Hydroxylic Solvents Research Articles

Synthetic Approaches and Reactions of 2-(Arylidene)benzo[b]thiophen-3(2H)one-1,1-dioxides

Abstract: 2-(Arylidene)benzo[b]thiophen-3(2H)one 1,1-dioxides are oxidized form of thioaurones. Various methods have been reported for their synthesis, e.g., a) condensation of benzo[b]thiophen-3(2H)one 1,1-dioxides with aryl aldehydes under acidic or basic conditions, b) oxidation of thioaurones with hydrogen peroxide or sodium perborate tetrahydrate, c) from the catalytic reaction of iodonium ylides with (bis(trifluoroacetoxy)iodo) benzene in presence copper(II)acetoacetonate, d)by ring contraction of 1-thioflavones in the presence of ceric ammonium nitrate. The reports have shown addition reactions with p-thiocresol in the absence of any catalyst, conjugated addition product without hetero ring opening with Grignard reagent, forms corresponding oxime and hydrazone with hydroxyl amine and phenyl hydrazine, respectively, produces polycyclic compounds with enamines, shows contrasting behavior with NBS and gives addition products with organophosphorus compounds in both hydroxylic and non-hydroxylic solvents which depends on reaction medium. In the present mini-review, we have discussed the various synthetic strategies and reactions of 2-(arylidene)benzo[b]thiophen-3(2H)one 1,1-dioxides, along with their reported utilities.

Variable-temperature solid-state NMR analysis of woody materials in the presence of small hydroxyl molecules

Interactions between the hierarchical structure of Japanese cypress and small hydroxylic solvents with high polarity were studied using variable-temperature 13C cross-polarization and magic-angle spinning nuclear magnetic resonance (CP/MAS) NMR spectroscopy, including low-temperature measurements. 13C CP/MAS NMR spectra were enhanced by dipolar interactions closely related to 1H–13C magnetization transfer, providing information about the interaction between woody materials and small hydroxyl molecules. The change in interaction was particularly near the melting point of the hydroxylic solvent, where a decrease in the intensity of the cypress carbohydrate signal and the appearance of the signal of solvent molecules were observed. The trend of signal intensity in the variable-temperature 13C CP/MAS NMR spectra of cypress and cellulose fibers in the presence of hydroxylic solvents indicated that the decrease in the carbohydrate signal intensity due to the transfer of magnetization near the melting point of the hydroxyl molecule is greater when the size of the hydroxyl molecule is smaller. Furthermore, molecular association in the nanopores of the hierarchical structure allowed the hydroxyl molecular signals of the impregnated cypress to appear above the melting point.

Nucleofugality of diphenylphosphinate and kinetic stabilities of secondary and tertiary benzylic diphenylphosphinates in aqueous solvents

AbstractFirst‐order rate constants for solvolyses of variously substituted benzhydryl diphenylphosphinates in four aqueous solvents have been measured conductometrically in order to investigate leaving group ability of diphenylphosphinate (DPP), that is, to determine corresponding nucleofuge‐specific parameters (Nf and sf) according to the correlation equation log k (25°C) = sf(Ef + Nf). DPP is the first of phosphorus leaving groups included on the Nf nucleofugality scale which presently covers a reactivity range of 15 orders of magnitude. Application of log k (25°C) versus Ef plots has unequivocally shown that benzhydryl diphenylphosphinates solvolyze in hydroxylic solvents by the SN1 mechanism. As the abovementioned equation and corresponding reactivity parameters can also be employed for predicting heterolytic reactivity of substrates in various solvents, the range of kinetic stability of secondary and tertiary benzylic diphenylphosphinates toward heterolysis has been examined in terms of reaction half‐lives. Further, in order to investigate the origin of stability of the DPP anion and, consequently, the ability of the DPP leaving group, quantum mechanical calculations and the Natural Bond Orbital (NBO) analysis were performed at the M06‐2X/6‐311+G(3df,3pd) level of theory using the SMD solvation model. The NBO analysis has revealed that negative hyperconjugation plays a dominant role in delocalizing the anionic charge in disubstituted phosphinate leaving groups.

