β-Cyclodextrin promoted allylation of aldehydes with allyltributyltin under supramolecular catalysis in water

A novel and highly efficient allylation of aldehydes using allyltributyltin has been developed in aqueous medium catalyzed by β-cyclodextrin in the presence of HCl without any metal catalysts to afford the corresponding homoallylic alcohols in good yields. The β-cyclodextrin can be recovered and reused for a number of runs without significant loss of activity.     

Effect of ultrasound power on HCl leaching kinetics of impurity removal of aphanitic graphite

This study aimed to investigate the effect of ultrasonic power and temperature on the impurity removal rate during conventional and ultrasonic-assisted leaching of aphanitic graphite. The results showed that the ash removal rate increased gradually (∼50 %) with the increase in ultrasonic power and temperature but deteriorated at high power and temperature. The unreacted shrinkage core model was found to fit the experimental results better than other models. The Arrhenius equation was used to calculate the finger front factor and activation energy under different ultrasonic power conditions. The ultrasonic leaching process was significantly influenced by temperature, and the enhancement of the leaching reaction rate constant by ultrasound was mainly reflected in the increase of the pre-exponential factor A. Ultrasound treatment improved the efficiency of impurity mineral removal by destroying the inert layer formed on the graphite surface, promoting particle fragmentation, and generating oxidation radicals. The poor reactivity of hydrochloric acid with quartz and some silicate minerals is a bottleneck limiting the further improvement of impurity removal efficiency in ultrasound-assisted aphanitic graphite. Finally, the study suggests that introducing fluoride salts may be a promising method for deep impurity removal in the ultrasound-assisted hydrochloric acid leaching process of aphanitic graphite.     

铈基复合氧化物的结构及其对HCl催化氧化性能的影响

采用氨水共沉淀法制备了一系列铈基复合氧化物(Ce0.9M0.1O2,M=Cu、Cr、Zr、Ti、La),借助XRD、Raman、N2吸附-脱附、ESEM和H2-TPR等手段对复合氧化物的结构进行了表征,并考察了其在HCl催化氧化制Cl2过程中的性能.结果显示:Cu、Cr和Zr掺杂能显著减小复合氧化物晶粒尺寸,提高复合氧化物的比表面积和孔容,并提供更多的低温可还原氧物种.而La和Ti的掺杂可以获得较大的表面氧空位浓度以及增加高温可还原氧物种数目.复合氧化物结构和表面性质的变化显著影响了其HCl催化氧化活性,在430℃下铈基复合氧化物催化剂活性顺序为:Ce0.9Cu0.1O2Ce0.9Cr0.1O2Ce0.9Zr0.1O2Ce0.9Ti0.1O2Ce O2Ce0.9La0.1O2,低温可还原氧物种数目直接与催化剂活性有关.反应动力学测试显示催化剂低温可还原氧物种有利于HCl在催化剂表面的吸附和活化,而催化剂表面的氧空位可以促进氧分子的吸附和活化.     

Development and validation of a stability-indicating LC method for simultaneous determination of related compounds of guaifenesin,terbutaline sulfate and ambroxol HCl in cough syrup formulation

A new liquid chromatographic method has been developed and validated for the determination of terbutaline sulfate (TLS), guaifenesin (GFN) and ambroxol HCl (AML), for its potential impurities in drug substances and drug products. Efficient chromatographic separation was achieved on X-Terra RP-18 column with a simple mobile phase combination containing a gradient mixture of solvents A and B at a flow rate of 1.0 mL min⁻¹ and quantitation was carried out using ultraviolet detection at 222 nm with column temperature of 35 °C. The resolution between TLS, GFN and AML, its associated impurities was found to be greater than 1.5. Regression analysis shows an r value (correlation coefficient) greater than 0.998. This method was capable to detect all the process impurities of TLS, GFN and AML, at a level below 0.015% with respect to a test concentration of 0.125, 5.0 and 1.5 mg mL⁻¹, respectively. The % RSD for the inter-day and intra-day precisions for all the impurities of TLS, GFN and AML were found to be less than 3.0. The method has shown good, consistent recoveries. The drugs were subjected to stress conditions of acid, base, water hydrolysis, oxidation, photolysis and thermal degradation, as prescribed by international conference on harmonization (ICH).     

