Tetrabutylammonium Hydrogen Sulfate Research Articles

Synthesis of a unique dimethyl thiazoline containing intermediate of novel peroxisome proliferator-activated receptors(PPAR)δ agonists

Peroxisome proliferator-activated receptor delta (PPARδ) is considered as a promising biological target for the development of new drugs to treat metabolic syndrome including hyperlipidemia. In this study, a simple and efficient method for the preparation of a unique dimethyl thiazoline containing intermediate (13) of new PPARδ agonists as GW501516 analogue is described. The intermediate 13 was readily obtained by coupling reaction of 4-(chloromethyl)-5,5-dimethyl-2-(4-(trifluoromethyl)phenyl)-4,5-dihydrothiazole (11) with 4-mercapto-2-methylphenol (12) in the presence of tetrabutylammonium hydrogensulfate (TBAHS) and Cs2CO3 in DMF at 80 °C for 1 h. This unique intermediate could be useful for the synthesis of various novel PPARδ agonists to understand the structural and biological significance of PPARδ.

A Potentiometric Study of the Briggs‐Rauscher Oscillatory Reaction in a Solution of Ionic Surfactants and Tetrabutylammonium Hydrogensulphate

AbstractThe concentration effect of ionic surfactants (sodium dodecyl sulphate, N‐hexadecyl‐N,N,N‐trimethylammonium hydrogensulphate, 3‐(N,N‐dimethyl‐N‐myristylammonio)propanesulfonate) and tetrabutylammonium hydrogensulphate was investigated on the Briggs‐Rauscher (BR) oscillatory reaction in a stirred batch reactor at 25 ± 0.1 °C in both the absence and presence of an ionic surfactant. In the presence of the anionic surfactant, the induction period (IP) and the oscillation period (OP) increase markedly, and the amplitude of oscillations decreases with increasing concentration of sodium dodecyl sulphate. These effects have been observed when the concentration of surfactant is much higher than its critical micelle concentration. Another effect on IP and OP has been observed in the presence of cationic and zwitterionic surfactants. A decrease in IP leads to its extinction at a certain concentration and at the same time, chemical oscillations divide into two series of chemical oscillations. TBAH does not have a major influence on IP and OP of the BR oscillatory reaction. The observed effects are explained in terms of micellar catalysis or inhibition in different extents of individual reactants solubilisation respectively.

An Efficient and Versatile Method for Synthesis of 1,4-Dihydropyridines at Mild Reaction Conditions

Herein a simple, efficient, versatile and convenient Hantzsch method for synthesis of 1,4-dihydropyridines using ethylacetoacetate, ammonium acetate and substituted arylaldehydes in the presence of Tetrabutylammonium Hydrogen Sulfate (TBAHS) have been reported. Among the popular reported heterogenous solid catalysts, TBAHS has gained high popularity in organic synthesis due to its selectivity, inertness and thermal stability. The method offers advantages such as good to better yields, short reaction times, a simple work-up procedure, easy isolation of catalyst and reusability of catalyst for several runs.

New stability indicating liquid chromatographic method for the determination of Pterostilbene in capsules

Pterostilbene is used for the treatment of cancer, diabetes, anti-hyperlipidemic and fungal infections.A new RP-UFLC method has been developed for the determination of Pterostilbene. Shimadzu Model UFLC system, equipped with PDA detector and SunfireC18 column was used for the present chromatographic study. Mobile phase consisting of a mixture of tetra butyl ammonium hydrogen sulphate andacetonitrile (32:68, v/v)with flow rate 1.0 mL/min was chosen for the determination of Pterostilbene. Linearity was observed over the concentration range 0.1–100 µg/ml (R2 = 0.9999) with linear regression equation y = 161775.7385x - 15849.1207. The LOD and LOQ were found to be 0.01642 µg/ml and 0.05421 µg/ml respectively. Solutions of Pterostilbenewere subjected to stress conditions such as acidic, alkaline, oxidation and thermal degradations. The method was validatedas per ICH guidelines. This method is quite suitable for the determination of Pterostilbene in pharmaceutical formulations.

