A Simple Approach to the Synthesis of Fluoren-9-Ones

Cyclohexene-l-Carboxylic acid (I) undergoes reaction with various aromatic substrates (2a-i) in presence of Polyphosphoric acid (PPA) at 100[ddot]c to give cis-1,2,3,4,4a,9a - hexahydrofluoren-9-ones (3a-i) in good yield. Dehydrogenation of (3a-i) with selenium powder afforded corresponding fluoren-9-ones (4a-i) in high yield.     

Effective removal of 4-Aminophenol from aqueous environment by pea (Pisum sativum) shells activated with sulfuric acid: Characterization,isotherm, kinetics and thermodynamics

The threat of phenol contamination in aquatic ecosystems is significant for the health of the earth's water systems as well as all humans on it. The present study was conducted to synthesize a cost-effective adsorbent (pea shells activated with sulfuric acid, PSASA) from agriculture waste (pea shells) and its use for effective removal of toxic 4-Aminophenol (4-AP). Newly designed PSASA exhibited significant adsorption of 4-AP which was confirmed by SEM, FT-IR, and XRD analysis. Surface topography confirmed high unevenness of the PSASA surface and the macroporous feature of the PSASA was confirmed by BET analysis. . Multiple testing was done to see how various factors affected adsorption such as adsorbent dose, temperature, pH, PZC, the effect of KCl and urea addition and the effect of the initial concentration of 4-AP. A drop in adsorption uptake of 4-AP was observed as the temperature increases from 25 °C to 45 °C. Maximum adsorption uptake (q_m) was found to be 106.11 mg/g at an optimum pH of 7.0 and 25 °C. Among various adsorption isotherm models tested, Langmuir Isotherm gave the best explanation with high R² values of experimental data. The pseudo-first-order model was found to explain the kinetics of adsorption well. The thermodynamic finding confirms the adsorption process was physical and exothermic. The adsorption of 4-AP was primarily governed by electrostatic interaction, hydrogen-bonding and π-π exchange mechanism. Because of the positive outcomes of the present research, we can use the PSASA as a cost-effective adsorbent for removing phenolic compounds.     

Artificial neural network‐based modeling of snow properties using field data and hyperspectral imagery

This study attempts to model snow wetness and snow density of Himalayan snow cover using a combination of Hyperspectral image processing and Artificial Neural Network (ANN). Initially, a total of 300 spectral signature measurements, synchronized with snow wetness and snow density, were collected in the field. The spectral reflectance of snow was then modeled as a function of snow properties using ANN. Four snow wetness and three snow density models were developed. A strong correlation was observed in near‐infrared and shortwave‐infrared region. The correlation analysis of ANN modeled snow density and snow wetness showed a strong linear relationship with field‐based data values ranging from 0.87–0.90 and 0.88–0.91, respectively. Our results indicate that an Artificial Intelligence (AI) approach, using a combination of Hyperspectral image processing and ANN, can be efficiently used to predict snow properties (wetness and density) in the Himalayan region. Recommendations for resource managers

• Snow properties, such as snow wetness and snow density are mainly investigated through field‐based survey but rugged terrains, difficult weather conditions, and logistics management issues establish remote sensing as an efficient alternative to monitor snow properties, especially in the mountain environment.
• Although Hyperspectral remote sensing is a powerful tool to conduct the quantitative analysis of the physical properties of snow, only a few studies have used hyperspectral data for the estimation of snow density and wetness in the Himalayan region. This could be because of the lack of synchronized snow properties data with field‐based spectral acquisitions.
• In combination with Hyperspectral image processing, Artificial Neural Network (ANN) can be a useful tool for effective snow modeling because of its ability to capture and represent complex input‐output relationships.
• Further research into understanding the applicability of neural networks to determine snow properties is required to obtain results from large snow cover areas of the Himalayan region.

