Classical chemical sciences
Optimized and validated spectrophotometric method is proposed for the determination of nickel and zinc simultaneously. 5- bromosalicylaldehyde thiosemicarbazone (5-BSAT) reacts with nickel(II) and zinc(II) to form [Ni(II)-(5-BSAT)2] and [Zn(II)-5-BSAT] complexes, respectively. The maximum absorbance of these complexes was found at 378 nm and 381 nm, respectively. For [Ni(II)-(5- BSAT)2], Beer’s law is obeyed over the concentration range of 2.0×10-6 M – 6.0×10-5 M with molar absorptivity, ε of 0.92×104 L.mol−1.cm−1. [Zn(II)-5-BSAT] complex obeys Beer’s law in 2.0×10-6 M – 6.0×10-5 M range with molar absorptivity, ε of 1.08×104 L.mol−1.cm−1. A simultaneous spectrophotometric H-point standard addition method (HPSAM) is proposed for the determination of these metals. The proposed method is successfully employed in the analysis of waste water sample for the determination of nickel and zinc content.
Keywords: H-point standard addition method, nickel and zinc, 5-bromosalicylaldehyde thiosemicarbazone, simultaneous determination, spectrophotometry, waste water
Coupling reaction of 4-nitroaniline with 3-aminobenzoic acid provided the corresponding bidentate azo ligand. The prepared ligand was identified by Microelemental Analysis, 1H-NMR, FT-IR, and UV-Vis spectroscopic techniques. Treatment of the prepared ligand with Y(III) and La(III) metal ions in 1:3 M:L ratio in aqueous ethanol at optimum pH yielded a series of neutral complexes with the general formula of [M(L)3]. The prepared complexes were characterized by flame atomic absorption, Elemental Analysis (C, H, N), FT-IR, and UV-Vis spectroscopic methods, as well as conductivity measurements. The nature of the complexes formed were studied following the mole ratio and continuous variation methods; Beer's law obeyed over a concentration range of 1·10–4 – 3·10–4 M. High molar absorbtivity of the complex solutions were observed. In addition, the dyeing performance of the prepared ligand and their complexes were investigated on cotton fabric. The dyes were tested for light and detergent fastness. Biological activity of the ligand and complexes against three selected types of bacteria were also examined. Some of the complexes exhibited good bacterial activities.
Keywords: transition metal complexes, synthesis, spectral studies, azo dyes.
An ionic liquid promoted green and environment friendly synthesis of N-tosyl imines of aromatic aldehydes is described. The present protocol involves use of ionic liquid without any added catalyst to afford the corresponding products in moderate to excellent yield (80- 95%). The process is easy for isolation, tolerance towards both electron-donating and electron-withdrawing substrates which makes it as a valuable method in synthetic chemistry.
Keywords: p-toluenesulfonamide, tosylation, N-tosyl imines, ionic liquid
Condensation of benzoin with para-substituted anilines, (X = H, Me, Cl) gave 1,2-diphenyl-2-(arylimino)ethanol derivatives (I), which were thermally stable up to 130 ◦C, but rearranged to 1,2-diphenyl-2-(arylimino)ethanol derivatives (II), under catalyzed effect of phenylhydrazine, para-substituted aniline and triethylamine. The products were characterized by IR- and NMR- spectral analysis.
Keywords: benzoin Schiff base, phenylhydrazine, para-substituted aniline and triethylamine
α-Mixed aryl(furyl)benzoins undergo spontaneous thermal isomerization to β-isomers in the absence of a base. It is facilitated by two structural features viz. the presence of a para-halogen substituent in the aryl moiety and of a Me2NN=CH-substituent at 5-position of the furan ring.
Keywords: benzoins, arylglyoxals, isomerization
2-Cyano-N'-(9H-fluoren-9-ylidene)acetohydrazide was prepared from the readily obtainable cyanoethanoic acid hydrazide with 9- fluorenone. The title compound underwent a series of heterocyclization reactions through its reaction with different electrophilic reagents such as aromatic aldehydes, arylidene malononitriles, malononitrile, ethyl acetoacetate, phenyl isothiocyanate and CS2 to give novel heterocyclic compounds. Moreover, its reaction with thioglycolic acid was also investigated. The spectral characterization (IR, 1H NMR, MS) of the newly synthesized compounds are discussed.
