Trifluoroethanol Research Articles

Ionic liquid catalysed synthesis of benzimidazolone from Ortho-Phenylenediamine in the presence of carbon dioxide as a carbonyl source under solvent free condition

In this study, we report synthesis of benzimidazolones from o-phenylene diamine by utilizing carbon dioxide as a carbonyl source under mild reaction conditions in the presence of ionic liquid as a catalyst. Six bifunctional protonic ionic liquids (PILs) were synthesised by reacting superbases 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) and 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU) with proton donors such as Trifluoroethanol (TFE), Cyclopropane carboxylic acid (CPCA) and 2,2,2-Trifluoroacetic acid (TFA). Among them, [TBDH+][TFE−] was the most effective, achieving high conversion rates of o-phenylene diamine to 2-benzimidazolone at 1 bar CO2 pressure and 60° C. This PIL could be reused for up to six cycles. Our method offers a green and efficient approach for producing 2-benzimidazolone derivatives, with potential applications in pharmaceuticals and materials science.

Cu@CuFe2O4 nanoparticles catalyzed oxidative functionalization of alkynes: Access to α,α‐dichloro ketones

In this study, novel Cu@CuFe2O4 nanoparticles were prepared by virtue of a simple method. By utilizing a compatible system involving N‐chlorosuccinimide (NCS) as the chlorine source and Cu@CuFe2O4 magnetic nanoparticles (NPs) as recyclable catalyst, we present a novel and practical method for directly obtaining aryl α,α‐dichloroketones in aqueous trifluoroethanol (TFE). The catalyst was recovered and reused up to five times with no significant decrease in activity. The current study provides a foundational raw material for the subsequent synthesis of chlorinated functional molecules, which is achieved through a mild transformation of arylalkynes using readily available commercial feedstocks and exhibiting good tolerance with various substituents on the aromatic ring, including the aliphatic alkyne. This novel heterogeneous catalyst may be used in numerous industrial applications because of its merits, such as considerable recyclability, low requirement for catalyst loading, cost‐effectiveness, and ease of handling.

Unveiling the Selectivity of Ru(II)-Catalyzed C-H Activation for Defluorinative Cyclization of 2-Arylbenzimidazole and Trifluoromethyl Diazo: A DFT Study.

The synthesis of monofluorinated heterocyclic compounds by C-H activation combined with defluorination is useful. Studies on the reaction mechanism and selectivity have shown that these processes play a positive role in promoting the development of monofluorinated reactions. Density functional theory (DFT) calculations were performed to investigate the mechanism and selectivity of Ru(II)-catalyzed 2-arylbenzimidazole with trifluoromethyl diazo. DFT calculations showed that C-H activation occurs through a concerted metalation/deprotonation (CMD) mechanism. After that, deprotonation and defluorinative cyclization are assisted by acetate and trifluoroethanol (TFE). Further mechanistic insights through noncovalent interaction (NCI) analysis were also obtained to elucidate the origin of the selectivity in the defluorination process.

1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP)-promoted regiospecific 1,6-hydroarylation of para-quinone methides with N-heteroarenes: Synthesis of unsymmetrical triarylmethanes

In this work, a recyclable and highly regioselective 1,6-hydroarylation of para-quinone methides (p-QMs) with N-heteroarenes has been developed under mild conditions. 1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP) as a solvent plays a significant role in this transformation to achieve a wide assortment of unsymmetrical triarylmethanes with high yields and excellent regioselectivity. This novel reaction is featured a very broad substrate scope and outstanding functional group tolerance and could also be scaled-up. Moreover, this Friedel-Crafts alkylation pathway is further supported by replacing HFIP with trifluoroethanol (TFE) in the control reactions.

Controllable 1,3-Bis-Functionalization of 2-Nitroglycals with High Regioselectivity and Stereoselectivity Enabled by a H-Bond Catalyst.

