bluuebunny/crossref_metadata_2025 huggingface dataset:
Benzoannulation of Quinones by a Cycloaddition‐Fragmentation Approach. A Simple Synthesis of Methoxycarbonyl‐Substituted Polyacenoquinones
Authors: Chou Teh‐Chang , Hsu Chia‐Jung , Chen Jao‐Yu
Published: May 2015

The cycloadducts 2A‐5A obtained from the Diels‐Alder cycloadditions of 1,2,3,4‐tetrachloro‐4,5‐dimethoxycyclopentadiene (1) with p‐benzoquinone (2), 1,4‐naphthoquinone (3), 1,4‐anthraquinone (4), and 2,3‐dicyano‐1,4‐benzoquinone (5) were subjected to the reaction with triethylamine in dichloromethane at room temperature. Cycloadducts 2A and 5A enolized to give the corresponding hydroquinones 2B and 5B, which were oxidized with DDQ to afford naphthoquinone ester 2D and anthraquinone ester 5D, respectively. In the cases of cycloadducts 3A and 4A, the enolization occurred concurrently with oxidation and fragmentation to produce directly the polyacenoquinone esters 3D and 4D, respectively. Under the same reaction condition, the unsymmetrical cycloadduct 6A derived from naphthoquinone ester 2D and 1 yielded isomeric polyacenoquinone esters 6Da and 6Db in a ratio of about 8:1.
Novel Polyhydroxysteroids from the Formosan Soft Coral Sarcophyton Glaucum
Authors: Wang Guey‐Horng , Su Jui‐Hsin , Chen Chien‐Ting , Duh Chang‐Yih , Dai Chang‐Feng , Sheu Jyh‐Horng
Published: May 2015

Two novel polyhydroxysteroids, (24S)‐24‐methylcholestane‐3β,5α,6β,25ξ;,26‐pentol 26‐n‐decanoate (1), (24S)‐24‐methylcholestane‐3β,5α,6β,25ξ;,26‐pentol 25,26‐diacetate (2), and three known sterols (3‐5), have been isolated from a Formosan soft coral Sarcophyton glaucum. The molecular structures of these compounds were determined by spectral methods. The cytotoxicity of these compounds toward various cancer cell lines has also been determined.
Triterpenoid Constituents of Borreria Articularis
Authors: Mukherjee K. S. , Mukhopadhyay B. , Mondal S. , Gorai D. , Brahmachari G.
Published: May 2015

The chloroform extract of the aerial parts and roots of Borreria articularis yielded a new triterpene, 3α‐acetoxy‐oleana‐12‐en‐29‐oic acid along with β‐amyrin. The structures were established by means of spectral as well as chemical studies.
1H NMR Study of Hindered Internal Rotation of Tetramethylthiuram Disulfide in Binary Dimethyl Sulfoxide‐Chloroform Mixtures
Authors: Bordbar Maryam , Bijanzadeh Hamid Reza , Alizadeh Naader
Published: May 2015

Hindered internal rotation about the C‐N single bonds joining the thiuram disulfide was studied by 1H NMR complete line‐shaped analysis in different dimethyl sulfoxide‐chloroform (DMSO‐CDCl3) mixtures. From the temperature dependence of methyls proton spectra, activation parameters (Ea, ΔH≠, ΔS≠, and ΔG≠) were obtained. The Arrhenius plots showed a distinct isokinetic temperature at about 35 °C at which the exchange rate is more or less independent of the solvent composition. The resulting ΔH≠ against TΔS≠ plot showed a firmly good linear correlation, indicating the existence of an enthalpy‐entropy composition in an exchange process.
Facile Total Synthesis of (±)‐Nimbiol
Authors: Du Zhen‐Ting , Yue Guo‐Ren , Li An‐Pai , Ma Jun‐Ying , Wu Tong‐Xing , She Xue‐Gong , Pan Xin‐Fu
Published: May 2015

A facile total synthesis of (±)‐nimbiol 1 has been achieved. In order to decrease the dioxo byproduct 2a, an improved oxidation system of CrO3/H2O/HOAc/NaOAc was used.
Solvent‐free Oxidation of Alcohols by Silica Sulfuric Acid/Sodium Dichromate Dihydrate or Potassium Permanganate/Wet SiO2 System
Authors: Mirjalili Bibi Fatemeh , Zolfigol Mohamad Ali , Bamoniri Abdolhamid , Zarei Amin
Published: May 2015

A combination of silica sulfuric acid and sodium dichromate dihydrate or potassium permanganate in the presence of wet SiO2 was used as an effective oxidizing agent for oxidation of alcohols to their corresponding aldehydes or ketones in solvent free conditions.
Hydrogen Chloride Improved Selectivity of Lead Ionic Selective Electrode (Pb‐ISE) under High Calcium Concentration
Authors: Huang Wu‐Jang , Chiu Chen‐Min
Published: May 2015

Leachants from the toxic characteristic leaching procedure (TCLP) of combustion residues, fly ash, usually contain calcium and lead ions as high as to 12000 and 1000 ppm, respectively. In this paper, the authors used a commercialized lead(II) ionic‐selective electrode (Pb‐ISE) to measure the lead(II) concentrations in such leachants and observed a serious interference from calcium(II) ions. The interference starts at the concentration ratio of ([Ca]/[Pb]) in the sample over 2.0. Reasons for the interference are not clear, but it can be suppressed by adding a chemical modifier, HCl(aq) solution, into the sample. The authors have found that the optimized addition amount in TCLP leachants is 4 mL of HCl(aq) per 20 mL sample, and the detection limit of the Pb‐ISE was 5.2 ppm.
Cetyltrimethylammonium Bromide as a Surface Modifier in Paper Separation of 2,4‐D and Silvex Herbicides from Aqueous Solutions
Authors: Wang Wan‐Kung , Liu Chih‐Hsien
Published: May 2015

The paper capillary permeation adsorption (PCPA) separation of 2,4‐D and silvex herbicides from water by the addition of cetyltrimethylammonium bromide (CTAB) was studied. The effect of pH, CTAB concentration, and the type of PCPA treatment on separatability has been investigated. A nearly 100% separatability was obtained for each of 2,4‐D and silvex at pH values larger than 7 and 5, respectively. The separatability is greater than that without an addition of CTAB. It was confirmed that 2,4‐D and silvex are adsorbed as molecules on the fiber surface that contains ion pairs CTA+COO− formed by the combination of CTA+ cations with the carboxyl groups bonded in the fiber surface.
Reaction of Pyrimidinonethione Derivatives: Synthesis of N‐Methyl‐2‐Hydrizinopyrimidine‐4‐One, Thiazolo[3,4‐b] N‐Methylpyrimidinone; 2‐(1‐Pyrazolonyl) N‐Methylpyrimidine‐4‐one and 2‐Hydrazino‐N‐Methyl Pyrimidine‐4‐One Derivatives
Authors: Al‐Shara'ey Abdullah A. Al‐Karim
Published: May 2015

