1,721,003 research outputs found
Synthesis and characterization of novel ligands and application of their transition metal complexes as catalysts or anticancer agents
Full text linkIn this Thesis work, we report an innovative approach for the synthesis of 2-bromoacrylic acid and its ester derivatives that are the key intermediates in the synthesis of chiral aryloxypropionic acid an important class of herbicides. The synthesis of the bromo substitued acrylics was carried out via carbonylation of (trimethylsilyl)acetylene using as catalytic system Pd(OCOCH3)2 in combination with CH3SO3H and 2-(6-methyl)(diphenylphosphine)pyridine. When the reaction is carried out in methanol, methyl 2-(trimethylsilyl)acrylate was obtained in good yields with a branched/linear ratio 95/5. On the other hand, hydroxycarbonylation reactions give 2-(trimethylsilyl)acrylic acid with lower conversions and selectivities (ca. 53%, and 93/7 respectively). The effects of phosphine/palladium, acid/palladium, reaction time, temperature, and CO pressure on the substrate conversion and selectivity towards branched isomer have been investigated. Methyl 2,3-dibromo-2-(trimethylsilyl)propanoate is easily prepared by reaction of methyl 2-(trimethylsilyl)acrylate with bromine in dry dichloromethane. Then bromodesylilation of 2-(trimethylsilyl)acrylate in the presence of an excess of base gives 2-bromoacrylic acid in good yield (ca. 90%).
A series of triazole ligands were synthesized by the CuAAC reaction. They were employed as chelating ligands to prepare Ru(II), Pd(II), and Co(II) complexes. Ligands and metal complexes have been characterized by analytical data, ESI-MS and 1H and 13C NMR spectroscopy.
The water soluble sodium 2-(1-((pyridin-2-yl)methyl)-1H-1,2,3-triazol-4-yl)ethyl sulfate ligand
has been employed as ligand in biphasic water/organic solvent catalysis. A preformed ruthenium complex and an iridium system containing this water soluble pyridyl-triazolyl ligand were successfully employed in water/toluene biphasic catalytic hydrogenation of C=C and C=O double bonds. The hydrogenation of styrene, 2-cyclohexene-1-one, m-diisopropenylbenzene, and cinnamaldehyde has been investigated. The water soluble 2-(1-(2-(methylthio)ethyl)-1H-1,2,3-triazol-4-yl)ethanol ligand in combination with [RhCl(COD)]2 gives a system displaying good activity in olefin hydroformylation.
The above water soluble [RuCl(η6-p-cymene)(sulphated ligand)] complex has been tested in vitro against several human cancer cell lines (A375, A431, BxPC3, A549 and HCT-15.) derived from solid tumors by the MTT test. Preliminary results indicate that the ruthenium complex is less cytotoxic than cisplatin but has a potential as antimetastatic agent
Biphase hydroformylation catalyzed by rhodium in combination with a water-soluble pyridyl- triazole ligand
No full text[RhCl(COD)]2 in combination with a water soluble sulphonated pyridyl-triazolyl N,N-bidentate ligand
efficiently catalyzes styrene and 1-hexene hydroformylation in water/organic solvent biphasic systems.
The catalyst displays a good activity affording mixtures of linear and branched aldehydes with complete
chemoselectivity. The aqueous catalytic phase may be recycled four times giving complete substrate
conversion by 18 h. Mercury-poisoning experiments and transmission electron microscopy indicate that,
after the first catalytic run, rhodium is present in the aqueous phase in nanoparticle form.[RhCl(COD)]2 in combination with a water soluble sulphonated pyridyl-triazolyl N,N-bidentate ligand efficiently catalyzes styrene and 1-hexene hydroformylation in water/organic solvent biphasic systems. The catalyst displays a good activity affording mixtures of linear and branched aldehydes with complete chemoselectivity. The aqueous catalytic phase may be recycled four times giving complete substrate conversion by 18h. Mercury-poisoning experiments and transmission electron microscopy indicate that, after the first catalytic run, rhodium is present in the aqueous phase in nanoparticle form
