Phosphorous Oxychloride Research Articles

SYNTHESIS, CHARACTERISATION AND ANTICANCER ACTIVITY OF SCHIFF BASE DERIVATIVES OF 5-(2-PHENOXYPYRIDIN-3-YL)-1, 3, 4-THIADIAZOL-2-AMINE

Schiff Bases of 5 - (2 - phenoxypyridin - 3 - yl) - 1, 3, 4 - thiadiazol - 2 - amine derivatives 6 (a - h ) have been synthesized with different aromatic aldehyde and tested for in vitro anticancer activity; th e 1, 3, 4 - thiadiazole derivatives were prepared by the reaction of thiosemicarbazide, phosphorousoxy chloride and aromatic acids. The synthesized final Schiff base compounds were purified by column - chromatography and t he structures of the titled Schiff bases were elucidated by IR, 1 H NMR and LCMS spectral measurements. Three different cell lines namely Hela, Hep - G2 and MCF7 are used for the present study. The compounds tested were, in m ost of cases shows cytotoxic effect but, only one compound showed good act ivity on breast carcinoma cell line having IC 50 = 2 .28 μg/ mL.

Synthesis, Characterization and X-ray Diffraction Studies on N-(3-Methoxybenzoyl)benzenesulfonamide

The title compound, N-(3-methoxybenzoyl)benzenesulfonamide, was synthesized by the reaction of benzenesulfo- namide with 3-methoxybenzoic acid in presence of phosphorous oxy chloride. It was characterized by IR, 1 H-NMR, 13 C-NMR and elemental analysis. The structure was further confirmed by single crystal x-ray diffraction studies. The compound crystal- lizes in trigonal crystal system and P31 space groupwith the unit cell parameters a = 18.4547(18) A, b = 18.4547(18) A, c = 11.0022(13) A, γ= 120° , Z = 1 and V = 3245.1(6) A 3 , R(F 2 > 2σ(F 2 )) = 0.0623 and wR(F 2 ) = 0.0670. The asymmetric unit of the title compound contains three molecules, the dihedral angle between the two benzene ring in the three molecules being 82.29(1) o , 76.27(1) o & 76.97(1) o . The crystal data revealed interesting results including the presence of few hydrogen bonds. The crystal structure is stabilized by N-H…O hydrogen bonds, C-H…O and C-H…π interactions.

Six Sigma-based approach to optimise the diffusion process of crystalline silicon solar cell manufacturing

Silicon-based photovoltaics (PV) plays the dominant role in the history of PV due to the continuous process and technology improvement in silicon solar cells and its manufacturing flow. In general, silicon solar cell process uses either p-type- or n-type-doped silicon as the starting material. Currently, most of the PV industries use p-type, boron-doped silicon wafer as the starting material. In this work too, the boron-doped wafers were considered as the starting material to create pn junction and phosphorus was used as n-type doping material. Industries use either phosphorous oxy chloride (POCl3) or ortho phosphoric acid (H3PO4) as the precursor for doping phosphorous. While the industries use POCl3 as the precursor, the throughput is lesser than that of the industries’ use of H3PO4 due to the manufacturing limitations of the POCl3-based equipments. Hence, in order to achieve the operational excellence in POCl3-based equipments, business strategies such as the Six Sigma methodology have to be adapted. This paper describes the application of Six Sigma Define–Measure–Analyze–Improve–Control methodology for throughput improvement of the phosphorus doping process. The optimised recipe has been implemented in the production and it is running successfully. As a result of this project, an effective gain of 0.9 MW was reported per annum.

Synthesis, Characterization and Screening of Anti-tubercular activity of 2, 5-Disubstituted-1, 3, 4-Oxadiazole

The synthesis of 2-furyl-5-(substituted)-1,3,4-oxadiazoles was carried out by microwave irradiation of 2-furoic acid and ethanol followed by subsequent hydrazinolysis with hydrazine hydrate. Finally furan-2-acid hydrazide was treated with appropriate carboxylic acid in the presence of phosphorous oxychloride to produce title compounds. The structures of the newly synthesized compounds were established on the basis of spectral analysis such as IR, H1NMR and Mass spectral data. The synthesized compounds were screened for their anti-tubercular activity.