6‐Aryl‐5‐cyano‐4‐pyrimidinone‐2‐thion derivatives 1a‐c reacted with methyl iodide (1:2) to give the corresponding 2‐S,N‐dimethyl pyrimidine‐4‐one derivatives 2a‐c. Compounds 2a‐c were in turn, reacted with hydrazine hydrate to give the sulfur free reaction products 3a‐c. These reaction products were taken as the starting materials for the synthesis of several new heterocyclic derivatives. Reaction of 3a‐c with acetic anhydride and formic acid gave pyrimido triazines 4a‐c and 7a‐c, respectively. Their reactions with active methylene containing reagents gave the corresponding 2‐(1‐pyrazonyl)‐N‐methyl pyrimidine derivatives 9a‐c and 10a‐c, respectively. Their reactions with aromatic aldehydes afforded the corresponding 2‐hydrazono pyrimidine derivatives 11a‐c. The structure of these reactions products were established based on both elemental analysis and spectral data studies.
Synthesis of New Fused Hetecrocyclic Compounds of Benzpyrid‐4‐One Derivatives and Their Some Biological Activity
Authors: Soleiman H. A. , Koraiem A. I. M. , Mahmoud N. Y.
Published: May 2015

A series of fused pyrazolino‐, Isoxazolino‐, Pyrimidino‐, Pyrimidinothino‐, thiazolidinones and β‐lactam incorporating benzpyrid‐4‐one derivatives have been synthesized by different methods of chemical reaction. The prepared compounds were established by universals and modern methods of physical and chemical confirmation.
Solid Supported Synthesis of New 2,4‐Dithioxo‐6‐aryl‐3‐(1′,3′,4′‐thiadiazolo)‐1,3,5‐triazines Using Microwaves
Authors: Kidwai Mazaahir , Mishra Akkal Deo
Published: May 2015

A series of novel 2,4‐dithioxo‐6‐aryl‐3‐(1′,3′,4′‐thiadiazolo)‐1,3,5‐triazines have been synthesized from 1,3,4‐thiadiazolo‐thioureas and arylaldehydes using microwave irradiations (MWI) over inorganic solid supports. The yield afforded in microwave reactions was 80% whereas it was 60% in conventional reactions. Solid supported synthesis using microwaves has eliminated the usage of toxic substances and organic solvents except for the limited consumption of methanol and ethanol in pre and post reaction stages. This methodology has been proved an efficient, facile, rapid, and ecofriendly synthetic technology.
Studies with Functionally Substituted Methylbenzotriazoles: Novel Synthesis of Functionally Substituted Pyrazolo[5,1‐c]‐1,2,4‐Triazines Benzotriazol‐1‐yl, 1‐Pyrazol‐4‐yl Benzotriazoles and 1‐Isoxazol‐4‐yl Benzotriazoles
Authors: Hassanien Abu Zeid A. , Ghozlan Said A. S. , Elnagdi Mohamed H.
Published: May 2015

1‐Benzotriazolylacetophenone 1 couples with aromatic diazonium salts to yield the corresponding coupling products 2. Reaction of 1 with diazotized aminopyrazole afforded the benzotriazolylpyrazolo[5,1‐c][1,2,4]triazine 6. Compound 1 condensed with DMFDMA to yield the enaminone 7 which reacted with hydrazines to yield the pyrazoles 8a,b. Isomeric pyrazoles 10 were synthesized via condensing 1 with phenyl‐hydrazine and subsequent condensation of the formed phenylhydrazone 9 with DMFDMA. Reaction of 7 with hydroxylamine afforded the isoxazole 11 which was converted into the nitrile 13 on reflux in dioxane in the presence of sodium hydride. Compound 13 was also directly obtained from reaction of 1 with 1‐cyanobenzo‐triazole. The reaction of 1 with hippuric acid and arylidenemalononitriles 18a‐c afforded the pyranone 17 and pyridine derivatives 23a‐c, respectively.
Syntheses of Substituted Naphthalenes and Naphthols
Authors: Huang Keng‐Shiang , Wang Eng‐Chi , Chen Hsing‐Ming
Published: May 2015

Syntheses of substituted naphthalenes and naphthols are described. Based on Claisen rearrangement, ring‐closing metathesis (RCM), and related reactions, isovanillin was successfully transformed into a series of substituted naphthalenes and naphthols with good overall yields.
Calix[4]quinones III: The Synthesis of p‐Hydroxycalix[4]arenes by Wolff‐Kishner Reduction
Authors: Tsoo Ching‐Yu , Chen Rong‐Fua , Wang Wen‐You , Lin Lee‐Gin
Published: May 2015

The Wolff‐Kishner reduction of the half‐protected ketal calix[4]monoquinone 3 and its basic hydrolysis product 4 produced a partially reducing product 5. When the same reduction conditions were applied to the calix[4]quinone benzoates 1 and 2, the corresponding title compounds, p‐hydroxycalix[4]arenes (6 and 7), were afforded in one step.
An Efficient Method for the Preparation of Nitriles via the Dehydration of Aldoximes with Phthalic Anhydride
Authors: Wang Eng‐Chi , Huang Keng‐Shiang , Chen Hsing‐Ming , Wu Chung‐Chin , Lin Gwo‐Jiun
Published: May 2015

A new and highly efficient method for the conversion of aldoximes to nitriles was established. By fusing with phthalic anhydride, aldoximes were efficiently and smoothly converted into nitriles, in high yields (over 85%) and in a short time (within 5 minutes). The mixture of phthalic anhydride, a cyclic anhydride, and aldoximes in fusing state set up an ideal transition state for a selective [3.3]‐sigmatropic rearrangement of the acylated aldoximes to nitriles.
Chemical Components of Seriphidium Santolium Poljak
Authors: Deng Yan‐Ru , Song Ai‐Xin , Wang Han‐Qing
Published: May 2015

