Sodium Trifluoroacetate Research Articles

Sodium Trifluoroacetate: an Efficient Difluorocarbene Precursor for Alkenes

Abstract A novel and efficient difluorocarbene precursor was achieved. In a convenient procedure, a variety of alkenes could be gem-difluorocyclopropanated with sodium trifluoroacetate to give the corresponding products in moderate to high yields, using azobisisobutyronitrile (AIBN) as the catalyst.

Sodium Trifluoroacetate: An Efficient Precursor for the Trifluoromethylation of Aldehydes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Trifluoromethylation of carbonyl compounds with sodium trifluoroacetate

In the presence of copper(I) iodide as catalyst, a variety of carbonyl compounds, such as aldehydes, ketones and acid anhydrous, could be trifluoromethylated with sodium trifluoroacetate to give the corresponding alcohols in moderate to high yields, and a possible mechanism was proposed to explain the roles of catalyst and solvent in the reaction system.

The perchlorate anion is more effective than the trifluoroacetate anion as an ion-pairing reagent for reversed-phase chromatography of peptides

The addition of salts, specifically sodium perchlorate (NaClO 4), to mobile phases at acidic pH as ion-pairing reagents for reversed-phase high-performance liquid chromatography (RP-HPLC) has been generally overlooked. To demonstrate the potential of NaClO 4 as an effective anionic ion-pairing reagent, we applied RP-HPLC in the presence of 0–100 mM sodium chloride (NaCl), sodium trifluoroacetate (NaTFA) or NaClO 4 to two mixtures of synthetic 18-residue peptides: a mixture of peptides with the same net positive charge (+4) and a mixture of four peptides of +1, +2, +3 and +4 net charge. Interestingly, the effect of increasing NaClO 4 concentration on increasing peptide retention times and selectivity changes was more dramatic than that of either NaCl or NaTFA, with the order of increasing anion effectiveness being Cl − ≪ TFA − < ClO 4 −. Such effects were more marked when salt addition was applied to eluents containing 10 mM phosphoric acid (H 3PO 4) compared to 10 mM trifluoroacetic acid (TFA) due to the lesser starting anion hydrophobicity of the former mobile phase (containing the phosphate ion) compared to the latter (containing the TFA − ion).

Sodium trifluoroacetate: an efficient precursor for the trifluoromethylation of aldehydes

In a convenient and efficient procedure, the nucleophilic trifluoromethylation of aldehydes with sodium trifluoroacetate was achieved, using copper(I) halides as the catalyst.

Hexafluoroisopropanol as size exclusion chromatography mobile phase for polyamide 6.

The present study deals with the use of hexafluoroisopropanol (HFIP) as size exclusion chromatography (SEC) mobile phase for polyamide 6 (PA6). Contradictory conclusions relating to the use of HFIP as SEC mobile phase for polyamides are found in the literature. By using a multi-detector SEC apparatus equipped with on-line viscometer and multi-angle light scattering we have studied the chromatographic artifacts and the validity of the universal calibration (UC) in HFIP for different PA6 samples (hydrolytic and anionic, monofunctional or bifunctional activator). Appropriate SEC columns and optimized experimental conditions allow most of the chromatographic artifacts to be avoided, even in neat HFIP. The use of a salt in the mobile phase, namely 0.01 M tetraethylammonium nitrate (TEAN), slightly increases the elution volume for both PA6 and PMMA polymers. Under the right conditions, the UC substantially holds for PA6. The validity of the UC is not linked to the presence of TEAN in the mobile phase. With some PA6 samples, namely those anionically synthesized using a bifunctional activator, aggregation becomes a problem and the molar mass in neat HFIP is overestimated. Addition of TEAN prevents any aggregation of the above anionically synthesized PA6. In contrast, the use of a different salt, namely potassium trifluoroacetate, increases the extent of aggregation.

A technique for obtaining matrix-assisted laser desorption/ionization time-of-flight mass spectra of poorly soluble and insoluble aromatic polyamides.

Wet grinding methods for obtaining matrix-assisted laser desorption/ionization time-of-flight mass spectra of poorly soluble and insoluble low molecular mass oligomers (<4600 Da) of Nomex and Kevlar are described. Optimum conditions for sample preparation are given along with a detailed analysis of the spectra obtained. Two matrix materials were employed in this analysis, 1,8-dihydroxyanthrone (dithranol) and 3-aminoquinoline with potassium trifluoroacetate used as the cationizing agent. The spectra obtained in this study are sensitive to the matrix, molar mixing ratios of matrix/polymer/cationizing agent, and the sample preparation method.

