bluuebunny/crossref_metadata_2025_split huggingface dataset:
Size of Micelles Determined by Static Fluorescence Quenching
Authors: Jeng Jiann‐Jong , Chen Jin‐Ming , Mou Chung‐Yuan 
Published: June 2015

AbstractWe developed a new method to measure the average aggregation number of large rod‐like micelles using static fluorescence self‐quenching of a solubilized fluorophore. The method is based on the increase of self‐quenching of micelle‐solubilized pyrene through excimer formation. We consider the effect of random distribution of pyrene in micelles and the micellar size distribution. The measured average aggregation <n> M is based on a new M‐weighted raging similar to our exponential‐weighted averaging in the transient decay method. We apply this method to study the effect of a large concentration of salt on the average aggregation behavior of sodium dodecyl sulfate (SDS) and cetyle tetraammonium bromide (CTAB). The sizes increase with increasing ionic concentrations. For SDS, we used the thermodynamic model developed by Missel et al. to calculate < n > M which we compare with experimental results.
Propylamido‐Modified C18 Reversed‐Phase for High‐Performance Liquid Chromatography
Authors: Lin Jer‐Yann , Yang Mei‐Hui 
Published: June 2015

AbstractThe synthesis and chromatographic properties of a propylamido‐modified C18 stationary phase are described. The propylamido‐modified C18 phase was prepared by bonding stearic acid to 3‐aminopropyl‐silica gel. The synthesis was simple and reproducible through amide formation by using N‐hydroxysuccinimide and dicyclohexylcarbodiimide. This prepared stationary phase exhibited excellent abilities to separate polycyclic aromatic hydrocarbons (PAHs), polysiloxanes and phenols by HPLC. The chromatographic results show that both the C3 moiety and the amido‐group in this phase contribute significantly to the HPLC separation process. The chromatographic behavior of the prepared phase and commercial C18 phases was also compared in analyses of PAHs and phenols. Although the commercial C18 phases have been extensively used, both the unique selectivity and the highly reproducible synthesis of our prepared phase make it an excellent complement to ordinary C18 phases.
Synthesis and Coordination of Tripodal‐Containing Copper(I) Complexes
Authors: Wang Hsin‐Ell , Liu Shiuh‐Tzung , Lee Gene‐Hsian , Cheng Ming‐Chu , Peng Shie‐Ming 
Published: June 2015

AbstractReaction of copper(I) chloride with 2,2‐bis(diphenylphosphinomethyl)‐l‐phenylthiopropane P2S produced a dimeric species [(P2S)CuC1]2 (2). Treatment of 2 with silver nitrate in acetonitrile gave a hexameric crystalline metal complex {[(P2S)Cu(CH3CN)]6+6NO3} (4), which had a “cyclodextrin‐type” structure. A linear polymeric copper complex [(P2S)Cu(NO3)]n was obtained by recrystallization of 4 in chloroform. These complexes were characterized by single crystal analyses, and their coordination behaviors in solution are discussed.
13C NMR Substituent Parameters of Dithioacetal Groups in Benzene Derivatives. The σp+ Values of Cyclic Dithioacetals
Authors: Tzeng Yih‐Ling , Wong Ken‐Tsung , Cheng Wen‐Lung , Luh Tien‐Yau 
Published: June 2015

AbstractThe 13C NMR spectra of forty‐six cyclic dithioacetals and their derivatives have been studied. A set of shift parameters was established for each of these heterocycles as substituent. Based on the Hammett type correlation for substituted benzenes, the σP +values of cyclic dithioacetal groups have been determined.
Nuclear Magnetic Resonance Studies VII. Carbon‐13 Chemical Shifts of Some Methyl‐Substituted Norbornyl P‐Nitrobenzoates
Authors: Liu Kwang‐Ting , Chen Hui‐Ju , Chiu Pao‐Feng , Lee Shu‐Ming 
Published: June 2015

AbstractThe 13C NMR spectra of two unsubstituted and twelve methyl‐substituted norbornylp‐nitrobenzoates (1–14) were measured and unambiguously assigned. The substituent effects were found to be similar to those observed in the corresponding alcohols, but the magnitudes varied. The γ‐effect is more complicated than solely spatially‐dependent.
Application of The Xα and PM3 Methods to Chloromethanes: Ionization Potentials and Electron Affinities
Authors: Lu Yuh‐Jy , Chao Jeng Shiow‐Yau 
Published: June 2015