Keywords: 9-Fluorenone, spirofluorene, dithiolan, dithian derivatives
A new series of 6-(aryl)-3,4-dihydro-1-(tetrahydro-3,4-dihydroxy-5-(hydroxymethyl)furan-2-yl)-4-phenylpyrimidine-2(1H)-thione derivative (5A-5J) have been synthesized from 6-(substituted aldehyde)-4-phenylpyrimidine-2(1H)-thione derivative (4A-4J) by the Claisen-Schmidt cyclization and Satos fusion. The structures of the synthesized compounds were elucidated by IR, 1H NMR, elemental analysis and mass spectroscopic techniques. The synthesized compounds were screened for in-vitro antioxidant activity using the DPPH(2,2 diphenyl 1-picrylhydrazyl) assay. The activity summarized by antioxidant activity unit (AAU) and antioxidant activity index (AAI). The antioxidant strength of compounds was compared against ascorbic acid. Among them, compounds 5A, 5D, 5E, 5F exhibited significant antioxidant activity.
Keywords: Thiones; synthesis; antioxidant activity index
The inhibitive effect of Tryptophan- Zn2+ system in controlling the corrosion of carbon steel in sea water was investigated by weight loss method. Results of weight loss method indicated inhibition efficiency increased with increasing the inhibitor concentration. The corrosion inhibition was observed due to the formation of more stable and compact protective film on the metal surface. The surface morphology of the protective film on the metal surface was analyzed by FTIR and AFM analysis.
Keywords: Corrosion inhibition, amino acids, carbon steel, tryptophan, FTIR, AFM
The corrosion inhibition efficiency of an aqueous extract of Aloe Vera (AV) in controlling the corrosion of carbon steel rain water in absence and presence of with Ni2+ has been studied by weight loss method. Weight loss study reveals that the formulation consisting of 5 ml of AV and 50 ppm of Ni2+ has 98% inhibition efficiency. The results of polarisation study show that the formulation function controls the cathodic reaction predominantly. The AC impedance spectra reveal that a protective film formed on the metal surface. The UV – visible absorption spectra indicates the possibility of formation of Fe2+-AV complex and also Ni2+-AV complex in the solution. FTIR spectrum reveal that the protective film consists of Fe2+-AV complex and Ni(OH)2.
Keywords: corrosion inhibition, Aloe Vera, rain water, carbon steel.
Materials and environmental chemistry
Iodine is a key regulator of the body's basic metabolic activity and insufficiency of this micronutrient can lead to a non-cancerous enlargement of the thyroid gland (goiter) as well as physical and mental disorders in both adults and children. Addition of 40 to 60 ppm of potassium iodide to table salt as recommended by Universal salt iodization (USI) mandate in 2000 can solve all these health problems. Quantitative analysis of iodine was performed on salt samples from different local markets, supermarkets and local stores in Adamawa, Benue, Lagos, Rivers and Kano State. The result showed that the majority of the Nigerian manufactured table salts were compliant with the standards of the World Health Organization standards and USI mandate. However, one had a value of 26.31ppm due to long term storage and exposure to harsh weather conditions. Salts tested from the local eateries had average iodine levels of 71ppm which will be adjusted to permissible limits due when the concentration is reduced by approximately 10% when exposed to high temperatures during cooking. Both commercially available salts and those from local eateries are compliant with the USI mandate and are therefore provide dietary intake of preventing nutritional problems such as Iodine Deficiency Disorders.