A new biflavonoid glucoside, apigenin‐7‐O‐β‐D‐glucopyranoside‐(3′‐O‐7″)‐quercetin‐3″‐methyl ether (1) together with twenty known compounds, apigenin (2), luteolin (3), chrysoeriol (4), tricin (5), hispidulin (6), pectolinarigenin (7), eupatilin (8), 5,7‐dihydroxy‐6,3′,4′,5′‐tetramethoxyflavone (9), 5,7,4′‐trihydroxy‐6,3′,5′‐trimethoxyflavone (10), 3,6‐O‐dimethylquercetagetin‐7‐O‐β‐D‐glucoside (11), 6‐hydroxy‐5,7‐dimethoxy‐coumarin (12), taraxerol (13), taraxeryl acetate (14), a mixture of β‐sitosterol (15) and stigmasterol (16), a mixture of the n‐alkyl trans‐p‐coumarates (17), a mixture of the n‐alkyl trans‐ferulates (18), 2‐hydroxy‐4,6‐dimethoxyacetophenone (19), 4‐hydroxy‐2,6‐dimethoxyphenol‐1‐O‐β‐D‐glucopyranoside (20), and 2‐hydroxycinnamoyl‐β‐D‐glucopyranoside (21), were isolated from the whole plant of Seriphidium santolium Poljak. The structures of these compounds were determined by means of spectral and chemical studies.
A New Thiophen Acetylene from Artemisia Absinthium
Authors: Yamari Abbas , Boriky Driss , Bouamrani M. L. , Blaghen M. , Talbi Mohammed
Published: May 2015

The investigation of the dried roots of A. absinthium afforded two known lignans of tetrahydrofuran skeleton, sesamin and yangambin, one known coumarin, 6‐methoxy‐7,8‐methylenedioxy coumarin and a new thiophen acetylene. The structures were elucidated by spectroscopic methods.
Purification and Characterization of Three Lectins Extracted from Cassia Fistula Seeds and Effect of Various Physical and Chemical Agents on Their Stability
Authors: Ali M. Abbas , Sayeed M. Abu , Absar Nurul
Published: May 2015

Three lectins designated as CSL‐1, CSL‐2 and CSL‐3 were purified from Cassia fistula seeds by gel filtration on Sephadex G‐50 followed by ion‐exchange chromatography on DEAE cellulose and finally by affinity chromatography on Sepharose 4B. The molecular weights of the lectins CSL‐1, CSL‐2 and CSL‐3, determined by gel filtration on Sephadex G‐75 column were 37,000, 42,400 and 46,000, and by SDS gel electrophoresis were 37500, 42000 and 46500, respectively. All three lectins agglutinated rat red blood cells and the agglutination was inhibited specifically by galactose and galactose containing saccharide. The neutral sugar contents of the lectins, CSL‐1, CSL‐2 and CSL‐3 were estimated to be 3.5, 3.1 and 2.0%, respectively. The sugar composition of the lectins was found to be galactose in CSL‐1, galactose and glucose in CSL‐2, and galactose and mannose in CSL‐3. The lectins exhibited maximum hemagglutinating activities around pH 7.2 to 7.5 and at a temperature range of 20° to 35 °C. Biological activities of the lectins were abolished sequentially with the increase in concentration of acetic acid and denaturant solutions such as urea and guanidine‐HCl.
pH Dependent Thermal Stabilization of DNA by Glcβ(1→3)GlcNAcβ1→STol
Authors: Lin Chun‐Cheng , Hung Sue‐Mei , Lu Kuo‐Cheng , Cheng Chien‐Chung
Published: May 2015

A disaccharide, Glcβ(1→3)GlcNAcβ1→STol (GGS, 1), was synthesized and demonstrated to stabilize ct‐DNA during the denaturing process. GGS at 50 μM shifted Tm of ct‐DNA by 23 °C and the behavior was pH dependent. Poly(dA‐dT)2 was found to be the preferable type of DNA for GGS stabilization by circular dichroism spectroscopy study.
Cytotoxic Constituents from the Stem Bark of Zanthoxylum Pistaciiflorum
Authors: Chen Jih‐Jung , Huang Hung‐Yi , Duh Chang‐Yih , Chen Ih‐Sheng
Published: May 2015

Two new esters, methyl 4‐(prenyloxy)dihydrocinnamate and methyl 4‐(geranyloxy)dihydrocinnamate, together with fourteen known compounds have been isolated from the stem bark of Zanthoxylum pistaciiflorum. The structures of two new compounds were determined through spectral analyses. Among the isolates, four compounds exhibited effective cytotoxicities against P‐388 and HT‐29 cell lines in vitro.
Sorptive Enrichment of Sulfur Compounds from Gaseous Samples on Polydimethylsiloxane
Authors: Sye Wen‐Fa , Chen Yen‐Chun , Tai Jia‐Wen
Published: May 2015

A method has been developed for preconcentrating the volatile sulfur compounds from gaseous samples using a trap filled with a sorption material, polydimethylsiloxane(PDMS), without the need for extensive cryotrapping with liquid cryogens. The system is based on enrichment of the solutes on a packed bed of 50% (w/w) PDMS on solid support without cryotrapping and is then analysed by using thermal desorption followed by capillary column (GS‐GASPRO) gas chromatography with simultaneous sulfur‐selective detection. The practicality of the system was demonstrated by the analysis of natural gas. Using the system described here, the sulfur gaseous compounds known to cause nuisance odors in the natural gas could be quantitatively trapped. The application of 50% PDMS on silcoport™ for the analysis of sulfur compounds from gaseous samples has been proved to be useful.
Membrane Filtration of Iron(III), Copper(II) and Lead(II) Ions as 1‐(2‐Pyridylazo) 2‐Naphtol (PAN) for Their Preconcentration and Atomic Absorption Determinations
Authors: Soylak Mustafa , Erdoǧan Nilgun Develioglu , Elci Latif
Published: May 2015

A membrane filtration procedure for the preconcentration and atomic absorption spectrometric determination of Pb(II), Co(II) and Fe(III) ions in natural water samples has been established. Cellulose nitrate membrane filters (0.45 μm and 47 mm diameter) were used in all experiments. The procedure is based on chelate formation of the analyte metals with 1‐(2‐pyridylazo) 2‐naphtol (PAN) and on retention of the chelates on cellulose nitrate membrane filter. The cellulose nitrate membrane and analyte ions were completely dissolved by 500 μL of nitric acid at 85 °C on a hood and then metal determinations were performed by flame atomic absorption spectrometry. The method was applied to natural water samples for the determination of analyte ions with satisfactory results, e.g., recoveries > 95%, RSD's < 10%.
Synthesis and Electroluminescence of Metal 4‐Styryl‐8‐hydroxyquinolates
Authors: Chen Mon‐Yao , Hsu Ming‐Ann , Liu Ching‐Yang , Chow Tahsin J.
Published: May 2015