Synthesis, Characterization and Antibacterial Activity on Dinuclear Schiff-base Macrocyclic Metal Complexes
No full textSchiff-bases and their dinuclear metal complexes have been extensively received special attention because of their wide range of applications including catalysts, medicine crystal engineering, anti-corrosion agent, and biological activities [1]. Dinuclear macrocyclic lead (II) complex, Pb2L1(SCN)4 was synthesized by template condensation of pyridine-2,6-dicarboxaldehyde and 1,2-bis (2-aminoethoxy) ethane in presence of Pb(SCN)2 as the metal source, here L1 is tetra-Schiff-base macrocycle. Transmetallation treatment of Pb2L1(SCN)4 with Co(PF6)2.6H2O produced the new complex, Co2L1(SCN)4 [2]. Reduction of lead (II) complex gave new reduced tetra-Schiff-base macrocyclic ligand, L2[3]. All the metal complexes and ligand were characterized by UV-Visible, FT-IR, 1H NMR spectroscopy. The antibacterial activities against some pathogenic gram positive and gram negative bacteria were studied by cylinder disk diffusion method. The complexes were found to inhibit the growth of bacteria
Stereoselective synthesis of 2-substituted acrylic derivatives via carbonylation reaction
No full textThe carbonylation of 1-alkynes is a versatile tool for the synthesis of important intermediates such as α,β-unsaturated carboxylic acids [1,2]. In our recent work, we have disclosed the synthesis of the important intermediate 2-(trimethylsilyl)acrylic acid and its methyl ester, starting from commercially available trimethylsilylacetylene, in the presence of the readily available catalytic system obtained in situ from Pd(OCOCH3)2/CH3SO3H/2-methyl(diphenylphosphino)pyridine. Reactions are carried out at 80 ºC; methoxycarbonylation reactions allow to obtain methyl 2-(trimethylsilyl)acrylate in good conversions (ca. 93%) and with a branched/linear ratio 95/5, whereas hydroxycarbonylation reactions give lower conversions and selectivities (ca. 53%, and 93/7 respectively).
[1] R. Romagnoli, P.G. Baraldi, M.K. Salvador, M.E. Camacho, J. Balzarini, J. Bermejo, F. Estévez, Eur. J. Med. Chem., 2013, 63, 544–557.
[2] B.S. Sekhon, J. Pestic. Sci., 2009, 34, 1–12.
[3] E. Drent, P. Arnoldy, P.H.M. Budzelaar, J. Organomet. Chem., 1993, 455, 247–253
A water-soluble pyridyl-triazole ligand for aqueous phase palladium catalyzed Suzuki–Miyaura coupling
No full textSynthesis of Water-soluble Triazole Ligands and Application of Their Metal Complexes in Biphasic Hydrogenations of C=C and C=O
No full textAbstract:
Homogenous catalysis is a powerful tool for organic synthesis but its success in industrial application is limited because of difficult catalyst separation and reuse. To overcome these issues, the use of biphasic catalysis is at present of great interest because the catalyst is confined in one of the two-phases and the product in the other phase allowing for a prompt recovery of the product and an easy recycle of the catalyst. In particular, the development of water soluble catalysts for aqueous/organic biphasic reactions is increasingly attractive [1]. Our research group has been involved in the synthesis of triazolyl ligands by taking advantage of the copper-catalyzed azide-alkyne [3+2] cyclization [2]. Recently, we have synthesized a small library of N-N or N-S ligands which have been employed in Suzuki-Miyaura reactions [3,4]. In this work, we wish to present our studies on biphasic (water/toluene) catalytic hydrogenation of C=O and C=C (Schemes 3 & 4) double bonds using a water soluble triazole ligand in combination with Ruthenium and Iridium.
