Advances in Chemistry http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. The Inhibition Effect of Potassium Iodide on the Corrosion of Pure Iron in Sulphuric Acid Wed, 24 Sep 2014 07:21:13 +0000 http://www.hindawi.com/journals/ac/2014/827514/ The use of inorganic inhibitors as an alternative to organic compounds is based on the possibility of degradation of organic compounds with time and temperature. The inhibition effect of potassium iodide on the corrosion of pure iron in 0.5 M H2SO4 has been studied by weight loss. It has been observed from the results that the inhibition efficiency (IE%) of KI increases from 82.17% to 97.51% with the increase in inhibitor concentration from 1·10−4 to 2·10−3 M. The apparent activation energy () and the equilibrium constant of adsorption () were calculated. The adsorption of the inhibitor on the pure iron surface is in agreement with Langmuir adsorption isotherm. Tarik Attar, Lahcène Larabi, and Yahia Harek Copyright © 2014 Tarik Attar et al. All rights reserved. Detection and Estimation of alpha-Amyrin, beta-Sitosterol, Lupeol, and n-Triacontane in Two Medicinal Plants by High Performance Thin Layer Chromatography Mon, 22 Sep 2014 05:53:30 +0000 http://www.hindawi.com/journals/ac/2014/143948/ A normal phase high performance thin layer chromatography (HPTLC) method has been developed and validated for simultaneous estimation of four components, namely, alpha-amyrin, beta-sitosterol, lupeol, and n-triacontane from two medicinally important plants, Leptadenia reticulata Wight & Arn. and Pluchea lanceolata (DC.) CB. Clarke. In Ayurveda, both plants have been reported to possess immunomodulatory activity. Chromatographic separation of the four components from the methanolic extracts of whole plant powders of Leptadenia reticulata Wight & Arn. and Pluchea lanceolata (DC.) CB. Clarke. was performed on TLC aluminium plates precoated with silica gel using a suitable mobile phase. The densitometric scanning was done after derivatization at λ = 580 nm for α-amyrin, β-sitosterol, and lupeol, and at 366 nm for n-triacontane. The developed HPTLC method has been validated and used for simultaneous quantitation of the four components from the methanolic extracts of whole plant powders of Leptadenia reticulata Wight & Arn. and Pluchea lanceolata (DC.) CB. Clarke. The developed HPTLC method is simple, rapid, and precise and can be used for routine quality control. Saikat S. Mallick and Vidya V. Dighe Copyright © 2014 Saikat S. Mallick and Vidya V. Dighe. All rights reserved. Increasing the Stability of Metal-Organic Frameworks Thu, 18 Sep 2014 09:03:51 +0000 http://www.hindawi.com/journals/ac/2014/182327/ Metal-organic frameworks (MOFs) are a new category of advanced porous materials undergoing study by many researchers for their vast variety of both novel structures and potentially useful properties arising from them. Their high porosities, tunable structures, and convenient process of introducing both customizable functional groups and unsaturated metal centers have afforded excellent gas sorption and separation ability, catalytic activity, luminescent properties, and more. However, the robustness and reactivity of a given framework are largely dependent on its metal-ligand interactions, where the metal-containing clusters are often vulnerable to ligand substitution by water or other nucleophiles, meaning that the frameworks may collapse upon exposure even to moist air. Other frameworks may collapse upon thermal or vacuum treatment or simply over time. This instability limits the practical uses of many MOFs. In order to further enhance the stability of the framework, many different approaches, such as the utilization of high-valence metal ions or nitrogen-donor ligands, were recently investigated. This review details the efforts of both our research group and others to synthesize MOFs possessing drastically increased chemical and thermal stability, in addition to exemplary performance for catalysis, gas sorption, and separation. Mathieu Bosch, Muwei Zhang, and Hong-Cai Zhou Copyright © 2014 Mathieu Bosch et al. All rights reserved. Determination of Tannins of Three Common Acacia Species of Sudan Wed, 17 Sep 2014 06:13:40 +0000 http://www.hindawi.com/journals/ac/2014/192708/ The objective of this study is to analyze and compare tannins of three common Acacia species of Sudan, since vegetable tannins are important in leather industry. Acacia nilotica and Acacia seyal samples were collected from Sunt Forest in Khartoum State, while Acacia senegal samples were collected from the Debabat Forest in South Kordofan State. Bark samples from bulk collections of the three Acacia species were extracted with boiled deionized water. The amount of tannins present in these bulk samples was determined by Folin-Denis method for total phenolic materials, followed