Keywords: Iodine, iodine deficiency disorders (IDD), iodization of salts, nutritional disorders
Corrosion resistance of two metals namely 18 carat gold and mild steel (MS) has been evaluated in artificial saliva in the presence of Dglucose. Potential dynamic polarization study has been used to investigate the corrosion behaviour of two metals. The order of corrosion resistance of metals in artificial saliva in the presence of D-glucose is 18 carat gold > MS. The decrease order of corrosion resistance of metals in artificial saliva only is: 18 carat gold>mild steel
Keywords: corrosion of metals, artificial saliva (AS), D-glucose, 18 carat gold and mild steel (MS)
In an attempt to find out what is happening during the chemical treatments of some agricultural residues (rice straw), as well as to link the theoretical aspects and the practical side, in an attempt to explain those changes that occur and thus control the quality and derivatives of the products of these treatment. Although theoretical studying cellulosic wastes, but this aspect of the studies and research has not obtained right after. The idea of this research on the essential elements, namely the first CAChe Program computer to design and expected IR behaviour for these materials, the second is what happened in the experimental treatments.
Keywords: CAChe Program applications, cellulose modelling and chemical treatment
Biochemistry, molecular biology and biotechnology
A new wavevector analysis performed by wavelet transform of Elastic Incoherent Neutron Scattering (EINS) data on three bioprotectant systems, i.e. on the homologous disaccharides trehalose, maltose and sucrose, is presented. The analysis allows to compare the spatial properties of the three systems in the wavevector range of Q = 0.28 - 4.27 Ǻ-1, revealing the existence of different kinds of protons dynamics. It emerges that, differently from previous wavevector analyses, both the low and high wavevector contributions for trehalose, at all the investigated temperature values, are constantly lower and sharper, giving rise to a global energy distribution along the wavevector range markedly less extended. These findings give an account for the bioprotectant effectiveness of trehalose in the medical, pharmaceutical and cosmetic fields.
Keywords: bioprotectant systems, biotechnological applications, neutron scattering, wavelet, disaccharides, trehalose, maltose, sucrose
Chronic stress may affect brain-gut axis and compromise blood-brain barrier (BBB) causing bacterial invasion and mounting nitrergic response that might be involved in stress-induced depression via direct impact on mitochondrial function in brain. The objectives of this study are to examine microbial composition in gut, blood and brain and assess a contribution of functionally different constitutive and inducible forms of nitric oxide synthase (cNOS and iNOS, respectively) to nitric oxide (NO) production in cytoplasm and mitochondria of cortico-limbic brain following chronic stress-induced depression. Depression-like behaviour of early adolescent male rats - resembling human depression - was developed by exposure to 2 weeks of chronic variable physical stress (CVS) (forced swimming, ether, restraint, cold, orthostatic shock and food deprivation).CVS induces in the rat gut a substantial enhancement the number of resident Candida albicans and manifestation of Staphylococcus aureus accompanied by a reduced number of obligate microbes immediately after CVS (stress group) and four days later (post-stress group). S. aureus and C. albicans were also detected in bloodstream and brain of CVS-treated rats. Simultaneously, the levels of L-arginine, L-citrulline and reactive nitrogen species were remarkably elevated in cytoplasm and mitochondria of the prefrontal cortex, striatum, hippocampus, and hypothalamus. We have found for the first time that CVS causes a persistent activation the iNOS in mitochondria of the mentioned brain regions, as well as in cytoplasm of the hypothalamus, while the cNOS activity was not significantly changed in mitochondria of the regions studied, with exception for the hypothalamic mitochondrial cNOS which reduced twice. We have also found a concurrent down-regulation the cNOS in cytoplasm of all the mentioned regions and a long-term up-regulation the iNOS in cytoplasm of the hypothalamus. CVS-induced opposite changes in the subcellular activity of distinct NOSs in cortico-limbic brain appear to be involved in the mitochondrial dysfunction leading to disturbances in neurotransmission, hemodynamic and energy impairment, pathophysiological pathways relevant to depression. We emphasize a role of gut microbiota in the persistent activation the mitochondrial iNOS in cortico-limbic brain and therefore the importance of origin the mitochondrial dysfunction involved in the pathological processes manifested during chronic stress-induced depression. This study would be helpful in understanding both brain-gut-microbiota communications and intracellular processes in the brain at depression, and therapeutic targeting of microbiome and nitrergic response might be included in future strategies in prevention and treatment of depression/anxiety.
