[Show abstract][Hide abstract] ABSTRACT: An improved sample preparation using dispersive solid-phase extraction clean-up was proposed for the trace level determination of 35 multiclass pesticide residues (organochlorine, organophosphorus and synthetic pyrethroids) in edible oils. Quantification of the analytes was carried out by gas chromatography-mass spectrometry in negative chemical ionisation mode (GC-NCI-MS/MS). The limit of detection and limit of quantification of residues were in the range of 0.01-1ng/g and 0.05-2ng/g, respectively. The analytes showed recoveries between 62% and 110%, and the matrix effect was observed to be less than 25% for most of the pesticides. Crude edible oil samples showed endosulfan isomers, p,p'-DDD, α-cypermethrin, chlorpyrifos, and diazinon residues in the range of 0.56-2.14ng/g. However, no pesticide residues in the detection range of the method were observed in refined oils.
[Show abstract][Hide abstract] ABSTRACT: Simultaneous esterification and transesterification method is employed for the preparation of biodiesel from 7.5% free fatty acid (FFA) containing karanja (Pongamia glabra) oil using water resistant and reusable carbon-based solid acid catalyst derived from glycerol in a single step. The optimum reaction parameters for obtaining biodiesel in >99% yield by simultaneous esterification and transesterification are: methanol (1:45 mole ratio of oil), catalyst 20wt.% of oil, temperature 160°C and reaction time of 4h. After the reaction, the catalyst was easily recovered by filtration and reused for five times with out any deactivation under optimized conditions. This single-step process could be a potential route for biodiesel production from high FFA containing oils by simplifying the procedure and reducing costs and effluent generation.
[Show abstract][Hide abstract] ABSTRACT: The effect of background derivatization on the signal enhancement of pesticide residues extracted from edible oil samples was studied by GC with negative chemical ionization MS. The analytes were extracted by a solvent extraction process and the extract was subjected to rapid low-temperature fat precipitation. The residual fatty acids are silylated by derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide. The chromatograms obtained from the derivatized samples showed higher signal intensity and lower detection levels when compared to the direct analysis without derivatization. The sensitivity levels of the method are either better or comparable to that of previously reported methodologies. The LODs of the analyzed organochlorine, organophosphorus and synthetic pyrethroid residues in sunflower, rice bran and ground oil samples were in the range of 0.02-0.5 ng/g, and the LOQs were in the range of 0.1-2 ng/g. The intra-day and inter-day accuracies were in the range of 81-116% with RSDs less than 14%. The recoveries obtained were in the range of 53-89% with the relative standard deviation values less than 13% for all the studied pesticide residues. This article is protected by copyright. All rights reserved.
Journal of Separation Science 10/2013; · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The first total synthesis of clavaminol-G (1) and 1-aminoundecan-2-ol (2) has been achieved from 10-undecenoic acid using epoxidation, regioselective azidolysis and in situ detosylation and reduction reactions as key steps. The methodology is extended for the synthesis of 1-aminoundecan-2-ol derivatives; namely, methyl 11-amino-10-hydroxyundecanoate (3), 11-amino-10-hydroxyundecanoic acid (4) and 11-aminoundecan-1,10-diol (5). Among these, 1-aminoundecan-2-ol (2) exhibited good antimicrobial activity and promising cytotoxicity towards HeLa, MDA-MB-231, MCF-7 and A549 cell lines with IC50 values of 4.36, 4.02, 3.88 and 6.78 μM, respectively. Compound 3 exhibited good activity against HeLa cells (IC50 = 3.59 μM), while compound 5 showed moderate activity towards HeLa and A549 cell lines. Clavaminol G (1) and compound 4 showed no activity towards all the cell lines.
European Journal of Medicinal Chemistry 07/2013; 67C:384-389. · 3.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A bioglycerol derived carbon-sulfonic acid is found to catalyze efficiently the three-component one-pot condensation of isatin, malononitrile, and 1,3-dicarbonyls to afford a wide range of spiro[4H-pyran-3,3′-oxindole]derivatives in good yields and selectivity. The use of a recyclable solid acid catalyst makes this method simple, convenient, and cost-effective.
[Show abstract][Hide abstract] ABSTRACT: An efficient synthetic method was developed for the preparation of 1-octacosanol (C28-alcohol) from commercially available lipid-based intermediates namely sebacic acid (decanedioic acid) and stearyl alcohol. The key step in the synthesis is the preparation of tert-butyl dimethyl octacos-10-enyloxy silane from 10-tert-butyl dimethyl silanyloxy decanal and octadecyl triphenylphosphonium bromide salt employing Witting reaction. This product on simultaneous hydrogenation of double bond and deprotection of TBDMS protecting group in a single step on treatment with Pd/C and H2 in methanol at ambient temperature resulted octacosanol in 95% yields. The products were characterised by IR, 1H NMR, and GC-MS analysis.
