ion, lead to very strong bonds between fluorine and most of the other elements of the periodical table. Treatments involving F2, fluorinated gases and rf plasma-enhanced fluorination (PEF) constitute exceptional tools for modifying the surface properties of materials. Many advantages of these techniques can be indeed outlined, when compared to more conventional methods: low-temperature reactions (even at room temperature), chemical modifications limited to surface only without changing the bulk properties, possible non-equilibrium reactions. Depending on the type of starting materials and employed techniques, the improved properties may concern wettability, adhesion, chemical stability, barrier properties, biocompatibility, grafting, mechanical behavior. Several examples of surface fluorination will be given on various types of carbon-based materials, elastomers and polymers. 相似文献