The selective modification of carbohydrates is significant for producing their unnatural analogues for drug discovery. C1-functionalization (glycosylation) and C1,C2-difunctionalization of carbohydrates have been well developed. In contrast, C3-functionalization or C1,C3-difunctionalization of carbohydrates remains rare. Herein, we report such processes that efficiently and stereoselectively modify carbohydrates. Specifically, we found that trifluoroethanol (TFE) could promote 1,3-bis-indolylation/pyrrolylation of 2-nitroglycals generated carbohydrate derivatives in up to 93% yield at room temperature; slightly reducing the temperature could install two different indoles at the C1- and C3-positions. Switching TFE to a bifunctional amino thiourea catalyst leads to the generation of C3 monosubstituted carbohydrates, which could also be used to construct 1,3-di-C-functionalized carbohydrates. This approach produced a range of challenging sugar derivatives (over 80 examples) with controllable and high stereoselectivity (single isomer for over 90% of the examples). The potential applications of the reaction were demonstrated by a set of transformations including the synthesis of bridged large-ring molecules and gram scale reactions. Biological activities evaluation demonstrated that three compounds exhibit a potent inhibitory effect on human cancer cells T24, HCT116, AGS, and MKN-45 with IC50 ranged from 0.695 to 3.548 μM.

Unraveling chemical glycosylation: DFT insights into factors imparting stereoselectivity

Stereoselective chemical glycosylation reactions are pivotal for preparing manifold biologically and medically important compounds, while mechanisms of chemical glycosylation reactions remain obscure and largely speculative. Herein, we performed DFT calculations to delve into the multifaceted mechanistic details of glycosylation reactions, including the equilibria among reactive glycosyl triflate intermediates in solution, the stereoselectivity imparting protecting groups, solvent effects, base, and the anomeric effect. Our results provided theoretical corroboration to 2-OAc neighbouring group participation (NGP), the arming/disarming effect, the coordination theory of solvent effect on glycosylation stereochemistry, and the influence of solvent polarity on the reaction kinetics spanning the SN1-SN2 continuum. For the first time, the existence of putative contact-ion-pairs (CIP) of glycosyl oxocarbenium and triflate anion in organic solutions was theoretically confirmed with the identification of multiple ground state structures employing an implicit Solvation Model based on Density (SMD). Kinetics of nucleophilic attack of model glucosyl triflates by simple alcohol acceptors ethanol (EtOH) and trifluoroethanol (TFE), complexed with 2,4,6-tri-tert-butylpyrimidine (TTBP) were explored, revealing the essential role of the close accompanying base for rendering glycosidic bond formation thermodynamically favourable. Our work deepens the comprehension of the glycosylation mechanism, paving the way for the rational design and future advancement of efficient and environmentally friendly stereoselective glycosylation reactions.

Pseudo-doping effect on structural and electrical properties of polyaniline-camphorsulfonic acid

Electroconductive polymers (ECP) are critical for the design of soft electronic and bioelectronic devices. Polyaniline:camphorsulfonic acid (PANI:CSA) is an example of a biocompatible and affordable ECP, whose electroconductivity is highly dependent on chain organization/conformation. PANI:CSA aggregation ordering is overlooked in most works, but it can greatly impact the performance of PANI:CSA-based devices and limit their applicability. A simple and cheap method to avoid random coil aggregation of PANI:CSA is to select solvents with pseudo-doping properties. This work presents a novel alternative solvent system, based on trifluoroethanol (TFE) and hexafluoropropanol (HFP) mixtures, capable of being removed without hampering the structural and electrical properties of PANI:CSA. For the first time, we present a systematic study that compares the performance of solvent systems containing different amounts of TFE and HFP, which, unlike m-cresol, the golden-standard of pseudo-doping, are easy to remove without compromising the ECP’s electroconductivity and biocompatibility. We also evaluate the influence of the processing method, drop-casting vs spin-coating, on the structural and electrical properties of the obtained samples. Samples obtained by spin-coating show a more consistent improvement in electroconductivity (σ(TFE) = 61 S cm−1, σ(TFE:HFP (50:50 vol)) = 70 S cm−1) and more intense near-infrared (NIR) absorption bands. Atomic force microscopy (AFM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) indicate that samples processed with HFP and m-cresol have higher benzenoid content, lower random coil aggregation and more efficient CSA doping. The solvent system comprised of equal parts of TFE and HFP was found to simultaneously enhance the electrical properties and structural ordering of PANI:CSA. We believe our results are critical for the fabrication of PANI-based next generation bioelectronic devices.