HPLC-MS/MS determination of a peptide conjugate prodrug of doxorubicin, and its active metabolites, leucine-doxorubicin and doxorubicin, in dog and rat plasma

A HPLC-MS/MS Electrospray (ESI) method was developed and validated to quantify a peptide conjugate prodrug of doxorubicin (Dox-Con) and its active metabolites leucine-doxorubicin (Leu-Dox) and doxorubicin (Dox) in dog and rat plasma. The analytes were extracted from plasma by solid-phase extraction on a Bond Elut® C8 cartridge and eluted with chloroform–methanol (2:1). Eluates were evaporated and reconstituted in acetonitrile–5 μM sodium trifluoroacetate in 0.1% aqueous formic acid (20:80) and injected onto a Waters Oasis® HLB column. Analytes were eluted from the column with a solvent gradient into the mass analyzer. The ions were quantified in the selected reaction-monitoring mode (SRM), using positive ions, on a triple quadrupole mass spectrometer. The lower limits of quantification for Dox-Con, Leu-Dox, and Dox in plasma, were approximately 5, 1 (dog)/6 (rat), and 0.5 ng/ml, respectively. Intra- and inter-assay accuracy (% of nominal concentration) and precision (%CV) for all analytes were within 15 and 16%, respectively.

Signal enhancement in ESR spin-trapping for hydroxyl radicals.

In an ESR spin-trapping measurement of hydroxyl radicals formed in a Fenton reaction, the trapping efficiency with DMPO increased by about 300 times in a sodium trifluoroacetate solution, whereas it was little changed in a phosphate buffer.

Analysis of polyamides by size exclusion chromatography and laser light scattering

AbstractThe molar mass analysis of polyamides is complicated due to the fact that only a limited range of solvents can be used and association and aggregation phenomena have to be screened by adding electrolytes to the mobile phase. Optimum SEC behaviour is obtained when hexafluoroisopropanol + 0.05 mol/L potassium trifluoroacetate is used as the mobile phase. The calibration of the SEC system can be conducted in different ways. While a calibration with narrow disperse polymethyl methacrylate standards does not yield accurate molar mass information, the quantification can be done using an “artificial” calibration curve. This calibration curve is obtained by correcting the PMMA calibration curve with polyamide molar mass data from light scattering. The resulting molar mass distributions for different types of polyamides are compared with molar masses that are determined by size exclusion chromatography with a light scattering detector and an excellent correlation is obtained.

New solid ionic conductor based on poly(ethylene oxide) and sodium trifluoroacetate

Solid polymer electrolytes consisting of poly(ethylene oxide) (PEO) and sodium trifluoroacetate (CF 3COONa) with various salt mass fractions ( x≤0.435) have been prepared by the solvent casting method. Temperature and concentration dependent impedance studies of the cells M ∣ electrolyte ∣ M (M stands for stainless steel electrodes), as well as the conductivity behavior of the electrolyte suggest the existence of a complex in the blend. This is confirmed by differential scanning calorimetry (DSC) that shows a high melting (400 K) phase with a EO/Na ratio corresponding roughly to a 4:1 ( x=0.435) complex. The DSC measurements also indicate that the blends are thermally stable up to approximately 480 K. The conductivity ( σ) of the electrolyte is very sensitive to temperature ( T) and salt mass fraction ( x) in the blend: samples with low salt concentration show a linear dependence of ln σ with (1/ T) below 333 K (the euthetic melting temperature of PEO+complex), with an activation energy of 0.1±0.05 eV, and an almost flat variation above this temperature. The sample with concentration x=0.306 shows only one activated process in the whole temperature range (T<400 K). Typically, blends with the highest salt concentrations exhibit an anhydrous conductivity of 10 −4.5 S cm −1 at 303 K and 10 −3.5 S cm −1 at 313 K. The conductivity results are discussed in terms of the high mobility of the Na + ions in the amorphous phase of the complex.

ChemInform Abstract: A Convenient Synthesis of Trifluoroacetamides from Sodium Trifluoroacetate and Amines.

Abstract Trifluoroacetamides were prepared readily by reaction of sodium trifluoroacetate with triphenylphosphine di-iodide and amines consecutively under mild conditions with good yields.

A Convenient Synthesis of Trifluoroacetamides from Sodium Trifluoroacetate and Amines

Trifluoroacetamides were prepared readily by reaction of sodium trifluoroacetate with triphenylphosphine di-iodide and amines consecutively under mild conditions with good yields.

