19430-93-4Relevant articles and documents
Siloxane based syntheses of fluorous ethenes and their tandem Heck reactions with aryl iodides
Csapo, Agnes,Rabai, Jozsef
, p. 79 - 85,7 (2020/09/16)
Perfluoroalkyl-ethenes (RfnCHCH2, 6a-c; a, n = 4; b, n = 6; c, n = 8) were prepared in good isolated yields (67-89%) and high purity (GC assay > 98%) from various fluorinated organosilanes in fluoride-anion assisted protodesilylation reactions. The environmentally more benign 'KF/NEt3/H2O' reagent combination introduced here was found as an effective substitute for the commonly used tetrabutylammonium- fluoride trihydrate (TBAF·3H2O) as a fluoride source. Fluorous styrenes ((E)-RfnCHCHAr, 8) were then prepared in good isolated yields (58-93%/iodoarene) and purities (GC assay > 95%) with the Pd(0) catalyzed Heck coupling of iodoarenes (Ar-I, 7) and perfluoroalkyl-ethenes generated in situ by the fluoride assisted cleavage of (β-perfluoroalkyl- α-iodo-ethyl)-siloxane ([RfnCH2CH(I)SiMe 2]2O, 3) precursors in DMF solution at elevated temperatures. They are accessible by the one-pot reaction of dimethylvinylchlorosilane (CH2CHSiMe2Cl, 2) and perfluoroalkyl iodides (Rfn-I, 1) as we reported earlier. Similarly, the radical chain addition of C8F17I to CH 2CHSi(OMe)3 (9) gave (β-perfluorooctyl-α-iodo- ethyl)-trimethoxysilane ([C8F17CH2CH(I)]Si(OMe) 3, 10) in good yield, which then was reacted with silica gel in dry toluene to obtain an SiO2-bonded (perfluorooctyl)ethene surrogate [silica(O)3SiCH(I)CH2C8F17, 11]. The fluoride assisted cleavage of 11 and tandem Heck reaction with iodobenzene afforded the appropriate cross-coupled product (E)-C8F 17CHCHPh.
Hiyama coupling reaction of fluorous alkenyl-fluorosilanes: Scope and mechanistic considerations
Rábai, József,Csapó, ágnes,Bodor, Andrea
, p. 85 - 92 (2012/05/20)
Novel fluorous alkenyl-fluorosilanes (CnF 2n+1CHCHSiMe2F; n = 4, 6, 8; 5a-c) were synthetized in a three step procedure from perfluoroalkyliodides and dimethylvinylchlorosilane. They were first reacted with iodobenzene at room temperature in Hiyama coupling reaction (DMF, Pd(OAc)2, TBAF, 72 h) to afford the appropriate ω-perfluoroalkyl-styrenes (CnF2n+1CHCHC 6H5, n = 4, 6, 8); then the reactivity of 5a with monosubstituted iodobenzenes was studied. The coupling reaction of 5a with o-substituted iodobenzenes usually failed, while that of with the m- and p-substituted ones gave fluorous styrenes [m- or p-(C4F 9CHCH)C6H4X], independently of the electronic effect of their substituent (X = Br, CF3, CH3, OCH 3). These volatile products can easily be isolated by steam-distilltaion and purified further by distillation. The mechanism of the above coupling reactions was a pure Hiyama type involving fluoride-ion induced transmetallation without any Heck type contribution, since no coupling product of C6F13CHCH2 and C6H5I was observed in blank control experiments using similar conditions (DMF, TBAF, Pd(OAc)2, 72 h, 25°C).
Impact of fluorine substituents on the rates of nucleophilic aliphatic substitution and β-elimination
Martinez, Henry,Rebeyrol, Adele,Nelms, Taylor B.,Dolbier Jr., William R.
experimental part, p. 167 - 175 (2012/03/27)
A measure of the quantitative effect of proximate fluorine substituents on the rates of SN2 and E2 reactions has been obtained through a study mainly of reactions of fluorinated n-alkyl bromides with weak base, strong nucleophile azide ion and strong base/nucleophile methoxide ion in the protic solvent methanol and the aprotic solvent, DMSO. The order of reactivity for SN2 reactions of azide in methanol at 50 °C was found to be: n-alkyl-Br > n-alkyl-CHFBr > n-perfluoroalkyl-CH2CH 2Br n-perfluoroalkyl-CH2Br > n-alkyl-CF2Br. Approximate relative rates of reaction were: 1, 0.20, 0.12, 1 × 10 -4, -5. The order of reactivity for E2 reactions was found to be: n-perfluoroalkyl-CH2CH2Br n-alkyl-CF2Br > n-alkyl-CHFBr > n-alkyl-Br. The approximate relative rates for reaction of methoxide in methanol at 50 °C were: 1100, 4.4, 1.9, 1.