New Stability indicating ultrafast liquid chromatographic method for the determination of Teicoplanin in injection

Teicoplanin is an antibiotic belonging to glycopeptides. A selective, specific and sensitive stability-indicating high-performance liquid chromatographic method was developed and validated for the determination of Teicoplanin in tablet dosage forms. Reversed-phase chromatography was performed on Shimadzu Model UFLC system equipped with PDA detector using Agilent column (150 mm × 4.6 mm i.d., 3.5 µm particle size) and mobile phase consisting of tetra butyl ammonium hydrogen sulphate and acetonitrile mixture (47:53, v/v) with flow rate 0.8 ml/min. Linearity was observed in the concentration range of 0.5-200 µg/ml with regression equation y = 115528x + 48907 (R2 = 0.9997). For precision and accuracy studies, relative standard deviation was <2%. Teicoplanin was subjected to stress conditions of degradation in aqueous solutions including acidic, alkaline, oxidation, photolysis and thermal degradation. The developed method was validated with regard to linearity, accuracy, precision, selectivity and robustness and the method was found to be precise, accurate, linear and specific.

Development and validation of a new stability indicating ultrafast liquid chromatographic method for the determination of Exemestane tablets

Exemestane is an irreversible steroidal aromatase inactivator. Exemestane is used for postmenopausal women who are suffering with estrogen receptor positive early breast cancer as an adjuvant treatment. A new stability indicating ultrafast liquid chromatographic method was developed and validated for the determination of Exemestane. Shimadzu Model UFLC system with PDA detector was used for the present study. Mobile phase consisting of tetra butyl ammonium hydrogen sulphate and acetonitrile (30: 70, v/v) was used with a flow rate of 1.2 mL/min (Detection wavelength 250 nm). Exemestane shows linearity 0.5–100 µg/mL with linear regression equation y = 62584 x + 599.1 (R2 = 0.9999). The LOD and LOQ were found to be 0.1401 and 0.4348 µg/mL. Stress degradation studies were performed and method was validated as per ICH guidelines.

Facile Synthesis and Fluorescent Properties of Two Novel 4-Aryl-2,6-Dicoumarinylpyridines

Two novel 4-aryl-2,6-dicoumarinylpyridines were synthesised in the presence of tetrabutylammonium hydrogen sulphate via a one-pot reaction. In addition, the absorption and fluorescence spectra of the synthesised compounds in chloroform were measured for the first time.

One Pot, Four-Component for the Synthesis of Pyrano Pyrazole Derivatives using TBAHS as Green Catalyst and their Biological Evaluation

A green, efficient and simple procedure has been developed for the synthesis of Pyrano [2, 3-c] Pyrazoles from a one pot four component condensation of ethylacetoacetate, malononitrile, hydrazine hydrate and different substituted aromatic aldehydes using Tetrabutyl ammonium hydrogen sulphate (TBAHS) as green catalyst in

Determination of Cabazitaxel (An Anti-prostate cancer agent) by reverse phase liquid chromatography

Cabazitaxel is used in the treatment of hormone-refractory prostate cancer. It is a semisynthetic taxane that can be used as a precursor molecule obtained from yew tree needles. The authors have developed a stability indicating liquid chromatographic method for the determination of Cabazitaxel in pharmaceutical products. Shimadzu Model CBM-20A/20 Alite HPLC system (PDA detector) with Zorbax SB C18 column (150 mm × 4.6 mm i.d., 3.5 µm particle size) was selected for the quantification of Cabazitaxel. A mixture of tetra butyl ammonium hydrogen sulphate and methanol was used as the mobile phase with a flow rate of 1.0 mL/min (UV detection at 210 nm). The proposed analytical method was statistically validated and forced degradation studies were conducted. Cabazitaxel has shown linearity over the concentration range 0.1-200 µg/mL with regression equation y = 26145x + 22943 (r2=0.9997) and considerable degradation was observed in acidic, alkaline and oxidation conditions. The method is specific as the resolution of Cabazitaxelwas good in presence of its degradation products. This validated stability indicating liquid chromatographic method can be used for the determination of Cabazitaxel in biological studies as well as for the pharmaceutical products.