by precipitation with hide-powder. The difference between the amount of phenolic materials present before and after addition of hide-powder represents the amount of tannins present. The percentage of tannins in the leaves, bark, and mature and immature fruits of collections of individuals of Acacia species was estimated; mature and immature fruits of Acacia nilotica contain tannins (22.15% and 22.10%, resp.). The leaves of Acacia nilotica and Acacia seyal contain tannins (11.80% and 6.30%, resp.). The barks of Acacia seyal, Acacia nilotica, and Acacia senegal contain tannins (12.15%, 10.47%, and 3.49%, resp.). Isam Eldin Hussein Elgailani and Christina Yacoub Ishak Copyright © 2014 Isam Eldin Hussein Elgailani and Christina Yacoub Ishak. All rights reserved. Allotropic Carbon Nanoforms as Advanced Metal-Free Catalysts or as Supports Mon, 15 Sep 2014 08:17:34 +0000 http://www.hindawi.com/journals/ac/2014/906781/ This perspective paper summarizes the use of three nanostructured carbon allotropes as metal-free catalysts (“carbocatalysts”) or as supports of metal nanoparticles. After an introductory section commenting the interest of developing metal-free catalysts and main features of carbon nanoforms, the main body of this paper is focused on exemplifying the opportunities that carbon nanotubes, graphene, and diamond nanoparticles offer to develop advanced catalysts having active sites based on carbon in the absence of transition metals or as large area supports with special morphology and unique properties. The final section provides my personal view on future developments in this field. Hermenegildo Garcia Copyright © 2014 Hermenegildo Garcia. All rights reserved. Separation and Characterization of Synthetic Polyelectrolytes and Polysaccharides with Capillary Electrophoresis Sun, 14 Sep 2014 09:12:49 +0000 http://www.hindawi.com/journals/ac/2014/798503/ The development of macromolecular engineering and the need for renewable and sustainable polymer sources make polymeric materials progressively more sophisticated but also increasingly complex to characterize. Size-exclusion chromatography (SEC or GPC) has a monopoly in the separation and characterization of polymers, but it faces a number of proven, though regularly ignored, limitations for the characterization of a number of complex samples such as polyelectrolytes and polysaccharides. Free solution capillary electrophoresis (CE), or capillary zone electrophoresis, allows usually more robust separations than SEC due to the absence of a stationary phase. It is, for example, not necessary to filter the samples for analysis with CE. CE is mostly limited to polymers that are charged or can be charged, but in the case of polyelectrolytes it has similarities with liquid chromatography in the critical conditions: it does not separate a charged homopolymer by molar mass. It can thus characterize the topology of a branched polymer, such as poly(acrylic acid), or the purity or composition of copolymers, either natural ones such as pectin, chitosan, and gellan gum or synthetic ones. Joel J. Thevarajah, Marianne Gaborieau, and Patrice Castignolles Copyright © 2014 Joel J. Thevarajah et al. All rights reserved. Synthesis and Characterization of Novel Processable and Flexible Polyimides Containing 3,6-Di(4-carboxyphenyl)pyromellitic Dianhydride Wed, 10 Sep 2014 07:25:43 +0000 http://www.hindawi.com/journals/ac/2014/759594/ A series of six novel polyimides containing 3,6-di(4-carboxyphenyl)pyromellitic dianhydride were synthesized via two steps condensation method. Aromatic diamines monomers, 4-(4-aminophenoxy)-N-(4-(4-aminophenoxy)benzylidene)-3-chloroaniline (DA1), 4-(4-amino-3-methylphenoxy)-N-(4-(4-amino-3-methylphenoxy)benzylidene)-3-chloroaniline (DA2), 4-(4-amino-2-methylphenoxy)-N-(4-(4-amino-2-methylphenoxy)benzylidene)-3-chloroaniline (DA3) 4-(4-aminophenoxy)-N-(4-(4-aminophenoxy)benzylidene)-2-methylaniline (DA4), 4-(4-amino-3-methylphenoxy)-N-(4-(4-amino-3-methylphenoxy)benzylidene)-2-methylaniline (DA5), and 4-(4-amino-2-methylphenoxy)-N-(4-(4-amino-2-methylphenoxy)benzylidene)-2-methylaniline (DA6) were prepared and used to synthesize new polyimides by reaction with resynthesized 3,6-di(4-carboxyphenyl)pyromellitic dianhydride by using two-step condensation method. The inherent viscosities of polyimides range from 0.68–1.04 dL gm−1 and were soluble in polar solvents. Polyimides have excellent thermal stability by showing 10% weight loss temperature was above 450°C. Their glass transition temperatures lie in the range of 250–335°C. Wide-angle X-ray diffractometer investigations revealed the amorphous nature of polyimides. Therefore, these polymers can be a potential candidate as processable high performance polymeric materials. Muhammad Kaleem Khosa, Muhammad Asghar Jamal, Rubbia Iqbal, and Mazhar Hamid