bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Relationships between the Hemiporphyrazine Macrocyclic Ligand and its Metal Complexes. I.: Saddle Shaped Neutral Ligand Hydrate, C26H16N8·‐H2O, and Nickel Complex, [Ni(C26H14N8)]
Authors: Peng Shie‐Ming , Wang Yu , Ho Tsang‐Feng , Chango I‐Chen , Tang Chia‐Pin , Wang Chiung‐Jane
Published: June 2015

Crystal and molecular structures of the neutral ligand hydrate, C24H16N8·H2O, and the diamagnetic nickel(II) complex, [Ni(C C24H16N8)], have been determined by three‐dimensional X‐ray crystallography. Pertinent data are: C24H16N8·H2O, Pnmm with Z=2, a=4.6142(3), b=14.7687(7), c=15.0650(5) Å, R=0.068, Rw = 0.038; [Ni(C24H16N8), 12/c with Z=4, a=22.0137(11), b=3.7637(4), c=23.4742(11) Å, β=92.7(1)°, R = 0.039, Rw=0.025. The overall conformations of the neutral ligand and the Ni(II) complex are similar, both have a pronounced saddle shape. The Ni(II) ‐N bond distances in the Ni‐complex are 1.861(2) and 1.998(2) Å. The distances from nitrogen atoms to the center of the ring in free ligand are 2.020(3) and 2.220(3)Å, which arc significantly longer than those of Ni(II) complex A detailed comparison about the core size with similar ligand is presented.
The Complexation of Some Sodium Sulphophenyl Hydrazo‐5‐Pyrazolone Dyes Towards Trivalent Lanthanide Ions “Stability Constants”
Authors: El‐Shetary B. , Stefan S.L. , Zidan F. , Moez M.S.
Published: June 2015

Acid dissociation constants of substituted‐5‐pyrazolone dyes have been determined potentiometrically in 75% (v/v) dioxane‐water mixture at 30°C and <0.1 ionic strength. The stability constants of their 1:1 and 1:2 chelates with tweleve trivalent lanthanide ions have been determined under the same conditions. The data were correlated and the results were taken to explain the stabilization of such. chelates by dative π ‐bonding between Ln (III) and the ligand.
The Reaction of 2,5‐Dimethoxy‐2,5‐Dihydrofuran with Dichloroketene
Authors: Yang Chia‐Hsi , Lin Huang‐Chin , Whang Maw‐John
Published: June 2015

2,5‐Dimethoxy‐2,5‐dihydrofuran (DDF) reacts with dichloroketene to give 7,9‐dimethoxy‐3,3,5,5‐tetrachloro‐8‐oxabicyclo[4,3,0]‐noan‐2,4‐dione (I), and methyl chloro‐(2,5‐dihydro‐5‐methoxy‐2‐furanylidene) acetate (II). The reactions of 2,5‐dihydrofuran and 2,5‐dimethoxy‐tetrahydrofuran with dichloroketene were also‐studied for comparison. Compound II was derived from the insertion of a molecule of dichloroketene into the C‐O bond of DDF with subsequent dehydrochlorination. Compound I resulted from the cycloaddition of two molecules of dichloroketene to the C=C bond of DDF. A mechanism involving a 1,5‐dipolar intermediate is proposed to account for this novel reaction.
13C‐NMR Spectra of 2‐ and 3‐Phthalimido‐3(2)‐Benzimidazolylpropanoic Acid and 2‐ and 3‐Phthalimidobenzimidazopyrrolone, Reaction Products of Phthaloylaspartic Anhydride with Ortho‐Phenylenediamine
Authors: Yang Chin‐Ping
Published: June 2015

Two pairs of isomers of 3‐ and 2‐phthalimido‐3(2)benzimidazolylpropanoic acid (V and VI) and 2‐ and 3‐phthalimidobenzimidazopyrrolone (VII and VIII) were produced from the reaction of phthaloylaspartic anhydride (I) with o‐phenylenediamine (II). The 13C‐NMR spectra of V and VI both showed 11 carbon signals indicating that the structures of their benzimidazole groups were symmetric. Isomers V and VI were easily distinguished from each other by the chemical‐shift‐differences (Δδ) of the methylene carbon and the methine carbon. Compounds VII and VIII displayed 14 carbon signals and no longer showed the symmetric structure of the benzimidazole moity, The chemical‐shift‐differences (Δδ) between methylene carbon and methine carbon in pyrrolones of VII and VIII can also be used to distinguish VII from VIII. The Δδ of compound VII is less than that of compound VIII.
Spectrophotometry Determination of Molybdenum with N‐Cyanoacylacetaldehyde Hydrazone
Authors: Kabil M. A. , Hafez M. A. H. , El‐Asmy A. A. , Mostafa M. M.
Published: June 2015

N‐cyanoacylacetaldehyde hydrazone (CAAH), which is a laboratory synthetic reagent, is proposed as a new reagent for spectrophotometry determination of microamounts of molybdenum at λmax 790 nm. The reagent forms 1:1 blue coloured complex with molybdenum (VI) in phosphoric acid solution. The stable blue colour is obtained finally after changing from yellow to green. The colour development depends on temperature, time and concentration of phosphoric acid. This reagent is applied for the determination of molybdenum in steel alloys and the results are satisfactory.
Synthesis of (S)‐Propranolol by Chemicoenzymatic Approach
Authors: Wang Yi‐Fong , Kou Hwang‐Shang , Lee Becky , Hwang Lih‐Yueh
Published: June 2015

