Hexafluoroacetone trihydrate

• CAS: 34202-69-2
• Catalog Number: ACM34202692-1
• Category: Other Products
• Molecular Weight: 220.07
• Molecular Formula: C3H6F6O4
• Synonyms: Perfluoroacetone trihydrate
• Complexity: 124
• Defined Atom Stereocenter Count: 0
• Exact Mass: 220.0170
• Formal Charge: 0
• Heavy Atom Count: 13
• Hydrogen Bond Acceptor Count: 10
• Hydrogen Bond Donor Count: 3
• Isotope Atom Count: 0
• Monoisotopic Mass: 220.0170
• Rotatable Bond Count: 0
• Topological Polar Surface Area: 20.1 Ų

Case Study

Helix-Stabilizing, Hydrogen-Bond Modulating and Solvent-Applicable Properties of Hexafluoroacetone Trihydrate

Rajan R, Awasthi S K, Bhattacharjya S, et al. Biopolymers, 1997, 42(2): 125-128.

Hexafluoroacetone trihydrate (HFA) exhibited remarkable peptide helix-stabilizing activity in aqueous solutions: Two peptide fragments derived from chicken riboflavin carrier protein were tested. In pure water at pH 2.8, both peptides showed no stable secondary structure. Gradual addition of HFA induced typical α-helical conformations, and the helical structure became fully formed at 50% (v/v) HFA. The 21-residue peptide reached a helicity of 40% in 50% HFA, while the same peptide only achieved 31% helicity in 50% trifluoroethanol (TFE), proving HFA had stronger helix-inducing capacity. It demonstrated potent hydrogen-bond modulating effects: HFA has a low pKa value of 6.58 and strong hydrogen bond donating ability, with a solvent-solute hydrogen bond strength of 7.56 kcal/mol, higher than water and TFE. Its fluorinated groups show weak hydrogen bond accepting ability, which prevents disruption of intramolecular peptide hydrogen bonds and facilitates the formation of compact helical structures. Additionally, HFA presented excellent practical advantages as a biocompatible solvent: It has no interfering residual protons and requires no deuteration for NMR testing, and features good far-ultraviolet transparency suitable for circular dichroism (CD) analysis. NOESY spectra clearly displayed characteristic helical \(d_{NN}\) and medium-range nuclear Overhauser effects, further confirming stable peptide conformations. These studies demonstrate that hexafluoroacetone trihydrate possesses significant helix-stabilizing, hydrogen-bond modulating and solvent-applicable properties for peptide conformational research.The experiment used two synthetic peptides purified by reversed-phase HPLC and identified via mass spectrometry. A series of aqueous solutions with different HFA volume fractions were prepared for CD spectral detection. 400 MHz NMR measurements were carried out in 50% HFA aqueous solution to analyze peptide spatial conformations. Comparative tests with ethanol and TFE were performed under identical conditions to evaluate helix induction efficiency. Hydrogen bond strength and solvent characteristics were also determined by spectroscopic methods. The results verified that HFA relies on hydrophobic effects and unique hydrogen bond properties to dehydrate peptide backbones, stabilize intramolecular hydrogen bonds, and effectively promote α-helix formation in peptides, serving as an excellent cosolvent for peptide structural analysis.

Hydrolytic Catalyst, Xerogel-Forming and Mixed-Oxide Synthesizing Properties of Hexafluoroacetone Trihydrate

Carpenter J P, Lukehart C M, Price B T, et al. Inorganica Chimica Acta, 1995, 229: 121-125.

Hexafluoroacetone trihydrate (HFATH) exhibited excellent hydrolytic catalytic activity for metal alkoxides: As a self-contained water source and mild acid catalyst with a pKa of 6.58, HFATH directly reacted with neat tetraethylorthosilicate (TEOS) without extra water, alcohol or aqueous catalysts. The reaction generated silica xerogel precipitates, and the ceramic yield rose steadily with the increase of HFATH/TEOS molar ratio, reaching the maximum value at the ratio of approximately 4:3. It presented remarkable xerogel-forming performance with controllable particle morphology: Reaction temperature and time greatly affected particle size and structure. At 5 °C with a 30-minute reaction, the obtained silica particles were as small as 25 nm; particles gradually grew to 0.1-1.5 μm and formed interconnected three-dimensional networks when the reaction lasted for 30 minutes at 64 °C. The prepared silica xerogel had a bulk density of 1.99 ± 0.03 g/cm³, higher than products from traditional sol-gel methods, and only trace fluorine residue (0.088 wt%) was detected in the final solid. Additionally, HFATH enabled efficient synthesis of mixed-metal oxide xerogels: When mixed TEOS and titanium isopropoxide reacted with HFATH at 5 °C, white mixed oxide precipitate formed immediately. The resultant Si/Ti mixed xerogel had a molar ratio of 9:6, with a titanium yield up to 92% and silicon yield of 27%. EDS and microscopic characterization confirmed uniform distribution of two metal elements in the particulate products. These studies demonstrate that hexafluoroacetone trihydrate possesses significant hydrolytic catalyst, xerogel-forming and mixed-oxide synthesizing properties for anhydrous sol-gel preparation.
The experiment adopted pure HFATH and metal alkoxides as raw materials under dry nitrogen protection. A series of reactions with different HFATH/TEOS molar ratios were carried out at room temperature, 5 °C and 64 °C respectively. After reaction, products were washed and vacuum dried. Karl Fischer titration was used to determine the total water content of HFATH. SEM, STEM and EDS were applied to analyze particle size, morphology and elemental composition. Ceramic yield and bulk density of xerogels were measured by microanalysis and flotation method. The results verified that HFATH can provide bound water and catalytic activity simultaneously, realizing anhydrous sol-gel reaction, and is especially suitable for preparing xerogels doped with water-sensitive substances and multi-component metal oxide materials.