AbstractThe resonance energies for attachment of an electron to the chloromethanes and the ionization potentials of the chloromethanes were studied both by the multiple scattering Xα‐SCF method and by the PM3 method. An external positively charged Watson sphere is used to stabilize the resonances in the Xα method. The calculated results provide support for the assignment of the features observed in the electron transmission spectra of the chloromethanes.
Enantioselective Addition of Iodine Azide to α,β‐Unsaturated Carboxylic Acid Derivatives
Authors: Lee Pey‐Chen , Wu Chi‐Cheng , Cheng Ming‐Chu , Yu‐Wang  , Wu Ming‐Jung 
Published: June 2015

AbstractThe addition of iodine azide to chiral conjugated N‐enoyl‐sultam or α,β‐unsaturated N‐acyloxazolidinones generated two asymmetric centers at C(α) and C(β) with high π‐face differentiation and regioselectivity. The diastereomerically pure product was easily obtained by crystallization with purity up to 94% de. The structure of 2a was determined by X‐ray diffraction analysis which also indicated that B and 4 are reactive conformations.
Synthesis and Ring Transformation of Pyrrolo[2,3‐d][1,3]oxazine to Pyrrolo[2,3‐d]Pyrimidines
Authors: Bayomi Said M. 
Published: June 2015

AbstractA convenient route is reported for the synthesis of fused pyrrolo[2,3‐d][1,3]oxazine and pyrrolo[2,3‐d]‐pyrimidine derivatives from 2‐amino‐1‐benzyl‐3‐t‐butoxycarbonyl]‐4,5‐dimethylpyrrole.
A Facile Diagnostic 1H NMR Method for Syn and anti Hydroxy Systems
Authors: Roos Gregory H. P. , Manickum Thavrin , Malissar Dean G. 
Published: June 2015

AbstractIn diastereomeric hydroxyl‐containing systems, the relative 1H‐NMR chemical shift of the carbamate NH of the in situ generated trichloroacetylisocyanate derivatives appear to be diagnostic for the syn and anti stereochemistry.
Advanced Methodologies for Adsorption/Thermal Desorption with Tenax‐TA for the Analysis of Polycyclic Aromatic Hydrocarbons and Sulfur Compounds
Authors: Sye Wen‐Fa , Wu Chun‐Yi 
Published: June 2015

AbstractWe have evaluated an analytical method for the determination of polycyclic aromatic hydrocarbons (PAHs) and sulfur compounds in air by means of adsorption/temperature‐programmed thermal desorption (ATPTD) with small bed volume (0.08g) Tenax‐TA cartridges, followed by a cryogenic trap in a precolumn with liquid nitrogen as an appropriate concentration method before capillary gas chromatography is described. The enriched components from the adsorption cartridges are transferred to the capillary column with a valveless switching system. Recoveries were determined for the complete ATPTD method. Desorption recoveries near 100% were found for various of polycyclic aromatic hydrocarbons and sulfur compounds. The sulfur compounds known to cause nuisance odors in the atmosphere near sulfur recovery and sewerage treatment works were also determined.
Photoluminescence of Acenaphthenone in Organic Solvents and Aqueoug Media
Authors: Chou Liang‐Chen , Tzeng Huey‐Fen , Fang Tai‐Shan 
Published: June 2015

AbstractThe configuration of the lowest excited state of acenaphthenone, S1(π, π*) or T1(π, π*), depending on the solvent, dominates photoluminescence. The T1(n, π*) state in aprotic organic solvents is responsible for the phosphorescence of acenaphthenone. The wavelengths of the phosphorescence measured in benzene are 576 nm and 635 nm (vibronic) with 3.3 × 10−4 quantum efficiency. However, the S1(π, π*) state in protic solution which dominates the fluorescence emission depending upon acidity is the most distinctive feature of acenaphthenone. The wavelengths of the emissions are 446 nm under water solvation with 0.185 quantum efficiency and 538 nm with 0.097 quantum efficiency under high acidity. The emission at 446 nm is assigned from a H‐bonded keto‐form excited state, whereas the emission at 538 nm is probably due to the excited state of protonated keto‐form. The pKa value in aqueous solution measured by diminution of fluorescence in basic solutions is 12.5 ± 0.4.
Synthesis of 4‐Oxo‐1,2,3,4‐tetrahydro‐β‐carbolines via Palladium‐Catalyzed Intramolecular Cyclization of Bromoenaminones
Authors: Yang Shyh‐Chyun , Wang Huey‐Min , Kuo Ching‐Shwu , Chen Ling‐Ching 
Published: June 2015