Facile protection-free one-pot synthesis of 7-deaza-2′-deoxyguanosine-5′-triphosphate — A versatile molecular biology probe

A simple, straightforward, reliable, and efficient protection-free “one-pot, three-step” chemical synthesis of 7-deaza-2′-deoxyguanosine-5′-triphosphate (7-deaza-dGTP) is described. The reaction involves monophosphorylation of 7-deaza-2′-deoxyguanosine using phosphorous oxychloride as the phosphorylating agent, followed by reaction with tributylammonium pyrophosphate, and subsequent hydrolysis affords 7-deaza-2′-deoxyguanosine-5′-triphosphate in a 52% yield with high purity (>99.9%).

Characteristics of silicon solar cell emitter with a reduced diffused phosphorus inactive layer

The diffusion of phosphorus using a phosphorous oxychloride (POCl3) source in silicon has been used widely in crystalline silicon solar cells. The thermal diffusion process in the furnace consists of two steps: pre-deposition and drive-in. The phosphorous doping profile via thermal diffusion often exhibits high concentrations in the surface-near emitter, which result in a recombination increase. This layer, called the dead layer, should be inhibited in order to fabricate high efficiency silicon solar cells. In this paper, the amount of the POCl3 flow rate was varied during the pre-deposition process in order to minimize the dead layer, and the characteristics of the phosphosilicate glass (PSG) and emitter were analyzed. From the secondary ion mass spectroscopy (SIMS) and electrochemical capacitance–voltage profiler (ECV) measurements, the emitter formed using a POCl3 flow rate of 1000 sccm contained the least amount of inactive dopant and resulted in reasonable performance in the silicon solar cell. As the POCl3 flow rate increased, the doped silicon wafer included electrically inactive P near the surface, which functions as a defect degrading the electrical performance of the emitter. As a result of this, the removal of the dead layer containing the inactive P was attempted through dipping the doped wafer in a HF solution. After this process, the emitter saturation current density and implied Voc were improved. The completed solar cells and their external quantum efficiencies at a short wavelength also demonstrated improved performance. A quantitative analysis of the emitter can provide a deeper understanding of methods to improve the electrical characteristics of the silicon solar cell.

Synthesis and Biological Evaluation of Some NewN1-[4-(4-Chlorophenylsulfonyl)benzoyl]-N 4-(aryl)-thiosemicarbazides and Products of Their Cyclization

In the present study, new 1,2,4-triazoles, 1,3,4-thiadiazoles, and acylthiosemicarbaz-ides derived from 4-(4-chlorophenylsulfonyl)benzoic acid hydrazide were synthesized and screened for their antimicrobial and analgesic activities. Acylthiosemicarbazides 2–4 were synthesized by a reaction of 4-(4-chlorophenyl-sulfonyl)benzoic acid hydrazide 1 with different arylisothiocyanates.4,5-Disubstituted-2,4-dihydro-3H-1,2,4-triazol-3-thiones 5–7 and 2,5-disubstituted-1,3,4-thiadiazoles 8–10 were obtained by dehydrative cyclization of corresponding acylthiosemicarbazide derivatives 2–4 in basic media (8% aqueous sodium hydroxide) and in acidic media (sulfuric acid or phosphorous oxychloride), respectively. The structures of the newly synthesized compounds have been confirmed on the basis of elemental analysis and spectral studies (IR, 1H NMR, 13C NMR, MS). Their antimicrobial activities against some bacteria and yeasts were investigated. The analgesic activity of all compounds was performed with two pharmacological tests: the writhing test induced with acetic acid and hot-plate test. The results showed that triazole 7 had the best antimicrobial activity against Bacillus cereus. In the chemical stimulus test, triazoles 6 and 7 were the most active compounds whereas in the hot-plate test thiadiazoles 9 and 10 exhibited the highest analgesic activity.

