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1.
Silvana Modena Pierangelo Calini Guglielmo Gregorio Giovanni Moggi 《Journal of fluorine chemistry》1988,40(2-3):349-357
Liquid phase fluorination of diethyleneglycol dimethyl ether tetraethyleneglycol dimethyl ether, 2[1,2-dichloro-1,2-difluoroethyl] tetrahydrofuran and 2[1,2-dichloro-1,2-difluoroethyl] dioxane 1,4 produce the corresponding perfluoroethers in 56, 43, 67 and 74 % yields respectively.
The by-products are partially fluorinated compounds and no fragmentation is observed.
The simplicity of the reactions and method of preparation make this approach to fluorinated fluids and oils industrially attractive. 相似文献
2.
Young-Ho Oh Wonhyuck Yun Chul-Hee Kim Sung-Woo Jang Sung-Sik Lee Sungyul Lee Dong-Wook Kim 《Molecules (Basel, Switzerland)》2021,26(10)
We present the intra- and inter-molecular organocatalysis of SN2 fluorination using CsF by crown ether to estimate the efficacy of the promoter and to elucidate the reaction mechanism. The yields of intramolecular SN2 fluorination of the veratrole substrates are measured to be very small (<1% in 12 h) in the absence of crown ether promoters, whereas the SN2 fluorination of the substrate possessing a crown ether unit proceeds to near completion (~99%) in 12 h. We also studied the efficacy of intermolecular rate acceleration by an independent promoter 18-crown-6 for comparison. We find that the fluorinating yield of a veratrole substrate (leaving group = −OMs) in the presence of 18-crown-6 follows the almost identical kinetic course as that of intramolecular SN2 fluorination, indicating the mechanistic similarity of intra- and inter-molecular organocatalysis of the crown ether for SN2 fluorination. The calculated relative Gibbs free energies of activation for these reactions, in which the crown ether units act as Lewis base promoters for SN2 fluorination, are in excellent agreement with the experimentally measured yields of fluorination. The role of the metal salt CsF is briefly discussed in terms of whether it reacts as a contact ion pair or as a “free” nucleophile F−. 相似文献
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4.
Taizo Ono Yoshihisa Inoue Chikara Fukaya Yoshio Arakawa Youichiro Naito Kazumasa Yokoyama Kouichi Yamanouchi Yoshiro Kobayashi 《Journal of fluorine chemistry》1985,27(3):333-346
Electrochemical fluorination of 2-methoxy-1,1,1-trifluoro-2-(F-methyl) octane gave the corresponding perfluorinated ether in 27% yield, along with cyclic by-products in 9%. A mixture of partly fluorinated tertiary amines, consisting of 1-dipropylamino-F-1-propene and 1-dipropylamino-2-hydryl-F-propane, did not afford a superior yield of tri(F-propyl)amine compared to the unfluorinated tripropylamine. 1-Diethylamino-2-(F-methyl)-F-1-pentene was fluorinated to give the corresponding F-tertiary amine in fairly good yields, together with 1-di(F-ethyl)amino-2-hydryl-2-(F-methyl)-F-pentane and their fragmented products. The study indicates that blocking of the α-carbon atom of an ether with F-methyl groups seems to reduce fragmentation, resulting in good yields of an unrearranged product. However, partial fluorination of a tertiary amine prior to electrochemical fluorination rather allows high yields of undesired by-products, as far as our experiments were concerned. 相似文献
5.
A simple, practical, and convenient fluorination of 1,3-dicarbonyl compounds was achieved by direct use of aqueous hydrofluoric acid and iodosylbenzene (PhIO). The reaction of ethyl benzoylacetate with the reagent system of aqueous HF and PhIO in CH(2)Cl(2) gave ethyl 2-fluoro-2-benzolyacetate in 98% yield. Other 1,3-dicarbonyl compounds including β-keto esters and 1,3-diketones underwent the fluorination reaction to give the corresponding fluorinated products in good yields. 相似文献
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7.
《Journal of fluorine chemistry》1986,32(1):41-76
It is known that the electrochemical fluorination of trialkylamines in liquid HF takes place readily in good yields, whereas dialkyl ethers give low yields. The latter fluorinated ethers are of interest for their low temperature properties. Our goal in this work was to prepare fluorinated aminoalkyl ether fluids which might combine the favorable yields of amines and properties of ethers. Several dialkylamine and alkylene units were combined in a variety of diamino monoethers, diamino diethers, and monoamino monoethers. Electrochemical fluorination yields as high as 50% were obtained in materials of the first class. The structure-yield relationships and the properties of these new fluids are described. 相似文献
8.