Copyright © 2014 Muhammad Kaleem Khosa et al. All rights reserved. Theoretical Simulations of Reactive and Nonreactive Scattering of Light Diatomic Molecules from Metal Surfaces: Past, Present, and Future Wed, 10 Sep 2014 06:10:32 +0000 http://www.hindawi.com/journals/ac/2014/175351/ In everyday life we are surrounded by surfaces and, therefore, by phenomena involving molecule-surface interactions. Furthermore, the processes of heterogeneous catalysis, which are governed by molecule-surface interactions, are of huge practical importance, because the production of most synthetic compounds involves catalytic processes, which explains the tremendous effort that surface science scientists have invested to understand the basic principles underlying elementary interactions between light molecules and surfaces. This effort was recognized in 2007 with the Nobel prize in chemistry awarded to Gerhard Ertl. Here we revise some of the most relevant studies performed so far in this field. We also point out the major challenges that the surface science community may face in this field in the years to come. C. Díaz Copyright © 2014 C. Díaz. All rights reserved. Synthesis and Antimicrobial Activity of Some Novel Heterocyclic Candidates via Michael Addition Involving 4-(4-Acetamidophenyl)-4-oxobut-2-enoic Acid Wed, 10 Sep 2014 00:00:00 +0000 http://www.hindawi.com/journals/ac/2014/619749/ This paper discusses the utility of 4-(4-acetamidophenyl)-4-oxobut-2-enoic acid as a key starting material for the preparation of a novel series of pyridazinones, thiazoles derivatives, and other heterocycles via interaction with nitrogen, sulfur, and carbon nucleophiles under Michael addition conditions and studies the antimicrobial activities of some of these compounds. Maher A. EL-Hashash, A. Essawy, and Ahmed Sobhy Fawzy Copyright © 2014 Maher A. EL-Hashash et al. All rights reserved. Quantum Calculation for Musk Molecules Infrared Spectra towards the Understanding of Odor Sun, 07 Sep 2014 10:51:18 +0000 http://www.hindawi.com/journals/ac/2014/398948/ It is not clear so far how humans can recognize odor. One of the theories regarding structure-odor relationship is vibrational theory, which claims that odors can be recognized by their modes of vibration. In this sense, this paper brings a novel comparison made between musky and nonmusky molecules, as to check the existence of correlation between their modes on the infrared spectra and odor. For this purpose, sixteen musky odorants were chosen, as well as seven other molecules that are structurally similar to them, but with no musk odor. All of them were submitted to solid theoretical methodology (using molecular mechanics/molecular dynamics and Neglect of Diatomic Differential Overlap Austin Model 1 methods to optimize geometries) as to achieve density functional theory spectra information, with both Gradient Corrected Functional Perdew-Wang generalized-gradient approximation (GGA/PW91) and hybrid Becke, three-parameter, Lee-Yang-Parr (B3LYP) functional. For a proper analysis over spectral data, a mathematical method was designed, generating weighted averages for theoretical frequencies and computing deviations from these averages. It was then devised that musky odorants satisfied demands of the vibrational theory, while nonmusk compounds belonging either to nitro group or to acyclic group failed to fulfill the same criteria. Elaine Rose Maia, Daniela Regina Bazuchi Magalhães, Dan A. Lerner, Dorothée Berthomieu, and Jean-Marie Bernassau Copyright © 2014 Elaine Rose Maia et al. All rights reserved. Mycotoxin Analysis: New Proposals for Sample Treatment Sun, 07 Sep 2014 07:25:25 +0000 http://www.hindawi.com/journals/ac/2014/547506/ Mycotoxins are toxic secondary metabolites produced by different fungi, with different chemical structures. Mycotoxins contaminate food, feed, or raw materials used in their production and cause diseases and disorders in humans and livestock. Because of their great variety of toxic effects and their extreme heat resistance, the presence of mycotoxins in food and feed is considered a high risk to human and animal health. In order to ensure food quality and health consumers, European legislation has set maximum contents of some mycotoxins in different matrices. However, there are still some food commodities susceptible to fungal contamination, which were not contemplated in this legislation. In this context, we have developed new analytical techniques for the multiclass determination of mycotoxins in a great variety of food commodities (some of them scarcely studied), such as cereals, pseudocereals, cereal syrups, nuts, edible seeds, and botanicals. Considering the latest technical developments, ultrahigh performance liquid chromatography coupled to tandem mass spectrometry has been chosen as an efficient, fast, and selective