(S)‐Propranolol, [1‐isopropylamino‐3‐(1‐naphthoxy)‐2‐propanol], which possesses important β‐adrenergic blocking activity, has been synthesized by a chemicoenzymatic approach. The 2S‐absolute configuration was created by the enzyme‐mediated asymmetric hydrolysis of the (±)‐2‐acetoxy‐1‐chloro‐3‐(1‐naphthoxy)‐2‐naphthoxy)‐2‐propanol. The enzymatically produced chiral intermediate was then chemically converted to optically pure (S)‐propranolol.
Reductive Coupling of Halomethylbenzene Derivatives by Nickel and Cobalt
Authors: Yang S. H. , Lee T. , Cheng C. H.
Published: June 2015

Reduction of benzyl bromide, benzal chloride and benzotrichloride with a commercial nickel powder at 150°C gave bibenzyl, trans‐stilbene, and trans‐1,2‐dichlorostilbene. The reaction intermediates 1,2‐dichloro‐1,2‐diphenylethane for benzal chloride and 1,1,2,2‐tetrachloro‐1,2‐diphenylethane for benzotrichloride were also isolated or detected by NMR spectroscopy. Dehalogenation of these intermediates by the nickel metal or by KI yielded the corresponding trans isomer as the main product. A commercial cobalt powder also reacted with these organic halides leading to similar results. Mechanisms for these reactions are proposed.
Identification of Abnormal Urinary Organic Acids in Inherited Metabolic Diseases by Gas Chromatography‐Mass Spectrometry
Authors: Yeh Sheau‐Farn , Hsiao Kwang‐Jen , Hung Su‐Hwi , Chang Kun‐Ten
Published: June 2015

A gas chromatography/mass spectrometry (GC/MS) coupled system has been established for the confirmatory identification of abnormal urinary organic acids in inherited metabolic diseases. Samples of patient urines were extracted with an organic solvent and trimethylsilylated (TMS). A mass spectra of gas chromatographically separated TMS derivatives can be obtained using the GC/MS coupled system with a single analytical run. Those compounds with close methylene units (e.g., 4‐hydroxyphenylacetaic acid and phenylpyruvic acid) in the gas chromatograph can be identified by their specific mass spectra. The results indicate that this GC/MS system is a powerful method for identifying abnormal urinary organic acids. These acids can be identified by comparison with authentic mass spectra established in our laboratories or with mass spectra files from other sources or they can be directly identified by analysis of the mass spectrum. By using this system, we were able to make positive identification of several inherited metabolic diseases found in Chinese patients, including phenylketonuria, propionic acidemia, and methylmalonic aciduria. This GC/MS system is a powerful tool for the diagnosis of inherited metabolic diseases.
A Study of the Cis‐Trans Isomerization of a Square Planar pt Ylide Complex
Authors: Lin Ivan J. B. , Chang C. P.
Published: June 2015

The isomerization of cis‐Pt(PPh3)2(I)(CH2P(O)(OCH3)2), 1, was studied by an NMR technique. An Arrhenius plot for the isomerization gives an activation energy of 99.2 KJ/mol, ΔH≠ = 97 KJ/mol and ΔS≠ = −8.3 J/mol‐K. Under a CO atmosphere the cis isomer catalytically isomerized to its trans form. Free PPh3 did not catalyze the cis‐trans isomerization. In the proposed isomerization mechanism the reaction goes through an intramolecular assisted phosphine dissociation, followed by dimer formation. The addition of phosphine to the dimer then completes the isomerization of the original monomer from cis to trans.
Electron Spin Resonanance Studies of Acid‐Doped Polyaniline
Authors: Yang Sze‐Ming , Chien Shu‐Hua
Published: June 2015

The electron spin resonance spectra of various acid‐doped polyanilines were studied. There are three significant changes in the ESR spectra upon acid‐doping as the acid concentration of the doping solution is varied from pH<3 to pH>1: (1) The linewidth decreases by a factor of three. (2) The intensity increases. (3) The spin density increases by a factor of twenty. By comparing the variation of the electric conductivity with the variation of the spin density upon acid‐doping, it is proposed that the polyaniline prepared by chemical oxidation consists of various oxidized and reduced units, and that the pi‐electron rearrangement upon acid‐doping results in highly conductive radical cations.
The Self Oxidation Reduction of N‐Arylhydroxylamines
Authors: Yang Chia‐Hsi , Lin You‐Chung
Published: June 2015

The reactions of N‐phenylhydroxylamine in the presence of dry hydrogen chloride to form azoxybenzene, aniline, 2‐chloroaniline and 4‐chloroaniline were studied. The molar ratio of the azoxybenzene and aniline obtained was very close to one. A similar reaction was also observed for 2‐methyl‐ and 4‐methyl‐N‐phenylhydroxylamine. A reasonable explanation is that N‐phenylhydroxylamine undergoes a self oxidation reduction reaction to give aniline and nitrosobenzene, and the latter subsequently reacts with N‐phenylhydroxylamine to give azoxybenzene. The reaction of N‐phenylhydroxylamine, catalyzed by trifluoroacetic acid to yield azoxybenzene, was previously studied by Okamoto et al. and was suspected to undergo a similar reaction. We repeated the reaction and evidence for the same self oxidation reduction reaction was found. A mechanism involving the anilenium ion is proposed to account for this reaction.
Reactions of Methylphenylvinylsulfonium Tetrafluoroborate with Ketone Enolates
Authors: Chou Shang‐Shing P. , Liu Jyanwei H.
Published: June 2015