Molten Globule Inducing, Conformational Regulating and Helix-Stabilizing Properties of Hexafluoroacetone Trihydrate

Bhattacharjya S, Balaram P. Protein Science, 1997, 6: 1065-1073.

Hexafluoroacetone trihydrate (HFA) exhibited prominent molten globule inducing activity on hen egg-white lysozyme: In aqueous solution containing 25% (v/v) HFA, lysozyme formed a stable equilibrium molten globule state. Near-ultraviolet CD signals nearly disappeared, indicating the complete disruption of native tertiary structure, while far-ultraviolet CD bands were enhanced, proving native-like secondary structures were well retained. It showed distinct conformational regulating effects with concentration dependence: At HFA concentrations below 25%, the protein gradually transformed from native state to compact molten globule state; when HFA content rose to 50% and above, the structure further converted into an open helical state, accompanied by sharp decline in ANS (1-anilino-8-naphthalene) binding capacity. Thermal testing revealed the molten globule state underwent cooperative unfolding at around 55 °C, reflecting stable side-chain interactions inside the structure. Additionally, HFA exerted selective structural stabilizing effects: Hydrogen-deuterium exchange experiments demonstrated that the four α-helices and C-terminal 3₁₀ helix of lysozyme had high proton protection factors, maintaining intact structures, whereas the triple-stranded antiparallel β-sheet domain showed rapid proton exchange and preferential unfolding. Tryptophan fluorescence quenching and ¹H-NMR tests further confirmed aromatic residues remained buried in the compact interior, with no native ring current signals observed. These studies demonstrate that hexafluoroacetone trihydrate possesses significant molten globule inducing, conformational regulating and helix-stabilizing properties for protein structural research.
The in vitro experiment adopted hen egg-white lysozyme as the research object, with multiple groups of aqueous solutions containing different H concentrations (0% to 60% v/v) prepared at pH 3.0. Circular dichroism, fluorescence spectroscopy and ¹H-NMR were used to detect protein conformational changes. ANS binding assays and iodide quenching tests were carried out to characterize surface hydrophobicity and residue exposure. Hydrogen-deuterium exchange experiments were performed to analyze structural stability of different protein domains, and thermal denaturation curves were recorded to evaluate structural cooperativity. The results verified that HFA acts as an effective protein structure modifier, which can sequentially induce molten globule state and open helical state, and selectively stabilize helical domains while destabilizing β-sheet regions of proteins.

Helix-Inducing, Conformational Modulating and Cold-Denaturation Inducing Properties of Hexafluoroacetone Trihydrate

Bhattachariya S, Venkatraman J, Kumar A, et al. Journal of Peptide Research, 1999, 54: 100-111.

Hexafluoroacetone trihydrate (HFA) exhibited prominent helix-inducing activity on melittin at low pH: In aqueous solution at pH 2.0, melittin existed as a random coil structure. Gradual addition of HFA triggered a highly cooperative conformational transition, and the transformation was fully completed at 3.6 M (50% v/v) HFA. Far-UV CD spectra displayed typical α-helix characteristic bands at 208 nm and 220 nm, proving the formation of a stable helical structure. Compared with 2,2,2-trifluoroethanol (TFE), HFA showed stronger helix-inducing capacity, as TFE required a concentration as high as 8 M to achieve the same structural effect. It exerted distinct conformational modulating effects on peptide molecules: 2D NMR experiments revealed continuous sequential NH/NH and medium-range NOE signals along the whole peptide chain, confirming a well-ordered monomeric helix. Only the T10-G11-T12 segment presented slight flexibility, while the C-terminal region with multiple positively charged residues also formed intact helical conformations under HFA treatment. Additionally, HFA induced obvious cold-denaturation phenomena: At low HFA concentrations, the helical structure of melittin unfolded at both low and high temperatures, with the maximum helical content appearing at around 30 °C. This phenomenon indicated that HFA interacted with peptides mainly through hydrophobic forces of trifluoromethyl groups. Fluorescence tests further verified HFA disassembled melittin tetramers into monomers and quenched tryptophan fluorescence effectively. These studies demonstrate that hexafluoroacetone trihydrate possesses significant helix-inducing, conformational modulating and cold-denaturation inducing properties for peptide molecules.
A series of in vitro experiments were carried out using melittin as the research object. Multiple groups of solutions with gradient HFA concentrations were prepared at pH 2.0. Circular dichroism spectroscopy was used to monitor conformational changes and thermal stability of melittin. 1D and 2D NMR techniques including NOESY and TOCSY were applied to analyze the spatial structure and dynamic characteristics of the peptide. Fluorescence spectroscopy was adopted to detect molecular aggregation and tryptophan quenching effects. Comparative tests with TFE were also conducted under identical conditions. The results verified that HFA relies on hydrophobic solvation to replace water molecules around peptides, promote intramolecular hydrogen bond formation, and efficiently induce stable helical conformations even under low pH conditions with electrostatic repulsion.