Synthesis of robust underwater glues from common proteins via unfolding-aggregating strategy

Underwater adhesive proteins secreted by organisms greatly inspires the development of underwater glue. However, except for specific proteins such as mussel adhesive protein, barnacle cement proteins, curli protein and their related recombinant proteins, it is believed that abundant common proteins cannot be converted into underwater glue. Here, we demonstrate that unfolded common proteins exhibit high affinity to surfaces and strong internal cohesion via amyloid-like aggregation in water. Using bovine serum albumin (BSA) as a model protein, we obtain a stable unfolded protein by cleaving the disulfide bonds and maintaining the unfolded state by means of stabilizing agents such as trifluoroethanol (TFE) and urea. The diffusion of stabilizing agents into water exposes the hydrophobic residues of an unfolded protein and initiates aggregation of the unfolded protein into a solid block. A robust and stable underwater glue can thus be prepared from tens of common proteins. This strategy deciphers a general code in common proteins to construct robust underwater glue from abundant biomass.

Mechanosensitive ion channels MSL8, MSL9, and MSL10 have environmentally sensitive intrinsically disordered regions with distinct biophysical characteristics in vitro.

Intrinsically disordered protein regions (IDRs) are highly dynamic sequences that rapidly sample a collection of conformations over time. In the past several decades, IDRs have emerged as a major component of many proteomes, comprising ~30% of all eukaryotic protein sequences. Proteins with IDRs function in a wide range of biological pathways and are notably enriched in signaling cascades that respond to environmental stresses. Here, we identify and characterize intrinsic disorder in the soluble cytoplasmic N-terminal domains of MSL8, MSL9, and MSL10, three members of the MscS-like (MSL) family of mechanosensitive ion channels. In plants, MSL channels are proposed to mediate cell and organelle osmotic homeostasis. Bioinformatic tools unanimously predicted that the cytosolic N-termini of MSL channels are intrinsically disordered. We examined the N-terminus of MSL10 (MSL10N) as an exemplar of these IDRs and circular dichroism spectroscopy confirms its disorder. MSL10N adopted a predominately helical structure when exposed to the helix-inducing compound trifluoroethanol (TFE). Furthermore, in the presence of molecular crowding agents, MSL10N underwent structural changes and exhibited alterations to its homotypic interaction favorability. Lastly, interrogations of collective behavior via in vitro imaging of condensates indicated that MSL8N, MSL9N, and MSL10N have sharply differing propensities for self-assembly into condensates, both inherently and in response to salt, temperature, and molecular crowding. Taken together, these data establish the N-termini of MSL channels as intrinsically disordered regions with distinct biophysical properties and the potential to respond uniquely to changes in their physiochemical environment.

Hydrogen bonding behavior of ethanol-trifluoroethanol binary mixtures and its effects on the water structure and dynamics in ternary aqueous-ethanol-trifluoroethanol solutions

The hydrogen bonding structure and dynamics of binary ethanol (EtOH) – trifluoroethanol (TFE) mixtures and in ternary aqueous-EtOH-TFE solutions are investigated by classical molecular dynamics simulations. Presence of water reduces hydrogen bonds between EtOH and TFE due to formation of new alcohol-water hydrogen bonds. In aqueous-EtOH-TFE mixtures, the tetrahedral order of water increases as we move from water-EtOH to water-TFE solution. Our calculated translational and rotational data suggests a slower dynamic of the species in their binary as well as in the ternary mixtures. The steep rise of the orientational relaxation times for TFE indicates a stronger aggregation among TFE molecules in both binary and ternary mixtures. A faster anisotropic decay of water is also observed with increasing TFE concentrations in the ternary solutions. The hydrogen bond lifetime associated with the hydrogen of TFE (HT⋯OT/OE/OW) is multiple times higher than that of H-bonds formed by the hydrogen of EtOH (HE)/water (HW).

An Intramolecular Radical C–N Coupling by N-Iodosuccinimide

AbstractA useful method for the formation of benzimidazole-fused phenanthridines through an intramolecular coupling of unactivated C(sp2)–H and N(sp3)–H bonds using N-iodosuccinimide (NIS) in trifluoroethanol (TFE) is presented. The synthesis of benzo[4,5]imidazo[1,2-f]phenanthridines from 2-([1,1′-biphenyl]-2-yl)-1H-benzo[d]imidazole derivatives is mild, efficient, and sustainable, with high yields and minimal waste generation. The control experiments and EPR studies were aimed at rationalizing the radical pathway of the reaction. Specifically, the use of 1,1-diphenylethylene, TEMPO, BHT, and DMPO as a free-radical spin-trapping reagent in EPR studies, allowed us to conceive a radical pathway. The gram-scale synthesis further supported the practical utility of the methodology for the field of synthetic chemistry.