European Journal of Lipid Science and Technology 02/2013; · 2.27 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A convinent and efficient method was developed for the synthesis of 1,2-azidoalcohols by ring opening of terminal epoxides with sodium azide employing glycerol-based sulphonic acid functionalized carbon as heterogeneous catalyst in aqueous acetonitrile. The reaction is highly regioselective and affords the corresponding products in excellent yields (78-100%) under mild reaction conditions. The catalyst exhibited efficient reusability without loosing its activity even after 5 cycles of azidolysis of methyl 10,11-epoxy undecanoate under optimized conditions within 2 h.
Journal of oleo science 01/2013; 62(10):849-855. · 1.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: a b s t r a c t A simple and efficient synthetic protocol has been developed for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones by using a novel bioglycerol-based sulfonic acid functionalized carbon catalyst, devoid of mois-ture sensitive metal catalysts and corrosive acidic reagents. The developed method has the advantages of good to excellent yields, short reaction times, operational simplicity, and a recyclable catalyst. The cata-lyst can be prepared by a simple procedure from inexpensive and readily available glycerol and has been shown to be recoverable and reusable up to four cycles without any loss of activity. Multi-component reactions (MCRs) 1 are important synthetic tools that can be useful in the preparation of biologically active compounds. 2 The Biginelli reaction allows access to dihydropyri-midinones (DHPMs), central features of compounds with antiviral, antitumor, antibacterial, cytotoxic, and antiflammatory proper-ties. 3 Some DHPMs possess remarkable pharmacological efficiency, demonstrated by their utility as the integral backbone of calcium channel blockers. 4 Notably, the anticancer agent Monastrol is the only cell-permeable molecule currently known to specifically inhi-bit mitotic kinesin Eg5. 5 DHPMs also feature prominently in SQ 32547 and SWO2, which have been identified as potent orally ac-tive antihypertensive agents (Fig. 1). 6 In addition, several alkaloids isolated from marine sources containing the dihydropyrimidine core unit have shown interesting biological properties. 7 In particu-lar, Batzelladine alkaloids have been found to be potent HIV gp-120-CD4 inhibitors. 8 Therefore, the synthesis of dihydropyrimidi-none derivatives has gained prominence in synthetic organic as well as medicinal chemistry. The Biginelli reaction, originally described by the Italian chem-ist Pietro Biginelli 9 in 1893, involves a one-pot condensation of an aldehyde, a b-ketoester, and urea or thiourea under strongly acidic conditions. The harsh reaction conditions, longer reaction times, and lower yields when using substituted aromatic and aliphatic aldehydes are the main drawbacks. Hence the original Biginelli condensation may not be suitable for compounds with sensitive functional groups. SO3H HO 3 S HO3S Scheme 1. Synthesis of 3,4-dihydropyrimidin-2-(1H)-ones catalyzed by bio-glyc-erol based carbon catalyst.
[Show abstract][Hide abstract] ABSTRACT: We report the total synthesis of (2S,3R)-2-aminododecan-3-ol has been achieved starting from commercially available 10-undecenoic acid. The key steps involved are Sharpless asymmetric epoxidation, Miyashita's boron-directed C-2 regioselective azidolysis, generated the asymmetric centers and in situ detosylation and reduction of azido tosylate. The antifungal activity of the synthesized (2S,3R)-2-aminododecan-3-ol was evaluated on several Candida strains and was comparable to miconazole, a standard drug.
[Show abstract][Hide abstract] ABSTRACT: The present study demonstrates the production of biodiesel from used cooking oil containing high free fatty acid by a two-step heterogeneously catalyzed process. The free fatty acids were first esterified with methanol using a 25 wt.% TPA/Nb(2)O(5) catalyst followed by transesterification of the oil with methanol over ZnO/Na-Y zeolite catalyst. The catalysts were characterized by XRD, FT-IR, BET surface area and CO(2)-TPD. In the case of transesterification the effect of reaction parameters, such as catalyst concentration, methanol to oil molar ratio and reaction temperature, on the yield of ester were investigated. The catalyst with 20 wt.% ZnO loading on Na-Y exhibited the highest activity among the others. Both the solid acid and base catalysts were found to be reusable for several times indicating their efficacy in the two-step process.
[Show abstract][Hide abstract] ABSTRACT: a b s t r a c t We report the total synthesis of (2S,3R)-2-aminododecan-3-ol has been achieved starting from commer-cially available 10-undecenoic acid. The key steps involved are Sharpless asymmetric epoxidation, Miyashita's boron-directed C-2 regioselective azidolysis, generated the asymmetric centers and in situ detosylation and reduction of azido tosylate. The antifungal activity of the synthesized (2S,3R)-2-amino-dodecan-3-ol was evaluated on several Candida strains and was comparable to miconazole, a standard drug Ó 2012 Elsevier Ltd. All rights reserved. Natural products have played an important role in the history of drug discovery and development process by providing novel, clin-ically useful medicines having various biological activities such as anticancer, anathematic, antifungal, anti-protozoal and antimicro-bial activities, among others. 1,2 In the last decades, natural prod-ucts having antifungal activity received increased attention from chemists since fungal infections are very common. So there is al-ways an ever increasing requirement of safe and effective anti-fungal agents to control fungal infections. The importance of antifungal chemotherapy continues to evolve rapidly because inva-sive fungal infections in immuno-compromised patients have be-come increasingly significant. Recently, new antifungal agents, such as voriconazole and caspofungin, 3 have entered the clinical arena. Ongoing efforts towards the search for new natural anti-fungal agents from marine organisms have been recently re-viewed. 4 (2S,3R)-2-Aminododecan-3-ol (1), is a natural product isolated from the ascidian Clavelina oblonga, 1 which showed strong activity against Candida albicans (MIC of 0.7 lg mL À1) and moder-ately active against Candida glabrata (MIC of 30 lg mL À1).