[1] (a) Cornils B.; Herrmann W. A.; Horvath I. T.; Leitner W.; Mecking S.; Olivier-Bourbigou H.; Vogt (Eds.) D. Multiphase Homogeneous Catalysis, Wiley-VCH, Weinheim, 2005. (b) Joo F. Aqueous Organometallic Catalysis, Kluwer Acad. Publ. Dordrecht, 2001. [2] V. V. Rostovtsev, L.G. Green, V.V. Fokin, K.B. Sharpless, Angew. Chem., Int. Ed. 2002, 41, 2596. [3] Amadio E.; Scrivanti A.; Chessa G.; Matteoli U.; Beghetto V.; Bertoldini M.; Rancan M.; Venzo A.; Bertani R. J. Org. Chem. 2012, 716, 193. [4] Amadio E.; Bertoldini M.; Scrivanti A.; Chessa G.; Beghetto V.; Matteoli U.; Bertani R.; Dolmella A. Inorg. Chim. Acta 2011, 370, 388
Banking Model of Education in Teacher-Centered Class: A Critical Assessment
Full text linkPaulo Freire in his seminal work Pedagogy of the Oppressed rigorously condemns banking model of education, which implies the learners’ receiving knowledge passively as empty vessels from the teacher , who is supposed to be store-house of knowledge, in the traditional teacher-centered classroom. This article presents relationships of banking education with some other learning theories, i.e., tabula rasa and nativist theory, Derrida’s logocentrism, CLT and post-method pedagogy, and lastly it explains the socio-cultural root of banking education and, therefore, the difficulty of replacing it by other pedagogical innovations. Key words: Paulo Freire, banking model of education, teacher, learners, knowledge, learner’s potentiality, post-method pedagogy, socio-cultural context, etc
APPLICATION OF VARIOUS DOSES OF NITROGEN ON THE PERFORMANCE OF OKRA IN ROOFTOP GARDEN
Full text linkA Thesis
Submitted to the Faculty of Agriculture
Sher-e-Bangla Agricultural University, Dhaka
In partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
IN
AGROFORESTRY AND ENVIRONMENTAL SCIENCE
SEMESTER: JANUARY- JUNE, 2020ABSTRACT
The present study was carried out at the roof of second floor of Academic Building,
Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, Bangladesh
during the period from June to September 2019 to investigate the performance of okra
with different doses of nitrogen (N) in rooftop garden. Four levels of N viz. N
=
Control (No N), N
1
= 120 kg N ha
-1
, N
2
= 150 kg N ha
-1
and N
3
= 180 kg N ha
. The
experiment was laid out in a Completely Randomized Design (CRD) with three
replications. Data on different growth, yield contributing parameters and yield were
recorded and analyzed statistically. The recorded data on different growth yield and
yield contributing parameters were significantly influenced by different N doses.
Regarding growth parameters, the highest plant height (123.20 cm), leaf length (30.17
cm) and stem base diameter (3.25) were recorded from the treatment N
whereas
control treatment gave the lowest values. Again, the highest leaf breadth (37.49 cm),
number of leaves plant
-1
(62.07), number of branches plant
-1
(9.87), number of nodes
plant
-1
(24.20), number of internodes plant
-1
(23.87), fruit petiole length (5.76 cm),
fruit length (13.20 cm) and fruit diameter (2.11 cm), number of fruits plant
(24.10),
single fruit weight (16.59 g), yield plot
-1
(3.80 kg) and yield ha
-1
(13.89 t) were found
in N
2
treatment. The lowest single fruit weight (15.14 g), number of fruits plant
(16.30), yield plot
-1
(2.53 kg) and yield ha
-1
(9.21 t) were recorded in control
treatment. Regarding quality parameters of soil moisture and light, the highest soil
moisture (22.13%) and soil temperature (16.20°C) were found from the treatment N
but the highest light intensity (32.54 klux) was found from N
whereas the lowest soil
moisture (20.55%), soil temperature (15.82°C) and light intensity (30.46 klux) were
recorded from the control treatment. From the above result, it can be concluded that
application of 150 kg N ha
-1
2
may ensure higher yield of okra in rooftop garden.
3
-1
-1
0
-1
Comparativeanalysis of qualitysystems and certifications ofBangladesh and Hungary
No full textA minőségügy nagyon fontos tényező lett többek között Magyarországon is, csakúgy,
mint a keleti országokban, köztük Bangladesben is. Ha Banglades kereskedni akar a világgal, akkor ahhoz megfelelő szabványügyi és minőségügyi rendszereket kell
működtetnie.Magyarországgal nagyon alacsony az áruforgalom. Ennek növelése érdekében
szükséges a minőségnek, valamint a szabványoknak való megfelelés, vagyis az üzleti környezet javítása.Minden termék piacra bocsátását minőségügyi megfelelőség előzi meg. Ha egy termék nem felel meg az adott minőségügyi követelményeknek, akkor arra vagy javító intézkedéseket kell hozni vagy meg kell akadályozni, hogy az adott termék kikerüljön a piacra.A minőségügy sok mindent meghatároz, úgymint a gazdaságot, vagy például a nemzetközi kereskedelmet is, de ezek is ugyanúgy befolyásolhatják a minőségügyet is.
Azzal, hogy Bangladesben gyártott termékeknek az országból való exportálása (például Európába) megkezdődött, nagyon eltávolodott egymástól a gyártó és a vevő.Manapság a Távol-Keleten több országban is jellemző, köztük Bangladesben is, hogy csak a termék egy részét készítik az adott gyárban, úgymond részfeladatokat végeznek.Ezzel a megoldással viszont azt érték el, hogy az emberek nem tudnak azonosulni munkájukkal, nem találkoznak a végtermékkel, amelyet a vevő megvesz.Kereskedelem és marketingBSc/B
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