Aluminum and zinc complexes of 4‐substituted 8‐hydroxyquinoline were used effectively as emissive materials in light‐emitting diodes (LED). The substituents chosen in this study were p‐methoxy‐2‐styryl, p‐diethylamino‐2‐styryl, and naphthalene‐2‐vinyl groups. Their emission spectra were red‐shifted with respect to that of aluminum tris(hydroxylquinolate) (Alq3) as a result of extending their π‐conjugation. All complexes formed amorphous glasses, which exhibited high thermal and electrical stability. Typical LED devices were fabricated by mixing the dyes with polyvinylcarbazole and spin‐coated to form thin films, which were sandwiched between ITO (indium tin oxide) and a metal electrode. These devices displayed yellow‐orange emissions with quantum efficiency ca. 0.4%.
Development of the Headspace SPME/ATR‐IR Method for Detection of Chlorinated Aromatic Compounds in Soils
Authors: Yang Jyisy , Shih Wan‐Ying , Meng Fan‐Chun
Published: May 2015

In this paper, a new method based on attenuated total reflection infrared (ATR‐IR) spectroscopy was developed to detect chlorinated aromatic compounds in soil. To eliminate the problems associated in inspection of soil samples by the ATR‐IR method, chlorinated compounds were evaporated from soil matrices and detected in the headspace. The sensing device was constructed by an internal reflection element (IRE) coated with a hydrophobic film to attract and concentrate chlorinated compounds evaporated to the headspace. Factors that influence the analytical signals were studied such as the moisture content, volatilities of analytes, and effect of heating temperature. Results indicated that the addition of thermal energy to the soil sample resulted in an increase of IR signal. However, the IRE was also warmed up and caused a slight decrease of the IR signals after a long detection time. The studies of the influence of moisture indicated that a small amount of water present in soils could tremendously increase the intensity of detected IR signals. The further increase of moisture contents resulted in a decrease of the analytical signals, and the optimal signal was found when soil samples contained 5% (v/w) water. Results in analyses of compounds with different volatilities indicated that even with vapor pressure lower than 0.017 Torrs, quality IR spectra could still be obtained. Using the optimal conditions found in this work, the results in determination of five compounds in soil samples indicated that the linear regression coefficients (R‐square) were higher than 0.992 with detection limits around a few hundreds of ppb.
Synthesis and Antibacterial Activity of Some 3,5‐Diphenyl and 1,3,5‐Triphenyl‐2‐pyrazolines
Authors: Shinde Sunita , Jadhav Wamanrao , Pawar Rajendra , Bhusare Sudhakar
Published: May 2015

Some new 3,5‐diphenyl and 1,3,5‐triphenyl‐2‐pyrazolines derivatives were synthesized by reacting 1,3‐diphenyl‐2‐propen‐1‐ones with hydrazine hydrates and phenyl hydrazine in ethanol. The structural elucidation of the compounds was performed by IR, 1H NMR and elemental analysis. All examined compounds showed appreciable antibacterial activity.
Syntheses of 4‐Alkoxy‐3‐methoxy‐5H‐benzocycloheptenes and 2‐Alkoxy‐3‐methoxy‐5H‐benzocycloheptenes from Isovanillin via Claisen Rearrangement and Ring‐closing Metathesis
Authors: Huang Keng‐Shiang , Wang Eng‐Chi , Chen Hsin‐Ming
Published: May 2015

New syntheses of 4‐alkoxy‐3‐methoxy‐5H‐benzocycloheptenes and 2‐alkoxy‐3‐methoxy‐5H‐benzocycloheptenes were studied. Based on Claisen rearrangement, O‐alkylation, nucleophilic addition of allyl magnesium bromide, ring‐closing metathesis, and dehydration, a series of new 4‐alkoxy‐3‐methoxy‐5H‐benzocycloheptenes and 2‐alkoxy‐3‐methoxy‐5H‐benzocycloheptenes were respectively synthesized from isovanillin in good overall yields.
A Rapid and Convenient Method for Preparing Acylhydrazines from Acyldiazenes
Authors: Li Jian‐Ping , Yu Shu‐Qiang , Qu Gui‐Rong , Wang Yu‐Lu
Published: May 2015

The synthesis of acylhydrazines by using hydrazine hydrate as the reductant to hydrogenate acyldiazenes is reported. Twelve acylhydrazines have been synthesized from acyldiazenes in excellent yields under mild conditions. This method is rapid, convenient, and efficient.
The Synthesis and Chemistry of 1,3‐Bridged Polycyclic Cyclopropenes: 8‐Oxatricyclo[3.2.1.02,4]octa‐2,6‐dienes
Authors: Lee Gon‐Ann , Chang Chih‐Yi , Cherng Chih‐Hwa , Chen Chi‐Sheng , Liu Mei
Published: May 2015

Three 1,3‐bridged polycyclic cyclopropenes, exo‐8‐oxatricyclo[3.2.1.02,4]octa‐2,6‐diene (10), endo‐8‐oxatricyclo[3.2.1.02,4]octa‐2,6‐diene (11), and exo‐6,7‐benzo‐1,5‐diphenyl‐8‐oxatricyclo[3.2.1.02,4]octa‐2,6‐diene (12), have been synthesized by elimination of 2‐chloro‐3‐trimethylsilyl‐8‐oxatricyclo[3.2.1.02,4]‐oct‐6‐enes, 17, 18 and 30, which were generated from 1‐chloro‐3‐trimethylsilylcyclopropene with furan and diphenylisobenzofuran. We have demonstrated a facile route to synthesize the highly strained 1,3‐fused polycyclic cyclopropenes, 10, 11, and 12. The stereochemistry of the Diels‐Alder reactions of cyclopropene 16 with furan and DPIBF are different. Cyclopropene 16 was treated with furan to form exo‐exo and endo‐exo adducts (5:2) and treated with DPIBF to generate an exo‐exo adduct. Compounds 10, 11 and 12 undergo isomerization reactions to form benzaldehyde and phenyl 4‐phenyl‐[1]naphthyl ketone to release strain energies via diradical mechanisms.
Benzofuran Derivatives from Ligularia Stenocephala
Authors: Yan Fu‐Lin , Wang Ai‐Xia , Jia Zhong‐Jian
Published: May 2015

Four new benzofuran derivatives were isolated from the roots of Ligularia stenocephala; they were named as ligustenin A (1), B (2), C (3) and D (4), and the structures were established by spectroscopic methods including 2D NMR techniques. Ligustenin A (1) was found to exhibit potent anti‐tumor activity against HL‐60 (human leukemia cells), Bel‐7402 (human hepatoma cells) and HO‐8910 (human ovarian neoplasm cells) with IC50 values of 18.6, 27.6 and 57.5 μM, respectively.
Chemical Constituents from Annona Glabra
Authors: Hsieh Tian‐Jye , Wu Yang‐Chang , Chen Su‐Ching , Huang Ching‐Shan , Chen Chung‐Yi
Published: May 2015