AbstractThe synthesis of 4‐oxo‐1,2,3,4‐tetrahydro‐β‐carbolines from bromoenaminones derived from 1‐substituted piperidine‐3,5‐dione is described. The reaction proceeds by the intramolecular cyclization of bromoenaminones involving arylpalladium complexes.
Isoquinoline Alkaloids from Neolitsea Konishii
Authors: Lee Shoei‐Sheng , Yang Hsih‐Chin 
Published: June 2015

AbstractBy combination of centrifugal partition chromatography (CPC) and common separation methods, twelve known bases were isolated and characterized from the first chemical investigation of Neolitsea konishii (H.) K. & S. They belong to isoquinoline alkaloids of four types: eight aporphines, nornuciferine (1), N‐methyllaurotetanine (2), laurolitsine (3), boldine (4), laurotetanine (5), isoboldine (6), actinodaphine (7) and corytuberine (8); two proaporphines, stepharine (9) and glaziovine (10); one benzylisoquinoline, reticuline (11); and one morphinan, pallidine (12). Among these, compounds 3, 6 and 11 are abundant and will be modified for pharmacological tests. The content of various alkaloids in the plant is useful as a basis for chemotaxonomy.
The Mediation Effect of a Polyaniline‐Coated Electrode on the Reduction of Iron (III) Ions
Authors: Chi Hsiang‐Fin , Lin Shujywan , Huang Hsuan‐Jung 
Published: June 2015

AbstractThe mediation effect of polyaniline‐coated platinum electrodes on the reduction of iron(III) ions was studied by the cyclic voltammetry and rotating disk electrode methods. The rate constants of the cross reaction between iron(III) ions and polyaniline (PA) were found to depend upon the amount of PA coated on the electrode. On the basis of the rate constants the PA‐coated electrode mediates the reduction of iron(III) ion efficiently and behaves as well as a metallic electrode.
Determination of Trace Butyltin Compounds in Sea Water by Gas Chromatography‐Atomic Absorption Spectrometry
Authors: Liou Der‐Chyuan , Lou Yuan‐Chi , Whang Chen‐Wen 
Published: June 2015

AbstractA gas chromatography‐atomic absorption spectrometric (GC‐AAS) method has been developed for the determination of trace butyltin compounds in sea water. Aqueous butyltin compounds were reduced to the volatile hydride forms by NaBH4 and were extracted with dichloromethane simultaneously. The dichloromethane extract was concentrated under reduced pressure, followed by direct injection into the GC‐AAS system for analysis. The butyltin species were separated with a 2‐m glass column packed with 2% OV‐101 on Chromosorb G HP (100‐120 mesh). Following GC separation, each species was transferred into an electrothermally heated (800 °C) quartz furnace for atomization. The tin atoms produced from individual butyltin compound were detected at 224.6 nm by an atomic absorption spectrometer. With a sea water sample (1 L), the detection limits (3σ) for monobutyltin, dibutyltin and tributyltin were approximately 20, 20 and 70 ng Sn L−1, respectively. The method has been applied to the analysis of trace butyltin compounds in the sea water of Keelung Harbor.
Solution Conformation of Gramicidin S Determined by Nuclear Magnetic Resonance and Distance Geometry Calculation
Authors: Yu Chin , Hwang Jan‐Fu , Yeh Chao‐Jung , Chuang Li‐Chin 
Published: June 2015

