From Trifluoroacetic Acid

Br COCp3 - Preparation by reaction of bromine on 2,4-dihydroxy-a,a,a-trifluoroacetophenone in acetic add at r.t. (49%) [4689]. 

There is also an erroneous reference. It concerns the 2, 6 -dihydroxytrif-luoroacetanilide [4698], 

COCF3 Obtained by reaction of 26% nitric acid on 2,4-dihy-droxy-3-methyl-a,a,a-trifluoroacetophenone in acetic acid at 0° (21%) [4689]. 

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Potassium trifluoroacetate [2923-16-2] M 152.1, m 140-142°, pK 0.52 (for CFjCOjH). To purify dissolve the salt in trifluoroacetic acid with ca 2% of trifluoroacetic anhydride, filter and evaporate carefully to dryness (avoid over heating), and finally dry in a vacuum at 100°. It can be recrystallised from trifluoroacetic acid (solubility in the acid is ca 50.1%). [J Am Chem Soc 74 4746 1952, 76 4285 1954-, J Inorg Nucl Chem 9 166 1959.]... 

A very common oxidizing reagent is peroxytrifluoroacetic acid, which is usually generated in situ from trifluoroacetic acid [29, 30, 31] or trifluoroacetic anhydride [32, 33, 34] and hydrogen peroxide Peroxytrifluoroacetic acid is one of the most efficient epoxidizing reagents [35] It can be used to prepare epoxides... 

Starting from Trifluoroacetic Acid Derivatives Trifluoroacetic acid and its derivatives (e.g., esters, anhydride, fluoral, trifluoroethanol) are the major channel of the organic fluorine industry. They are relatively inexpensive and, compared to halons, they do not exhibit major environmental problems. They are the main source for the synthesis of trifluoromethylated compounds. 

Thiophenes are best converted to the tetrahydro derivatives by the so-called ionic hydrogenation. This depends on the successive addition of a proton (from trifluoroacetic acid) and a hydride ion (from triethylsilane) (75T311). A subsequent improvement involved the use of HC1/A1C13 to form the thiophenium ion and then reaction with triethylsilane (78T1703) best results are obtained with the substrate/Et3SiH/AlCl3 ratio of 1 3 0.3. The mechanism of the reaction is shown in Scheme 43. Evidence for this has been provided by the use of Et3SiD, when D enters positions 3 and 5 in the product. 

The preparation of fluonnated acid anhydrides can be done by simple methods Phosphorus pentoxide removes a molecular equivalent of water from trifluoroacetic acid and tnfluoromethanesulfomc acid and forms the mixed anhydride [Si] (equation 53)... 

The large MS peak at 69 may be the CF3 radical derived from trifluoroacetic acid. The peak at 126 may represent AIC from partial hydrolysis of the sample. 

Reversed-phase high-performance liquid chromatography (RP-HPLC) is the usual method of choice for the separation of anthocyanins combined with an ultraviolet-visible (UV-Vis) or diode-array detector (DAD)(Hebrero et al., 1988 Hong et ah, 1990). With reversed-phase columns the elution pattern of anthocyanins is mainly dependent on the partition coefficients between the mobile phase and the Cjg stationary phase, and on the polarity of the analytes. The mobile phase consists normally of an aqueous solvent (water/carboxylic acid) and an organic solvent (methanol or acetonitrile/carboxylic acid). Typically the amount of carboxylic acid has been up to 10%, but with the addition of a mass spectrometer as a detector, the amount of acid has been decreased to as low as 1 % with a shift from trifluoroacetic acid to formic acid to prevent quenching of the ionization process that may occur with trifluoroacetic acid. The acidic media allows for the complete displacement of the equilibrium to the fiavylium cation, resulting in better resolution and a characteristic absorbance between 515 and 540 nm. HPLC separation methods, combined with electrochemical or DAD, are effective tools for anthocyanin analysis. The weakness of these detection methods is a lack of structural information and some nonspecificity leading to misattribution of peaks, particularly with electrochemical... 

To prevent N-oxide formation the tertiary nitrogen of (181) is blocked by protonation. The salt prepared from trifluoroacetic acid and (181) is epoxidized with CP3CO3H work-up of the reaction mixture furnishes the epoxide (182 equation 66). ... 