The reactions of methylphenylvinylsulfonium tetrafluoroborate (1) with the lithium enolates of 1,3‐dicarbonyl compounds, acyclic ketones and cyclic ketones have been studied. Cyclopropanes and cyclic ethers are obtained. The reaction mechanisms are also discussed.
A Facile Method for the Synthesis of Chloroiodomethane from Diiodomethane Under Aluminum Mediation
Authors: Lin Yih‐Tsung , Chang Ming‐Ju , Yang Paw‐Hwa
Published: June 2015

In the presence of iodine and at room temperature, a stirred mixture of diiodomethane, dichloromethane and aluminum powder gave chloroiodomethane ClCH2I (III) in excellant yield (90%).
Optical Properties of Model Compounds of Polyaniline
Authors: Yang Sze‐Ming , Chen Hsin Juan , Lin Jiann Shen
Published: June 2015

The UV and visible spectra of six model compounds were studied. These compounds can be considered as models of polyaniline in the reduced, cation radical, partially oxidized and oxidized forms. After treatment of a mixture of equal molar quantities of the reduced form (DPPD) and the oxidized form (QDIM) with acid, the following reaction was observed:

DPPD(I)+QDIM(III)+2H+=2DPPD+(II)

After similar treatment of the partially oxidized form (V) with acid, the radical cation salt formed.

The UV and visible spectra of polyaniline in the reduced form, oxidized form and conductive form are similar to the spectra of DPPD, QDIM and DPPD+ or radical cation salt of V respectively. We propose that the polyaniline synthesized by chemical oxidation of aniline consists of oxidized and reduced repeat units. Upon protonation a redox reaction (or electron rearrangement) occurs and forms delocalized radical cations (polarons) in the polymer chain which are highly conductive.
Synthesis of Oxidized Nitro‐Polycyclic Aromatic Hydrocarbons
Authors: Wu Y.C. , Lai C.C. , Fu P.P. , Unruh L.E.
Published: June 2015

A series of phenolic and cis‐dihydrodiol derivatives of 6‐nitrobenzo[a] pyrene and 7‐nitrobenz[a]anthracene were synthesized. The common structural feature of these compounds is that their nitro groups are perpendicular or near perpendicular to the aromatic moieties. From the synthesis of these compounds, it was found that an acetoxy group does not affect the regioselectivity of electrophilic nitration to a polycyclic aromatic hydrocarbon (PAH) and that a nitro substituent can substantially reduce the concerted electrophilic 1,2‐addition of osmium tetroxide to the most olefinic aromatic double bond of a PAH.
Organotransition‐Metal Complexes of Multidentate Ligands 3. The Unexpected Derivatives of Bis(3,5‐Dimethylpyrazol‐1‐YL)Methanetetracarbonylmolybdenlim(0) and‐Tungsten(0) Complexes
Authors: Shiu Kom‐Bei , Liou Kuen‐Song
Published: June 2015

Thermolysis of (H2CPz′2)M(CO)4 (H2CPz′2 = bis(3,5‐dimethylpyrazol‐1‐yl)methane; M=Mo, W) in 1,2‐dimethoxyethane did not give the expected 16‐electron complexes, (H2CPz′2)M(CO)3, but gave dinuclear compounds, [(H2CPz′2)M(CO)3]2, probably containing two linear carbonyl bridges and no metal‐metal interactions. The dimers reacted with CH3CN to give mononuclear compounds, (H2CPz′2)M(CO)3(NCCH3), identical to the substitution products between (H2CPz′2)M(CO)4 and CH3CN.
An Unprecedented Oxidation Reaction of Cyclopentadiene Derivatives by Pyridinium Chlorochromate
Authors: Wu Hsien‐Jen , Pan Kai , Hsia Ket‐Shang , Liu Wei‐Chi
Published: June 2015

Oxidation of the furan cyclopentadienes (2) and (4) with pyridinium chlorochromate gave the cyclopentenones (5) and (6) respectively. Oxidation of the alkyl cyclopentadienes (7a and 7b) also gave the corresponding cyclopentenones (8a and 8b) as the major products.
Reaction of Carbon Anions With Iron α,β‐Unsaturated Ketimine Complexes
Authors: Cheng Chien‐Hong
Published: June 2015

Complexes (η4‐PhCH=CHCR=NPh)Fe(CO)3, where R=H(1a) and CH3 were synthesized in excellent yield from the reaction of the corresponding α,β‐unsaturated ketimines with excess Fe2(CO)9. Reaction of la with (Ph)2CHLi and (CH3)2(NC)CLi at −78°C or ambient temperature followed by acid quenching gave trans‐PhCH=CHCHRNHPh, where R=CHPH2 and C(CH3)2CN, respectively, in good yield. In the presence of 1 atm. of CO the reaction of 1a with (CH3)2(NC)CLi, followed by CuCl2 oxidation resulted in the formation of a carbamyl choride, trans‐PhCH=CHCH[C(CH3)2CN]N(Ph)COCl. This species was converted to a carbamate compound trans‐PhCH=CHCH[C(CH3)2 ‐ CN]N(Ph)COOCH3 in MeOH in the presence of Ag+.
Electrodeposition and Mössbauer Spectra of Fe‐Zn Alloys on Aluminum Foil
Authors: Chang Jiin‐Chuan , Wei Ho‐Hsiang
Published: June 2015