powerful analytical technique. In addition, alternative sample treatments based on emerging methodologies, such as dispersive liquid-liquid microextraction and QuEChERS, have been developed, which allow an increased efficiency and sample throughput, as well as reducing contaminant waste. Natalia Arroyo-Manzanares, José F. Huertas-Pérez, Ana M. García-Campaña, and Laura Gámiz-Gracia Copyright © 2014 Natalia Arroyo-Manzanares et al. All rights reserved. New Strategy for the Cleaning of Paper Artworks: A Smart Combination of Gels and Biosensors Tue, 02 Sep 2014 05:30:43 +0000 http://www.hindawi.com/journals/ac/2014/385674/ In this work an outlook on the design and application, in the cultural heritage field, of new tools for diagnostic and cleaning use, based on biocompatible hydrogels and electrochemical sensors, is reported. The use of hydrogels is intriguing because it does not require liquid treatment that could induce damage on artworks, while electrochemical biosensors not only are easy to prepare, but also can be selective for a specific compound and therefore are suitable for monitoring the cleaning process. In the field of restoration of paper artworks, more efforts have to be done in order to know how to perform the best way for an effective restoration. Rigid Gellan gel, made up of Gellan gum and calcium acetate, was proposed as a paper cleaning treatment, and selective biosensors for substances to be removed from this gel have been obtained by choosing the appropriate enzymes to be immobilized. Using this approach, it is possible to know when the cleanup process will be completed, avoiding lengthy and sometimes unnecessary cleaning material applications. Laura Micheli, Claudia Mazzuca, Eleonora Cervelli, and Antonio Palleschi Copyright © 2014 Laura Micheli et al. All rights reserved. Synthesis of Disodium Salt of Sulfosuccinate Monoester from the Seed Oil of Terminalia catappa and Its Inhibitive Effect on the Corrosion of Aluminum Sheet in 1 M HCl Mon, 01 Sep 2014 09:36:34 +0000 http://www.hindawi.com/journals/ac/2014/896965/ Oil was extracted from the seed of Terminalia catappa and used to synthesize disodium salt of sulfosuccinate monoester using simple reaction mechanism. The disodium salt of sulfosuccinate monoester was applied as corrosion inhibitor of aluminum sheet in 1 M HCl via weight loss method. The adsorption was found to obey Langmuir isotherm. The results presented disodium salt of sulfosuccinate monoester as an efficient inhibitor of aluminum sheet corrosion in 1 M HCl. Adewale Adewuyi, Adewale Dare Adesina, and Rotimi A. Oderinde Copyright © 2014 Adewale Adewuyi et al. All rights reserved. Meticulous Overview on the Controlled Release Fertilizers Thu, 28 Aug 2014 12:57:47 +0000 http://www.hindawi.com/journals/ac/2014/363071/ Owing to the high demand for fertilizer formulations that will exhaust the possibilities of nutrient use efficiency (NUE), regulate fertilizer consumption, and lessen agrophysicochemical properties and environmental adverse effects instigated by conventional nutrient supply to crops, this review recapitulates controlled release fertilizers (CRFs) as a cutting-edge and safe way to supply crops’ nutrients over the conventional ways. Essentially, CRFs entail fertilizer particles intercalated within excipients aiming at reducing the frequency of fertilizer application thereby abating potential adverse effects linked with conventional fertilizer use. Application of nanotechnology and materials engineering in agriculture particularly in the design of CRFs, the distinctions and classification of CRFs, and the economical, agronomical, and environmental aspects of CRFs has been revised putting into account the development and synthesis of CRFs, laboratory CRFs syntheses and testing, and both linear and sigmoid release features of CRF formulations. Methodical account on the mechanism of nutrient release centring on the empirical and mechanistic approaches of predicting nutrient release is given in view of selected mathematical models. Compositions and laboratory preparations of CRFs basing on in situ and graft polymerization are provided alongside the physical methods used in CRFs encapsulation, with an emphasis on the natural polymers, modified clays, and superabsorbent nanocomposite excipients. Siafu Ibahati Sempeho, Hee Taik Kim, Egid Mubofu, and Askwar Hilonga Copyright © 2014 Siafu Ibahati Sempeho et al. All rights reserved. GC Analyses of Salvia Seeds as Valuable Essential Oil Source Wed, 27 Aug 2014 11:59:29 +0000 http://www.hindawi.com/journals/ac/2014/838162/ The essential oils of seeds of Salvia verbenaca, Salvia officinalis, and Salvia sclarea were obtained by hydrodistillation and analyzed by gas chromatography (GC) and GC-mass spectrometry. The oil yields (w/w) were 0.050, 0.047, and 0.045% in S. verbenaca, S. sclarea, and