Practical Implication of Stability Indicating Chromatographic Method for Estimation of Clomipramine Hydrochloride and its Related Substances from Capsule Dosage Form

Clomipramine Hydrochloride is Tricyclic antidepressants (TCAs) drug which cause increased concentration of monoamines in the synaptic cleft, ultimately resulting in antidepressant effect. Literature reveals that all the reported methods are developed for estimation of Clomipramine Hydrochloride (CLH) in bulk and solid dosage form. My research is based on estimation of CLH and its related substances from capsule dosage form by HPLC method. A rapid, precise, selective and sensitive and accurate stability-indicating High Performance Liquid Chromatographic (HPLC) method for estimation of Clomipramine Hydrochloride and its related substances from capsule dosage form was developed and validated in the present work. The chromatographic separation was performed by using BDS Hypersil C18, 250 X 4.6 mm, 5 μ with 2 gm/L Tetra Butyl Ammonium Hydrogen Sulphate (TBAS) in Water (pH 2.5): Methanol (40:60 v/v) mobile phase, at a flow rate of 1.2 ml/min. The method was validated according to ICH guidelines. The effluent was monitored using a UV detector set at 252nm. The retention time for CLH was observed at 6.2 min. Impurity spiked A, B, C, are retained at 7.8, and 9.4, 3.6, min respectively. The linearity of CLH and impurities was in the range of 1050–1800 μg/ml and 0.7–4.5μg/ml respectively. The developed method was successfully applied to the analysis of the drugs in their commercial dosage form.

Sensitive and Rapid RP-HPLC Quantification of Zoledronic Acid in a Hydroxyapatite-based Nanoparticles

The aim of this study was to develop and validate a rapid and sensitive reverse-phase high performance liquid chromatography method for the quantitative determination of zoledronic acid in nanoparticles. The mobile phase was a mixture of methanol (30%) and 7 mM tetra butyl ammonium hydrogen sulphate, 2 mM di-sodium hydrogen orthophosphate and sulphate and 8 mM di-potassium hydrogen orthophosphate (70%), pH adjusted to 3 with trifluoroacetic acid. C18 column was used as a stationary phase. The flow rate was maintained at 1 ml/min. The detection of the constituents was done at 215 nm using an ultraviolet detector. Method validation was executed according to the International Conference on Harmonisation guidelines. The retention time of zoledronic acid was 3.27±0.03 min (n=6). The assay was linear over the concentration range of 200-800 μg/ml. The proposed method was sensitive with the limit of detection and limit of quantification values equal to 200 and 800 μg/ml, respectively. The method was accurate with percent mean recovery from 99.01±1.31 to 100.80±0.094% and precise as percent relative standard deviation values were less than 1%. The method was successfully applied for the estimation of zoledronic acid loading efficiency on hydroxyapatite nanoparticles and in vitro zoledronic acid release profile analysis in hydroxyapatite-based nanoparticles.

Electrochemical Behavior of Aromatic Diamines and the Growth of Conducting Films

Aromatic diamine compounds have p-conjugated organic systems based on a phenylene and two amino groups.1 They also have been used commercially as precursors for dyes, pigments, curing agents and high performance polymer materials; however, electrochemistry of the aromatic diamine compounds have not been adequately established, despite the fact that the aromatic diamine compounds contain electrochemically active aniline units in their chemical structures. On the other hand, we have designed and proposed electropolymerization systems of p-conjugated aromatic compounds such as pyrrole, thiophene and aniline in highly conductive ionic liquid media, electrochemically and morphologically characterizing the polymerized conducting films grown on the electrode surface.2 In this work, we report the voltammetric behavior of several aromatic diamine compounds containing a biphenyl framework (Fig. 1), investigating the conducting film formation on the electrode surface. Four aromatic diamines (Bzd(m-Me)2, Bzd(m-CF3)2, Bzd(o-Me)2 and Bzd(o-OMe)2) were supplied by SEIKA Corporation. The electrooxidative behavior of the aromatic diamine compounds was evaluated by cyclic voltammetry (CV) method using a conventional three-electrode cell equipped with a Pt disk working electrode (0.020 cm2), a Pt wire counter electrode and an Ag/Ag+ reference electrode. A 0.1 mol dm-3 tetrabutylammonium hydrogen sulfate (TBA-HS) / MeCN was used as an electrolytic media for the CV measurement. All electrochemical measurements were carried out under dry argon atmosphere at ambient temperature. The electrical conductivity of the films was estimated by the resistivity measured by a dc 4-prove method.Fig. 2 depicted the cyclic voltammograms for the electrochemical oxidation of Bzd(m-Me)2 and Bzd(m-CF3)2. It was found that an irreversible oxidation peak was observed in each aromatic diamine compound; however, the oxidation peak of Bzd(m-CF3)2 drastically shifted to the potential region more positive than that of Bzd(m-Me)2 because of the electron withdrowing by the trifluoromethyl group in Bzd(m-CF3)2. It should be noted that no film formation on the working electrode surface was observed in the case of Bzd(m-Me)2 and Bzd(m-CF3)2 whereas both Bzd(o-Me)2 and Bzd(o-OMe)2 significantly formed the films on the electrode surface, giving the relatively large voltammetric responses. From this result the position of the substituents seems likely to play an important role in the film growth. The electrical conductivity of the film formed in the electrochemical oxidation of Bzd(o-OMe)2 was 1.2 S cm-1, which was similar to the conductivity value previously found in the electropolymerized polypyrrole film.2 The electrochemical activity and morphology of the films obtained will be discussed.

