Enhancements of Trifluoroacetic Acylated Five‐membered Heterocyclic Compounds Using as Additives in Dye Sensitized Solar Cells

In this study, five‐membered heterocyclic compounds are trifluoroacetic acylated for the purpose of providing more long pairs to enhance electrolyte in dye sensitized solar cells (DSSCs). Four five‐membered heterocyclic compounds will be trifluoroacetic acylated with trifluoroacetic anhydride by Friedel‐Crafts acylation: furan, thiophene, pyrrole and N‐methylpyrrole. The properties will be measured by cyclic voltage (CV), Fourier transform infrared spectroscopy (FTIR), solar simulator, and electrochemical impedance spectroscopy (EIS). We find out that furan and thiophene which we add in electrolyte as additives can increase short circuit current and photovoltaic efficiency, and furthermore, all the trifluoroacetic acylated heterocyclic compounds perform better photoelectric abilities than non‐trifluoroacetic acylated one. The photovoltaic efficiency will be increased from 4.439% to 5.197% when 1wt% trifluoroacetic acylated thiophene is added in electrolyte as additives.     

Convenient synthesis of 4-triflouromethylpyrazoles by cyclization of triflouroacetylated hydrazones

Several 4-trifluoromethyl-1-alkylpyrazoles were synthesized in good yields by trifluoroacetic anhydride-pyridine induced cyclization reaction of acylhydrazones prepared from aldehyde dialkylhydrazones and trifluoroacetic anhydride.     

Analytical isotachophoresis utilizing computer simulation. II. Assessment of optimum separation conditions for urinary trifluoroacetic acid metabolized from anaesthetic halothane

Experimentally determined optimum separation conditions for a metabolite of anaesthetic halothane in urine, trifluoroacetic acid, were assessed by means of computer simulation of the isotachophoretic steady-state. The simulation confirmed that urinary acids and trifluoroacetic acid can be separated in the limited pH range of 3.5-3.7 buffered by beta-alanine, as far as the pH dependence of effective mobility is utilized. The separated fraction of the trifluoroacetic acid zone was identified by mass spectrometry. The simulated coefficient of the calibration curve agreed well with the observed value.     

High-resolution microwave studies of ring-structured complexes between trifluoroacetic acid and water

The rotational spectra of the complexes between one trifluoroacetic acid molecule and up to three water molecules have been recorded using a pulsed nozzle Fourier transform microwave spectrometer. The unambiguous assignments of them are made on the basis of the agreement between the experimentally determined rotational constants and the theoretical predictions from ab initio calculations using MP2/6-311++G(2df,2pd). All the complexes exhibit hydrogen-bonded ring structures. The fine splittings observed in some of the a-type transitions of the trifluoroacetic acid-H2O dimer were analyzed in terms of the likely tunneling motions of the hydrogens in the H2O molecule. Further calculations of the equilibrium constants for these three hydrated complexes of trifluoroacetic acid were also made to evaluate their fractions against the trifluoroacetic acid monomer in the atmosphere.     

BAL resin for the preparation of secondary amines

Although amino acids anchored through the amino function to BAL resins can not easily be released from the resin by treatment with neat trifluoroacetic acid, we have shown that secondary amines can be obtained from BAL resins using trifluoroacetic acid solutions.     

Synthesis of tri- and tetrasubstituted furans catalyzed by trifluoroacetic acid

Substituted 2-hydroxy-3-acetylfurans are synthesized by alkylation of tert-butyl acetoacetate with an alpha-haloketone followed by treatment of the obtained intermediate with trifluoroacetic acid (TFA). A second alkylation of the intermediate followed by treatment with trifluoroacetic acid provides access to disubstituted 2-methylfurans.     

Reactivity of aminopyrroles: Protonation

The behaviour of 2- and 3-aminopyrroles towards protonation is similar. In dimethyl sulphoxide/trifluoroacetic acid they are protonated at the exocyclic nitrogen, whereas in pure trifluoroacetic acid, protonation at the 5- and/or 3-position of the ring takes place.     

Use of Tert-Butyl Sulfoxides as Latent Sulfenyl Cation Equivalents

This paper reports a new and practical method of trifluoro-acetoxysulfenylation of olefins, starting from t-butyl sulfoxides. The latter, in a mixture of trifluoroacetic anhydride and trifluoroacetic acid, do not undergo the Pummerer reaction. Instead, sulfenyltrifluoroacetates 2 are formed and they add in situ to olefins.     

Temperature-controlled Cascade Reaction of Phloroglucinoltribenzyl Ether Promoted by Trifluoroacetic Anhydride and Trifluoroacetic Acid

We report the first trifluoroacetic anhydride-and trifluoroacetic acid-promoted cascade reaction with phloroglucinoltribenzyl ether and carboxylic acid as starting materials. By simply varying the temperature of systems containing the same starting materials, different products were produced in high yields. A three-step consecutive reaction process was also proposed.     

New methods for preparing N,N-dialkyltrifluoroacetamides

N,N-Dialkylacetamides and N,N-dialkylformamides can be converted into N,N-dialkyltrifluoroacetamides by treatment with either trifluoroacetic anhydride or trifluoroacetic acid.     