S. officinalis, respectively. Seventy-five compounds were identified. The essential oil composition of S. verbenaca seeds showed that over 57% of the detected compounds were oxygenated monoterpenes followed by sesquiterpenes (24.04%) and labdane type diterpenes (5.61%). The main essential oil constituents were camphor (38.94%), caryophyllene oxide (7.28%), and 13-epi-manool (5.61%), while those of essential oil of S. officinalis were α-thujone (14.77%), camphor (13.08%), and 1,8-cineole (6.66%). In samples of S. sclarea, essential oil consists mainly of linalool (24.25%), α-thujene (7.48%), linalyl acetate (6.90%), germacrene-D (5.88%), bicyclogermacrene (4.29%), and α-copaene (4.08%). This variability leads to a large range of naturally occurring volatile compounds with valuable industrial and pharmaceutical outlets. Mouna Ben Taârit, Kamel Msaada, Karim Hosni, and Brahim Marzouk Copyright © 2014 Mouna Ben Taârit et al. All rights reserved. Synthesis and Antimicrobial Studies of Pyrimidine Pyrazole Heterocycles Mon, 25 Aug 2014 10:58:22 +0000 http://www.hindawi.com/journals/ac/2014/329681/ Prompted from the diversity of the wider use and being an integral part of genetic material, an effort was made to synthesize pyrimidine pyrazole derivatives of pharmaceutical interest by oxidative cyclization of chalcones with satisfactory yield and purity. A novel series of 1,3-dimethyl-6-hydroxy-2,4-dioxo-5-(1′-phenyl-3′-aryl-1H-pyrazol-5′-yl)-1,2,3,4-tetrahydropyrimidines (5a–d) and 1,3-diaryl-6-hydroxy-4-oxo-2-thioxo-5-(1′-phenyl-3′-aryl-1H-pyrazol-5′-yl)-1,2,3,4-tetrahydropyrimidines (5e–l) has been synthesized. The structures of these compounds were established on the basis of FT-IR, 1H NMR, 13C NMR, and mass spectral analysis. All the synthesized compounds were screened for their antimicrobial activity against bacteria and fungi. Among all the compounds, 5g was found to be the most active as its MIC was 31.25 µg/mL against S. aureus and B. cereus. The compounds 5h, 5c, and 5e also possess antibacterial activity with MIC values as 62.50, 125.00, and 500.00 µg/mL, respectively. The compounds 5c and 5j were found to have antifungal activity against Aspergillus spp. As antifungal drugs lag behind the antibacterial drugs, therefore we tried in vitro combination of these two compounds with standard antifungal drugs (polyene and azole) against Aspergillus spp. The combination of ketoconazole with 5c and 5j showed synergy at 1 : 8 (6.25 : 50.00 µg/mL) and 1 : 4 (25 : 100 µg/mL) against A. fumigatus (ITCC 4517) and A. fumigatus (VPCI 190/96), respectively. Rakesh Kumar, Jyoti Arora, Sonam Ruhil, Neetu Phougat, Anil K. Chhillar, and Ashok K. Prasad Copyright © 2014 Rakesh Kumar et al. All rights reserved. XPS Study of the Chemical Structure of Plasma Biocopolymers of Pyrrole and Ethylene Glycol Sun, 24 Aug 2014 06:43:19 +0000 http://www.hindawi.com/journals/ac/2014/965920/ An XPS study about the structure of plasma biocopolymers synthesized with resistive radio frequency glow discharges and random combinations of ethylene glycol, pyrrole, and iodine, as a dopant, is presented in this work. The collisions of molecules produced structures with a great variety of chemical states based in the monomers, their combinations, crosslinking, doping, fragmentation, and oxidation at different levels in the plasma environment. Iodine appears bonded in the copolymers only at high power of synthesis, mainly as C–I and N–I chemical bonds. Multiple bonds as C≡C, C≡N, C=O, and C=N were found in the copolymers, without belonging to the initial reagents, and were generated by dehydrogenation of intermediate compounds during the polymerization. The main chemical states on PEG/PPy/I indicate that all atoms in pyrrole rings participate in the polymerization resulting in crosslinked, partially fragmented, and highly oxidized structures. This kind of analysis can be used to modify the synthesis of polymers to increase the participation of the most important chemical states in their biofunctions. Maribel González-Torres, Ma. Guadalupe Olayo, Guillermo J. Cruz, Lidia Ma. Gómez, Víctor Sánchez-Mendieta, and Francisco González-Salgado Copyright © 2014 Maribel González-Torres et al. All rights reserved. Cobalt(II) and Manganese(II) Complexes of Novel Schiff Bases, Synthesis, Charcterization, and Thermal, Antimicrobial, Electronic, and Catalytic Features Thu, 21 Aug 2014 06:24:21 +0000 http://www.hindawi.com/journals/ac/2014/506851/ Carbazoles containing two new Schiff bases (Z,Z)-N,N′-bis[(9-ethyl-9H-carbazole-3-yl)methylene]propane-1,3 diamine (L1) and (Z,Z)-N,N′-bis[(9-ethyl-9H-carbazole-3-yl)methylene]-2,2-dimethylpropane-1,3-diamine (L2) and their Co(II) and Mn(II) complexes were synthesized and characterized using various spectroscopic methods and thermal analysis, which gave high thermal stability