By controlling the current density, pH and temperature of the electrodepositing iron‐zinc bath, various compositions of electrodeposited Fe1‐xZnx (0.95 > x > 0.15) alloys on Al‐foil have been prepared. The electronic state, intermetallic phases and magnetic hyperfine interactions have been studied by means of 57Fe Mössbauer spectroscopy at 298K for these electrodeposited Fe‐Zn alloys. The isomer shifts obtained from the Mössbauer spectral of the alloys increased with increasing Zn content. An alloy containing above 50% Fe, exhibits a linear dependence of the internal magnetic field, Hin, on the Zn content.
Hydrocarbon Formation in the Catalytic Conversion of Methanol Over Zeolite ZSM‐5
Authors: Chao Kuei‐Jung , Wei Min‐Shan , Lo Jiunn‐Guang , Shyu Shio‐Jin
Published: June 2015

The reaction mechanism of methanol conversion to hydrocarbons on HZSM‐5 zeolite was studied. From the selectivity plots of products in an integral fixed‐bed flow reactor, paraffins were classified as primary and secondary stable products, light olefins as primary unstable products, aromatics as primary and secondary unstable or stable products. The results of the 14C‐labelled methanol reaction indicated that the C1–C5 surface intermediates generated by dimethyl ether / methanol equilibrium gave paraffins and olefins at 300°C. The concentration of intermediates and adsorbed methanol on ZSM‐5 decreased with increasing temperature. The distribution of radioactivity showed that propylene played an important role in the autocatalysis of the reaction.
Iron (III) Ion Selective Electrode Based on Dithia 12‐Crown‐4
Authors: Wang Tzong‐Yaw , Shih Jeng‐Shang
Published: June 2015

An iron (III) ion selective PVC membrane electrode based on 1,7‐dithia 12‐crown‐4 as a neutral carrier was prepared. Monovalent responses with a Nerstian slope of 56+1 mV/decade was observed for the Fe (III) ion‐selective electrode within the concentration range 10−3–10−5 M Fe (NO3)3. The monovalent responses may be attributed to the formation of Fe (OH)2+ or Fe (OH)2(H2O)+4 species in aqueous solutions and the absorption of these ions into the PVC electrode membrane. The electrode exhibited good selectivity for Fe (III) in comparison with various alkali, alkali‐earth and some heavy metal ions. The effects of the composition of the membrame, addition of STPB (sodium tetraphenyl borate), the concentration of internal solution of the electrode and anions in the test solutions were discussed.
Polarography of Uranium Chelate with 2,3‐Cresotic Acid
Authors: Chen S.N. , Chen T.H. , Gi H.C. , Wang J.J.
Published: June 2015

The polarography of uranyl ion in 2,3‐cresotic acid solution has been studied at 25°C under varying conditions of ligand concentration and pH. The ligands species were proved to be a 2,3‐cresotate anion. The half‐wave potential vs. pH value interpreted on the basis of pK value for the acid ionization, and resulted in agreement with the deduction.

The mole ratio of metal to ligand was found to be 1:1 and 1:2 by conductometric titration. At pH < pK1, the complex species of UO2(H2A)2+ and UO2(HA)+ was identified. At pK1 < pH < pK2, the co‐existence of UO2(HA)+, UO2(OH)(HA)2− and UO2(A)22– was confirmed. At pH > pK2, the complex species of UO2(OH) (A)23– was formed.
Preparation and Characterization of Dioxotungsten (VI) Complexes of Schiff Bases Derived from Salicylaldehydes and O‐Aminothiophenol
Authors: Gupta Mala , Kansal B.D.
Published: June 2015

Several dioxotungsten(VI) complexes of the type WO2L and WO2L.X (where LH2 = Schiff base derived from o‐aminothiophenol and salcylaldehyde, 5‐chlorosalicylaldehyde, 5‐bromosalicylaldehyde, and X = dimethyl formamide, dimethyl sulfoxide or pyridine) have been prepared and characterized by elemental analysis, electrical conductance, magnetic and spectral measurements. These complexes are non‐electrolyte, diamagnetic, six‐coordinated and possess an octahedral geometry.
Organotransition‐Metal Complexes of Multidentate Ligands 5. Structural Characterization of Cis‐Tetracarbonyl(3,5‐Dimethylpyrazol‐1‐Yl) Methanemolybdenum(0)
Authors: Shiu Kom‐Bei , Chang Cho‐Jin , Wang Yu , Cheng Ming‐Chu
Published: June 2015

The title compound crystallizes in space group P 21/c of the monoclinic system in a cell of dimensions: a = 9.231(2), b = 15.931(2), c = 12.420(2) Å, β = 108.37(1)°. The observed density is 1.60 g/cm3 and the density calculated for four molecules in the cell is 1.58 g/cm3. The refinement converged with R = 0.029 and Rw = 0.028 based on 2569 reflections with I > 2.5 σ. The molecule has approximate Cs symmetry with a mirror plane roughly containing the central Mo atom and two cis‐carbonyls, C(1)O(1) and C(4)O(4), while bisecting the bidentate, H2CPz2, and two trans‐carbonyls. The four carbonyls and tine bidentate adopt a quasi‐octahedral arrangement around the Mo atom. The C(NN)2Mo linkage of the (H2CPz′2)Mo fragment is observed to be in the boat form. The two cis‐carbonyls are bent away by the bulky H2CPz′2 bidentate giving ∠C(1)‐Mo‐C(4) ≃ 167.3(1)°. The distortion explains the facile allyl bromination and decarbonylation observed for the title compound.
Nickel Boride Catalyst in Organic Synthesis—The Effects of Promoters on Nickel Borides for Hydrogenation Reactions
Authors: Chen Yin‐Zu , Sheu Lin‐Lon , Rei Min‐Hon
Published: June 2015