Rhodium catalyzed cyanide-free cyanation of aryl halide by using formamide as a cyanide source

This work reports rhodium–xantphos as a new catalytic system for cyanide-free cyanation of aryl halides to aryl nitriles. The reaction takes place in the presence of phosphorous oxychloride as an acid and formamide as a cyanide source cum solvent. The developed protocol avoids the use of highly toxic metal cyanides. This methodology is a simple, single step reaction involving formamide as a safe and nontoxic source of cyanation. A variety of aryl iodides/bromides were well tolerated under optimized reaction conditions providing moderate to excellent yield of corresponding cyanides.

Synthesis and antimicrobial activity of novel substituted ethyl 2-(quinolin-4-yl)-propanoates.

Substituted 4-hydroxyquinolines were synthesized from anilines and diethyl 2-(ethoxymethylene)malonate by the Gould-Jacobs reaction via cyclization of the intermediate anilinomethylenemalonate followed by hydrolysis and decarboxylation. The 4-hydroxyquinolines reacted with phosphorous oxychloride to form 4-chloroquinolines, which reacted on heating with diethyl sodiomethylmalonate in DMF to yield moderate yields of substituted ethyl 2-(quinolin-4-yl)propanoates, many of which showed potent antimicrobial activity against Helicobacter pylori.

Synthesis, characterization and anticancer evaluation of 2-(naphthalen-1-ylmethyl/naphthalen-2-yloxymethyl)-1-[5-(substituted phenyl)-[1,3,4]oxadiazol-2-ylmethyl]-1H-benzimidazole

In the present study o-phenylenediamine and naphtene-1-acetic acid/2-naphthoxyacetic acid were used as a starting material through a series of steps and 2-(naphthalen-1-ylmethyl/Naphthalen-2-yloxymethyl)-1H-benzimidazol-1-yl]acetohydrazide 5a, 5b were obtained. In the first series 1,3,4-oxadiazole derivatives have been synthesized from Schiff base of the corresponding hydrazide i.e. 2-[2-(naphthalen-1-ylmethyl)-1H-benzimidazol-1-yl]acetohydrazide 5a by using Chloramin-T. In the second series 1,3,4-oxadiazole has been synthesized from 2-{2-[(naphthalen-2-yloxy)methyl]-1Hbenzimidazol-1-yl}acetohydrazide 5b by using phosphorous oxychloride and aromatic acid. These compounds were evaluated by IR, NMR, Mass spectrometry, elemental analysis and finally in vitro anticancer evaluation was carried out by NCI 60 Cell screen at a single high dose (10–5M) on various panel/cell lines. One compound 7c was found to be the most active on breast cancer cell line and compounds 4b and 7d were moderately active.

Synthesis and Evaluation of Antibacterial Activities of some Important Bridge-head Nitrogenous Heterocyclic Compounds