Effect of tetrabutylammonium hydrogen sulphate on the Solution thermodynamics of thiamine hydrochloride in aqueous solutions

The densities and viscosities of thiamine hydrochloride (vitamin-B1) in aqueous tetrabutylammonium hydrogen sulphate (Bu4NHSO4) solutions with several molal concentrations (mBu4NHSO4=0.000, 0.005, 0.010, 0.015 and 0.020mol⋅kg‐1) of Bu4NHSO4 were determined at T=(298.15, 308.15 and 318.15) K under atmospheric pressure. Using experimental data apparent molar volume (φV), standard partial molar volume (φV0), the slope (SV), standard isobaric partial molar expansibility (φE0) and its temperature dependence(∂φE0/∂T)P, the viscosity B-coefficient and solvation number (Sn), etc., were determined. Viscosity B-coefficients were further utilized to obtain the free energies of activation of viscous flow per mole of the solvents (Δμ10≠) and of the solute (Δμ20≠). Effects of molality, solute structure and temperature on all these parameters were analyzed in term of ion-ion and ion-solvent interactions; results revealed that the solutions are characterized predominantly by ion-solvent interactions and thiamine hydrochloride behaves as a long-range structure maker.

Volumetric and viscometric behaviour of pyridoxine hydrochloride in aqueous tetrabutylammonium hydrogen sulphate solutions at different temperatures

Apparent molar volumes and viscosity B-coefficients for pyridoxine hydrochloride in aqueous tetrabutylammonium hydrogen sulphate (TBAHS) solutions were determined from solution density and viscosity measurements at T=(288.15–318.15)K and p=101kPa as a function of pyridoxine hydrochloride concentration. The standard partial molar volume and slopes, obtained from the Redlich-Meyer equation, have been interpreted in terms of solute-solvent and solute-solute interactions respectively. The viscosity data were analyzed using the Jones-Dole equation and the derived parameters A and B were interpreted in terms of solute-solute and solute-solvent interactions respectively. The standard volume of transfer and viscosity B-coefficients of transfer of pyridoxine hydrochloride from water to aqueous TBAHS solutions were derived to study various interactions in the ternary solutions. The activation parameters of viscous flow for the ternary solutions were also calculated and explained in terms of transition state theory.

Optimization of Ultrasound-Assisted Oxidation of Thiophene Using Phase Transfer Catalyst

Thiophene oxidation with hydrogen peroxide was studied with tetrabutylammonium bromide, phenyltrimethylammonium tribromide, ethyltriphenylphosphonium bromide, benzyltrimethylammonium tribromide, tetrapropylammonium bromide, tetrabutylammonium hydrogensulphate, and 18-crown-6-ether as phase transfer catalysts (PTC) under ultrasound. Highest conversion (82.59%) was achieved with benzyltrimethylammonium tribromide at 1,200 rpm and 30 kHz frequency. The effect of parameters such as oxidant-to-sulphur mole ratio, intensity of ultrasound, stirrer speed, catalyst amount, and operating temperature on oxidation was explored by using benzyltrimethylammonium tribromide. Central composite design was chosen for optimization of conversion using temperature, catalyst loading, and molar ratio. The pseudo first-order kinetics with apparent activation energy of 79.55 kJ/mol was established.