Effects of hydroxyl group, glycosylation and solvents on the antioxidant activity and mechanism of maclurin and its derivatives: Theoretical insights

Maclurin (MAC) and its derivatives received increasing interest due to their diverse biological activities. However, understanding of their antioxidant properties remains insufficient. Herein, the antioxidant activity and mechanism of maclurin (MAC) and iriflophenone (IRF) as well as their glucosides, maclurin-3-C-glucoside (MAC-Glu) and iriflophenone-3-C-glucoside (IRF-Glu) were evaluated using density functional theory (DFT) approach based on descriptors involved in the double (2H+/2e-) radical-trapping processes. Effects of hydroxyl group, glycosylation, hydrogen bonding, and solvents were explored. Moreover, thermodynamic and free energy barrier calculations of MAC with hydroperoxyl (HOO•) radical have also been performed to further explore the radical-trapping behavior. Results showed that double hydrogen atom transfer (dHAT) mechanism represents the dominant pathway in the gas and non-polar phases, while double sequential proton loss electron transfer (dSPLET) is the prevailing mechanism in the polar media. Results also revealed the important role of ortho-dihydroxyl group and C-glycosylation on antiradical activity.

Computational study of metformin hydrochloride nucleation in hydroxylic solvents: Experimental kinetics and DFT simulation

Metformin hydrochloride (MET-HCl) was applied as a model compound to investigate the nucleation behavior in four hydroxylic solvents based on the experimental and simulated methods. Over 320 induction time experiments were measured in four solvents, and the induction time increased in the order: water < methanol < ethanol < n-propanol. The metastable zone widths were determined with different cooling rates and saturation temperatures. According to classical nucleation theory, the nucleation kinetics and thermodynamic parameters (interfacial energy, critical nucleus size and Gibbs free energy) were estimated. The result indicates that the nucleation rate of MET-HCl in water was highest among four solvents. The density functional theory (DFT) calculation was applied to reveal the solvent–solute interaction in crystal nucleation, showing the binding energies increased in the order: water < methanol < ethanol < n-propanol. The simulation results combined with experimental data suggested that the stronger the interactions of solvent–solute molecules, the more difficult the nucleation becomes.

Hydroxyl-containing bis(sulfonates). Reaction of 1,4-dibromo-2,3-butanedione with water, methanol and sodium sulfite

Sulfonates are well-known substances with a variety of applications, e.g. as surfactants. On the other hand, bis(sulfonates) bearing hydroxyl or keto group(s) in between the sulfonate groups can be used with or without further modification as starting materials for the preparation of new type of molecules capable to form either complexes or in general supramolecular structures. The synthesis of three hydroxyl-bearing bis(sulfonates), 2-hydroxypropane-1,3-bis(sodium sulfonate) 4, DL-2,3-dihydroxybutane-1,4-bis(sodium sulfonate) 8, and sodium 2,3,4-trihydroxy-1-sulfonate 7 (as by-product) via the Strecker sulfonation are described. Interestingly, under similar conditions, sulfonation of 1,4-dibromo-2,3-butanedione 9 was found to be very complicated and no pure product could be isolated, despite previously reported results on sulfonation of α-halogenated ketones in high yields. There are indications that SO32- attacks at the carbonyl carbon of 9 followed by rearrangement and expulsion of SO42-. 1,4-dibromo-2,3-butanedione 9, bearing two keto groups next to methylene groups, can potentially exist as enols or in the case of its solution in hydroxylic solvents in the form of hemiketals or geminal diols. This behavior of 9 when is dissolved in CDCl3, CD3OD and D2O was studied by means of UV-Vis, 1H and 13C NMR and the nature of the adducts formed was elucidated.

Some Aryl-1,2,4-triazol-1-ium Phenacylids in Binary Hydroxyl Solvent Mixtures. Computational and Spectral Study

Four carbanion monosubstituted p-aryl-1,2,4-triazol-1-ium methylids are subjected to a comparative study between their spectral and quantum-mechanical parameters in order to obtain more information about their structural features in hydroxyl solvents as water and ethanol and also on the nature of electronic absorption transitions from the visible range. The quantum mechanical analysis, made by the Spartan’14 program, established a series of molecular parameters of the studied ylids important for their reactivity and for intermolecular interactions with hydroxyl liquids. An extensive solvatochromic study of 1,2,4-triazol-1-ium ylids is impossible due to their limited solubility in liquids. Binary solvent mixtures of water and ethanol with known solvent parameters from the literature were used for this study. The electronic absorption spectra in binary solvents water and ethanol were used to establish the influence of intermolecular interactions on the spectral characteristics of the studied methylids and also on the composition of their first solvation shell in ternary solutions. The difference between the interaction energies in molecular pairs ylid–water and ylid–ethanol was determined based on the statistical cell model applied to the ternary solutions of the type of ylid + water + ethanol. The obtained values are very small due to the hydroxylic nature of the two solvents.

