Trifluoroacetic Acid

Milne, J. B.

doi:10.1016/b978-0-12-433841-8.50007-9

Cited by 16 publications

(5 citation statements)

References 206 publications

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“…Correlation of rates with these concentrations, presented in Figures 7 and 8, correspond well with the uninomial kinetic equation (12). Values of k, p, and q were obtained…”

Section: Table IIIsupporting

confidence: 72%

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Acidolytic ring opening of cyclic siloxane and acetal monomers. Role of hydrogen bonding in cationic polymerization initiated with protonic acids

Wilczek¹,

Chojnowski²

1981

Macromolecules

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The kinetics of ring-opening reactions between trifluoroacetic acid and hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), and dioxolane (DXL) was studied in the inert solvent methylene chloride and in some cases in n-heptane. The equilibrium constants of hydrogen-bond formation in the reaction system were determined by an independent method-infrared spectroscopy. Consideration of these constants in kinetic analysis proved to be necessary to obtain a consistent interpretation of the kinetic data. The competition between acid-acid interaction and acid-monomer interaction dominates the kinetic pattern and is suggested as a common phenomenon in cationic polymerization initiated with protonic acids. The role of H-bonded polymeric complexes in the process, including charge stabilization, multifunctional action, and cooperative hydrogen-bond migration, is discussed.

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“…Correlation of rates with these concentrations, presented in Figures 7 and 8, correspond well with the uninomial kinetic equation (12). Values of k, p, and q were obtained…”

Section: Table IIIsupporting

confidence: 72%

“…Parameters of the Kinetics Equation (12) a Unit, mol1"•9"9 dm30H9"l) s"'. b p and q are orders in the catalyst and in the monomer, respectively.…”

Section: Table IIImentioning

confidence: 99%

Acidolytic ring opening of cyclic siloxane and acetal monomers. Role of hydrogen bonding in cationic polymerization initiated with protonic acids

Wilczek¹,

Chojnowski²

1981

Macromolecules

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“…Equilibrium constants for dimerization of TFA or TCA in acetonitrile are not available (one previous study even noted that no dimerization was observed via IR spectroscopy) . However, there is literature precedent for dimerization of carboxylic acids in acetonitrile .…”

Section: Resultsmentioning

confidence: 99%

Reactivity of Proton Sources with a Nickel Hydride Complex in Acetonitrile: Implications for the Study of Fuel-Forming Catalysts

Rountree

Dempsey

2016

Inorg. Chem.

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The reactivity of the nickel hydride complex [HNi(P2 PhN2 Ph)2]+ (P2 PhN2 Ph = 1,3,5,7-tetraphenyl-1,5-diaza-3,7-diphosphacyclooctane) with a variety of acids to form hydrogen in acetonitrile was evaluated using stopped-flow spectroscopy in order to gain a better understanding of how the proton source influences the reaction kinetics when evaluating fuel-forming catalysts in acetonitrile. This reaction is initiated by the rate-determining step in the catalytic cycle for the hydrogen-evolving catalyst [Ni(P2 PhN2 Ph)2]2+. Proton sources were evaluated with respect to pK a, homoconjugation, dimerization, heteroconjugation, and aggregation (for water). The effects of water and conjugate base were also studied. A linear free energy relationship between rate constant and pK a was revealed; rate constants increased with the magnitude of the homoconjugation constant for acids prone to homoconjugation, and second-order reactivity was observed for trifluoroacetic and trichloroacetic acid, suggesting dimerization. Upon the addition of water, an increase in the observed rate constant was seen, in line with the formation of hydronium. When added to trifluoroacetic acid, water was shown to cause a decrease in the observed rate constant, suggesting that water inhibits acid dimerization. Collectively, these findings highlight that the selection of proton sources for the study of molecular electrocatalysts in acetonitrile must account for more than acid pK a.

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“…We have chosen the interaction of the unsubstituted phosphacoumarin PHOS with toluene as the model reaction. Note that due to the complex equilibria between monomeric, dimeric, trimeric, etc., species in TFA [ 53 ], it is hard to estimate the most feasible counter-anions. Additionally, the compound 1 is also an acid, and thus may take part in these equilibria, forming complexes with TFA.…”

Section: Resultsmentioning

confidence: 99%

“…We have also tried to estimate the relative energies of mono- and dicationic species. Note that multiple positively charged ions are likely to be present in TFA solution, including dimeric, trimeric and polymeric species [ 53 ]. Therefore, the accurate prediction of the nature of the protonated species has to account for all of them.…”

Section: Resultsmentioning

confidence: 99%

Superelectrophilic Activation of Phosphacoumarins towards Weak Nucleophiles via Brønsted Acid Assisted Brønsted Acid Catalysis

Zalaltdinova,

Sadykova,

Gazizov

et al. 2024

IJMS

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The electrophilic activation of various substrates via double or even triple protonation in superacidic media enables reactions with extremely weak nucleophiles. Despite the significant progress in this area, the utility of organophosphorus compounds as superelectrophiles still remains limited. Additionally, the most common superacids require a special care due to their high toxicity, exceptional corrosiveness and moisture sensitivity. Herein, we report the first successful application of the “Brønsted acid assisted Brønsted acid” concept for the superelectrophilic activation of 2-hydroxybenzo[e][1,2]oxaphosphinine 2-oxides (phosphacoumarins). The pivotal role is attributed to the tendency of the phosphoryl moiety to form hydrogen-bonded complexes, which enables the formation of dicationic species and increases the electrophilicity of the phosphacoumarin. This unmasks the reactivity of phosphacoumarins towards non-activated aromatics, while requiring only relatively non-benign trifluoroacetic acid as the reaction medium.

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Trifluoroacetic Acid

Cited by 16 publications

References 206 publications

Acidolytic ring opening of cyclic siloxane and acetal monomers. Role of hydrogen bonding in cationic polymerization initiated with protonic acids

Acidolytic ring opening of cyclic siloxane and acetal monomers. Role of hydrogen bonding in cationic polymerization initiated with protonic acids

Reactivity of Proton Sources with a Nickel Hydride Complex in Acetonitrile: Implications for the Study of Fuel-Forming Catalysts

Superelectrophilic Activation of Phosphacoumarins towards Weak Nucleophiles via Brønsted Acid Assisted Brønsted Acid Catalysis

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