     

Study of degradation behavior of besifloxacin,characterization of its degradation products by LC–ESI–QTOF–MS and their in silico toxicity prediction

Knowledge and understanding of the stability profile of a drug is important as it affects its safety and efficacy. In the present work, besifloxacin, a new, fourth‐generation fluoroquinolone antibiotic, was subjected to different forced‐degradation conditions as per International Conference on Harmonization (ICH) guidelines such as hydrolysis (acid, base and neutral), oxidation, thermal and photolysis. The drug degraded under acidic, basic, oxidative and photolytic conditions while it was found to be stable under dry heat and neutral hydrolytic conditions. In total, five degradation products (DPs) were formed under different conditions—DP1 and DP2 (photolysis), DP3 (oxidation), DP4 (acidic), DP3 and DP5 (basic). The chromatographic separation of besifloxacin and its degradation products was achieved on a Sunfire C₁₈ (250 mm × 4.6 mm, 5 μm) column with 0.1% aqueous formic acid–acetonitrile as a mobile phase. The gradient RP‐HPLC method was developed and validated as per ICH guidelines. The degradation products were characterized with the help of LC–ESI–QTOF mass spectrometric studies and the most likely degradation pathway of the drug was proposed. In silico toxicity assessment of the drug and its degradation products was carried out, which indicated that DP3 and DP4 carry a mutagenicity alert.     

Distereoselective one-pot synthesis of pyrimidopyrimidines using sulfated tin oxide as a reusable catalyst： An extension of Biginelli-type reaction

The Biginelli-type compounds 4,5,8a-triarylhexahydropyrimido[4,5-d]pyrimidine-2,7（1H,3H）-diones were synthesized by a one-pot three-component reaction using sulfated tin oxide as a reusable catalyst. This method has the advantages of high yields, short reaction time, simple starting materials and reusability of catalyst for several times.     

Quality by design: A systematic and rapid liquid chromatography and mass spectrometry method for eprosartan mesylate and its related impurities using a superficially porous particle column

The present work describes the systematic development of a robust, precise, and rapid reversed‐phase liquid chromatography method for the simultaneous determination of eprosartan mesylate and its six impurities using quality‐by‐design principles. The method was developed in two phases, screening and optimization. During the screening phase, the most suitable stationary phase, organic modifier, and pH were identified. The optimization was performed for secondary influential parameters—column temperature, gradient time, and flow rate using eight experiments—to examine multifactorial effects of parameters on the critical resolution and generated design space representing the robust region. A verification experiment was performed within the working design space and the model was found to be accurate. This study also describes other operating features of the column packed with superficially porous particles that allow very fast separations at pressures available in most liquid chromatography instruments. Successful chromatographic separation was achieved in less than 7 min using a fused‐core C₁₈ (100 mm × 2.1 mm, 2.6 μm) column with linear gradient elution of 10 mM ammonium formate (pH 3.0) and acetonitrile as the mobile phase. The method was validated for specificity, linearity, accuracy, precision, and robustness in compliance with the International Conference on Harmonization Q2 (R1) guidelines. The impurities were identified by liquid chromatography with mass spectrometry.     

Total Stereospecific Synthesis of (3E,7Z)-Tetradecadienyl Acetate,the Major Sex Pheromone Component of the Potato Pest Symmetrischema tangolias

Chemistry of Natural Compounds - (3E,7Z)-Tetradecadienyl acetate, the major sex pheromone component of the potato pest Symmetrischema tangolias (Gyen), was stereoselectively synthesized from the...     

Synthesis and biological evaluation of novel 4-(6-substituted quinolin-4-yl)-N-aryl thiazol-2-amine derivatives as potential antimicrobial agents

Cyclocondensation reaction of 4-(2-bromoacetyl)quinolin-1-ium bromide ( 4a–d ) with substituted arylthiourea, ( 5a–g ) afforded 4-(6-substituted quinolin-4-yl)-N-aryl/pyridyl thiazol-2-amine ( 6a-ab ). These newly synthesized derivatives were evaluated for in vitro antibacterial activity against Escherichia coli (NCIM 2574), Proteus mirabilis (NCIM 2388) (Gram-negative strains), Bacillus subtilis (NCIM 2063), Staphylococcus albus (NCIM 2178) (Gram-positive strains) and in vitro antifungal activity against Aspergillus niger (ATCC 504) and Candida albicans (NCIM 3100). Compounds 6a , 6b , 6d , 6f , 6k , and 6l showed moderate to good antibacterial activity against S. albus. Ten derivatives 6c , 6q , 6r , 6s , 6t , 6v , 6w , 6x , 6y , and 6aa , showed moderate to good activity against A. niger. N-[4-(Quinolin-4-yl)-1,3-thiazol-2-yl]pyridin-2-amine presented comparable activity against A. niger with respect to standard drug Rouconazole.