Development of CHARMM additive potential energy parameters for α-methyl amino acids.

Potential energy parameters for α-methyl amino acids were generated with ab initio calculations on α-methyl-N-acetylalanyl-N′-methylamide (the α-methyl “alanine dipeptide”) which served as an input to a grid-based correction to the backbone torsional potential (known as CMAP) consistent with the CHARMM36m additive protein force field. The new parameters were validated by comparison with experimentally determined helicities of the 22 residue C-terminal peptide (H10) from apolipoprotein A1 and five α-methylated variants in water and 0.3:0.7 trifluoroethanol (TFE)/water. Conventional molecular dynamics simulation totaling 30 μs for each peptide is in overall good agreement with the experiment, including the increased helicity in 30% TFE. An additional 500 ns of simulation using two-dimensional dihedral biasing (bpCMAP) replica exchange reduced left-handed conformations, increased right-handed helices, and thereby mostly decreased agreement with the experiment. Analysis of side chain–side chain salt bridges suggests that the overestimation of the helical content may be, in part, due to such interactions. The increased helicity of the peptides in 30% TFE arises from decreased hydrogen bonding of the backbone atoms to water and a concomitant increase in intramolecular backbone hydrogen bonds. The present inclusion of parameters for amino acids methylated at the α-carbon can be extended to all amino acids that contain two β-carbons such as isovaline and stapled peptides.

Incorporating nanoconfined chitin-fibrils in poly (ε-caprolactone) membrane scaffolds improves mechanical and chemical properties for biomedical application.

Engineered composite scaffolds composed of natural and synthetic polymers exhibit cooperation at the molecular level that closely mimics tissue extracellular matrix's (ECM) physical and chemical characteristics. However, due to the lack of smooth intermix capability of natural and synthetic materials in the solution phase, bio-inspired composite material development has been quite challenged. In this research, we introduced new bio-inspired material blending techniques to fabricate nanofibrous composite scaffolds of chitin nanofibrils (CNF), a natural hydrophilic biomaterial and poly (ɛ-caprolactone) (PCL), a synthetic hydrophobic-biopolymer. CNF was first prepared by acid hydrolysis technique and dispersed in trifluoroethanol (TFE); and second, PCL was dissolved in TFE and mixed with the chitin solution in different ratios. Electrospinning and spin-coating technology were used to form nanofibrous mesh and films, respectively. Physicochemical properties, such as mechanical strength, and cellular compatibility, and structural parameters, such as morphology, and crystallinity, were determined. Toward the potential use of this composite materials as a support membrane in blood-brain barrier application (BBB), human umbilical vein endothelial cells (HUVECs) were cultured, and transendothelial electrical resistance (TEER) was measured. Experimental results of the composite materials with PCL/CNF ratios from 100/00 to 25/75 showed good uniformity in fiber morphology and suitable mechanical properties. They retained the excellent ECM-like properties that mimic synthetic-bio-interface that has potential application in biomedical fields, particularly tissue engineering and BBB applications.

Bovine dentin collagen/poly(lactic acid) scaffolds for teeth tissue regeneration

Electrospun scaffolds with diameter fibers compared to those in the extracellular matrix were produced with poly(lactic acid) (PLA) and non-denatured collagen from bovine dentin (DCol). DCol was obtained through an improved version of the Longin method by acid erosion of the hydroxyapatite of the roots of teeth from a 2-year-old cattle. The dentin collagen was characterized by energy dispersive X-ray spectroscopy (EDS), and carbon, nitrogen, and oxygen were found to be the main elements of the protein. Infrared analysis revealed the typical bands of collagen at about 3300, 1631, 1539, and 1234 cm−1 for amides A, I, II, and III, respectively. Calorimetric and infrared analyses also demonstrated that the collagen was non-denatured. With scanning electron microscopy, it was found that the thinnest fibers with a diameter comparable to that of fibers in the extracellular matrix were obtained when dentin collagen and acetic acid (AAc) were added to the solution of PLA in trifluoroethanol (TFE). The scaffolds with the thinnest diameter had also the highest porosity, and we considered that they could be beneficial in the growth of dentin cell. Human placenta-derived mesenchymal stem cells were seeded onto electrospun scaffolds. After 24, 48 and 96 h of culture, cell proliferation was evaluated by two independent strategies. In both assays, it was found that the pl-MSCs were capable of adhering and proliferating in different scaffolds. It was also observed that cell adhesion and proliferation increased significantly in scaffolds containing collagen, although the addition of AAc slightly decreased this effect on all scaffolds.Graphical abstract

Electrocatalytic CO2 Reduction with a Binuclear Bis-Terpyridine Pyrazole-Bridged Cobalt Complex.