Cr, Co and Rh were introduced into P‐1, P‐2 and P‐2W nickel boride catalysts as promoters. The substrates of cyclohexanone and cyclohexene were used to examine the effects of those promoters on nickel borides for hydrogenation reactions. On cyclohexanone with strongly‐polared carbonyl group, Cr, Co and Rh are effective for all nickel borides. On cyclohexene with slightly‐polared olefinic group, Rh is also good for all nickel borides. But Cr and Co are only effective for P‐2W and P‐1 nickel borides respectively.
Synthesis of 2,2′‐Bifuran
Authors: Chang Chung‐Song , Hwang Wen‐Shu
Published: June 2015

2,2′‐Bifuran was synthesized via a much more efficient way directly from furan.
Synthesis of Alkyllysophospholipid Analogues with Readily Functionalized 1‐O‐Alkyl Side Chain
Authors: Tsai Yeun‐Min , Jiang Shu‐Li
Published: June 2015

Synthesis of alkyllysophospholipid analogues 5a and 5b are described. These lipids have imide functional group attached on the terminal of 1‐O‐alkyl side chain suitable for further manipulations. Our approach features the use of mesylate 8 in which the mesyl group serves both as protecting group and electrophile.
HPLC Determination of Amino And Carbonyl Compounds with Dabsyl Chloride and Dabsyl Hydrazine
Authors: Lin Jen‐Kun , Chang Su‐Chen , Huang Chian‐Chyi
Published: June 2015

The new chromophoric reagent, 4‐dimethylaminoazobenzene‐4′‐sulfonyl chloride (dabsyl chloride) was synthesized by reaction of sodium 4‐dimethylaminoazobenzene 4′‐sulfonate with phosphorus pentachloride. Dabsyl chloride reacted rapidly with all amino acids, aliphatic amines, and polyamines to form the corresponding dabsyl derivatives. The dabsyl amino acids (10−11 mol) were visualized on thin layer plates and found to be photo‐stable. During the last 12 years, in combination with HPLC, this newly developed labeling reagent has been shown to be very promising for microdetermination of amino acids, aliphatic amines and polyamines.

Recently, another new chromophoric reagent, dabsylhydrazine, was synthesized from the reaction of dabsyl chloride with hydrazine. This reagent reacted readily with monosaccharides and carbonyl compounds to form the corresponding chromophoric dabsylhydrazones with strong absorbance at 425 nm. The application of this new reagent in HPLC analysis of monosaccharides was discribed. By use of Nova‐PAK C18 reverse‐phase column and a concave gradient system of water and acetonitrile as eluent, the detection limits of monosaccharides in the range of 10 pmol have been reached.
Synthesis on Al‐Mg Polynuclear Bridged‐Complexes (I): Reactions of Aluminum‐Trialkoxide with Magnesium‐Di‐N‐Butyl
Authors: Chang Chung‐Cheng , Chang Mei‐Yen , Cheng Cheu‐Pyeng
Published: June 2015

The reaction of magnesium di‐n‐butyl with alumium trialkoxide (R=C2HS, Sec·C4H9) gave the major product [Bu2Mg Al(OR)3]2. which was characterized by elemental analysis, mass spectral data, infrared data and 2D‐nuclear magnetic resonance spectral data. The nmr spectral data indicated that the most likely structure of the major products were cyclic with bridging butyl and alkoxide groups.
Mass Spectra of Acridone Alkaloids
Authors: Lin Shaw‐Tao , Wu Tian‐Shung
Published: June 2015

The mass spectra of a variety of simple acridones, prenylacridones, pyranoacridones, dihydropyranoacridones, and furoacridones are presented and discussed. The results illustrate that the characteristic fragmentation patterns are of considerable utility in the application of mass spectrometry to structure elucidation in the acridone alkaloids.
Studies of the Deposit Formation on Storage of a High Energy Fuel
Authors: Wang S. M. , Li N. C. , Chang H. , Huang P. J.
Published: June 2015

Storage stabilities of a petroleum‐derived jet fuel (JP‐5), manufactured by the Chinese Petroleum Corporation in Taiwan, were studied. Fuel degradation was monitored in the presence of added specific heteroatomic (O, N, S) and unsaturated compounds, copper, iron and aluminum powders and mixtures of some of these at room temperature and 80°C. A mechanism is suggested for the sediment formation with the sulfur compounds. The extent of light scattering and of metal drawn into JP‐5 from added metal powder measured by ICP‐AES are correlated with the extent of deposit formation in degradation of the fuel. Metal promotes deterioration of JP‐5, because of metal complex formation.
Synthesis of Substituted 2,2,4,4‐Tetramethylcyclobutanones
Authors: Lin Wen‐Chung , Cannon George W.
Published: June 2015

Some of the alkyl substituted 2,2,4,4‐tetramethylcyclobutanones were synthesized by conventional methods.
Symmetry and Intervalent Charge Transfer in Copper‐Oxide Superconducting Precursors
Authors: Chiu Ying‐Nan
Published: June 2015