MALDI-TOF MS analysis of a library of polymerizable cyclodextrin derivatives.

Polymerizable cyclodextrin derivatives (PCDs) have been proposed as candidates for use in dental therapeutics (Bowen, 1996; Bowen and Reed, 1997). Here, PCD "libraries" were synthesized by quasi-random reactions of 6 moles of methacrylic anhydride plus 6 moles of cyclic glutaric anhydride per mole of beta-cyclodextrin (BCD) in solution. BCD has 21 reactive sites on each of its molecules. These proportions were based on probability calculations, which predicted that the products should have a minimum of 2 polymerizable substituents and acidic ligand groups on practically every one of the diverse product molecules. Matrix-assisted laser desorption/ionization (MALDI) time of flight (TOF) mass spectrometry (MS) gave valuable information regarding the masses of molecular ions representing the molecules that made up the PCD libraries. For the MALDI-TOF MS analyses, small samples were analyzed by the successive application of 3 solutions to the sample holder: the matrix in acetone, the products in water, and sodium trifluoroacetate in water. The resulting spectra had > 40 envelopes of mass peaks above background. The ionic-abundance peak heights had quasi-Gaussian configurations, with central peaks having masses in the neighborhood of 2000 g/mol (Daltons). Regardless of structural permutations within each peak, the range of these peaks was between about 1500 g/mol and 2900 g/mol. This range of masses was in accord with, but perhaps somewhat more narrow than, that predicted by the statistical method, which was based on equal reactivity of all hydroxyl groups. Analysis by MALDI-TOF MS gave valuable data regarding the masses, structures, and characteristics of the products formed and provided unanticipated information to facilitate improvements in future PCD syntheses.

Matrix-assisted laser desorption ionization time of flight mass spectrometry analysis of living cationic polymerization of vinyl ethers. I. Optimization of measurement conditions for poly(isobutyl vinyl ether)

Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) was utilized for the analysis of polymers obtained by the living cationic polymerization of isobutyl vinyl ether (IBVE) with the HCl-VE adduct/SnCl4/n-Bu4NCl initiating system in CH2Cl2 at −78 °C. Under optimized analysis conditions, well-resolved spectra were obtained for samples with number-average molecular weights of ≤104 with the use of 1,8-dihydroxy-9(10H)-anthracenone (dithranol) as a matrix and sodium trifluoroacetate as an added salt. The MS spectra showed only one series of peaks separated exactly by the mass of the IBVE. The observed mass of each peak was in good agreement with the theoretical one, which possesses one initiator fragment at the α end and one methoxy group originated from quenching with methanol at the ω end. Thus, detailed end group analysis is possible for poly(VE). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4023–4031, 2000

Toxicity of trifluoroacetate to aquatic organisms

AbstractAs a result of the atmospheric degradation of several hydrofluorocarbons and hydrochlorofluorocarbons, trifluoroacetate (TFA) will be formed. Through precipitation, TFA will enter aquatic ecosystems. To evaluate the impact on the aquatic environment, an aquatic toxicity testing program was carried out with sodium trifluoroacetate (NaTFA). During acute toxicity tests, no effects of NaTFA on water fleas (Daphnia magna) and zebra fish (Danio rerio) were found at a concentration of 1,200 mg/L. A 7‐d study with duckweed (Lemna gibba G3) revealed a NOEC of 300 mg/L. On the basis of the results of five toxicity tests with Selenastrum capricornutum, we determined a NOEC of 0.12 mg/L. However, algal toxicity tests with NaTFA and Chlorella vulgaris, Scenedesmus subspicatus, Chlamydomonas reinhardtii, Dunaliella tertiolecta, Euglena gracilis, Phaeodactylum tricornutum, Navicula pelliculosa, Skeletonema costatum, Anabaena flos‐aquae, and Microcystis aeruginosa resulted in EC50 values that were all higher than 100 mg/L. The toxicity of TFA to S. capricornutum could be due to metabolic defluorination to monofluoroacetate (MFA), which is known to inhibit the citric acid cycle. A toxicity test with MFA and S. capricornutum revealed it to be about three orders of magnitude more toxic than TFA. However, a bioactivation study revealed that defluorination of TFA was less than 4%. On the other hand, S. capricornutum exposed to a toxic concentration of NaTFA showed a recovery of growth when citric acid was added, suggesting that TFA (or a metabolite of TFA) interferes with the citric acid cycle. A recovery of the growth of S. capricornutum was also found when TFA was removed from the test solutions. Therefore, TFA should be considered algistatic and not algicidic for S. capricornutum. On the basis of the combined results of the laboratory tests and a previously reported semi‐field study, we can consider a TFA concentration of 0.10 mg/L as safe for the aquatic ecosystem.