A pyrazole-based ligand substituted with terpyridine groups at the 3 and 5 positions has been synthesized to form the dinuclear cobalt complex 1, that electrocatalytically reduces carbon dioxide (CO2 ) to carbon monoxide (CO) in the presence of Brønsted acids in DMF. Chemical, electrochemical and UV-vis spectro-electrochemical studies under inert atmosphere indicate pairwise reduction processes of complex 1. Infrared spectro-electrochemical studies under CO2 and CO atmosphere are consistent with a reduced CO-containing dicobalt complex which results from the electroreduction of CO2 . In the presence of trifluoroethanol (TFE), electrocatalytic studies revealed single-site mechanism with up to 94 % selectivity towards CO formation when 1.47 M TFE were present, at -1.35 V vs. Saturated Calomel Electrode in DMF (0.39 V overpotential). The low faradaic efficiencies obtained (<50 %) are attributed to the generation of CO-containing species formed during the electrocatalytic process, which inhibit the reduction of CO2 .

Thermo-reversible gelation of myofibrillar protein: Relationship between coiled-coil and thermal reversibility

Thermo-reversible gel of myofibrillar protein (MP) can be made by tactics of elaborate deamidation using protein-glutaminase (PG), and this work aimed to disclose the link between thermally reversible gelation of MP and the coiled-coil (CC). Enzymatic deamidation fragmented myofibril filaments and triggered structural reassembly to create small-sized aggregates. The coiling and dissociation of CC structure in the myosin tails is the fundamental structural basis of the PG deamidated MP (DMP) in the dynamic evolution of reversible gelation. After specific inhibition of CC assembly by trifluoroethanol (TFE), the thermo-reversible gel ability of DMP was impaired, which confirmed that the dynamic assembly of CC with temperature response played a key role in the thermo-reversible gelation of DMP. The findings may broaden the molecular basis of natural CC reversible gelation and foster advances for the development of new muscle protein products.

Structural and functional studies of scorpine: A channel blocker and cytolytic peptide

Scorpine is an antimicrobial and antimalarial peptide isolated from Pandinus imperator scorpion venom. As there are few functional and structural studies reported on scorpine-like peptides, we investigated the recombinant truncated N- and C-terminal domains as well as complete scorpine using biological assays and determined the N- and C-terminal structures using solution nuclear magnetic resonance. The study was conducted using recombinant N- and C-terminal peptides and complete scorpine expressed in Escherichia coli. The results showed that N-scorpine presented a random coil structure in water and adopted α-helical folding in the presence of 50% trifluoroethanol (TFE). C-scorpine contains three disulfide bonds with two structural domains: an unstructured N-terminal domain in water that can form a typical secondary alpha-helix structure in 50% TFE and a C-terminal domain with the CS-αβ motif. Our findings demonstrate cytolytic activity associated with C-scorpine, N-scorpine, and scorpine, as well as channel blocking activity associated with the C-scorpine domain.

Optimization and Identification of Single Mutation in Hemoglobin Variants with 2,2,2 Trifluoroethanol Modified Digestion Method and Nano-LC Coupled MALDI MS/MS.