A vibrationally coupled intervalent charge transfer theory is proposed for the copper oxide‐superconductors. The proposed B1g‐vibrational distortion exactly interchanges the chemical environment of the neighboring copper atoms. A quadruple cell is constructed to accommodate the non‐stoichiometry and a double copper‐oxide‐conducting chain with distorted symmetry is postulated. The distorted structure, prone to switching of the copper sites by vibration, is postulated to be the superconducting precursor. The left over‐oxygen, due to oxygen deficiency, is allowed to serve as a bridge between the chains and 10 oscillate with the vibration. Symmetry of the system, before and after distortion, is used to explain the spin‐angular momentum change, needed to arrive at Cooper‐paired electron/holes. The O− and O= atoms are postulated to be the bridge for superexchange and charge flow between the Cu+1/Cu+3 and Cu+1/Cu+2 pairs. The same theory is used to interpret the mechanisms for the following three types of copper oxide‐superconductors: YBa2Cu3OT‐x; La2‐xSrxCuO4 and the newly discovered electron superconductor Nd2‐xCexCuO4‐y. The bridge oxygen oscillation may be chosen not to come from the breathing mode but from the bending deformation mode that involves the relative motion of the Cu atoms (to the oxygen) giving rise to smaller oxygen isotope effect.
Cylic Voltammetric Studies on the Electrode Reaction of Polyacetylene Secondary Cell
Authors: Wang Jeng‐Jong , Chen Shou‐Nan , Chen Ying‐Chung
Published: June 2015

Cells of lithium / Polyacetylene containing 0.5 · 1.5 M LiClO4 in propylene carbonate as supporting electrolyte are constructed. The mechanism for electrochemical redox process of polyacetylene is studied using cyclic voltammetry in the potential range from −0.8 to 0.2 volt vs. S.C.E. The electrode reactions are identified to be diffusion controlled. The difference of the peak potentials between the oxidation and reduction, ΔEp, is found to be a function of the scan time per cycle (τ sec/cycle) and is influenced by concentration of supporting electrolyte and isomeric structures of polyacetylene. However, there is a better reversible redox process of polyacetylene when the ClO4− ‐ ions diffuse successfully in and out of the Polymer film, which has the cis‐form structure, in concentrated supporting electrolyte solution and having a long scan time per cycle (τ). When the scan potential is extended to a more positive region, another peak is found, which may correspond to the irreversible chemical reaction caused by over‐doping. The over‐doping process is found to be controlled by the electrical field strength, concentration of the supporting electrolyte and isomerism of polyacetylene.
The Interaction of Oxygen with Silver Powders. A Comparison Between Esca Results and Volumetric Measurement
Authors: Chen Jr‐Jyan , Cheng Chi‐Fong , Yeh Chuin‐Tih
Published: June 2015

Interactions of oxygen with silver powders have been studied with a combination of angle‐resolved ESCA and volumetric adsorption. Three states of adsorbed oxygen, i.e., atomically adsorbed oxygen, dissolved oxygen, and surface oxide, are characterized by 0(1s)‐ESCA peaks at binding energies of 530.2, 532.0, and 529.3 eV respectivcly. The ESCA studies also suggest that atomically adsorbed oxygen dissolves into the subsurface of silver powders at temperatures above 100 °C, and then transforms into oxide (Ag2O) at 175 °C. Adsorbed oxygen on the silver powders was partially desorbed at temperatures higher than 180 °C. The transformation and desorption information obtained from ESCA satisfactorily explains the variation of the adsorption isotherm with temperature obtained from the volumetric adsorption of oxygen on Ag/SiO2 catalysts.
Role of Modern Analytical Chemistry in Material Analyses for Trace Metals
Authors: Rains Theodore C.
Published: June 2015

The trend in the modern analytical laboratory is toward lower and lower analytical concentration measurements. The analyst has a variety of analytical instruments and techniques in which to meet the ever growing need for lower concentration measurements with improved precision and accuracy. Techniques available to the analyst include flame and electrothermal atomization‐atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, inductively coupled plasma/mass spectrometry, laser enhanced ionization spectrometry, neutron activation analysis, spectrophotometry, isotope dilution mass spectrometry, X‐ray fluorescence spectometry, electroanalytical, and chromatography. However, there is no analytical technique that is a panacea for all analytes in the modern analytical laboratory. Steps the analyst must consider to obtain the highest degree of precision and accuracy include the obtaining of a representative sample, the selection of the “best” analytical method, the preparation of the sample, the calibration of the instrumentation, the deciding on the level of effort for the chemical measurement and the evaluation of the data are discussed.
Reactions of 2,3‐Butanedione Monoxime with Diamine Compounds
Authors: Wang Yun‐Ming , Chung Chung‐Sun , Ting Gann
Published: June 2015

A number of diazadioximes have been prepared by reactions of the corresponding diamines with 2,3‐butanedione monoxime in the presence of p‐toluenesulfonic acid or in ethanol.
Mixed Titanium and Phosphorus Oxides. II. — The Effect of pH Values of Solutions on Surface Acidity
Authors: Huang Chun‐Lan , Cheng Soofin
Published: June 2015

A series at mixed oxides of titanium and phosphorus were prepared by co‐precipitation method accompanying refluxing treatment. The effect of the pH values of the solutions on the structures, compositions, and surface acidities of the resultants compounds was determined. The samples were characterized by BET surface area measurement, X‐ray powder diffraction (XRD) for structural analysis and amine‐titration for surface acidities. After calcinating the oxides at 773 K, the surface acidities were attributed mainly to Ti(OH)PO4 structure. Elemental analysis revealed that the P/Ti ratios in the samples decreased with increasing the pH value of the preparative solution. When the mixed oxides were used as catalysts for 2‐propanol decomposition reaction, the highest activities were obtained over the samples prepared in the solutions with the pH values being 2 or 3. That result was in agreement with the variation in surface area and acid amount of the catalysts.
Preconcentration of Trace Elements in Water for Speciation Studies
Authors: Mizuike Atsushi
Published: June 2015