AbstractThe solution conformation of the homodetic decapeptide antibiotic Gramicidin S has been determined by two‐dimensional 1H NMR spectroscopy and distance geometry followed by energy minimization. All structures corresponding to energy minima have four intramolecular hydrogen bonds between Leu and Val residues.
Spectrophotometric Determination of Ziram by Coprecipitating the Corresponding Copper(II) or Palladium(II) Complex with Naphthalene
Authors: Malik Ashok Kumar , Rao A. L. J. 
Published: June 2015

AbstractA spectrophotometric method has been developed for the determination of zinc dimethyldithiocarbamate (ziram) by converting it into dimethyldithiocarbamate and coprecipitating its copper(II) and palladium(II) dimethyldithiocarbamate complexes and coprecipitating onto microcrystalline naphthalene. Palladium(II) and copper(II) complexes absorb strongly at 395 nm and 430 nm, respectively. The interference of various ions has been studied and the method has been applied to determine ziram in commercial samples and grains.
Synthesis and Chemistry of 2,5‐Dimethylene‐2,5‐Dihydrofuran
Authors: Chen Ping‐Shu , Chou Chin‐Hsing 
Published: June 2015

Abstract2,5‐Dimethylene‐2,5‐dihydrofuran (3), generated flash pyrolitically, underwent di‐ and trimerization reactions to give cyclic dimer and trimer. Compound 3 was trapped with methanol, ethanol, bromine, acetic acid, thiophenol and oxygen. Results from trapping experiments suggest that the diradical form of 3 is involved.
Reinvestigation of the Cleavage of Canadine, A Protoberberine Bearing a Methylenedioxy Function, with Sodium in Liquid Ammonia
Authors: Lee Shoei‐Sheng , Lee Jih‐Horng , Lin Chia‐Yin , Ng Siew‐Leng , Chen Chung‐Hsiung 
Published: June 2015

AbstractTwo products, 3‐hydroxy‐9,10‐dimethoxyprotoberberine and 3,9‐dihydroxy‐10‐methoxyprotoberberine in addition to those reported, 2‐hydroxy‐9,10‐dimethoxyprotoberberine and 2,9‐dihydroxy‐10‐methoxyprotoberberine, were identified from cleavage of canadine with sodium in liquid ammonia. This reaction indicates regioselectivity rather than the reported regiospecificity by cleavage mainly at a site para to the N‐methine carbon.
Electron Paramagnetic Resonance Study on Supported Molybdenum Catalysts. Part 1: Interaction of Molybdenum Oxide with Silica and Signal Anlsotropy
Authors: Wang Yih‐Pean , Yeh Chuin‐Tih 
Published: June 2015

AbstractThe effects of reduction, evacuation and adsorbate adsorption on Mo/SiO2 catalysts prepared by impregnation were studied by means of the electron paramagnetic resonance (EPR) technique. Pentavalent molybdenum species in the overlayer (Mo05+, g⟂ = 1.941, g| = 1.895) and at the interface (Moi5+, g⟂ = 1.952, g| = 1.866) between MoO3 and SiO2 were distinguished in the EPR spectra; they were observed from samples reduced at T < 573 K and T > 573 K respectively. The difference in their nature reflected the extent of their interaction with the support. Mo05+ existed in the MoO3 overlayer of the catalyst and interacted only weakly with the support. Moi5+ from the Mo ions connected directly to SiO2 was affected strongly by the support. The anisotropic factor of the measured Moi5+ signals increased with the extent of support interaction.Superoxide ions (O2, g1 = 2.016, g2 = 2.011, g3 = 2.006) were found upon oxygen adsorption on samples evacuated at temperatures above 573 K. The observed O2 may exist at the interface between MoO3 and the support.
Determination of Iodide as an Organic Derivative by Gas‐Chromatography
Authors: Kou Hwang‐Shang , Wu Hsin‐Lung , Chen Su‐Hwei , Lin Shun‐Jin 
Published: June 2015

AbstractA simple and specific method is described for the analysis of iodide in trace proportions. The method is based on the reaction of iodide with pentafluorobenzyl 5‐dimethylamino‐1‐naphthalenesulfonate.in a biphasic system. The resulting derivative was determined on a gas chromatograph with a flame‐ionization detector. The detection limit was about 8 nmol of iodide in 1.0 mL of aqueous sample (S/N = 2; sample size, 5 μL). Application of the method to the analysis of available iodine in povidone‐iodine solution proved feasible.
Facile Synthesis of α‐Polythienyls via 1,4‐Diketones
Authors: Luo Thung‐Mei H. , Legoff Eugene 
Published: June 2015