Background: Hemoglobin (Hb) variants arise due to point mutations in globin chains and their pathological treatments rely heavily on the identification of the nature and location of the mutation in the globin chains. Traditional methods for diagnosis such as HPLC and electrophoresis have their own limitations. Therefore, the present study aims to develop and optimize a specific method of sample processing that could lead to improved sequence coverage and analysis of Hb variants by nano LC−MALDI MS/MS. Methods: In our study, we primarily standardized various sample processing methods such as conventional digestion with trypsin followed by 10% acetonitrile treatment, digestion with multiple proteases like trypsin, Glu−C, Lys−C, and trypsin digestion subsequent to 2,2,2 trifluoroethanol (TFE) treatment. Finally, the peptides were identified by LC−MALDI MS/MS. All of these sample processing steps were primarily tested with recombinant Hb samples. After initial optimization, we found that the TFE method was the most suitable one and the efficiency of this method was applied in Hb variant identification based on high sequence coverage. Results: We developed and optimized a method using an organic solvent TFE and heat denaturation prior to digestion, resulting in 100% sequence coverage in the β−chains and 95% sequence coverage in the α−chains, which further helped in the identification of Hb mutations. A Hb variant protein sequence database was created to specify the search and reduce the search time. Conclusion: All of the mutations were identified using a bottom−up non−target approach. Therefore, a sensitive, robust and reproducible method was developed to identify single substitution mutations in the Hb variants from the sequence of the entire globin chains. Biological Significance: Over 330,000 infants are born annually with hemoglobinopathies and it is the major cause of morbidity and mortality in early childhood. Hb variants generally arise due to point mutation in the globin chains. There is high sequence homology between normal Hb and Hb variant chains. Due to this high homology between the two forms, identification of variants by mass spectrometry is very difficult and requires the full sequence coverage of α− and β−chains. As such, there is a need for a suitable method that provides 100% sequence coverage of globin chains for variant analysis by mass spectrometry. Our study provides a simple, robust, and reproducible method that is suitable for LC−MALDI and provides nearly complete sequence coverage in the globin chains. This method may be used in the near future in routine diagnosis for Hb variant analysis.

Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel.

Tardigrades are able to tolerate almost complete dehydration by entering a reversible ametabolic state called anhydrobiosis and resume their animation upon rehydration. Dehydrated tardigrades are exceptionally stable and withstand various physical extremes. Although trehalose and late embryogenesis abundant (LEA) proteins have been extensively studied as potent protectants against dehydration in other anhydrobiotic organisms, tardigrades produce high amounts of tardigrade-unique protective proteins. Cytoplasmic-abundant heat-soluble (CAHS) proteins are uniquely invented in the lineage of eutardigrades, a major class of the phylum Tardigrada and are essential for their anhydrobiotic survival. However, the precise mechanisms of their action in this protective role are not fully understood. In the present study, we first postulated the presence of tolerance proteins that form protective condensates via phase separation in a stress-dependent manner and searched for tardigrade proteins that reversibly form condensates upon dehydration-like stress. Through a comprehensive search using a desolvating agent, trifluoroethanol (TFE), we identified 336 proteins, collectively dubbed "TFE-Dependent ReversiblY condensing Proteins (T-DRYPs)." Unexpectedly, we rediscovered CAHS proteins as highly enriched in T-DRYPs, 3 of which were major components of T-DRYPs. We revealed that these CAHS proteins reversibly polymerize into many cytoskeleton-like filaments depending on hyperosmotic stress in cultured cells and undergo reversible gel-transition in vitro. Furthermore, CAHS proteins increased cell stiffness in a hyperosmotic stress-dependent manner and counteract the cell shrinkage caused by osmotic pressure, and even improved the survival against hyperosmotic stress. The conserved putative helical C-terminal region is necessary and sufficient for filament formation by CAHS proteins, and mutations disrupting the secondary structure of this region impaired both the filament formation and the gel transition. On the basis of these results, we propose that CAHS proteins are novel cytoskeleton-like proteins that form filamentous networks and undergo gel-transition in a stress-dependent manner to provide on-demand physical stabilization of cell integrity against deformative forces during dehydration and could contribute to the exceptional physical stability in a dehydrated state.

The Use of MM/QM Calculations of 13C Chemical Shifts in the Analysis of Edaravone Tautomers

The 13C NMR chemical shifts of the three Edaravone tautomers (keto, enol, and amine) were calculated using a combined molecular mechanics (Pcmod 9.1/MMFF94) and ab initio (GIAO (B3LYP/DFT, 6–31 + G(d)) model. This method gave such good agreement with experiment that the assignment of the complex spectrum of Edaravone in solution, which is a mixture of the three tautomers could be made. This has been attempted previously by various methods with diverse results. In CDCl3 solution, the observed spectra show only one form, the keto tautomer, and this is also the case with acetonitrile solvent. Acetone solvent reacts with Edavarone in the NMR tube. In the other solvents studied, methanol, pyridine, DMSO, trifluoroethanol (TFE), there is a mixture of the tautomers with populations which vary with the solvent. The application of the shift predictions allows the assignment of the 13C spectra to the three tautomers and from this the proportions of the tautomers in the solution. The results at times differ significantly from previous studies, and this is discussed.