Measured in cycles per second from trifluoroacetic acid standard. Measured in cycles per second from benzene standard. 

CF3-substituted reagents may be classified according to their number of carbon atoms. The C[-reagents may furnish F3C-radicals, radical ions or ions. C2 reagents containing a CF3 group may readily be obtained from trifluoroacetic acid or its aldehyde or alcohol. 

This report describes mainly C2-C4 CF3-substituted reagents derived from trifluoroacetic acid, trifluoroacetoacetate or from trifluoropropene. Several useful C2 reagents with CF3-substitution were obtained from N-tertiary trifluorothioacetamides as shown in the schemes to be detailed below. We have also elaborated the chemistry of the so far hardly studied trifluoroacetic dithioesters and of several CF3-substituted iminium salts (schemes 5a and 5b). 

The selection of results shows the usefulness of simple and readily available trifluoromethylated compounds deriving mainly from trifluoroacetic acid or trifluoropropene as CF3-carrying reagents. Such an approach avoids tedious Cl-F exchange reactions and leads directly to convergent synthesis of more complex trifluoro-methylated molecules. 

Complementary to the traditional xanthate system used to make viscose rayon, films, and sponges, or the use of aqueous NaOH to dissolve cellulose under limited conditions, many nonaqueous solvent systems for cellulose have subsequently been developed. Apart from trifluoroacetic acid, which is the only volatile solvent known for cellulose, the others consist of reagents that react with the hydroxyl groups of cellulose in a polar aprotic solvent, such as dimethyl sulfoxide or A,A-dimethylacet-amide (DMAC). 

Figures 8.3 and 8.4 show the synthetic pathways for mefenacet [19] and flu-fenacet [20], respectively. The new key intermediates to produce flufenacet are acetoxyacetamide derivative 3, derived from acetoxyacetylchloride (2) and N-isopropyl-4-fluoroaniline (1), and 2-methylsulfonyl-5-trifluoromethyl-l,3,4-thiadiazole (5), derived from trifluoroacetic acid.

American Industrial Hygiene Association Laboratory Safety Committee. Hydrofluoric Acid Bum from Trifluoroacetic Acid available at http //www2.umdnj.edu/eohssweb/aiha/accidents/chemicalexposure. htm Trifluoracetic (accessed August 15, 2009). 

The initial studies on the capacity of the mercurial PhHg-CF, to act as a CFj-transfer reagent were carried out with material obtained by fluorination of the chloro- or, preferably, bromo-analogue [PhHg CX, (X = Cl or Br, respectively)] with PhHgF-HF. - A better synthesis has been developed recently this involves the preparation of trifluoromethylmercuric bromide starting from trifluoroacetic acid and mercuric oxide (see above) and then a... 

Imporved procedure 120 g FeCls was suspended in 500 ml H2SO4 (70%), and 30 ml o-dimethosybenzene added under stirring. After 18 hours of stirring, 500 g ice was added and the precipitate filtered off. Washing with 1000 ml H2O, 500 ml ethanol and 300 ml xylene and crystallization from trifluoroacetic acid yielded 13.8 g (46%) of 2,3,6,7,10,11-hexamethoxytripheny-lene, mp > 300°C. 

Space requirement for the repeat units of the polymers as measured by Langmuir-Blodgett technique by means of pressure-area isotherms on water (polymers spread from trifluoroacetic acid/chloroform (1/4 vol/vol) mixtures as reported in Reference 150) does only less depend on the number of alkyl groups in the main chain. The required space per basic unit is 37.5 for x = 2, 41.0 for Ph and goes only slightly up to 51 A forx = 10. From those results, it becomes obvious that the main influence on self-aggregation comes from the sf side chains. 

Proton conductivity phosphoric acid. Nation N117 and HjPO -PBI membranes as a function of temperature.The membrane prepared by the PPA process has an acid doping level of 32, and the conductivity was measured at 0% relative humidity the DMAc-cast and acid-imbibed membrane has an acid doping level of 5.7 (proton conductivity measurement in an atmosphere with water to air molar ration of 0.7) the membrane cast from trifluoroacetic acid has an acid doping level of 6.0 and the proton conductivity was measured in a relative humidity of 5%. (Source Li ef... 

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