Preferential Solvation of 4-Carboxyl-2, 6-Dinitrophenylazohydroxynaphthalenes in Mixed Hydroxylic Solvents

Background: The applications of a group of 4-carboxyl-2,6-dintrophenylazohydroxynaphathalenes, AZ-01 to 04, as colourants, chemosensors or synthetic intermediates have been limited by their solubility.Aim: To investigate the effect of solvent mixture composition on the solubility, solution thermodynamics and position of equilibrium processes of the dyes.Method: The UV-visible spectral patterns of the dyes in binary mixtures including Methanol:Water, Ethanol:Water, Methanol:Ethanol, Methanol:Propan-1-ol, Methanol:Propan-2-ol, Propan-1-ol:Water and Propan-2-ol:Water were acquired. The type and quantitative estimation of solute-solvent interactions at play were determined by fitting spectral patterns to solvent parameters using multilinear regression.Results: Preferential solvation was detected by the non-ideality of the plots of E12 as against the mole fractions of co-solvent in all binary mixtures. In pure solvents, the spectral shifts of AZ-01, 03 and 04, which exist predominantly in the hydrazone form, were affected by polarity of solvent milieu while solvent basicity and acidity, in that order, were the significant parameters for AZ-02. In aqueous alcoholic mixtures, solvent polarity was contributory, although to different degrees, to the observed spectral data of the four dyes. However, solvent acidity and basicity were the primary determinants of spectral shifts observed with AZ-04 and AZ-03 respectively. Spectra-structure relationships identified the formation of the charged hydrazone tautomer which requires stabilisation by polar solvent milieu as responsible for the observed trend. In addition, interactions between new aggregated solvent-solvent species and the propionic acid substituent present in AZ-03 contributed to its spectral shifts.Conclusion: The solvatochromic properties of the phenylazonaphthalene series in binary mixtures have been successfully studied.

Rate and Product Studies with 1-Adamantyl Chlorothioformate under Solvolytic Conditions.

A study was carried out on the solvolysis of 1-adamantyl chlorothioformate (1-AdSCOCl, 1) in hydroxylic solvents. The rate constants of the solvolysis of 1 were well correlated using the Grunwald–Winstein equation in all of the 20 solvents (R = 0.985). The solvolyses of 1 were analyzed as the following two competing reactions: the solvolysis ionization pathway through the intermediate (1-AdSCO)+ (carboxylium ion) stabilized by the loss of chloride ions due to nucleophilic solvation and the solvolysis–decomposition pathway through the intermediate 1-Ad+Cl− ion pairs (carbocation) with the loss of carbonyl sulfide. In addition, the rate constants (kexp) for the solvolysis of 1 were separated into k1-Ad+Cl− and k1-AdSCO+Cl− through a product study and applied to the Grunwald–Winstein equation to obtain the sensitivity (m-value) to change in solvent ionizing power. For binary hydroxylic solvents, the selectivities (S) for the formation of solvolysis products were very similar to those of the 1-adamantyl derivatives discussed previously. The kinetic solvent isotope effects (KSIEs), salt effects and activation parameters for the solvolyses of 1 were also determined. These observations are compared with those previously reported for the solvolyses of 1-adamantyl chloroformate (1-AdOCOCl, 2). The reasons for change in reaction channels are discussed in terms of the gas-phase stabilities of acylium ions calculated using Gaussian 03.