Trace element speciation has recently become one of the most important problems in water analysis. Proper combination of preconcentration techniques with instrumental determination methods is essential to speciation analysis, because sensitivity and selectivity of direct determination methods are generally lacking. The present paper describes such preconcentration techniques as filtration, centrifugation, flotation and sorption, which have been developed in the author's laboratory for the speciation of heavy metals in river and pond waters by electron microscopy, X‐ray microanalysis and chemical analysis. The application of freeze concentration to the speciation of silica in high‐purity waters is also discussed.
A New Pentacyclic Triterpene from Ecdysanthera Rosea
Authors: Huang Keh‐Feng , Sy Maa‐Lih , Lai Jeng‐Shiow
Published: June 2015

D‐friedours‐14‐en‐11α, 12α‐epoxy‐3β‐yl palmitate (1), a new pentacyclic triterpene of the ursane series, was isolated from the aerial parts of Ecdysanthera rosea, and the structure was elucidated on the basis of the spectral data. The partial synthesis of this compound from α‐amyrin acetate via a few steps was also achieved.
Characterization of Anilinepentacyanoferrate (II) and (III)
Authors: Chao Feng‐Hsien , Sun Bin‐Kuo , Juang Po‐Chuang , Yeh Andrew
Published: June 2015

The anilinepentacyanoferrate (II) complex has been characterized in aqueous solution. The complex exhibits a predominant ligand field transition at λmax = 415 nm with ϵmax = 494 M−1 cm−1. The corresponding Fe(III) complex displays a strong absorption at λmax = 700nm(ϵmax = 1.61×104 M−1 sec−1) which can be assigned as a ligand to metal charge transfer transition. The rate constants of formation and dissociation for the Fc(II) complex are (3.14±0.18)×102 M−1W−1 and 0.985±0.005 sec−1, respectively, at μ = 0.10 M LiClO4, pH = 8 and T = 25°C. The cyclic voltammetry of the complex shows that a reversible redox process is observed with E1/2 value of 0.51±0.01 V vs. NHE at μ = 0.10 M LiClO4, pH = 8 and T = 25°C. The kinetic study of the oxidation of the Fe(II) complex by ferricyanide ion yielded the rate constant of the reaction ket = (1.43±0.04)x10 M sec−1 at μ = 0.10 M LiClO4, pH = 8 and T = 25°C.
The Micellar Dissociation Concentration of Polyoxyethylene Mono N‐Decylether Nonionic Surfactants in Water
Authors: Chiu Ying‐Chech , Chang Cheng‐Yen
Published: June 2015

This paper will demonstrate a method for determining the micellar dissociation concentration (MDC) of polyoxyethylene mono n‐decylether nonionic surfactants in water. Turbidity and surface tension measurements were applied to commercial samples without further purification. Complicated curves containing turbidity maxima and surface tension minima were obtained for some impure samples. It is difficult to determine the critical micellar concentration (CMC) for impure surfactants. Explanations are given for all curves obtained for pure and impure samples and the method of identifying the MDC values is illustrated. It is more practical for surfactant users to determine the MDC values in their own laboratory than to search for the CMC values in the literature when the surfactants arc impure.
The Polarographic Reductions of 4‐Cyano‐3‐Substitutedsydnones
Authors: Wang Lai‐Hao , Tien Hsien‐Ju
Published: June 2015

The reducing behaviors of five 4‐cyano‐3‐substitutedsydnones were studied with dropping mercury electrode. Their reducing potentials obey the modified Hammett equation and possible reaction mechanisms are discussed.
Keto‐Enol Tautomeric Equilibrium in 4‐Oxo‐1,1,3‐Cyclohexanetricarboxylic Acid Trialkyl Esters and 4‐Oxo‐1, 1, 3‐Cyclopentanetricarboxylic Acid Trialkyl Esters
Authors: Yang Chia‐Hsi , Yu Hwa , Wu Jiin‐Sheng
Published: June 2015

4‐Oxo‐1,1,3‐cyclohexanetricarboxylic acid trialkyl esters in deuterochloroform and dimethylsulfoxide‐d6 (DMSO) exist exclusivly in the enol form. The keto form is the major component in the analogous compounds of five‐membered ring. The 1, 3 interaction between carboalkoxy groups in the six‐membered ring should be the reason why the carboalkoxy group at 3‐position is in equatorial configuration and engages in the intramolecular hydrogen bond, so that the enol form is dominating.
On the Electrochemical Reduction of α‐Cyanothioacetamide Derivatives (I) Polarographic Behaviour of 2‐Arylhydrazono‐2‐Cyanothioacetamides
Authors: Abdel Aziz Mahfouz A. , Fahmy Hussein M. , Azzem Magdi Abdel , Hathoot Abla A.
Published: June 2015

The polarographic reduction of a series of 2‐aryl‐hydrazono‐2‐cyanothioacetamides ((Ia‐e) has been examined in 50% ethanolic buffer solutions. The obtained data indicate that these compounds are in the hydrazono form and that they are reduced to give an amino acid and the corresponding primary aromatic amine. A mechanism has been proposed and discussed. Recombination and dissociation rate constants (kr) and (kd) have been computed using the appropriate spectrophotometric, potentiometric and apparent acid equilibrium constants.
Mössbauer Spectra and Magnetic Properties of Polydiimine Complexes of Iron(II) Sulfate
Authors: Sheu Jinn‐Fu , Wei Ho‐Hsiang , Yao Yeong‐Der
Published: June 2015