An efficient method for synthesis of bis(indolyl)methane and di-bis(indolyl)methane derivatives in environmentally benign conditions using TBAHS

AbstractAn efficient procedure for the synthesis of bisindolylmethanes from condensation of indole and aromatic aldehydes or ketones is described. The aromatic electrophilic substitution reactions of indole with aromatic aldehydes and ketones are achieved in the presence of tetrabutylammonium hydrogen sulfate as a mild and efficient solid acid catalyst. This methodology offers several advantages such as good yields, simple procedure, mild and environmentally benign conditions.

Solution Thermophysics of l-Ascorbic Acid in Aqueous Tetrabutylammonium Hydrogen Sulfate

The densities and viscosities of l-ascorbic acid (vitamin C) in aqueous tetrabutylammonium hydrogen sulfate (Bu4NHSO4) solutions at several different concentrations of Bu4NHSO4 (\( m_{{{\text{Bu}}_{4} {\text{NHSO}}_{4} }} \) = 0.000, 0.005, 0.010, 0.015 and 0.020 mol·kg−1) were determined at T = (298.15–318.15) K under atmospheric pressure. Using these experimental data, values of the apparent molar volume (\( \phi_{V} \)), standard partial molar volume (\( \phi_{V}^{ 0} \)), the slope (\( S_{V}^{ *} \)), standard isobaric partial molar expansibility (\( \phi_{E}^{ 0} \)) and its temperature derivative \( ({{\partial \phi_{E}^{ 0} } \mathord{\left/ {\vphantom {{\partial \phi_{E}^{ 0} } {\partial T}}} \right. \kern-0pt} {\partial T}})_{p} \), the viscosity B-coefficient and solvation number (\( S_{\text{n}} \)), etc., were determined. Viscosity B-coefficients were further utilized to obtain the Gibbs energies of activation of viscous flow per mole of the solvents (\( \Delta \mu_{ 1}^{ 0\ne } \)) and of the solute (\( \Delta \mu_{ 2}^{ 0\ne } \)). The effects of molality, solute structure and temperature on all these parameters were analyzed in term of ion–ion and ion–solvent interactions, which revealed that the solutions are characterized predominantly by ion–solvent interactions and l-ascorbic acid behaves as a long-range structure maker.

A systematic approach for reversed phase liquid chromatographic method development of fingolimod hydrochloride via design augmentation

A stability indicating reversed phase liquid chromatographic (RP-LC) method was developed for the analysis of fingolimod hydrochloride (FIM) and its related compounds in drug substance and its dosage form. Separation of seven related compounds and three degradation products was achieved in a C18 stationary phase with 3mM tetrabutyl ammonium hydrogen sulfate in 0.02% orthophosphoric acid and acetonitrile in gradient elution. Aqueous mobile phase components and column temperature were optimized through Design of experiments (DoE) for a fixed gradient program. Major degradation products were identified by LC-MS and degradation pathway is proposed. The validation results indicated that the method is sensitive in detection, linear, precise and accurate. The developed method was also demonstrated in UHPLC.

ChemInform Abstract: Facile Synthesis of 5‐Substituted 1H‐Tetrazoles Catalyzed by Tetrabutylammonium Hydrogen Sulfate in Water.

AbstractThe introduced procedure is environmentally‐friendly, practical, and provides excellent yields of tetrazoles (II).

Determination of eight pharmaceuticals in an aqueous sample using automated derivatization solid-phase microextraction combined with gas chromatography–mass spectrometry

An automated aqueous derivatization solid-phase microextraction (SPME) coupled with a gas chromatography/mass spectrometry (GC/MS) method was developed for simultaneous determination of eight pharmaceuticals in water samples. Dimethyl sulfate and tetrabutylammonium hydrogen sulfate were selected as derivatization and activation reagents for the esterification reaction. An experimental design approach, central composition design (CCD), was employed to investigate and optimize the operative factors influencing the extraction efficiency, including extraction time, extraction temperature and ionic strength. The other parameters such as type of fiber coating, pH and derivatization conditions were also evaluated. SPME was finally carried out in headspace mode at 80°C for 60min with the presence of 3.00g Na2SO4, using a home-made 44μm PDMS fiber. Wide linear ranges and low limits of detection (0.06–1.24ngL−1) were obtained under the optimized conditions. The relative standard deviations (RSDs) and recoveries ranged from 0.5% to 12.3% and 85% to 110%, respectively. The proposed method was successfully applied to the analysis of the real surface water samples from the Pearl River Estuary.