Double proton transfer in a polar nano-droplet: Phototautomerization of alloxazine in AOT/alkane reverse micelles containing water or glycerol

Alloxazine phototautomerization is believed to occur through an excited state double proton transfer (ESDPT) mechanism involving cyclic intermolecular H-bonded complexes between Alloxazine and hydroxylic solvents like water and alcohols. In AOT/alkane dispersions in the absence of any polar liquid, Alloxazine molecules reside inside the polar core of the AOT reverse micelle nanoparticles, where they involve in H-bonding with the anionic sulfonate head-groups of the AOT molecules, but are unable to generate the appropriate cyclic intermolecular H-bonded complexes conducive to ESDPT. However, tautomerization is switched on with addition of water and formation ofwater nano-droplet at the core of reverse micelle. Evidently, the Alloxazine⋅⋅⋅⋅AOT H-bonds are now replaced by Alloxazine⋅⋅⋅⋅Water H-bonds, promotingESDPT. On the other hand, Alloxazine phototautomerization is hindered in Glycerol, irrespective of whether the latter is in the bulk liquid state or in the form of a polar nano-droplet. This may be explained by steric considerations.

Synthesis of β-keto-sulfones using alkyl/aryl sulphinates in ionic liquids [bmim-BF4] as an efficient and reusable reaction medium

Synthesis of β-keto-sulfones using alkyl/aryl sulphinates in ionic liquids [bmim-BF4] as an efficient and reusable reaction medium

The Influence of a Terminal Chlorine Substituent on the Kinetics and the Mechanism of the Solvolyses of n-Alkyl Chloroformates in Hydroxylic Solvents.

A previous study of the effect of a 2-chloro substituent on the rates and the mechanisms of the solvolysis of ethyl chloroformate is extended to the effect of a 3-chloro substituent on the previously studied solvolysis of propyl chloroformate and to the effect of a 4-chloro substituent on the here reported rates of solvolysis of butyl chloroformate. In each comparison, the influence of the chloro substituent is shown to be nicely consistent with the proposal, largely based on the application of the extended Grunwald–Winstein equation, of an addition-elimination mechanism for solvolysis in the solvents of only modest solvent ionizing power, which changes over to an ionization mechanism for solvents of relatively high ionizing power and low nucleophilicity, such as aqueous fluoroalcohols with an appreciable fluoroalcohol content.

The removal of bronze paint repairs from overgilded picture frames using an Erbium:YAG laser

The removal of old repairs made using metal flake paint, commonly referred to as bronze paint, has often been difficult to achieve from gilded wood and especially from oil gilded surfaces with similar solubility parameters. Conservators at the National Trust's Knole Conservation Studio in the UK treated gilded picture frames from the Knole House collection using an energy-attenuated Fotona (Dualis XS) Erbium:YAG laser, with fluencies between 0.5 and 1.0J/cm2, pre-wetted with hydroxyl and non-hydroxyl group-containing solvents. Comparisons of the effects of cleaning using only solvents and with the laser were made, and cross-sectional and media composition analysis carried out using optical microscopy, scanning electron microscopy with energy dispersive X-ray (SEM-EDX), Raman and Fourier transform infrared (FTIR) spectroscopies.

Cyclobutane-Containing Scaffolds as Useful Intermediates in the Stereoselective Synthesis of Suitable Candidates for Biomedical Purposes: Surfactants, Gelators and Metal Cation Ligands

Efficient and versatile synthetic methodologies are reported for the preparation of products that are suitable candidates to be used as surfactants, gelators for hydroxylic solvents or metal cation ligands, with potential use in several fields including biomedical applications. The common structural feature of all the synthesized products is the presence of a cis or trans-1,2- or cis-1,3-difunctionalized cyclobutane ring. In the two first cases, the key intermediates including enantiomerically pure 1,3-diamines and 1,3-amino alcohols have been prepared from β-amino acid derivatives obtained, in turn, from a chiral half-ester. This compound is also precursor of γ-amino esters. Furthermore, two kind of polydentate ligands have also been synthesized from a symmetric 1,5-diamine obtained from norpinic acid, which was easily prepared from commercial verbenone.

The Effect of the ortho Nitro Group in the Solvolysis of Benzyl and Benzoyl Halides.