AbstractUnsubstituted and substituted linear polythienyls including thiophenes in both even and odd numbers are conveniently prepared from the Michael addition of thiophenecarboxaldehydes to Mannich bases and the vinyl sulfone. Cyclization of the resulting 1,4‐diones with Lawesson's reagent gives α‐polythienyls.
Radial Functions of AIH X 1∑+ from Vibration‐Rotational Spectra ana Spectral Properties of the Group 13 Hydrides
Authors: Ogilvie J. F. 
Published: June 2015

AbstractThe coefficients Cj, j ≤ 9, defining the potential‐energy V(z) and coefficients of two other radial functions related to adiabatic and nonadiabatic effects have been determined for AlH in the electronic ground state X 1∑+ by a direct fit to the published frequencies and wavenumbers of vibration‐rotational transitions of 27Al1H and 27Al2H. The functions are valid in the range of internuclear distance/10−10 m [1.24, 2.60]. Some trends in the spectral properties of the group 13 hydrides AlH, GaH, InH and TlH are discussed. The possibility of determining the rotational magnetogyric factor gj from the available data of only wavenumbers of vibration‐rotational transitions is considered; an approximate value gj ∼ −2.25 is deduced for 27Al1H.
Determination of Aggregation Parameters of Hexadecyltrimethylammonium Bromide from Probe Absorption
Authors: Amire O. A. , Layemo F. E. , Burrows H. D. 
Published: June 2015

AbstractThe mean aggregation number (n) and the critical micelle concentrations (CMC) of reverse micelles formed by hexadecyltrimethylammonium bromide have been determined by means of an optical absorption probe (acridine orange). The procedure to obtain these quantities from absorption spectrophotometric measurements is described. The CMC and mean aggregation number are in satisfactory agreement with published results obtained from more sophisticated methods.
Nucleophilic Addition to (η3‐Allyl)Fe(CO)4 Cations with Functionalized Zinc‐Copper Reagents RCu(Znl)CN
Authors: Tau Sen‐I , Yeh Ming‐Chang P. 
Published: June 2015

AbstractRegioselectivity of the addition of the highly functionalized zinc‐copper reagents to (η3‐allyl)Fe(CO)4 cationic salts was studied. For 1,1‐disubstituted allyl cation 1, the zinc‐copper reagents added predominantly at the unsubstituted terminus. For 1,1,2‐trisubstituted allyl cation 2, reactive zinc‐copper reagents attacked mainly at the unsubstituted terminus while less reactive zinc‐copper reagents added to a coordinated CO ligand. For 1,1,3‐trisubstituted allyl cation 3, the addition occurred at both the less substituted allyl terminus and a coordinated CO ligand.
Photochemical Rearrangements of 6‐Methoxymethylbicyclo[4.4.0]Dec‐1‐En‐3‐One and 6‐Methoxymethylbicyclo[4.3.0]Non‐1‐En‐3‐One
Authors: Lai An‐Kuo , Liao Chun‐Chen 
Published: June 2015

AbstractThe irradiation of the title compounds 6 and 12 in isooctane and benzene was investigated. The photochemical reactions took place sluggishly upon n→π* excitation (λ > 300 nm) in deoxygenated solutions but more rapidly in the presence of air; deconjugation to yield β,γ‐unsaturated ketones and lumiketone rearrangement were the main primary photochemical reactions. In contrast, intramolecular hydrogen abstraction by the Cα‐carbon was the main reaction upon π→* excitation (λ = 254 nm).
Reglochemistry in Electrophilic Reactions of Propanedlthio‐Substituted Allylic Anions Influenced by the γ‐Substituents
Authors: Fang Jim‐Min , Chen Ming‐Yi 
Published: June 2015