The direct chiral Lewis acidic enantioselective chlorination and fluorination of beta-keto phosphonates is presented; the chlorination proceeds in high yields and with up to 94% ee using NCS as the chloro source, while the fluorination with (PhSO2)2NF (NFSI) gives the optically active alpha-fluoro-beta-keto phosphonates in moderate to good yields and with up to 91% ee. 相似文献
9.
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
10.
1,3-Ketoesters and 1,3-diketones react with fluorine gas, using Durham multichannel modular microreactor technology, on a preparatively useful scale. High conversions and yields of monofluorinated products were obtained. A consideration of the mechanism of fluorination of dicarbonyl systems provides a rationale of the scope and limitations of the use of microreactor technology for such direct fluorination processes. We conclude that it is especially appropriate for the fluorination of diketones and ketoesters that exist mainly in the enol form at equilibrium and/or undergo rapid keto-enol interconversion. A one-stage route to fluoroketones from ketoesters was achieved by allowing the crude product mixture obtained from the fluorination of the ketoesters to stand for a period of time before reaction work-up. 相似文献
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12.
《Tetrahedron》1988,44(7):2055-2062
Organocopper compounds add to enones and enoates in the presence of chlorotrimethylsilane in ether giving the conjugate adducts in preparatively useful yields via the silyl enol ethers. Presence of lithium iodide is important and excess of chlorotrimethylsilane accelerates the reactions.The combination of organocopper compound, iodotrimethyl-silane and dimethyl sulfide gave faster reactions and very high yields, particularly in dichloromethane, where the reaction mixtures gradually became homogeneous. 相似文献
13.
Klaus Meyersen Jean Y. C. Wang 《Journal of polymer science. Part A, Polymer chemistry》1967,5(8):1827-1844
The synthesis and cyclocopolymerization with sulfur dioxide of four 1,5- and 1,6-dienes (bicyclopentene, bicyclohexene, dicyclopentenyl ether, and dicyclohexenyl ether) and one tetraene (quartercyclopentene) is described. Under optimum conditions, completely soluble copolymers are obtained from bicyclopentene in high conversions at temperatures down to ?39°C. Bicyclohexene also gave soluble copolymers, but in a by far slower reaction and in low conversion. Quartercyclopentene does copolymerize, but as expected, gives only insoluble polymers. The two compounds with 1,6-diallyl ether structure, dicyclopentenyl ether and dicyclohexenyl ether, failed to polymerize. The influence of initiator, temperature, reaction medium, diene concentration, etc., on the properties of the polymers was studied in detail for copolymerizations of bicyclopentene. Only a very limited number of peroxides in unusual large quantities was found to be effective in initiating this copolymerization. The reaction is further limited to a narrow choice of solvents, e.g,. diethyl ether and tetrahydrofuran, in order to obtain soluble products. Polymerization could not be achieved in ethanol, benzene, methylene chloride, dimethyl sulfoxide, and tetramethylene sulfone; excess sulfur dioxide yields only dark and insoluble products. Diene concentrations of below 0.3 wt.-% are normally required to obtain poly(bicyclopentene sulfones) which are soluble in dimethyl sulfoxide, tetramethylene sulfone, or sulfuric acid. Polymerization can be carried out from room temperatures down to ?39°C.; optimum results are generally obtained around 0°C. Inherent viscosities of 1.72 (0.5 g./100 ml. dimethyl sulfoxide) have been measured. X-ray diffractions are those of amorphous polymers. 相似文献
14.
A facile and direct fluorination process of alkynes and diynes was developed. In the presence of n‐butyllithium, the reaction of a series of terminal alkynes and diynes with the electrophilic fluorinating reagent (NFSI) proceeded to afford various 1‐fluoroalkynes and 1‐fluoro‐1,3‐diynes in moderate to high yields. 相似文献
15.
《Journal of fluorine chemistry》1986,34(2):183-189
Electrochemical fluorination of N,N-diethylcyclohexylamine and N-ethyldicyclohexylamine gave the corresponding F-amines together with several other compounds arising from incomplete fluorination and fragmentation reactions. In the case of N,N-diethylcyclohexylamine yields of 51–52% were obtained and most of the reaction products were isolated and identified. With N-ethyldicyclohexylamine a lower yield (16%) was observed; the resultant reaction mixture was too complex to allow the identification of its components. Comments are made about the reaction mechanism, and NMR and IR data are reported for identified compounds. 相似文献
16.