A kinetic study was carried out on the solvolysis of o-nitrobenzyl bromide (o-isomer, 1) and p-nitrobenzyl bromide (p-isomer, 3), and o-nitrobenzoyl chloride (o-isomer, 2) in a wide range of solvents under various temperatures. In all of the solvents without aqueous fluoroalcohol, the reactions of 1 were solvolyzed at a similar rate to those observed for 3, and the reaction rates of 2 were about ten times slower than those of the previously studied p-nitrobenzoyl chloride (p-isomer, 4). For solvolysis in aqueous fluoroalcohol, the reactivity of 2 was kinetically more reactive than 4. The l/m values of the extended Grunwald–Winstein (G–W) equation for solvolysis of 1 and 2 in solvents without fluoroalcohol content are all significantly larger than unity while those in all the fluoroalcohol solvents are less than unity. The role of the ortho-nitro group as an intramolecular nucleophilic assistant (internal nucleophile) in the solvolytic reaction of 1 and 2 was discussed. The results are also compared with those reported earlier for o-carbomethoxybenzyl bromide (5) and o-nitrobenzyl p-toluenesulfonate (7). From the product studies and the activation parameters for solvolyses of 1 and 2 in several organic hydroxylic solvents, mechanistic conclusions are drawn.

Molecular Structure of a Free-Base β-Octaiodo-meso-tetraarylporphyrin. A Rational Route tocisPorphyrin Tautomers?

Although a cis tautomer has long been invoked as an intermediate in porphyrin tautomerism, the first such species was only recently isolated and structurally characterized in the form of a β-heptakis(trifluoromethyl)-meso-tetraarylporphyrin. Reported herein is the molecular structure of a β-octaiodo-meso-tetraarylporphyrin solvate, which also exhibits a cis tautomeric structure. Both structures implicate two factors as critical to the stabilization of the cis tautomeric form—a free-base porphyrin that is naturally strongly saddled on steric grounds and a hydroxylic or amphiprotic solvent that can provide hydrogen-bonded N–H···X-H···N (X = O in both the above examples) straps connecting the central NH groups with the antipodal unprotonated nitrogens. The results raise the prospect that a rational strategy affording cis porphyrin tautomers in a predictable manner may be within reach.

Effect of temperature on thermodynamic properties of protic ionic liquids: 2-hydroxy ethylammonium lactate (2-HEAL) + short hydroxylic solvent

In this study, we have synthesized the protic ionic liquid 2-hydroxy ethylammonium lactate (2-HEAL), and investigated its volumetric and acoustic behaviour into different hydroxylic media (water, methanol and ethanol) at the temperature 288.15-323.15 K and atmospheric pressure. Total solubility of the ionic liquid into these solvents was observed at this range of temperature. Apparent molar volume and apparent molar isentropic compressibility values have been computed from the experimental data and fitted to a temperature dependent Redlich-Mayer equation. From these correlations, the limiting infinite dilution values of the apparent magnitudes have also been computed. Derived magnitudes such as isobaric expansibility and isothermal coefficient of pressure excess molar enthalpy were computed due to their importance in the study of specific molecular interactions among the ions and covalent molecules enclosed into mixtures. The measured experimental data were used to test the accuracy of prediction of different models (Mchaweh-Nasrifar–Moshfeghian model (MNM model) and the modified Heller temperature dependent equation (MHE) for density and Collision Factor Theory (CFT) for ultrasonic velocity). The obtained results indicate that ionic liquid interactions in water are weaker than in the studied alcoholic solutions, as previously observed in analogous protic ionic liquids.

Role of Solvent Polarity and Hydrogen-Bonding on Excited-State Fluorescence of 3-[(E)-{4-[Dimethylamino]benzylidene}amino]-2-naphthoic Acid (DMAMN): Isomerization vs Rotomerization.

The present experimental and theoretical study on a new chromophore DMAMN of the type push-π-pull (push = dimethylaniline, π = imine, pull = 2-naphthoic acid), allows understanding of the mechanism by which the molecular conformational undergoes isomerization/rotomerization following electronic excitation. The steady-state fluorescence spectra of this compound, carried out in solvents of different polarities and proticities, showed significant changes in both the shape and peak positions. The wavelength and intensity change depend on the polarity and hydrogen-bonding environment. In highly polar solvents, the emission is weak and red-shifted compared to that for cyclohexane, but it is more red-shifted in moderate aprotic polar solvents. In hydroxyl solvents, a new weak low-energy emission band appears at ∼525 nm, attributed to the intermolecularly H-bonded open conformer. On the basis of the generated potential energy landscapes of the ground state and low-lying excited state in the gas phase and solution, we found that selective photon absorption, brings this molecule to a "bright" state, from which N═C isomerization Z → E, takes place. This isomerization in gas-phase and low-polarity solvents leads to two minima with a barrier, whereas in highly polar-protic media, it gives one minimum on the S1 surface with low ΔES1/T1 (0.17 eV), facilitating deactivation via ISC.