Synthesis,molecular modeling of N-acyl benzoazetinones and their docking simulation on fungal modeled target

A series of stable N-acyl benzoazetinones have been synthesized in moderate to good yields (58–85%) from easily available substrates such as 2-(N-acyl) amino benzoic acids through intramolecular amidation under mild conditions. These geometry-optimized benzoazetinones were docked in the model target of P450, class CYP53A15, a benzoate 4-monooxygenase abundantly found in the genome of ascomycetes and Basidiomycetes classes of pathogenic fungi. Low per residue root-mean-square deviation (RMSD) of modeled structure of the enzyme indicated similar topology as template (4D6Z.pdb). Observed score judges site-specific docking, and the interaction of quantum mechanically optimized benzoazetinone derivatives with the target enzyme. These results suggest that 3i is the best antifungal agent. The specific hydrophobic substituent in the benzoazetinones contributed to the stability of ligand–target complex. Overall, the study provided insight into the specificity of the site-specific interactions, thereby, facilitating the possibility of development of broad-spectrum antifungal agents against opportunistic and infectious fungi.     

Electroanalysis of Benazepril Hydrochloride Antihypertensive Drug Using an Ionic Liquid Crystal Modified Carbon Paste Electrode

Electroanalysis of benazepril HCl was successful using a carbon paste electrode modified with an ionic liquid crystal ( 1‐butyl‐1‐methylpiperidinium hexafluorophosphate) in presence of sodium dodecyl sulfate. The electrode performance was compared to ionic liquids (1‐n‐hexyl‐3‐methyl imidazolium tetrafluoroborate and 1‐butyl‐4‐methyl pyridinium tetrafluoroborate). Electrochemical determination of benazepril HCl was in the linear dynamic range of 8.89×10^?7 to 1.77×10^?5 mol L^?1 (correlation coefficient 0.999) and LOD 7.17×10^?9 mol L^?1. benazepril HCl was determined using this sensor in presence of urine metabolites such as uric acid, ascorbic acid. Binary mixtures of dopamine/benazepril and amlodipine/benazepril were also determined successfully.     

Enhanced corrosion resistance of mild steel in molar hydrochloric acid solution by 1,4-bis(2-pyridyl)-5H-pyridazino[4,5-b]indole: Electrochemical, theoretical and XPS studies

The inhibition effect of the new pyridazine derivative, namely 1,4-bis(2-pyridyl)-5H-pyridazino[4,5-b]indole (PPI) against mild steel corrosion in 1 M HCl solutions was evaluated using weigh loss and electrochemical techniques (potentiodynamic polarisation curves and impedance spectroscopy). The experimental results suggest that PPI is a good corrosion inhibitor and the inhibition efficiency increased with the increase of PPI concentration, while the adsorption followed the Langmuir isotherm. X-ray photoelectron spectroscopy (XPS) and theoretical calculation of electronic density were carried out to establish the mechanism of corrosion inhibition of mild steel with PPI in 1 M HCl medium. The inhibition action of this compound was, assumed to occur via adsorption on the steel surface through the active centres contained of the molecule. The corrosion inhibition is due to the formation of a chemisorbed film on the steel surface.     

Photodissociation of a HCl molecule adsorbed on ice at T = 210 K

This theoretical work concerns the study of the photodissociation of a HCl molecule adsorbed on an ice surface at T = 210 K. Temperature induced disorder is taken into account by a statistics over several configurations extracted from a classical molecular dynamics (MD) simulation. For each configuration, 3D quantum dynamics of the hydrogen photofragment is investigated using the multi-configuration time-dependent Hartree (MCTDH) method. The absorption spectrum at 210 K is obtained by an average over the spectra calculated for each configuration. The surface disorder results in a smoothing of the interferences structures that appear for some given orientations of HCl depending on the surrounding water molecules orientations.     

改性消石灰吸收剂用于干法脱除HCI的研究

特定浓度的NaOH、Na     

HCl浸提-FAAS法测定小麦面粉中的微量营养元素

采用HCl浸提－FAAS法同时测定小麦面粉中的Cu,Zn,Fe,Mn,Ca,Mg六种微量营养元素，并且对浸提温度，浸提时间以及浸提浓度（酸度）进行选择，结果表明，除镁不能完全浸提外，其余五种元素与湿灰化法测定结果比较，结果基本一致，该方法操作简便，快速准确，干扰少，是一种较为理想的样品预处理方法。