HYDROFLUOROCARBON REFRIGERANT COMPOSITIONS AND USES THEREOF
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, (2008/06/13)
Disclosed herein are hydrofluorocarbon refrigerant or heat transfer fluid compositions that are useful in refrigerain or air conditioning apparatus or as heat transfer fluids. The compositions of the present invention are also useful in centrifugal compressor apparatus that employ two-stage compressors or single slab.single pass heat exchangers.
Process for producing a polyfluoroalkyl (meth)acrylate
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Page 5; 6, (2008/06/13)
A process for producing a polyfluoroalkyl (meth)acrylate, which comprises isolating, from a reaction mixture containing a polyfluoroalkyl (meth)acrylate obtained by reacting a polyfluoroalkyl iodide of the formula CnF2n+1(CH2)mI (wherein n is an integer of from 2 to 7, and m is an integer of from 1 to 4) with a metal (meth)acrylate in tert-butanol, said polyfluoroalkyl (meth)acrylate by the following steps (1) to (3):(1) a step of taking out a crude liquid from the reaction mixture by solid-liquid separation;(2) a step of distilling the crude liquid to separate it into compound group A of compounds having a lower boiling point than the polyfluoroalkyl (meth)acrylate and compound group B of the polyfluoroalkyl (meth)acrylate and compounds having a higher boiling point than the polyfluoroalkyl (meth)acrylate; and(3) a step of distilling and purifying the polyfluoroalkyl (meth)acrylate from the compound group B in the presence of a polymerization inhibitor.
Nucleophilic displacements of 2-perfluoroalkyl-1-iodoethanes: Improved synthesis of fluorine-containing malonic esters
Trabelsi,Szoenyi,Geribaldi
, p. 177 - 181 (2007/10/03)
The replacement of iodide in 2-perfluoroalkyl-1-iodoethanes by anions derived from dialkyl malonate affords α-(2-perfluoroalkyl)ethyl malonic esters in high yields with negligible elimination and dialkylation, using bases such as K2CO3/su
Application of trimethylvinylsilane as a convenient synthetic precursor of (perfluoroalkyl)ethenes: An unusual fluoride-induced elimination-desilylation coupled reaction
Szlávik, Zoltán,Tárkányi, Gábor,G?m?ry, ágnes,Rábai, József
, p. 2347 - 2349 (2007/10/03)
(equation presented) A convenient and effective method for the preparation of perfluoroalkylated ethenes is described. First, the free radical addition of perfluoroalkyl iodides to trimethylvinylsilane in the presence of AIBN gave iodoethylsilane intermediates (F(CF2)nCH2CHISiMe3, n = 4 (1), 6 (2),8 (3), 10 (4); 94-99%). Then an unusual dehydrohalogenation-desilylation reaction was effected by tetrabutylammonium fluoride, and finally the product isolation (F(CF2)nCH=CH2 (5-8), 62-87%) was facilitated using a fluorous phase separation technique. This novel approach can also be applied to adjust short C2 hydrocarbon units to functionalized fluorinated segments (e.g., HOCH2(CF2)8CH=CH2 (11), 71%). All structures were verified by state-of-the-art multinuclear one- and two-dimensional NMR experiments involving both homo-(19F-19F) and heteronuclear (1H-13C, 19F-13C) correlations based on the GMQFCOPS and inverse 1H and/or 19F detected GHSQC, GHMQC sequences with broad-band adiabatic 13C decoupling.
Effect of a Perfluoroalkyl Group on the Elimination and Substitution Reactions of Two Homologous Series of Perfluoroalkyl-Substituted Iodoalkanes
Brace, Neal O.,Marshall, Lawrence W.,Pinson, Carol J.,Wingerden, Gail van
, p. 2361 - 2368 (2007/10/02)
Substitution and elimination reactions of two homologous series of compounds, induced by strong bases, were studied in aqueous alcohol and anhydrous methanol solution.Series I compounds, RF(CH2)nI having n = 2 (RF = a perfluoroalkyl group, also named an F-alkyl group), gave only RFCH=CH2 under all conditions.By contrast, RF(CH2)3Igave 4-10 times as much substitution as elimination products.Isomerization of RFCH2CH=CH2 (6) to RFCH=CHCH3 (7) occurred; this result may account, in part, for the extremely high 7/6 alkene ratios (37-81/1) obtained from elimination reactions of RFCH2CHICH3.All series II compounds, RFCH2CHI(CH2) nCH3 (n = 0-5), gave entirely elimination, and principally toward the RF group.E/Z isomer ratios varied from 2.65 to 5.These results were compared to those obtained from 1- and 2-iodooctane under the same conditions.A practical synthesis of CF3(CF2)5CH2CH2CH2I is described; the isomeric (F-alkyl)propenes 6 and 7 were also separately prepared.Rates of reactions under standard conditions for both series I and II compounds were measured.Kinetically, only second-order processes were observed, but a sharp break occurred in rate as the RF group was separated more than two carbons from the departing iodine atom, in series I compounds.Series II compounds reacted about one-tenth as fast as series I compounds.These results are discussed in the context of previous work with F-alkyl-substituted compounds.