A new kaurane diterpenoid, annoglabasin G (16α‐hydro‐19‐acetoxy‐ent‐kauran‐17‐al) (1), along with 27 compounds including 18 kaurane diterpenoids, 16β‐hydro‐ent‐kauran‐17‐oic acid (2), 16α‐hydro‐ent‐kauran‐17‐oic acid (3), 19‐nor‐ent‐kauran‐4α‐ol‐17‐oic acid (4), 16α‐hydro‐19‐ol‐ent‐kauran‐17‐oic acid (5), ent‐kaur‐16‐en‐19‐oic acid (6), 16α‐hydroxy‐ent‐kauran‐19‐oic acid (7), 16α,17‐dihydroxy‐ent‐kauran‐19‐oic acid (8), 16β,17‐dihydroxy‐ent‐kauran‐19‐oic acid (9), 16α‐hydro‐ent‐kauran‐17,19‐dioic acid (10), 16β‐hydroxy‐17‐acetoxy‐ent‐kauran‐19‐oic acid (11), 16β‐hydro‐17‐hydroxy‐ent‐kauran‐19‐al (12), 16α‐hydro‐17‐hydroxy‐ent‐kauran‐19‐al (13), 16β,17‐dihydroxy‐ent‐kauran‐19‐al (14), 16α‐hydro‐19‐al‐ent‐kauran‐17‐oic acid (15), 16α‐hydro‐17‐acetoxy‐ent‐kauran‐19‐al (16), 16α‐hydro‐19‐acetoxy‐ent‐kauran‐17‐oic acid (17), ent‐kaur‐15‐en‐19‐oic acid (18) and ent‐kaur‐15‐en‐17‐ol‐19‐oic acid (19); four acetogenins, annomontacin (20), annonacin (21), isoannonacinone (22) and squamocin (23); four steroids, β‐sitosterol (24), stigmasterol (25), β‐sitosteryl‐D‐glucoside (26) and stigmasteryl‐D‐glucoside (27) and one oxoaporphine, liriodenine (28), were isolated from the fresh fruits of Annona glabra. These compounds were characterized and identified by physical and spectral evidence.
Comment on “Symbolic Calculation of Two‐Center Overlap Integrals Over Slater‐type Orbitals”
Authors: Guseinov I. I.
Published: May 2015

Published by Gümüş. and Özdoǧan formulas for the evaluation of two‐center overlap integrals (Gümüş, S.; Özdoǧan, T. J. Chin. Chem. Soc. 2004, 51, 243) are critically analyzed. It is demonstrated that the formulas presented in this work are not original and they can easily be derived from the relationships contained in our papers (Guseinov, I. I. J. Phys. B 1970, 3, 1399; Phys. Rev. A 1985, 32, 1864; J. Mol Struct. (Theochem) 1995, 336, 17) by changing the summation indices and application of a simple algebra. It should be noted that the symbolic results of overlap integrals between different combinations of quantum numbers given in Table 1 and 2 can also be obtained from the use of established in above mentioned our papers general formulas or presented in the literature relations for overlap integrals in terms of the products of molecular auxiliary functions An(p) and Bn(pt) (see, e.g., Lofthus, A. Mol. Phys. 1962, 5, 105).
Synthesis Characterization and Biological Screening of Tri‐benzyl Tin(IV) Complexes of Some Schiff Bases
Authors: Rehman Wajid , Badshah Amin , Baloch Musa Kaleem , Ali Saqib , Hameed Gulzar , Khan Khalid M.
Published: May 2015

Synthesis and characterization of some novel di and tri‐benzyl tin(IV) complexes of some Schiff bases are reported. The 1H‐NMR, 13C‐NMR, 119Sn‐NMR, IR, Elemental Analysis and 119Sn Mössauber studies are made for structural determination. Spectroscopic data reveals that the ligand molecule is bound to the tin atom through oxygen. On the basis of spectroscopic data tetrahedral geometry is proposed for the synthesized compounds. The synthesized compounds have been tested against various microorganisms. The results obtained show that the synthesized compounds have promising activity against all the tested micro‐organisms.
Strengthening of Anticorrosion Passivity by Newly Developed Multi‐silicon Coatings
Authors: Hashem Khaled M. E.
Published: May 2015

The combination of ultrasonic vibratory beam and gas chromatography‐mass spectrometry techniques was used to produce monomers of new organo‐multi‐silicon coating materials. The reactants of these materials were exposed to high passive conditions through all the experimental phase. By the aid of a capillary column, RTX‐5MS, and an EI detector of the Finnigan‐Mat GC, a sample was analyzed on the basis of the rules of the predominant M‐1(s) ions of the main chromatographic pattern. Fragmentation analysis of the high resolution mass spectrometry patterns led to detection of three new compound structures, designated A, B, and C isomers. These isomers were identified by the differences between their retention times. The mechanistic root for each of the three isomers is fully discussed herein by a process of stepped number of cleavages per molecule.
A Simple Spectrophotometric Method for the Determination of Nicotine in Environmental Samples
Authors: Asthana Anupama , Rastogi Rachana , Sunita G. , Gupta V. K.
Published: May 2015

A new simple and sensitive spectrophotometric method for the determination of nicotine is described. The method is based on the bromination of nicotine to form dibromonicotine which reacts with potassium iodide to liberate iodine. The iodine liberated then selectively oxidizes leuco crystal violet, and the crystal violet dye formed shows maximum absorbance at 592 nm. Beer's law is obeyed over the concentration range 0.2 μg–2.2 μg of nicotine in a final solution volume of 25 mL (0.008–0.088 ppm). The molar absorptivity of the colour system is 1.40 × 106 1 mol−1 cm−1. The method is free from the interference of other major toxicants. The various analytical parameters were optimized, and the method was applied for the determination of nicotine in cigarette smoke, food, and biological samples.
First Enantioselective Synthesis of the Neolignans Rhaphidecursinol A and Virolongin B
Authors: Ren Xinfeng , She Xuegong , Peng Kun , Su Ying , Xie Xingang , Pan Xinfu , Zhang Hongbin
Published: May 2015

The enantioselective synthesis of the neolignans Rhaphidecursinol A and Virolongin B is reported for the first time. The key reactions in the synthesis were Sharpless asymmetric dihydroxylation and Mitsunobu reaction. The absolute configuration of Rhaphidecursinol A was confirmed.
Effects of Irradiation on the Storage Stability of Red Palm Oil
Authors: Bangash Fazlullah Khan , Ahmad Taufiq , Atta Shaheen , Zeb Alam
Published: May 2015