The key intermediates in the present study to synthesize the title bridge-head nitrogen heterocycle compounds were N-substituted semicarbazides 2(a-c), which prepared by hydrazinolysis of the ethyl substituted carbamates 1(a-c) with hydrazine hydrate. These carbamates were prepared by the reaction of proper amines and ethylchloroformate. The reaction of these semicarbazides with ethanolic solution of carbon disulfide under strong basic conditions at room temperature, followed by acidification resulted in the formation of the corresponding potassium (2-arylcarbamoyl)hydrazine carbodithioate 3(a-c), while refluxing the ethanolic solution for three hours afforded 5-(arylamino)-1,3,4-oxadiazole-2- thioles 4(a-c). The potassium salts 3(a-c) were cyclized with hydrazine hydrate to 4-amino-5-arylamino-1,2,4-triazole-3-thiones(thioles) 5(a-c). Compounds 5(a-c) were excellent precursors for 3-(arylamino)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 6(a-c) by dehydrative ring closure of the proper triazole with formic acid in benzene in presence of phosphorous oxychloride or using microwave irradiation technique. Also, refluxing of the proper triazoles with carbon disulfide under basic conditions afforded 3-(arylamino)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole-6-thiones 7(a-c). Finally 4-amino-3-(4-(5-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-ylamino)-1,3,4-thiadiazol-2-yl)phenylamino)-1H-1,2,4-triazole-5(4H)-thione 5(d) were synthesized by the same procedures that were followed to synthesize its analogs starting from 5-(4-aminophenyl)-1,3,4-thiadiazole-2-amine and duplicated all the scales of the reactants. The structures of these compounds were confirmed by their physical properties in addition to the IR, UV and NMR spectra. All synthesized compounds were tested for their in vitro growth inhibitory activity against a panel of standard strains of pathogenic microorganism including bacteria Staphylococcus, Streptococcus and Salmonella. All these compounds were practically inactive against the tested microorganisms.

Radiolabeling of the cannabinoid receptor agonist AZD1940 with carbon-11 and PET microdosing in non-human primate

N-(2-tert-butyl-1-((4,4-difluorocyclohexyl)methyl)-1H-benzo[d]imidazol-5-yl)ethanesulfonamide (AZD1940) is a candidate drug for treatment of neuropathic pain. As part of the preclinical evaluation of AZD1940, a microdosing study with positron emission tomography (PET) was conducted to assess brain exposure. AZD1940 was radiolabeled with carbon-11 in the benzimidazole moiety. The radioactive precursor, lithium [(11)C]pivalate was obtained via (11)C-carboxylation of tert-butyl lithium. The target compound, [(11)C]AZD1940, was in turn obtained by the microwave assisted reaction between lithium [(11)C]pivalate and the o-phenylene diamine analog of AZD1940 (N-(3-amino-4-((4,4-difluorocyclohexyl)methylamino)phenyl)ethanesulfonamide) in neat phosphorous oxychloride. A brain PET measurement was performed in cynomolgus monkey. The overall radiochemical yield of final formulated radiochemically pure (>99%) [(11)C]AZD1940 was 0.4% (uncorrected for decay) and the specific radioactivity was 13GBq/μmol at time of administration (58min after end of bombardment). After intravenous injection to cynomolgus monkey, the maximum concentration of radioactivity detected in the brain region of interest was 0.7% of the total injected radioactivity. The regional distribution of radioactivity within brain was homogenous. AZD1940 was radiolabelled with carbon-11 and its brain exposure, assessed using PET, was relatively low in comparison to peripheral organ exposure.

Novel Synthesis Approach and Antiplatelet Activity Evaluation of 6-Arylmethyleneamino-2-Alkylsulfonylpyrimidin-4(3<i>H</i>)-one Derivatives and Its Nucleosides

A new and efficient procedure has been designed for the preparation of 6-arylmethylene-amino-2-alkyl sulfonyl-pyrimidine. The first alkylthio group was introduced into the pyrimidine ring by S-alkylation. The introduction of the second one was successfully achieved using the phosphorous oxychloride method to afford 4-chloro-2-alkylthio-pyrimidines. Subsequent nucleophilic displacement by the corresponding alkylamines followed by glycoside bromide addition conveniently gave a series of the target compounds. Thus, the two same or different alkylamino groups were easily introduced into the pyrimidine ring through the two different approaches. The human anti-platelet aggregation activity of the newly synthesized compounds was also described.

