Abstract We report here a method by which Ni-nanoparticles can be used efficiently to catalyze th... more Abstract We report here a method by which Ni-nanoparticles can be used efficiently to catalyze the acetylation of a variety of amines and thiols under ambient conditions at room temperature. However in a competitive reaction, the thiol was acetylated selectively while the amine remained almost unaffected. The demonstrated chemoselectivity could have multiple potential synthetic applications.
Cu-nanoparticles were synthesized and utilized as an efficient, novel and recyclable catalyst for... more Cu-nanoparticles were synthesized and utilized as an efficient, novel and recyclable catalyst for a multi-component coupling reaction using aldehyde, amine and diethyl phosphite. This method provides a wide range of substrate applicability and devoid of co-catalyst/heavy metals with an excellent yield of bioactive α-amino phosphonates. Besides this, catalyst could be recovered and reused up to four runs with almost consistent activity.
View Article Online nanoparticles are spherical in shape and have an average size distribution of... more View Article Online nanoparticles are spherical in shape and have an average size distribution of 5-100 nm. Our protocol provides a rapid and low cost procedure for the synthesis of both copper and copper oxide nanoparticles in the same microemulsion pool. The nanoparticles so formed have been successfully used for catalyzing various chemical reactions. Key words: copper nanoparticles; copper oxide nanoparticles; Water-in-Oil Microemulsions; non-ionic surfactant.
A convenient one-pot synthetic method for the formation of thioethers from various aryl/alkyl hal... more A convenient one-pot synthetic method for the formation of thioethers from various aryl/alkyl halides using heteropoly acid, is described. Heteropoly acid is a simple, cheap and robust catalyst that couples a broad range of electron-deficient as well as electron-rich substrates in excellent yields in short time.
Abstract We report the synthesis and characterization of two nontoxic, thermogelling drug deliver... more Abstract We report the synthesis and characterization of two nontoxic, thermogelling drug delivery systems which are liquid at room temperatures but become a gel at physiological temperature (37 C) potentially leading to release of a drug molecule. We selected temperature as the stimulus for drug release as it is physiologically invariant.
Abstract The present study was designed to systematically compare the conventional and reverse tr... more Abstract The present study was designed to systematically compare the conventional and reverse transfection methodologies for chitosan/DNA complexes using a low molecular weight (MW) chitosan. The hydrodynamic diameter of the complexes, measured by Dynamic Light Scattering (DLS) was found to be∼ 216 nm and TEM investigations showed spherical and compact complexes with an average size of 200 nm.
In this work, we present a novel method for the synthesis of copper nanoparticles. We utilize the... more In this work, we present a novel method for the synthesis of copper nanoparticles. We utilize the charge compensatory effect of ionic liquid [bmim] BF 4 in conjunction with ethylene glycol for providing electro-steric stabilization to copper nanoparticles prepared from copper sulphate using hydrazine hydrate as a reducing agent. The formed copper nanoparticles showed extended stability over a period of one year.
Abstract An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activat... more Abstract An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. An efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles is also reported in this article. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield. Graphical Abstract Selective Protection of Carbonyl Compounds Over Nano-sized Nickel Catalysts Ajeet Kumar,a Santosh Kumar,a Amit Saxena,a Arnab De,b Subho Mozumdara* aDepartment of Chemistry, University of Delhi, Delhi, 110007, India; b Department of Chemistry, Indiana University, Bloomington, USA; subhoscom@yahoo.co.in An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. We report an efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield.
Aldehydes and mercaptoacetic acid are coupled in the presence of a catalytic amount of economical... more Aldehydes and mercaptoacetic acid are coupled in the presence of a catalytic amount of economical and non-toxic molecular iodine in [bmim][BF4] ionic liquid under mild conditions to afford the corresponding 1,3-oxathiolan-5-one in excellent yields. Molecular iodine acts faster in ionic liquids when compared to conventional solvents such as DMSO, DMF, ethyl acetate, and acetonitrile. The recovered ionic liquids can be recycled in subsequent reactions with consistent activity.Aldehydes and mercaptoacetic acid are coupled in the presence of a catalytic amount of economical and non-toxic molecular iodine in [bmim][BF4] ionic liquid under mild conditions to afford the corresponding 1,3-oxathiolan-5-one in excellent yields. Molecular iodine acts faster in ionic liquids when compared to conventional solvents such as DMSO, DMF, ethyl acetate, and acetonitrile. The recovered ionic liquids can be recycled in subsequent reactions with consistent activity.
An efficient methodology employing copper nanoparticles for the preparation of 2-naphthol condens... more An efficient methodology employing copper nanoparticles for the preparation of 2-naphthol condensed 1,3-oxazinone derivatives employing one-pot condensation reaction in the presence of K2CO3 and copper nanoparticles in PEG-400 is described which offers several advantages, viz. high yields, clean reaction, short reaction times, recyclability of the catalyst and simple workup procedure. PEG-400 was found to be the best solvent out of a range of solvents examined for this scheme. Moreover, PEG could stabilize the nanoparticles from oxidation and thus could increase the catalyst efficiency by escalating the TON (Turn over Number) and TOF (Turn over Frequency) of the catalyst, making the protocol greener, eco-friendly and environmentally benign.
Ni-nanoparticles provide efficient catalyst for the reduction of aromatic and aliphatic ketones u... more Ni-nanoparticles provide efficient catalyst for the reduction of aromatic and aliphatic ketones using ammonium formate or hydrogen (H2) gas as hydrogen donor. Comparative studies were done on both hydrogen donors, i.e. ammonium formate and H2 gas and it was found that ammonium formate was better than H2 gas. This method devoid usage of metal oxide or toxic metals, which are required in excess amount.