The samples of Red Palm Oil (RPO) were irradiated with gamma rays using a Cobalt‐60 source (ISSLEDOVATEL, CIS), to dose levels of 1, 5, 10, 15 and 20 KGy and kept for the storage period of 8 weeks along with an untreated control at ambient conditions. The samples were tested for physical characteristics, i.e., Peroxide Value (POV), Iodine Value (IV), Free Fatty Acid value (FFA), Anisidine Value (AV), Color and β‐Carotene. Results revealed that the POV, FFA, and AV were higher in the irradiated samples than the control at the completion of the experimental period. It was also observed that these effects were positively correlated with increasing the irradiation dose. However, a reversed trend was noted in the case of Iodine Value, color and β‐Carotene.
Total Synthesis of Six Natural Products of Benzodioxane Neolignans
Authors: Jing Xiao‐Bi , Wang Li , Han Ying , Shi Yao‐Cheng , Liu Yong‐Hong , Sun Jing
Published: May 2015

(±)‐Eusiderin E, (±)‐Eusiderin F, (±)‐Eusiderin K, (±)‐Eusiderin J, (±)‐Eusiderin M and (±)‐Eusiderin G were first synthesized from pyrogallol, in which the Claisen Rearrangement was used to afford two important C6‐ C3 units.
The Mechanism Study of Free Radical SH2′ Reactions by Leaving Group Effect and Secondary α‐Deuterium Kinetic Isotope Effect
Authors: Wu Yuh‐Wern , Huang Shu‐Hui , Tseng Teong‐Fuh , Yang Jyh‐Ferng
Published: May 2015

The reactions of free radical addition to allylic compounds are believed to proceed the SH2′ mechanism. It is not clear whether the SH2′ mechanism is concerted or stepwise. The leaving group effects and the secondary α‐deuterium kinetic isotope effects in free radical SH2′ reactions have been determined. The leaving group effect, kBr/kCl, is from 1.88 to 14.3. The secondary α‐deuterium kinetic isotope effects, kH/kD, are 1.20 for 2‐methylallyl chloride and 1,1‐d2‐2‐methylallyl chloride and 1.22 for allyl chloride and 1,1‐d2‐allyl chloride. The free radical SH2′ reactions seem to favor the concerted mechanism.
Ultrasonic Irradiated Synthesis of N‐(5‐aryl‐2‐furoyl)thiourea Derivatives Containing Substituted Pyrimidine Ring under Phase Transfer Catalysis
Authors: Xue Si‐Jia , Ke Shao‐Yong , Wei Tai‐Bao , Duan Li‐Ping , Guo Yan‐Ling
Published: May 2015

A series of N‐(5‐aryl‐2‐furoyl)thiourea derivatives containing substituted pyrimidine ring were synthesized in good yield using PEG‐400 as solid‐liquid phase transfer catalyst under ultrasonic irradiation. The structures of all newly synthesized compounds were elucidated and confirmed by IR, 1H NMR and elemental analysis. Our method has the advantage of shorter reaction time and higher reaction yield compared to the conventional heating method. Preliminary biological tests show that some of the target compounds have better inhibitory activities against roots and stalks of monocotyledon and dicotyledon plants.
A New Synthesis of Angelicin from 7‐Hydroxycoumarin via C‐Propenation‐O‐Vinylation and Ring‐Closing Metathesis
Authors: Tsai Tzu‐Wei , Wang Eng‐Chi
Published: May 2015

A new and concise method for the synthesis of angelicin was described. 7‐Hydroxycoumarin was converted into angelicin in good overall yields via the process of c‐propenation‐o‐vinylation and ring‐closing metathesis (RCM).
Chemical Constituents from Clinopodium Urticifolium
Authors: Wei Xiao‐Mei , Cheng Jie‐Kai , Cheng Dong‐Liang , Gao Li‐Ming
Published: May 2015

Six new triterpene saponins and a new lignan have been isolated from the n‐BuOH and EtOAc solubles of the MeOH extracts of the whole plant of Clinopodium urticifolium. The structures of the new secondary metabolites, named clinopodiside I‐V (6, 1, 2, 3, 4), clinoposaponin Ga (5) and R‐(Z)‐rosmarinic acid B (7), were deduced from the spectroscopic data (1D, 2D‐NMR, FAB‐MS, HRESI‐MS, EI‐MS) and by chemical transformation studies.
Fluorimetric Determination of Ethionamide in Pharmaceutical Preparations and Biological Fluids
Authors: Walash M. I. , El‐Brashy A. M. , Metwally M. E. S. , Abdelal A. A.
Published: May 2015

A highly sensitive and specific fluorimetric method was developed for the determination of ethionamide in pharmaceutical preparations and biological fluids (urine and plasma). The proposed method is based on the study of the quantitative quenching effect of ethionamide on the native fluorescence of eosin in acidic medium due to complex formation. The fluorescence intensity was measured at 536 nm (after excitation at 337 nm). The different experimental parameters affecting the quenching of the native fluorescence of eosin were carefully studied and incorporated into the procedure. Under the described conditions, the method is applicable over the concentration range of 1–8 μg/mL with a detection limit of 80 ng/mL. The percentage recoveries for dosage form, spiked urine and plasma were 99.38 ± 0.824, 99.44 ± 1.58 and 99.25 ± 1.15%, respectively. The results obtained were in good agreement with the official methods. A proposal of the reaction pathway is suggested.
Comment on “Evaluation of Multicenter Electric Multipole Moment Integrals over Integer and Noninteger n‐STOs”
Authors: Guseinov I. I.
Published: May 2015

Özdoǧan (J. Chin. Chem. Soc. 2004, 51, 13) published formulas for evaluating the multicenter electric multipole moment (EMM) integrals over Slater‐type orbitals (STOs). It is demonstrated that all of the formulas presented in this work are not original and they are available in our already published papers or can easily be derived by means of a simple algebra (I. I. Guseinov, J. Mol. Struct. (Theochem) 1996, 367, 83; 1998, 427, 263; Int. J. Quantum Chem. 1998, 68, 145; I. I. Guseinov, B. A. Mamedov, Int. J. Quantum Chem. 2003, 93, 9.
The Copper Clusters in the Particulate Methane Monooxygenase (pMMO) from Methylococcus Capsulatus (Bath)
Authors: Chen Kelvin H.‐C. , Chen Chang‐Li , Tseng Chiu‐Fou , Yu Steve S.‐F. , Ke Shyue‐Chu , Lee Jyh‐Fu , Nguyen Hiephoa T. , Elliott Sean J. , Alben James O. , Chan Sunney I.
Published: May 2015