results for the ligands and their cobalt complexes. The title compounds were examined for their antimicrobial and antifungal activities, which resulted in high activity values for the ligands and their manganese complexes. Oxidation reactions carried out on styrene and cyclohexene revealed that the complex compounds were the most effective catalysts for styrene oxidation, giving good selectivities than those of cyclohexene oxidation. Electronic features of the synthesized compounds were also reported within this work. Selma Bal and Sedat Salih Bal Copyright © 2014 Selma Bal and Sedat Salih Bal. All rights reserved. Dual Wavelength Spectrophotometric Method for Simultaneous Estimation of Atorvastatin Calcium and Felodipine from Tablet Dosage Form Thu, 21 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/ac/2014/131974/ Atorvastatin calcium (ATR) and felodipine (FEL) are beneficial in combination for elderly people in management of hypertension and atherosclerosis. Aim of present study is to develop simple, accurate, and precise method for simultaneous quantitative estimation of ATR and FEL from combined tablet dosage form. Method involves simultaneous equation, using acetonitrile—double distilled water (70 : 30)—common solvent showing absorption maxima at 245 and 268 nm. Calibration curves determination for both drugs has been carried out in 0.1 N HCl, phosphate buffer pH 6.8, and acetonitrile (ACN)—water (70 : 30 V/V). Linearity range was observed in the concentration range of 2 to 12 µg/mL for FEL and 20 to 100 µg/mL for ATR. Percent concentration estimated for ATR and FEL was 100.12 ± 1.03 and 99.98 ± 0.98, respectively. The method was found to be simple, economical, accurate and precise and can be used for quantitative estimation of ATR and FEL. Namdeo R. Jadhav, Ramesh S. Kambar, and Sameer J. Nadaf Copyright © 2014 Namdeo R. Jadhav et al. All rights reserved. Philicity and Fugality Scales for Organic Reactions Mon, 18 Aug 2014 07:48:29 +0000 http://www.hindawi.com/journals/ac/2014/541547/ Theoretical scales of reactivity and selectivity are important tools to explain and to predict reactivity patterns, including reaction mechanisms. The main achievement of these efforts has been the incorporation of such concepts in advanced texts of organic chemistry. In this way, the modern organic chemistry language has become more quantitative, making the classification of organic reactions an easier task. The reactivity scales are also useful to set up a number of empirical rules that help in rationalizing and in some cases anticipating the possible reaction mechanisms that can be operative in a given organic reaction. In this review, we intend to give a brief but complete account on this matter, introducing the conceptual basis that leads to the definition of reactivity indices amenable to build up quantitative models of reactivity in organic reactions. The emphasis is put on two basic concepts describing electron-rich and electron-deficient systems, namely, nucleophile and electrophiles. We then show that the regional nucleophilicity and electrophilicity become the natural descriptors of electrofugality and nucleofugality, respectively. In this way, we obtain a closed body of concepts that suffices to describe electron releasing and electron accepting molecules together with the description of permanent and leaving groups in addition, nucleophilic substitution and elimination reactions. Rodrigo Ormazábal-Toledo and Renato Contreras Copyright © 2014 Rodrigo Ormazábal-Toledo and Renato Contreras. All rights reserved. Effect of γ-Irradiation and Calcination Temperature of Nanosized ZnO/TiO2 System on Its Structural and Electrical Properties Mon, 18 Aug 2014 06:57:33 +0000 http://www.hindawi.com/journals/ac/2014/301410/ ZnO/TiO2 powders were synthesized by sol-gel method using ammonium hydroxide. The effects of calcination temperature (500–1000°C) and gamma rays (with doses from 25 to 150 kGy) on the phases present and their electrical properties were investigated. The results revealed that heating the system investigated at 500°C led to the formation of ZnTiO3-rohom and TiO2-rutile. The degree of crystallinity of the phases produced increased by increasing the calcination temperature. When heating at 1000°C, ZnTiO3-rohom turned to ZnTiO3-cubic but the rutile phase remained stable. γ-Irradiation decreased considerably the crystallite size of the rutile phase from 146 to 63 nm and that of ZnTiO3-cubic decreased from 101 to 39 nm. This treatment led also to the creation of holes in the matrix of irradiated solids which increased the mobility of charge carriers (electrons) leading to a significant increase in the electrical conductivity reaching to 102 to 103-fold. Abdelrahman A. Badawy, Shaymaa E. El-Shafey, Suzan Abd El All, and Gamil A. El-Shobaky Copyright © 2014 Abdelrahman