[Show abstract][Hide abstract] ABSTRACT: Biodiesel synthesis from rice bran fatty acids (RBFA) was carried out using cesium exchanged 12-tungstophosphoric acid (TPA) catalysts. The physico-chemical properties of the catalysts were derived from X-ray diffraction (XRD), Fourier transform infrared (FTIR), temperature programmed desorption (TPD) of NH(3) and scanning electron microscopy (SEM). The characterization techniques revealed that the Keggin structure of TPA remained intact as Cs replaced protons. The partial exchange of Cs for protons resulted in an increase in acidity and the catalysts with one Cs(+) (Cs(1)H(2)PW(12)O(40)) showed highest acidity. Under optimized conditions about 92% conversion of RBFA was obtained. The catalyst was reused for five times and retained of its original activity. Pseudo-first order model was applied to correlate the experimental kinetic data. Modified tungstophosphoric acids are efficient solid acid catalysts for the synthesis of biodiesel from the oils containing high FFA.
[Show abstract][Hide abstract] ABSTRACT: The new bioglycerol-based carbon catalyst acts as an efficient, readily available, and reusable catalyst for the synthesis of 2,4,5-trisubstituted imidazoles/1,2,4,5-tetrasubstituted imidazoles, when aromatic aldehyde, ammonium acetate/amine, and 1,2-diketone are reacted in acetonitrile.
[Show abstract][Hide abstract] ABSTRACT: 1. Rice bran lysolecithin (RBL) was evaluated in broiler chicken diets. In the first experiment, RBL was included in diet at 0, 0·5, 2, 8 and 32 g/kg and fed to 250 broiler chickens from 0 to 42 d of age. In the second experiment, RBL was fed at 0, 25 and 50 g/kg diet to 405 day-old broiler chickens until 21 d of age, while during the finisher phase (22-35 d of age) chickens receiving each concentration of RBL were given all three concentrations of RBL in a 3 × 3 factorial manner. The diets were isocaloric. 2. Body weight, food consumption and food conversion efficiency were unaffected by feeding RBL, while the weight of pancreas increased at ≥2 g/kg of RBL in diet (experiment 1). In experiment 2, body weight was greater in the chickens receiving RBL at either 25 or 50 g/kg (21 d) and 50 g/kg (35 d of age). At 21 d of age, food consumption was greater at 25 or 50 g RBL/kg diet, while food conversion efficiency improved with 50 g RBL/kg diet. 3. Fat digestibility increased with RBL at 32 g/kg (experiment 1) and ≤25 g/kg (experiment 2). Rice bran lysolecithin increased ready to cook weight at 50 g/kg during starter phase and decreased abdominal fat at 25 and 50 g/kg during finisher phase (experiment 2). Liver and meat fat content were not affected. 4. It is concluded that lysolecithin from rice bran oil could be used as energy supplement in broiler chicken diet.
British Poultry Science 12/2011; 52(6):769-74. · 1.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel carbon catalyst with –SO3H, –OH and –COOH functional groups was prepared from glycerol
pitch by in situ partial carbonization and sulfonation with sulfuric acid. The activity of the catalyst was
investigated through tetrahydropyranylation and dehydropyranylation of a wide variety of alcohols and
phenols at room temperature by changing the solvent medium from dichloromethane to methanol. Excellent
yields, short reaction times, easy and quick isolation of the products and reusability of the catalyst
are the main attractions of this method. The novel carbon catalyst holds great potential in the green
Journal of Molecular Catalysis A Chemical 07/2011; 345(1-2):96-100. · 3.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 12-Tungstophosphoric acid (TPA) with varying contents supported on SnO2 catalysts was prepared and their efficacy as solid acid catalysts for the esterification of palmitic acid with methanol was investigated. The catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), temperature programmed desorption (TPD) of NH3, Laser Raman, Brunner–Emmett–Teller (BET) surface area and scanning electron microscopy (SEM) techniques. The esterification activity depends on the amount and dispersion of TPA on SnO2 which in turn relates to the amount of acidity. Among the catalysts, 15 wt% TPA/SnO2 was the most promising one with the highest fatty acid conversion. Further, reaction parameters such as catalyst concentration, methanol to palmitic acid mole ratio and reaction temperature were also optimized. The catalyst was recycled and reused with consistent activity. A pseudo first order model was applied to correlate the experimental kinetic data and kinetic parameters were evaluated. The activation energy of the catalysts is comparable to that of mineral acids and lower than usual solid acid catalysts.