Keywords: arginine, blood, brain, Candida albicans, chronic stress-induced depression, citrulline, gut, nitric oxide synthase, Staphylococcus aureus
To study the secondary metabolites in Polygonum Strindbergii Schust. in Bull. Herb. Boiss. ser. in Yunnan province of China, the ground roots were extracted with IL (ionic liquid) aqueous solution, then partitioned by organic solvents and isolated by column chromatography repeatedly. Eight compounds were obtained and their structures were identified by spectral methods, which were found from the plant for the first time. Moreover, the key conditions of ILs application were investigated, which are wished to be helpful for related researchers. The plant is supposed to be further utilized and developed as a meaningful natural resource in the genus.
Keywords: Polygonum Strindbergii Schust. in Bull. Herb. Boiss. ser., secondary metabolites, Ionic liquids, separation and identification
Industrial and engineering chemistry
Conveersion of both Na+ and Cl- found in saline water into separable chemical products was achieved by bubbling ammonia through brine followed by the chemical reaction with carbon dioxide gas. The products obtained are soda ash (Na2CO3) and ammonium chloride (NH4Cl) along with partially desalted water. A development is introduced in the process synthesis to allow for ammonia to be recycled rather than consumed, since ammonia plays a key role in this staged chemical reaction sequence. A conceptual flow scheme for the modified process is presented along with the production- consumption analysis. A comparison is made between the proposed method and the Solvay process.
Keywords: Ammonia, carbon dioxide, soda ash, saline water, Solvay, desalination
With the advent of superplasticizers, dream to discover method of making ready mixed concrete at the lowest possible water cement ratio while maintaining a high workability has achieved. In addition, these concrete material are also suitable for use with other cementations materials like fly ash. Poly(styrene-co-acrylonitrile) prepared with the help of p-acetyl benzylidene triphenyl arsonium ylide had made it possible, the production of concrete at low water cement ratio. Many waste materials of today become the useful by products of tomorrow water cement ratio was maintained between 0.38-0.47. Use of fly ash in concrete improves the penetration rate of CO2 or chloride ions. The result have shown substantial improvement in the properties of concrete after use of copolymer of styrene and acrylonitrile as superplasticizer.
Keywords: p-Acetylbenzylidenetriphenylarsonium ylide (p-ABTAY), ready-mixed concrete (RMC), fly ash, water cement ratio, styrene, acrylonitrile, copolymer
Effects of different reaction conditions such as different water carrying agents, the amount of water carrying agent, the calcination temperature, the calcination time and the amount of catalysts, the reaction time, the molar ratio of acetic acid to benzyl alcohol, the reaction temperature, the amount and type of catalyst (tris(trimethylsilylmethyl)tin chloride, S2O8 2--Fe2O3-CoO, N-methylpyrrolidone hydrosulfate, FeCl3(46 %)/carbon, SO4 2--ZrO2-Nd2O3, strong acid cation exchange resin loaded Fe3+ and the catalyst drying temperature) on the synthesis of benzyl acetate from benzyl alcohol and acetic acid are discussed.
Keywords: Effect; reaction condition; benzyl acetate; synthesis
Asphaltene is one of the constituents of crude oil that plays an important role in the physical behaviour of crude oil. It precipitates and deposits on the surface of equipments that are used to process crude oil and this is because asphaltene is the solid constituent of crude oil that contains a high percentage of Carbon, Nitrogen, Oxygen and Sulphur. The composition of asphaltene is yet to be fully explored due to the fact that it has a complex molecular structure. Several scholars have done research on the asphaltene content of crude oil, but this one concentrates on the effects that asphaltene has on the production and processing of petroleum. In this research paper, we highlighted past and current works and findings on the effect of asphaltenes on petroleum processing.
Keywords: Asphaltenes, asphaltene content, petroleum processing, crude oil