A. Badawy et al. All rights reserved. Hydroboration of Substituted Cyclopropane: A Density Functional Theory Study Mon, 18 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/ac/2014/427396/ The hydroboration of substituted cyclopropanes has been investigated using the B3LYP density functional method employing 6-31G** basis set. Borane moiety approaching the cyclopropane ring has been reported. It is shown that the reaction proceeds via a three-centered, “loose” and “tight,” transition states when boron added to the cyclopropane across a bond to a substituents. Single point calculations at higher levels of theory were also performed at the geometries optimized at the B3LYP level, but only slight changes in the barriers were observed. Structural parameters for the transition state are also reported. Satya Prakash Singh and Pompozhi Protasis Thankachan Copyright © 2014 Satya Prakash Singh and Pompozhi Protasis Thankachan. All rights reserved. A Rapid Extractive Spectrophotometric Method for the Determination of Tin with 6-Chloro-3-hydroxy-2-(2′-thienyl)-4-oxo-4H-1-benzopyran Thu, 14 Aug 2014 09:49:20 +0000 http://www.hindawi.com/journals/ac/2014/750973/ An extractive spectrophotometric method for the determination of the trace amounts of tin has been carried out by employing 6-chloro-3-hydroxy-2-(2′-thienyl)-4-oxo-4H-1-benzopyran (in acetone) (CHTB) for the complexation of the metal ion in HCl medium. The colored species thus produced is quantitatively extracted into dichloromethane and shows the maximum absorbance at 432–437 nm. The method obeys Beer’s law in the range 0.0–1.3 μg mL−1 of tin with molar absorptivity and Sandell’s sensitivity of  L mol−1 cm−1 and 0.0020 μg Sn cm−2, respectively, at 435 nm. The method is highly selective and free from the interference of a large number of elements including platinum metals. The ratio of metal to ligand in the extracted species is 1 : 2. Utilizing this method, the analysis of various synthetic and technical samples including gun metal and tin can have been carried out satisfactorily. Ramesh Kataria and Harish Kumar Sharma Copyright © 2014 Ramesh Kataria and Harish Kumar Sharma. All rights reserved. Synthesis of Highly Stable Cobalt Nanomaterial Using Gallic Acid and Its Application in Catalysis Mon, 11 Aug 2014 11:43:49 +0000 http://www.hindawi.com/journals/ac/2014/686925/ We report the room temperature (25–30°C) green synthesis of cobalt nanomaterial (CoNM) in an aqueous medium using gallic acid as a reducing and stabilizing agent. pH 9.5 was found to favour the formation of well dispersed flower shaped CoNM. The optimization of various parameters in preparation of nanoscale was studied. The AFM, SEM, EDX, and XRD characterization studies provide detailed information about synthesized CoNM which were of 4–9 nm in dimensions. The highly stable CoNM were used to study their catalytic activity for removal of azo dyes by selecting methyl orange as a model compound. The results revealed that 0.4 mg of CoNM has shown 100% removal of dye from 50 μM aqueous solution of methyl orange. The synthesized CoNM can be easily recovered and recycled several times without decrease in their efficiency. Saba Naz, Abdul Rauf Khaskheli, Abdalaziz Aljabour, Huseyin Kara, Farah Naz Talpur, Syed Tufail Hussain Sherazi, Abid Ali Khaskheli, and Sana Jawaid Copyright © 2014 Saba Naz et al. All rights reserved. A Simple and Advantageous Synthesis of the Privileged 1,4-Benzodiazepine Nucleus Mon, 11 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/ac/2014/628326/ A novel domino approach has been described for an easy access of the privileged nucleus of 5-carbomethoxy substituted 1,4-benzodiazepin-2-ones 4(a–i) from an in situ methanolic hydrolysis of an incipient species formed from the interaction of 1-chloroacetylisatin 2(a–i), hexamethyldisilazane, and n-butyl lithium. The reaction is believed to take place through a consecutive series of intramolecular reactions in a cascade to first generate a highly reactive carbene intermediate 3(a–i) from 1-chloroacetylisatin and n-butyl lithium which is simultaneously trapped by hexamethyldisilazane before undergoing its in situ hydrolysis with methanol to initiate its concomitant cyclocondensation to produce 4(a–i) in high yield and purity. Neetu Jain and Dharma Kishore Copyright © 2014 Neetu Jain and Dharma Kishore. All rights reserved. A Conformational Model for MTPA Esters of Chiral N-(2-Hydroxyalkyl)acrylamides Sun, 10 Aug 2014 11:07:57 +0000 http://www.hindawi.com/journals/ac/2014/736417/ The absolute stereochemistry of novel chiral N-(2-hydroxylalkyl)acrylamides prepared by a lipase-catalyzed resolution was successfully determined by 1H NMR of their MTPA esters. The method was validated for this particular case by computational experiments. Eduardo M. Rustoy, Alicia Baldessari, and Leandro