The particulate methane monooxygenase (pMMO) from Methylococcus capsulatus (Bath) is a multi‐copper protein that hydroxylates methane and other small n‐alkanes to their corresponding alcohols with high regiospecificity and stereoselectivity. The copper ions appear to be arranged into ˜5 trinuclear copper clusters. Two of these clusters are thought to be involved in the dioxygen chemistry and alkane hydroxylation mediated by the enzyme. Accordingly, these catalytic clusters (C‐clusters) are typically oxidized, as the protein is isolated. The remaining copper ions are normally reduced, and it has been suggested that they provide a reservoir of reducing equivalents needed for the turnover of the enzyme. In this study, we have oxidized the protein to different levels of oxidation of the copper ions using dioxygen, hydrogen peroxide, ferricyanide, and dioxygen in the presence of the suicide substrate acetylene, and have characterized the oxidized copper centers using low temperature electron paramagnetic resonance (EPR) and X‐ray absorption spectroscopy. The results are consistent with the grouping of the copper ions into catalytic clusters and electron transfer clusters (E‐clusters). Quantification indicates that there are, indeed, two C‐clusters. A model in which the two C‐clusters are activated by dioxygen starting from their fully reduced states and mediate the hydroxylation chemistry of methane will be presented and discussed.
Mutational Analysis of the Yeast Nucleotide Exchange Factor Mge1p
Authors: Flower Todd R. , Witt Stephan N.
Published: May 2015

Mge1p is an essential nucleotide exchange factor, expressed by the budding yeast Saccharomyces cerevisiae, that catalyzes the release of ADP from Hsp70 molecules. Without such catalysis the Hsp70 reaction cycle comes to a halt. There is intriguing evidence that Mge1p and its homologues are more than just nucleotide exchange factors; specifically, these proteins may also be molecular thermosensors. In this study, a structure‐function analysis of Mge1p was conducted to ascertain the functional significance of the putative thermosensing domain of Mge1p, which comprises the first ˜66 N‐terminal residues of the protein. We show that (i) yeast cells that express Mge1p 66 exhibit a severe growth defect compared to cells expressing wt Mge1p; and (ii) preliminary results from a genetic screen reveal that mutating Ile102 to Asn in the Mge1p 66 protein partially restores cell growth. To further elucidate the role of the 66 N‐terminal residues, in the future we plan to isolate Mge1p 66 and variants that contain suppressor mutations and conduct biophysical studies that probe the binding of these proteins to mtHsp70.
Configurational Entropy of Proteins: Covariance Matrix versus Cumulative Distribution Calculations
Authors: Sullivan David C. , Lim Carmay
Published: May 2015

Calculating the configurational entropy associated with conformational fluctuations constitutes an important challenge in modeling macromolecules. Properly estimating configurational entropy is particularly critical for thoroughly understanding protein folding and assessing contending protein folding mechanisms. Here we use tractable systems where the relative configurational entropy can be calculated analytically to assess two such methods: one based on the atom‐position covariance‐matrix and another based on the cumulative distribution function (CDF) of conformational differences as measured by the root‐mean‐square difference in atomic coordinates. In cases where the conformational distribution of one state is highly dispersed relative to that of another state, the covariance‐matrix greatly overestimates the configurational entropy difference, whereas the CDF reproduces the expected (analytical) difference. As a corollary, the covariance‐matrix discounts the majority of entropy loss associated with imposing excluded‐chain volume constraints in compact polyalanine conformations with chain lengths corresponding to small proteins (50 to 70 amino acids), compared to CDF‐based entropy calculations. The strengths/weakness of the covariance matrix vs. the CDF method for computing relative configurational entropies revealed in this work pave the road to more accurate calculations of the relative configurational entropy of real proteins, in particular upon protein folding.
Support for Nickel as the Labile Metal in the A‐center of the M. Barkeri Acetyl‐CoA Decarbonylase/Synthase Complex
Authors: Arndt Joseph W. , Chen Kelvin H.‐C. , Zhong Xuejun , Krzycki Joseph A. , Chan Michael K.
Published: May 2015

The α8β8γ8δ8ϵ8 acetyl‐CoA decarbonylase synthase (ACDS) complex catalyzes the first step in the conversion of acetate to methane. The critical C‐C bond cleavage of the acetyl group is mediated by the A‐center, aNi‐X‐Fe4S4 cluster that has been localized to the β‐subunit. To elucidate the identity of the labile metal X in the A‐center of purified enzyme, the β‐subunit of the M. barkeri ACDS complex was isolated and studied. Metal analysis revealed the presence of both nickel (1.9) and copper (0.2) per subunit indicating a mixture at the metal site. Treatment of the β‐subunit with the Cu(I) specific chelator, bathocuproine disulfonate (BCS), allowed for the complete removal of the copper in the sample as confirmed by fluorescence quenching of the BCS chelator and subsequent metal analysis. The BCS‐treated β‐subunit was found to have nearly identical activity to the as‐isolated enzyme; importantly, addition of Ni(II) to this BCS‐treated β‐subunit resulted in a 24% increase in acetyltransferase activity over that of the isolated enzyme consistent with activation of the A‐center by incorporation of Ni(II) into sites previously occupied by Cu. These results suggest that while Cu can occupy the labile metal site, it is the Ni‐bound form that is active ‐ providing additional support that the A‐center of the methanogenic ACS consists of aNi‐Ni‐Fe4S4 cluster. Perhaps equally important, these studies demonstrate that BCS/Ni(II) treatment provides a means of curing samples from Cu inactivation ‐ a key step towards obtaining the uniform A‐center needed for detailed structural and mechanistic studies.
Synthesis and Characterization of Organosilicon Substituted Fluorenyl Derivatives
Authors: Khan Shah Alam
Published: May 2015

Friedel‐Crafts cycloalkylation of biphenyl with 2,3‐dichlorobutyltrichlorosilane(Cl3Si‐CH2CHClCHClCH3) at a temperature of 100°C in the presence of anhydrous aluminum chloride catalyst gave cyclized product, 9‐methyl‐9‐(2‐trichlorosilylethyl)fluorene 1a, in 33% yield. Methylation of 1a with nucleophilic reagent such as methyl magnesium chloride, gave 9‐methyl‐9‐(2‐trimethylsilylethyl)fluorene 2 while bromination of 2 with excess amount of bromine in DMF resulted in 2,7‐dibromo‐9‐methyl‐9‐(2‐trichlorosilyl)fluorene 3 in good yield. All the compounds were structurally identified by GC/MS, 1H and 13C‐NMR spectroscopy.
Electrocatalysis of the SiC Particle‐Modified Glassy Carbon Electrode for the Oxidation of Adrenaline
Authors: Yu Zhang‐Yu , Kong De‐Sheng , Wu Shu‐Xin , Wang Han‐Qing
Published: May 2015

The electrocatalytic properties of the SiC particle‐modified glassy carbon electrode (MGC) for adrenaline oxidation were studied by cyclic voltammetry (CV), double‐potential step chronocoulometry (DPSCC), and electrochemical impedance spectroscopy (EIS) techniques in McIlvaine buffer solution. It was shown that the electrode modified with SiC particles markedly displayed an electrocatalytic effect on the process of the electrochemical reaction of adrenaline, i.e., the activity and the reversibility of the MGC electrode has been significantly improved. This was attributed to the adsorption effect of the electroactive adrenaline molecules on the MGC electrode surface.
Improvement of Pulse Amperometric Detection Integrated Automated Flow Injection Analysis of Ethylenethiourea Determination
Authors: Lin Meng‐Shan , Wang Jun‐Sheng , Chen Pei‐Yan , Yeh Hsiu‐Hsuan
Published: May 2015

