Chemoselective C-benzoylation of phenols by using AlCl3 under solvent-free conditions

Substituted phenols were chemo-selectively reacted with benzoylchloride in presence of aluminum chloride under solvent-free condition to afford the corresponding 2'-hydroxy aryl benzophenones in excellent yields (72-96%). Naphthol benzoylation resulted in lower yields as compared to phenols. Both reactions completed in 5-10 min with quantitative yields providing excellent control over regioselectivity of products. KEY WORDS: Chemoselective C-acylation, F-C reaction, Fries rearrangement Bull. Chem. Soc. Ethiop. 2015, 29(2), 319-325DOI: http://dx.doi.org/10.4314/bcse.v29i2.1

A convenient method for lactonization of α-allyl esters using iodine in dimethyl- sulphoxide

A simple method for the synthesis of α-γ-disubstituted-γ-butyrolactones by cyclization of α-allyl esters using iodine in dimethylsulphoxide is reported. This method is efficient and operationally simple in comparison to methods using transition metal complexes. KEY WORDS: γ-Butyrolactones, α-Allyl esters, Iodine, Dimethyl sulphoxide Bull. Chem. Soc. Ethiop. 2014, 28(3), 469-473.DOI: http://dx.doi.org/10.4314/bcse.v28i3.1

THERMODYNAMICS OF UNI-UNIVALENT ION EXCHANGE REACTIONS USING STRONGLY ACIDIC CATION EXCHANGE RESIN TULSION T-46

Abstract The study on thermodynamics of ion exchange equilibrium for uni-univalent H + / Na + and H + / K + reaction systems was carried out using strongly acidic cation exchange resin Tulsion T-46. The equilibrium constant K calculated for uni-univalent ion exchange reaction systems were observed to increase with rise in temperature indicating the endothermic ion exchange reactions having the enthalpy values 4.19 and 3.80 kJ /mol respectively

Digital Watermarking Algorithm for Color Images

Abstract: Digital watermarking methods describe the technologies that allow hiding of information in digital media such as images, video and audio. Watermarking techniques embed information in images by introducing changes that are imperceptible to the human eye but recoverable by a computer program. Generally, the watermark is a code to identify the owner of the image. The locations in which the watermark is embedded are determined by a secret key. Doing so prevents possible pirates from easily removing the watermark. Furthermore it should be possible to recover the watermark from an altered image. Possible alterations of watermarked images include compression, filtering and cropping. These alterations are referred to as attacks. The first watermarking application that might come to mind is related to copyright protection of digital media Watermarking algorithms have been proposed to protect varieties of content, such as official documents

Recycling and treatment of herbal pharmaceutical wastewater using Scenedesmus quadricuada

Globally, herbal pharmaceutical industries are among the leading pharmaceutical industries. They generate large volume of wastewater during processing and production, which is highly biodegradable in nature and cannot be discharged into environment as such. Hence efforts are being made to evaluate the toxicity of herbal pharmaceutical effluents using green algae Scenedesmus quadricauda. Physico-chemically treated effluents (PCTEs) as well as biologically treated effluents (BTEs) were observed after the application of S. quadricauda. Also, S. quadricauda showed higher growth rate after the addition of PCTE and BTE. The highest yield of algae was observed in BTE up to 15 days of incubation by synthesis of chlorophyll and cell metabolites, even with 10–100% dilution of effluents. The present study also discusses the evaluation of biotoxicity and recycling on herbal pharmaceutical wastewater along with heavy metal remova

Synthetic approach from polypyrrole nanotubes to nitrogen doped pyrolyzed carbon nanotubes for asymmetric supercapacitors

Pseudocapacitive materials are highly capable to achieve high energy density integrated with high power electrostatic capacitive materials. However, finding a suitable electrostatic capacitive material to integrate with pseudocapacitive material in order to achieve high energy density with good rate capability is still a challenge. Herein, we are providing a novel synthetic approach starting from the synthesis of polypyrrole nanotubes (PPy-NTs) and ending up at the carbonization of PPy-NTs to obtain N-doped carbon nanotubes (N-CNTs). With highly porous nature of PPy-NTs and great graphitic texture with copious heteroatom functionalities, N-CNTs significantly promoted the faradic pseudo-capacitors, demonstrating high single-electrode capacitance over 332 F/g and 228 F/g in 1 M HSO aqueous solution. Further, a novel asymmetric supercapacitor with PPy-NTs as positive and N-CNTs as negative electrode has been fabricated. This PPy-NTs//N-CNTs cell effectively provides high operation voltage (1.4 V) and hence high energy density over 28.95 W h/kg (0.41 mW h/cm) with a high power density of 7.75 kW/kg (113 mW/cm) and cyclic stability of 89.98% after 2000 cycles

Annealing study and thermal investigation on bismuth sulfide thin films prepared by chemical bath deposition in basic medium

This is a post-peer-review, pre-copyedit version of an article published in Applied Physics A 124.2 (2018): 166. The final authenticated version is available online at: http://doi.org/10.1007/s00339-018-1584-7Bismuth sulfide thin films were prepared by chemical bath deposition using thiourea as sulfide ion source in basic medium. First, the effects of both the deposition parameters on films growth as well as the annealing effect under argon and sulfur atmosphere on as-deposited thin films were studied. The parameters were found to be influential using the Doehlert matrix experimental design methodology. Ranges for a maximum surface mass of films (3 mg cm-2) were determined. A well crystallized major phase of bismuth sulfide with stoichiometric composition was achieved at 190°C for 3 hours. The prepared thin films were characterized using Grazing Incidence X-ray diffraction (GIXRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX). Second, the band gap energy value was found to be 1.5 eV. Finally, the thermal properties have been studied for the first time by means of the electropyroelectric (EPE) technique. Indeed, the thermal conductivity varied in the range of 1.20 - 0.60 W m-1 K-1 while the thermal diffusivity values increased in terms of the annealing effect ranging from 1.8 to 3.5 10-7 m2s-1This work was financially supported by the Tunisian Ministry of Higher Education and Scientific Research and by the WINCOST (ENE2016-80788-C5-2-R) project funded by the Spanish Ministry of Economy and Competitivenes