Abstract We report here a method by which Ni-nanoparticles can be used efficiently to catalyze th... more Abstract We report here a method by which Ni-nanoparticles can be used efficiently to catalyze the acetylation of a variety of amines and thiols under ambient conditions at room temperature. However in a competitive reaction, the thiol was acetylated selectively while the amine remained almost unaffected. The demonstrated chemoselectivity could have multiple potential synthetic applications.
Cu-nanoparticles were synthesized and utilized as an efficient, novel and recyclable catalyst for... more Cu-nanoparticles were synthesized and utilized as an efficient, novel and recyclable catalyst for a multi-component coupling reaction using aldehyde, amine and diethyl phosphite. This method provides a wide range of substrate applicability and devoid of co-catalyst/heavy metals with an excellent yield of bioactive α-amino phosphonates. Besides this, catalyst could be recovered and reused up to four runs with almost consistent activity.
View Article Online nanoparticles are spherical in shape and have an average size distribution of... more View Article Online nanoparticles are spherical in shape and have an average size distribution of 5-100 nm. Our protocol provides a rapid and low cost procedure for the synthesis of both copper and copper oxide nanoparticles in the same microemulsion pool. The nanoparticles so formed have been successfully used for catalyzing various chemical reactions. Key words: copper nanoparticles; copper oxide nanoparticles; Water-in-Oil Microemulsions; non-ionic surfactant.
A convenient one-pot synthetic method for the formation of thioethers from various aryl/alkyl hal... more A convenient one-pot synthetic method for the formation of thioethers from various aryl/alkyl halides using heteropoly acid, is described. Heteropoly acid is a simple, cheap and robust catalyst that couples a broad range of electron-deficient as well as electron-rich substrates in excellent yields in short time.
Abstract We report the synthesis and characterization of two nontoxic, thermogelling drug deliver... more Abstract We report the synthesis and characterization of two nontoxic, thermogelling drug delivery systems which are liquid at room temperatures but become a gel at physiological temperature (37 C) potentially leading to release of a drug molecule. We selected temperature as the stimulus for drug release as it is physiologically invariant.
Abstract The present study was designed to systematically compare the conventional and reverse tr... more Abstract The present study was designed to systematically compare the conventional and reverse transfection methodologies for chitosan/DNA complexes using a low molecular weight (MW) chitosan. The hydrodynamic diameter of the complexes, measured by Dynamic Light Scattering (DLS) was found to be∼ 216 nm and TEM investigations showed spherical and compact complexes with an average size of 200 nm.
In this work, we present a novel method for the synthesis of copper nanoparticles. We utilize the... more In this work, we present a novel method for the synthesis of copper nanoparticles. We utilize the charge compensatory effect of ionic liquid [bmim] BF 4 in conjunction with ethylene glycol for providing electro-steric stabilization to copper nanoparticles prepared from copper sulphate using hydrazine hydrate as a reducing agent. The formed copper nanoparticles showed extended stability over a period of one year.
Abstract An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activat... more Abstract An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. An efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles is also reported in this article. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield. Graphical Abstract Selective Protection of Carbonyl Compounds Over Nano-sized Nickel Catalysts Ajeet Kumar,a Santosh Kumar,a Amit Saxena,a Arnab De,b Subho Mozumdara* aDepartment of Chemistry, University of Delhi, Delhi, 110007, India; b Department of Chemistry, Indiana University, Bloomington, USA; subhoscom@yahoo.co.in An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. We report an efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield.
Aldehydes and mercaptoacetic acid are coupled in the presence of a catalytic amount of economical... more Aldehydes and mercaptoacetic acid are coupled in the presence of a catalytic amount of economical and non-toxic molecular iodine in [bmim][BF4] ionic liquid under mild conditions to afford the corresponding 1,3-oxathiolan-5-one in excellent yields. Molecular iodine acts faster in ionic liquids when compared to conventional solvents such as DMSO, DMF, ethyl acetate, and acetonitrile. The recovered ionic liquids can be recycled in subsequent reactions with consistent activity.Aldehydes and mercaptoacetic acid are coupled in the presence of a catalytic amount of economical and non-toxic molecular iodine in [bmim][BF4] ionic liquid under mild conditions to afford the corresponding 1,3-oxathiolan-5-one in excellent yields. Molecular iodine acts faster in ionic liquids when compared to conventional solvents such as DMSO, DMF, ethyl acetate, and acetonitrile. The recovered ionic liquids can be recycled in subsequent reactions with consistent activity.
An efficient methodology employing copper nanoparticles for the preparation of 2-naphthol condens... more An efficient methodology employing copper nanoparticles for the preparation of 2-naphthol condensed 1,3-oxazinone derivatives employing one-pot condensation reaction in the presence of K2CO3 and copper nanoparticles in PEG-400 is described which offers several advantages, viz. high yields, clean reaction, short reaction times, recyclability of the catalyst and simple workup procedure. PEG-400 was found to be the best solvent out of a range of solvents examined for this scheme. Moreover, PEG could stabilize the nanoparticles from oxidation and thus could increase the catalyst efficiency by escalating the TON (Turn over Number) and TOF (Turn over Frequency) of the catalyst, making the protocol greener, eco-friendly and environmentally benign.
Ni-nanoparticles provide efficient catalyst for the reduction of aromatic and aliphatic ketones u... more Ni-nanoparticles provide efficient catalyst for the reduction of aromatic and aliphatic ketones using ammonium formate or hydrogen (H2) gas as hydrogen donor. Comparative studies were done on both hydrogen donors, i.e. ammonium formate and H2 gas and it was found that ammonium formate was better than H2 gas. This method devoid usage of metal oxide or toxic metals, which are required in excess amount.
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