One-pot synthesis of poly(cyclic ortho ester)s by the reaction of potassium perfluoroalkanoates with epibromohydrin using two-step catalysis of quaternary onium salts

One-pot synthesis of poly(cyclic ortho ester)s by the reaction of potassium perfluoroalkanoates with epibromohydrin (EBH) using quaternary onium salts is described. The reaction of potassium trifluoroacetate (KTFA) with EBH using quaternary onium salts such as tetrabutylphosphonium bromide (TBPB) produces the polymer with five-membered cyclic ortho ester structure in the backbone. This means that quaternary onium salts act as phase-transfer catalysts in the first step and polymerization catalysts in the second step during the reaction.

Effects of acid anion additions (trifluoroacetate and bromide) on soil solution chemistry of a northern hardwood forest soil

Experimental plots within the Hubbard Brook Experimental Forest, NH, were treated with sodium trifluoroacetate (TFA) and lithium bromide (Br), to study the impact of TFA alone and in the presence of increased anion concentrations (e.g. acid deposition) on the soil solution chemistry of a northern hardwood forest soil. Trifluoroacetate is a major atmospheric degradation product of replacement compounds of chlorofluorocarbons (CFC) and Br is widely used as a hydrologic tracer. Calculated drainage losses via soil water flow were less than 60% of inputs, added during the summer, and TFA and Br were temporarily retained in the soil until fall. The initial indication of an acid input of the treatments (HTFA, HBr) in the Bs2 horizon, which reflects stream water chemistry as well, was an increase of base cations in the soil solution, decreasing the soil's acid neutralizing capacity. Thereafter, trifluoroacetate and Br concentrations peaked after the peak in base cations, synchronous with peaks in H+ and Al concentrations. Organic anions, nitrate and chloride played the major role in accompaning base cations out of the solum. Sulfate retention at soil adsorption sites was increased by the presence of TFA and Br, reducing its role as a mobile anion of base cations in this experiment. Relative retention of anions for the whole profile of this northern hardwood forest soil was estimated by correlation analyses and input-output balances in decreasing order on an equivalant basis: SO4 > TFA = Br ≥ Cl > NO3 > organic anions. Recovery from acid additions were recorded within several weeks after the treatments were stopped. Evaluating the impact of added chemical compounds to soils must be considered within the context of linkages among element cycles and pools.

Environmental Risk Assessment of Trifluoroacetic Acid

The Montreal Protocol was developed in 1987 in response to concerns that the chlorofluorocarbons (CFCs) were releasing chlorine into the stratosphere and that this chlorine was causing a depletion of stratospheric ozone over Antarctica. This international agreement called for a phase out of these CFCs. Industry initiated a major effort to find replacements that are safe when properly used and safe to the environment. The toxicology and environmental fate of these first generation replacements has been studied extensively. It was determined that the new substances break down in the environment to give predominantly carbon dioxide, water and inorganic salts of chlorine and fluorine. The only exception is that some substances also break down to yield trifluoroacetic acid (HTFA), a substance resistant to further degradation. Recognizing this, industry embarked on a research and assessment program to study the potential effects of trifluoroacetate (TFA) on the environment and to investigate possible degradatio...

Electrochemical oxidation of cyclic polysilanes under ‘oxygen-free’ and ‘water-free’ conditions

Abstract The electrochemical behavior of seven substituted cyclic polysilanes, namely hexamesitylcyclotrisilane (Mes2Si)3 (I), 1,2,3,4-tetra-tert-butyltetramethyl-cyclotetrasilane [t-Bu(Me)Si]4 (II) (mixture of isomers), decapropylcyclopentasilane (Pr2Si)5 (III), dodecamethylcyclohexasilane (Me2Si)6 (IV), tetradecaethylcycloheptasilane (Et2Si)7 (V), hexadecamethylcyclooctasilane (Me2Si)8 (VI) and octadecamethylcyclononasilane (Me2Si)9 (VII), have been studied by cyclic voltammetry and preparative electrolysis in ‘oxygen-free’ and ‘water-free’ solutions of CH2Cl2+CH3CN+CF3COOH (4:1:1) containing sodium trifluoroacetate as the supporting electrolyte. The products are cyclic compounds with one or two oxygen atoms as well as silicon atoms in the rings. The effects of ring size and nature of substituent on the oxidation peak potentials and reactivity of starting materials, and on the selectivity of the outcoming products, are discussed.