Improvement of pulse amperometric detection (PAD) method is demonstrated in determination of ethylenethiourea (imidazolidine‐2‐thione, ETU). The anodic detection of ETU will produce polymeric film on an electrode leading to an inactive electrode surface. Here, the PAD method was used to remove the polymeric film formed on the electrode surface between ETU detection. Further, the scheme was integrated with automated flow injection analysis (AFIA) for determining ETU. The operational parameters of PAD in the AFIA system were discussed thoroughly. The analytical characteristics of the system were evaluated at optimum conditions. The linear range of calibration plot was between 20 to 300 μM (the correlative coefficient, r = 0.999) and the detection limit was 0.9 μM (S/N = 3). The relative standard deviations of detection of 50 μM ETU were 0.82% with and 9.07% without PAD scheme. The results indicate the system is a very promising tool for ETU determination. Finally, the matrix effects of two water samples that were collected from a campus and a farm show good recoveries of 92% and 96%.
Indirect Atomic Absorption Determination of Cocaine via Formation and Liquid‐liquid Extraction of the Iron(III)‐cocaine Complex
Authors: Mohammadzai Imdad Ullah , Hinze Willie L.
Published: May 2015

The principles of metal‐alkaloid ion‐pair formation and liquid‐liquid extraction are applied to the development of a sensitive and convenient atomic absorption spectrophotometery (AAS) method for the indirect determination of cocaine. In an aqueous medium of 5 M hydrochloric acid, cocaine is protonated and is associated with tetrachloro ferrate (III) anion prior to its extraction into 1,2‐dichloroethane. The critical experimental variables were identified and optimized. The method is simple and reproducible with a detection limit (DL) of 0.1 ng cm−3 cocaine in water, a relative standard deviation of 0.07 (n = 12), and the calibration graph was linear up to 50 ng cm−3 cocaine.
Solid‐Phase Synthesis of 2‐Alkenamides from Polystyrene‐Supported α‐Selenocarboxylic Acids
Authors: Liu Xiao‐Ling , Wang Xing‐Cong , Sheng Shou‐Ri
Published: May 2015

The polystyrene‐supported α‐selenoacetic acid and α‐selenopropionic acid were prepared and used for the synthesis of 2‐alkenamides from primary and secondary amines in good yields and high purities.
Comparison of Electrochemical Behavior of Hydroxyl‐substituted and Nonhydroxyl‐substituted Azo Dyes at a Glassy Carbon Electrode
Authors: Yu Jiefei , Jia Jinping , Ma Zifeng
Published: May 2015

The voltammetric behaviour of four azo dyes has been compared at a glassy carbon electrode. It is shown that the azo dyes (e.g. Reactive Brilliant Red x‐3b (RBR x‐3b), Acid Red 6b (AR 6b)) with a hydroxyl group in the ortho position with respect to the azo bridge give rise to well defined, irreversible peaks for the oxidation and reduction process within a pH range of 2–12. In the case of the non‐hydroxyl azo dye (e.g. Reactive Yellow x‐rg (RY x‐rg)), or azo dye with a meta hydroxyl group (e.g. Reactive Orange x‐gn (RO x‐gn)), the oxidation was comparatively tougher, and the peak was not clear or even invisible in the accessible potential range. The mechanism of electrochemical oxidation of RBR x‐3b, as well as AR 6b is proposed. The reduction steps were only accessible when pH < 8 for RY x‐rg and RO x‐gn dye compounds. For the hydroxyl‐substituted dyes, re‐oxidation peaks were obtained in the subsequent scan, owing to the oxidation of reduction products‐amine or hydroazo intermediates.
A New Route to Synthesis of 3,6‐Diaryl‐1,2,4‐triazolo[3,4‐b]1,3,4‐oxadiazoles
Authors: Qiu Zao‐Zao , Dai Chao‐Feng , Chao Shu‐Jun , Xu Peng‐Fei , Zhang Zi‐Yi
Published: May 2015

Five new 3,6‐diaryl‐1,2,4‐triazolo[3,4‐b]1,3,4‐oxadiazole derivatives were synthesized by 9 steps from aromatic acids and evaluated for their activities of anticancer and antibacteria. The structures of all new compounds synthesized were elucidated by MS, IR, 1HNMR and HRMS.
Synthesis of Ethyl 2‐Arylaminoimidazo[2,1‐b]benzothiazole‐3‐carboxylates
Authors: Khalafy Jabbar , Ebrahimlo Ali Reza Molla , Dilmaghani Karim Akbari
Published: May 2015

3‐Arylamino‐4‐ethoxycarbonylisoxazol‐5(2H)‐ones, substituted on nitrogen with a benzothiazole group, reacts with triethylamine in ethanol under reflux conditions to provide a convenient synthesis of ethyl 2‐aryl‐aminoimidazo[2,1‐b]benzothiazole‐3‐carboxylates.
Kinetic Spectrophotometric Determination of Trace Amounts of Nitrite by Catalytic Reaction between Methylthymol Blue and Bromate
Authors: Pouretedal Hamid Reza , Nazari Behzad
Published: May 2015

A kinetic spectrophotometric method for determination of trace nitrite in two dynamic ranges (2–100 and 100–500 ng/mL) based on its catalytic effect on the reaction between methylthymol blue and potassium bromate in acidic (sulfuric acid) media is described. The reaction was monitored spectrophotometrically by measuring the decreasing color of methylthymol blue at 437 nm by the fixed‐time method of 4.0 min at 30°C. The detection limit is 0.6 ng/mL, and the relative standard deviations for 50.0 and 250.0 ng/mL nitrite are 1.6% and 1.3%, respectively. The method was used for the determination of nitrite in water samples.
Mild Oxidation of 1,3,5‐Trisubstituted Pyrazolines with N‐Bromo‐sulphonamides
Authors: Ghorbani‐Vaghei Ramin , Azarifar Davood , Maleki Behrooz
Published: May 2015

1,3,5‐Trisubstituted pyrazolines to pyrazoles are carried out efficiently in the presence of new reagents N,N,N′, N′‐tetrabromo‐benzene‐1,3‐disulfonylamine [TBBDA] and N,N′‐dibromo‐N,N′‐1,2‐ethanediylbis‐(p‐toluenesulphonamide) [BNBTS] in solvent‐free conditions with catalytic amounts of SiO2 under microwave irradiation in high yields.