AbstractThe dienyl anion 1f, generated from metallation of 2‐(1,3‐pentadienyl)‐1,3‐dithianc with n‐BuLi in THF, reacted exclusively at the C‐1 position (α‐site) with alkylating agents and ketones, but it showed some tendency toward the C‐3 position (γ‐site) in the reactions with benzyl bromide and aliphatic aldehydes. No reaction at the C‐5 position (ϵ‐site) was observed in any studied case. Examination of the related propanedithio‐substituted allylic anions having various γ‐substituents revealed that the regiochemistry was remarkably influenced by the γ‐substituents and the attacking electrophiles. The electronic effect according to the principle of hard and soft acids and bases is proposed to account for the observed regiochemistry, while the steric factor was minor. Two trienes, obtained by alkylations of the dienyl anion 1f with 4‐bromo‐1‐butene and 5‐pentenyl methanesulfonate, were applicable to intramolecular Diels‐Alder reactions to give bicyclic compounds.
Free Radical Reaction between 1,6‐Dienes and P‐Toluenesulfonyl Cyanlde
Authors: Chuang Che‐Ping , Ngoi Tak Ho Johnny 
Published: June 2015

AbstractA sulfonyl‐radical‐induced addition‐cyclization reaction of 1,6‐dienes with p‐toluenesulfonyl cyanide giving functionalized cyclopentane systems is described.
Acetylation and Debromination of Sydnones Accelerated by Ultrasound
Authors: Tien Hsien‐Ju , Yeh Jong‐Chuan , Wu Shi‐Chen 
Published: June 2015

AbstractIn the presence of a catalytic amount of 60% perchloric acid, 4‐acetyl‐3‐substituted sydnones were obtained more conveniently with greater yields by the sonochemical reaction of 3‐substituted sydnone with acetic anhydride. Some 4‐acetylsydnones which are difficult to synthesize by a known process were obtained in 17‐68% yields.4‐Bromo‐3‐(bromoaryl)sydnones with activated zinc powder dispersed in methanol were debrominated regioselectively by ultrasound in high yields (60‐96%). 3‐(2′‐/4′‐Amino‐3′,5′‐dibromophenyl)sydnone is synthesized easily from 3‐(2′/4′‐aminophenyl)sydnone by reduction, bromination and debromination subsequently.
Synthesis of (±)‐Lsodeoxypodophyllotoxin
Authors: Zee Sheng‐Hsu , Chou Shan‐Yen 
Published: June 2015

AbstractA process for the synthesis of (±)‐isodeoxypodophyllotoxin starting from ethyl 3,4‐methylcnedioxy‐benzoacetate and methyl 3,4,5‐trimethoxycinnamate is described.
Additional Isoquinoline Alkaloids from Lltsea Cubeba
Authors: Lee Shoei‐Sheng , Chen Chien‐Kuang , Chen Ih‐Sheng , Liu Karin C. S. 
Published: June 2015

AbstractBy combination of centrifugal partition chromatography (CPC) and common separation methods, seven additional known bases were isolated and characterized from the reinvestigation of L. cubeba besides three previously isolated bases‐ isocorydine (10), N‐methyllaurotetanine (9), and boldine (2). They are laurolitsine (1), laurotetanine (3), isoboldine (4), norisocorydine (5), N‐methyllindcarpine (7), isodomesticine (8), and glaziovine (6). Among these, compound 9 is the most abundant (7.5 × 10−4) and will be modified for pharmacological tests. This work will be of value for chemotaxonomy.
Determination of Tributyltin in Sea Water by Hydride Generation‐Atomic Absorption Spectrometry
Authors: Chen Jia‐Jeng , Lou Yuan‐Chi , Whang Chen‐Wen 
Published: June 2015

AbstractA hydride generation‐atomic absorption spectrometry (HG‐AAS) procedure is described for the analysis of tributyltin (TBT) in sea water. TBT is first converted to its volatile hydride form by reaction with sodium borohydride, followed by cryogenic trapping at −196°C, and finally detection by atomic absorption spectrometry using an electrically heated quartz atomization cell. The linear range of calibration is 5‐250 ng TBT (as tin). At the 5‐ng level, the relative standard deviation (RSD) is 13%. The absolute detection limit (3σ) is 1.8 ng. Based on a sample volume of 500 mL, this value corresponds to a concentration detection limit 3.6 ng L−1 TBT This method has been successfully applied to the analysis of TBT in sea water collected from Keelung and Kaohsiung harbors.