Some Pyridyl- and Thiophenyl-Substituted 1,2,4-Triazolo[3,4-b]1,3,4-thiadiazole Derivatives as Potent Antibacterial

The target compounds 6-11a-e were synthesized by condensing 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones 5a-f with various aromatic carboxylic acids in the presence of phosphorous oxychloride. The structures of newly synthesized compounds were characterized by IR, 1 H NMR, 13 C NMR, elemental analysis and mass spectrometric studies. All the synthesized compounds were screened for their antibacterial activity. Almost all the tested compounds were potent against four different strains of bacteria when compared with that of reference drug ciprofloxacin. Compounds 6c, 6e, 8d, 9b, 9e, 11a and 11b showed nearly equal or lower MIC values than standard drug, against all four tested bacterial strains but rest of the compounds showed excellent antibacterial activities.

Formulation development and evaluation of lamivudine controlled release tablets using cross-linked sago starch

Objectives: Modified starches based polymeric substances find utmost applicability in pharmaceutical formulation development. Cross-linked starches showed very promising results in drug delivery application. The present investigation concerns with the development of controlled release tablets of lamivudine using cross-linked sago starch.Methods: The cross-linked derivative was synthesized with phosphorous oxychloride and native sago starch in basic pH medium. The cross-linked sago starch was tested for acute toxicity and drug-excipient compatibility study. The formulated tablets were evaluated for various physical characteristics, in vitro dissolution release study and in vivo pharmacokinetic study in rabbit model.Results: In vitro release study showed that the optimized formulation exhibited highest correlation (R) in case of zero order kinetic model and the release mechanism followed a combination of diffusion and erosion process. There was a significant difference in the pharmacokinetic parameters (Tmax, Cmax, AUC, Vd, T1/2, and MDT) of the optimized formulation as compared to the marketed conventional tablet Lamivir®.Conclusion: The cross-linked starch showed promising results in terms of controlling the release behavior of the active drug from the matrix. The hydrophilic matrix synthesized by cross-linking could be used with a variety of active pharmaceutical ingredients for making their controlled/sustained release formulations.

Synthesis, characterization and antimicrobial activity of 1,3,4-oxadiazole bearing 1H-benzimidazole derivatives

2-(Phenoxymethyl)-1H-benzimidazole (3) obtained by acidic condensation of o-phenylene diamine with phenoxyacetic acid, was reacted with ethyl chloroacetate under anhydrous condition to get ethyl [2-(phenoxymethyl)-1H-benzimidazol-1-yl]acetate (4). The ethyl [2-(phenoxymethyl)-1H-benzimidazol-1-yl]acetate (4) on treatment hydrazine hydrate gave 2-[2-(phenoxymethyl)-1Hbenzimidazol-1-yl]acetohydrazide (5). The acid hydrazide group of 5 was cyclocondensed with various aromatic acids in presence of phosphorous oxychloride to get the titled compounds (6a–p). The structures of all the compounds were established on the basis of elemental and spectral analysis. The synthesized compounds were evaluated for their antimicrobial activity. The compound 6d, 6f, 6h and 6d, 6h and 6I a is most active compounds against Escherichia coli and Staphylococcus aureus respectively. The compound 6d, 6f and 6l is most active against Candida albicans and Aspergillus flavus.

Resonance enhanced multiphoton ionization time-of-flight (REMPI-TOF) study of phosphorous oxychloride (POCl3) dissociation at 235 nm: Dynamics of Cl(2Pj) formation

In one-color REMPI-TOF experiment, the photodissociation dynamics of POCl3 has been studied by photolyzing POCl3 and probing the chlorine atom photofragments, namely, Cl(2P3/2) and Cl∗(2P1/2) using 2+1 REMPI scheme, in the 234–236nm region. We have determined the centre-of-mass photofragment speed distribution, recoil anisotropy parameter, and the spin–orbit branching ratio for chlorine atom elimination channels. The anisotropy parameters for Cl and Cl∗ are the same, and characterized by a value of 0.0±0.05. Two components, namely, the fast and the slow, are observed in the translational energy distributions of Cl and Cl∗. The average translational energies for the Cl and Cl∗ channels for the fast components are 12.5±1.5 and 16.8±1.5kcal/mol, while, for the slow components, the average translational energies are 1.5±1.0 and 2.5±1.0kcal/mol, respectively. Apart from the chlorine atom elimination channel, Cl2 elimination is also observed in the photodissociation of POCl3.