Exploring the effect of hydroxylic and non-hydroxylic solvents on the reaction of [VIVO(β-diketonate)2] with 2-aminobenzoylhydrazide in aerobic and anaerobic conditions.

Refluxing [VIVO(β-diketonate)2], namely [VIVO(acetylacetonate)2] and [VIVO(benzoylacetonate)2], separately with an equivalent or excess amount of 2-aminobenzoylhydrazide (ah) in laboratory grade (LG) CH3OH in aerobic conditions afforded non-oxidovanadium(iv) and oxidovanadium(v) complexes of the type [VIV(L1)2] (1), [VVO(L1)(OCH3)]2 (3) and [VIV(L2)2] (2), and [VVO(L2)(OCH3)] (4), respectively. (L1)2- and (L2)2- represent the dianionic forms of 2-aminobenzoylhydrazone of acetylacetone (H2L1) and benzoylacetone (H2L2), respectively, (general abbreviation, H2L), which was formed by the in situ condensation of ah with the respective coordinated [β-diketonate] in medium-to-good yield. The yield of different resulting products was dependent upon the ratio of ah to [VIVO(β-diketonate)2]. For example, the yield of 1 and 2 complexes increased significantly associated with a decrease in the amount of 3 and 4 with an increase in the molar ratio of ah. Upon replacing CH3OH by a non-hydroxylic solvent, LG CHCl3, the above reaction yielded only oxidovanadium(v) complexes of the type [VVO(L1)(OH)]2 (5), [VVO(L2)(OH)] (6) and [VO3(L)2] (7, 8) whereas, upon replacing CHCl3 by another non-hydroxylic solvent, namely LG CH3CN, only the respective [VO3(L)2] (7, 8) complex was isolated in 72-78% yield. However, upon performing the above reactions in the absence of air using dry CH3OH or dry CHCl3, only the respective [VIV(L)2] complex was obtained, suggesting that aerial oxygen was the oxidising agent and the type of pentavalent product formed was dependent upon the nature of solvent used. Complexes 3 and 4 were converted, respectively, to 7 and 8 on refluxing in LG CHCl3via the respective unstable complex 5 and 6. The DFT calculated change in internal energy (ΔE) for the reactions 2[VVO(L2)(OCH3)] + 2H2O → 2[VVO(L2)(OH)] + 2CH3OH and 2[VVO(L2)(OH)] → [VO3(L2)2] + H2O was, respectively, +3.61 and -7.42 kcal mol-1, suggesting that the [VVO(L2)(OH)] species was unstable and readily transformed to the stable [VO3(L2)2] complex. Upon one-electron reduction at an appropriate potential, each of 7 and 8 generated mixed-valence [(L)VVO-(μ-O)-OVIV(L)]- species, which showed valence-delocalisation at room temperature and localisation at 77 K. Some of the complexes showed a wide range of toxicity in a dose-dependent manner against lung cancer cells comparable with that observed with cis-platin.

Hydroxyl solvents prompted interwoven morphological deposition of iron sulfide nanoparticles as an effective counter electrode for quantum dot sensitized Solar cell

A low-cost, stable and efficient FeS thin film counter electrode (CE) was fabricated for quantum dot-sensitized solar cells (QDSSCs) by a facile chemical bath deposition method using different acidic hydroxyl solvents (ethanol, isopropanol, and tert-butanol) and triethanolamine. The choice of solvents greatly affected the surface morphology and thickness of FeS CEs. Apart from surface morphology, the increase in the atomic percentage of sulfur in tert-butanol and triethanolamine-mediated FeS also plays a crucial role in increasing the electrocatalytic activity of the CE. The QDSSC’s power conversion efficiency was 2.15%, which is attributed to the high fill factor (FF) of 0.443. The obtained PCE is far better than the previously reported value of 1.76% for FeS in QDDSC’s. Excellent stability of the photoelectric performance of the FeS CE is also demonstrated. The enhanced electrochemical performance of the interwoven FeS networks can be attributed to their unique morphology, which possesses a shorter diffusion length of the ions and easier transportation of the electrons.