Reactions of N-thiobenzoyl-α-amino-acids and related N-substituted thiobenzamides with trifluoroacetic anhydride

5-(2'-Benzamidoacyloxy)thiazoles are formed by the reaction of N-thiobenzoyl-α-amino-acids with trifluoroacetic anhydride. Corresponding esters on similar treatment undergo isosteric S-O exchange, giving N-benzoyl-α-amino-acid esters. While these are further examples of the differences shown in the reactions of N-(2-carboxyalkyl)thiobenzamides compared with their benzamide analogues, N^α-thiobenzoyl-α-amino-acid amides are found to undergo cyclisation in trifluoroacetic anhydride to give 5-trifluoroacetamido-thiazoles, following the same reaction path as their N-benzoyl analogues. Terminal N-thiobenzoyl dipeptides give 5-(N-2-carboxyalkyl) trifluoroacetamido-thiazoles on treatment with trifluoroacetic anhydride, and it is established that trifluoroacetic anhydride fails to cleave the amide group of terminal N-thioacyl dipeptides, and is therefore not a suitable reagent for Edman-type sequence analysis of polypeptides.The present work completes a project establishing routes from α-amino-acids to thiazoles carrying a heteroatom (O, N or S) at the 5-position.     

A diastereoselective synthesis of 4-azidotetrahydropyrans via the Prins-cyclization

A three component coupling of aldehydes, homoallylic alcohols and sodium azide is achieved in the presence of trifluoroacetic acid in dichloromethane to produce 4-azidotetrahydropyran derivatives in high yields with all cis-selectivity. The use of trifluoroacetic acid makes this procedure simple and cost-effective.     

A powerful cascade approach for expeditious synthesis of trifluoromethylated furans

A powerful approach to synthesize trifluoromethylated furans has been developed. The method is operationally simple, broad in substrate scope, and amenable to scale-up using trifluoroacetic anhydride. Meanwhile, the strategy not only provided a versatile approach to synthesize trifluoromethylated furans but also provides a new method for exploring the new reactivity of trifluoroacetic anhydride.     

Ambident Properties of 4-Substituted Thiosemicarbazides in Condensations with Fluoroacetic Acids

4-Substituted thiosemicarbazides react with di- and trifluoroacetic acids to give the corresponding 3-fluoroalkyl-4,5-dihydro-1,2,4-triazole-5(1H)-thiones. Condensation of 4,4-disubstituted thiosemicarbazides with trifluoroacetic acid leads to formation of 2-amino-5-trifluoromethyl-1,3,4-thiadiazoles.     

Tandem rearrangement involving a β-hydroxysulfoxide and cyclization processes toward the 1-benzenesulfonyl-5-benzenethio-1,2,2a,3,4,5-hexahydrobenz[c,d]indole oxygenated at the 4-position

Treatment of compound 4 with trifluoroacetic anhydride under reflux in chlorobenzene underwent a tandem rearrangement to produce compound 5 . When the acetylated derivative of 4 , was treated with trifluoroacetic anhydride in the presence of Lewis acids produced two cis cyclized conformers 7a and 7b , presumably through the intermediate B .     

An Efficient Method for the Iodination of C5-Position of Dialkoxy Pyrimidines and Uracil Bases1,2

N-Iodosuccinimide in trifluoroacetic acid and trifluoroacetic anhydride was found to be an excellent reagent for the conversion of 2,4-dialkoxy pyrimidines to 2,4-dialkoxy-5-iodopyrimidines. Iodination at C₅-position of uracil and its derivatives was also accomplished with the above reagent.     

A one-pot procedure for trifluoroacetylation of arylamines using trifluoroacetic acid as a trifluoroacetylating reagent

A convenient procedure for the preparation of aryl trifluoroacetamides from aryl amines is described that employs 2-4 M equiv of trifluoroacetic acid in refluxing xylene as a trifluoroacetylating agent. Addition of an amount of pyridine that is equimolar to the amount of trifluoroacetic acid present in the reaction mixture facilitates the trifluoroacetylation of rather basic arylamines.     

Solid–liquid equilibria in the acetic acid–propanoic acid and propanoic acid–trifluoroacetic acid systems

Solid–liquid equilibria in the binary systems, propanoic acid–acetic acid and propanoic acid–trifluoroacetic acid, were measured by a synthetic method. A solid compound (1:1) was found in the propanoic acid–trifluoroacetic acid system. The obtained activity coefficients were successfully fitted by the Wilson equation.     

Trifluoroacetic anhydride. A convenient NMR solvent for carbohydrates. 270 MHz 1H NMR studies of 2-acetamido-2-deoxyhexoses

The use of trifluoroacetic anhydride as an NMR solvent for sugars has been explored. Dissolution of carbohydrates in this solvent is accompanied by trifluoroacetylation at the hydroxyl groups. Esterification results in downfield shifts of the sugar protons yielding very well resolved ¹H NMR spectra. The use of trifluoroacetic anhydride in the analysis of complex systems is exemplified.     

Functional group oxidation using sodium perborate1

Sodium perborate in acetic acid is an effective reagent for the oxidation of anilines to nitroarenes and of sulphides to either sulphoxides or sulphones. It is also an excellent reagent for the oxidative deprotection of ketone dimethylhydrazones. Baeyer-Villiger oxidation of ketones can be carried out with sodium perborate in either trifluoroacetic acid or acetic acid/trifluoroacetic acid mixtures, and hydroquinones and certain highly substituted phenols are smoothly converted into quinones.