Nontoxic poly(ethylene oxide phosphonamidate) hydrogels as templates for biomimetic mineralization of calcium carbonate and hydroxyapatite architectures

A simple protocol has been developed for the creation of the biomimetic hybrid materials, calcium carbonate, and hydroxyapatite, by in situ growth and mineralization in newly developed nontoxic hydrogel templates. A series of poly(ethylene oxide phosphonamidate) hydrogels with different network structures were synthesized by reacting various poly(ethylene glycol)s with phosphorous oxychloride and diamines in a one-pot protocol, which exhibits promising advantages including a short reaction time, an easy separation, and a high yield with a mass producible feasibility. The hydrogels were proven to be nontoxic according to an in vitro viability assay using human embryonic kidney 293T cells. Careful control of growth and mineralization conditions such as ions transport rate, pH, type of hydrogel, and mineralization temperature resulted in a variety of calcium carbonate and hydroxylapatite architectures including nanorods, nanowires, and well-defined hybrid structures. The resulting materials were analyzed by infrared spectroscopy, electron microscopes, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction.

An Efficient Synthesis of Pyrimidine Specific 2′-Deoxynucleoside-5′-Tetraphosphates

An efficient chemical synthesis of pyrimidine specific 2′-deoxynucleoside-5′-tetraphosphates, such as 2′-deoxycytidine-5′-tetraphosphate (dC4P) and thymidine-5′-tetraphosphate (T4P) is described. The present three-step synthetic strategy involves monophosphorylation of 2′-deoxynucleoside using phosphorous oxychloride, conversion of 5′-monophosphate into the corresponding imidazolide salt, followed by reaction with tris[tributylammonium] triphosphate leading to the 2′-deoxynucleoside-5′-tetraphosphate in good yields.

Polymer Electrolyte Membranes for High Temperature PEMFC

This Journal is Korean Society of Photoscience 2012 C 43 PEMFC has been in great interest because it offers high power density and efficiency for various applications such as electric vehicles, portable electronics and residential power generation. Sulfonic acid based membranes, ‐ represented by NafionR, have to be hydrated for the electrolytes to be very conductive and this restriction limits the operation temperature of PEMFC less than 80 C. When PEMFC is operated at high temperatures above 100 o C, it assures much faster reaction rate along with additional advantages such as prevention of catalyst poisoning by CO, higher system efficiency and better water management. Thus, we developed two types of membranes which had phosphonic acid groups which do not require the hydration due to their self dissociation nature. The first one was Nafion nanocomposite using phosphonic acid ‐ functionalized ZrP (zirconium diphosphophenyl phosphate, Zr3P). The nanocomposite membrane showed higher proton conductivity (~0.025 S/cm at 120 o C, <30% RH) and resulted in good cell performance at high temperature (250 mA/cm at 0.6 V at 120 C). Also, we synthesized the thermostable material that had phosphonic acid groups based on poly(dimethyl siloxane) (PDMS). We introduced 3 aminopropyl triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) to ‐ form nanopores and treated them with phosphorous oxychloride (POCl3). And PDMS connected the nanopores by sol gel method. Thus, intrinsically PDMS was modified to be amphiphilic by substituting end groups with ‐ phosphonic acid groups, which result in the phase separation between hydrophobic PDMS and hydrophilic phosphonic acid groups. The phase separation would form the proton conducting channels in the membrane which would assure high proton conductivity (0.06 S/cm at 20 ~ 130 C). Due to such high proton conductivities and conducting mechanism of phosphonic acid groups, they could be used for high temperature PEMFC at low humid conditions