N. Monsalve Copyright © 2014 Eduardo M. Rustoy et al. All rights reserved. An Efficient One Pot Protocol to the Annulation of Face “d” of Benzazepinone Ring with Pyrazole, Isoxazole, and Pyrimidine Nucleus through the Corresponding Oxoketene Dithioacetal Derivative Wed, 06 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/ac/2014/358153/ A highly facile single step approach to the annulation of face “d” of benzazepinone nucleus with pyrazole, isoxazole, and pyrimidine ring has been described. The annulation proceeded smoothly on the reaction of oxoketene dithioacetal derivative 3 with (i) NH2–NH2·H2O, (ii) NH2OH·HCl, (iii) acetamidine hydrochloride, (iv) guanidine nitrate, (v) urea, and (vi) thiourea which yielded the pyrazolo, isoxazolo, and pyrimido annulated analogues of benzazepinone 4–9, respectively, in acceptable yields. The 4-ketene dithioacetal analogue of 7-fluorobenzo[b]azepine-2,5-dione (3) was in turn obtained from the reaction of 7-fluoro-3,4-dihydro-1H-benzo[b]azepine-2,5-dione (2) (with CS2 + CH3I in presence of t-BuOK). 7-Fluoro-3,4-dihydro-1H-benzo[b]azepine-2,5-dione (2) resulted from the acylation of p-fluoroaniline with succinyl chloride followed by cyclocondensation of the later with polyphosphoric acid (PPA). Aditi Anand, Navjeet Kaur, and Dharma Kishore Copyright © 2014 Aditi Anand et al. All rights reserved. Baphia nitida Leaves Extract as a Green Corrosion Inhibitor for the Corrosion of Mild Steel in Acidic Media Mon, 04 Aug 2014 11:09:45 +0000 http://www.hindawi.com/journals/ac/2014/808456/ The inhibiting effect of Baphia nitida (BN) leaves extract on the corrosion of mild steel in 1 M H2SO4 and 2 M HCl was studied at different temperatures using gasometric and weight loss techniques. The results showed that the leaves extract is a good inhibitor for mild steel corrosion in both acid media and better performances were obtained in 2 M HCl solutions. Inhibition efficiency was found to increase with increasing inhibitor concentration and decreasing temperature. The addition of halides to the extract enhanced the inhibition efficiency due to synergistic effect which improved adsorption of cationic species present in the extract and was in the order KCl < KBr < KI suggesting possible role of radii of the halide ions. Thermodynamic parameters determined showed that the adsorption of BN on the metal surface is an exothermic and spontaneous process and that the adsorption was via a physisorption mechanism. V. O. Njoku, E. E. Oguzie, C. Obi, and A. A. Ayuk Copyright © 2014 V. O. Njoku et al. All rights reserved. Pulsed Supersonic Beams from High Pressure Source: Simulation Results and Experimental Measurements Sun, 03 Aug 2014 08:52:13 +0000 http://www.hindawi.com/journals/ac/2014/636042/ Pulsed beams, originating from a high pressure, fast acting valve equipped with a shaped nozzle, can now be generated at high repetition rates and with moderate vacuum pumping speeds. The high intensity beams are discussed, together with the skimmer requirements that must be met in order to propagate the skimmed beams in a high-vacuum environment without significant disruption of the beam or substantial increases in beam temperature. U. Even Copyright © 2014 U. Even. All rights reserved. Chiral Recognition by Fluorescence: One Measurement for Two Parameters Wed, 23 Jul 2014 00:00:00 +0000 http://www.hindawi.com/journals/ac/2014/987640/ This outlook describes two strategies to simultaneously determine the enantiomeric composition and concentration of a chiral substrate by a single fluorescent measurement. One strategy utilizes a pseudoenantiomeric sensor pair that is composed of a 1,1′-bi-2-naphthol-based amino alcohol and a partially hydrogenated 1,1′-bi-2-naphthol-based amino alcohol. These two molecules have the opposite chiral configuration with fluorescent enhancement at two different emitting wavelengths when treated with the enantiomers of mandelic acid. Using the sum and difference of the fluorescent intensity at the two wavelengths allows simultaneous determination of both concentration and enantiomeric composition of the chiral acid. The other strategy employs a 1,1′-bi-2-naphthol-based trifluoromethyl ketone that exhibits fluorescent enhancement at two emission wavelengths upon interaction with a chiral diamine. One emission responds mostly to the concentration of the chiral diamine and the ratio of the two emissions depends on the chiral configuration of the enantiomer but independent of the concentration, allowing both the concentration and enantiomeric composition of the chiral diamine to be simultaneously determined. These strategies would significantly simplify the practical application of the enantioselective fluorescent sensors in high-throughput chiral assay. Shanshan Yu and Lin Pu Copyright © 2014 Shanshan Yu and Lin Pu. All rights reserved.