Anodic fluorination of N-substituted pyrroles was carried out in MeCN containing supporting fluoride salts such as Et3N-nHF (n = 2-5) and Et4NF-4HF with use of platinum electrodes under constant current conditions. Anodic fluorination of N-methyl- and N-p-tosylpyrroles having an electron-withdrawing cyano group proceeded smoothly to provide the corresponding fluorinated products in moderate to excellent yields, while anodic fluorination of N-methylpyrrole devoid of an electron-withdrawing cyano group did not take place and a polymeric product was formed at the anode surface. In sharp contrast to the cases of N-methylpyrroles, even N-p-tosylpyrrole devoid of an electron-withdrawing cyano group underwent anodic fluorination efficiently. Diels-Alder reaction of 5,5-difluoro-1-methyl-3-pyrrolin-2-one (2e) derived from anodic fluorination of 2-cyano-1-methylpyrrole (2a) with various dienes was carried out to provide the cycloaddition products in excellent yields. Furthermore, Michael reaction of 2e with various nucleophiles was also successfully carried out to provide the Michael addition products in good to excellent yields. 相似文献
17.
Aldehydes and ketones have been converted efficiently to their corresponding Mannich products by various dimethyl(methylene)ammonium salts under a range of reaction conditions. The several methods used to form these derivatives are compared. Excellent approaches to aldehyde derivatives involve treating the enol silyl ether of the carbonyl compound with methyllithium and then an iminium salt, or directly adding the iminium salt to the enol silyl ether. Ketones may be derivatized effectively by treatment with potassium hydride, followed by an iminium salt, or from the enol silyl ether by addition of the iminium reagent. Use of iminium reagents in the Mannich reaction is recommended because the yields are often good and the site of attachment on an unsymmetrical ketone is both predictable and controllable. 相似文献
18.
Max M. Boudakian 《Journal of heterocyclic chemistry》1968,5(5):683-684
Previous studies on the solvent-free fluorination of partially-chlorinated heterocyclics such as 2-chloropyridine, 2,3,4,6- and 2,3,5,6-tetrachloropyridine, and 2,4,6-trichloropyrimidine with alkali metal fluorides or hifluorides revealed an inconsistent product pattern: degradation, partial or complete halogen exchange could occur. The present study concerned application of the solvent-free halogen exchange technique (potassium fluoride) to 2,6-dichloropyridine (I). The latter, as well as its fluorination products, exhibited good stability at 400° to provide an 80% yield of 2,6-difluoropyridine (III). Moderation of fluorination conditions also permitted isolation of the precursor, 2-chloro-6-fluoropyridine (II), a new compound. The above solvent-free process to III is superior to the previously-reported halogen-exchange route in dimethyl sulfone solvent on the basis of yield, reaction time and number of processing steps. 相似文献
19.
V. A. Matyshak L. A. Berezina O. N. Sil’chenkova V. F. Tret’yakov G. I. Lin A. Ya. Rozovskii 《Kinetics and Catalysis》2009,50(1):111-121
In situ IR spectroscopic studies show that a formate, an aldehyde-like complex, and bridging and linear methoxy groups exist on the alumina surface involved in methanol conversion. In the absence of methanol in the gas phase, the interaction between two bridging methoxy groups yields dimethyl ether in the gas phase. When methanol is present in the gas phase, it interacts with methoxy groups on the surface. This reaction makes the main contribution to the formation of dimethyl ether. The linear methoxy group undergoes conversion via several routes. The main route is desorption with methanol formation in the gas phase, and no more than 10% of the linear methoxy groups are converted into formate and aldehyde, which are CO2 sources in the gas phase. In the absence of methanol in the gas phase, the conversion rate of the methoxy groups is independent of the presence of water and oxygen. A scheme of the surface reactions is suggested to explain the conversion of the methoxy groups. 相似文献
20.
采用一维层流预混火焰模型对二甲醚/甲醇/空气预混气体的流动反应过程进行了数值模拟, 考察甲醛、甲酸等污染物的生成规律. 结果表明: 在低流速下, 添加甲醇能够改变二甲醚反应途径, 抑制二甲醚的低温氧化反应. 当添加和二甲醚等质量的甲醇时, 二甲醚几乎不发生低温氧化反应, 生成的OH自由基减少是导致其发生的主要原因. 随着甲醇添加量的增加, 甲酸排放指数EIHCOOH迅速降低, 而甲醛排放指数EIHCHO在少量增加后持续降低. 添加适量甲醇能够同时降低这两种污染物的排放指数. 相似文献