A new series of polynuclear iron complexes with polydiimine ligand have been prepared from the Schiff‐base condensation of pyridine‐2, 6‐dialdehyde or 2, 6‐diacetylpyridine with aliphatic diamines. The structures of the complexes are represented by [−N = CR‐Py‐CR = N‐(CH2)n‐]2FeSO4·xH2O; where R = H, CH3; n = 4−10, × = 5∼8. Mössbauer spectra and magnetic measurements show several complexes have unusual magnetic properties.
Study on the Nucleophilic Addition to (η4‐Cis‐1‐Methoxy‐1,3‐Butadiene)Iron Tricarbonyl Complex
Authors: Yeh Ming‐Chang P. , Chu Chih‐Hong , Sun Mei‐Ling , Kang Kuo‐Ping
Published: June 2015

Reaction of the reactive carbanion with (η4‐cis‐l‐methoxy‐1,3‐butadiene)Fe(CO)3, followed by acid quenching, generates the C‐1 substitution product (27%) together with the regular C‐2 adduct (71%). A very stable ferracyclopentanone was isolated and its x‐ray diffraction analysis determined.
The Mass Spectra of 4‐(3‐Arylsydnonyl)Methanols and Their Derivatives: Formation of Ar‐N=C‐H Cation via a Hydrogen Migration
Authors: Shaw‐Taolin  , Tien Ling‐Ling
Published: June 2015

Fourteen mass spectra of the sydnonylmethanols and their derivatives have been measured under EI conditions. The process of losing a OR' radical and hydrogen migration reaction are accompanyed with lost of a CO and an NO channel. The competition between cleavage of C‐0 bond and hydrogen migration is mainly controlled by the type and size of the R' group.
Synthesis of (±) Peperomins
Authors: Zee Sheng‐Hsu , Chou Shan‐Yen
Published: June 2015

The total synthesis of natural antitumor agent (±) peperomin A, B and C are reported. These syntheses were started from benzophenones and diethyl succinate by Stobbe condensation. Three successive steps were employed to give the (±)‐peperomins.
Kinetics of the Electron‐Transfer Reactions between (Ethylenediaminetetraacetato) Cobaltate (III) and (4‐Aminopyridine)Pentacyanoferrate (II) Complexes
Authors: Lin Charng‐Sheng , Chien Chiu‐Feng , Yeh Andrew
Published: June 2015

Kinetic measurements for the forward reaction Fe(CN)54‐AmPy3− + Co(edta)− ⇌ Fe(CN)5s4‐AmPy2− + Co(edta)2− have been carried out; the rate constant is 2.72 ± 0.07 M−1s−1, at pH = 8, μ = 0.10 M LiClO4, and T = 25°C. The activation parameters of the reaction were also studied with and . The mechanism of the reaction is discussed in the context of the Marcus cross relation for an outer‐sphere process.
Cleavage of C‐S Bond of Sulfolane Induced by Ultrasonically Dispersed Potassium
Authors: Chou Ta‐Shue , Hung Shao‐Hwa , Peng Man‐Li , Lee Shwu‐Jiuan
Published: June 2015

The reductive cleavage of the carbon‐sulfur bond of sulfolane has been reinvestigated; a reaction mechanism is proposed.
Substituent Effects on Phosphate‐Catalyzed Proton Exchange in Amides
Authors: Wang Wei‐Hsien , Cheng Ching‐Chih , Lee Ming‐Chao , Huang Chiung‐Yi
Published: June 2015

The kinetics of phosphate‐catalyzed proton exchange have been measured with NMR lineshape analysis for a series of amides, ureas, and carbamates. A hypothetical energy profile for transition structures of concerted phosphate catalysis ‡c and of stepwise phosphate catalysis ‡1, ‡2 is used for discussion of the substituent effects. The concerted mechanism of phosphate catalysis operates only for amides RCONHCH3 for which the electron‐donating ability of the substituent R is comparable with, or better than, that of the methyl group. We conclude that concerted phosphate catalysis is inoperative in proteins or polypeptides.
Cleavage of (–)‐Eschscholtzine with Sodium in Liquid Ammonia
Authors: Lee Shoei‐Sheng , Lin Chia‐Yin , Chen Chung‐Hsiung
Published: June 2015

(–)‐Eschscholtzine was cleaved with sodium in liquid ammonia to yield 2,8‐dihydroxy‐N‐methylpavine and 2,9‐dihydroxy‐N‐methylpavine. This reaction indicates regioselectivity by cleavage mainly at a site para to the methine carbon of a bridgehead.
Reaction of Tricarbonyl(η3‐allyl)iron(0) Anions with Bromine
Authors: Yeh Ming‐Chang P. , Kang Kuo‐Ping , Hwu Chong‐Chen
Published: June 2015

The addition of reactive carbanions to tricarbonyl(η4‐1,3‐diene)iron(0) complexes proceeded at 23°C to give putative tricarbonyl(η3‐allyl)iron(0) anion complexes. Trapping of the reactive intermediates with bromine produced nucleophilic‐substituted tricarbonyl(η4‐1,3‐diene)iron(0) complexes.
Synthesis of Novel 7‐Allyl‐8‐Substituted Guanosines
Authors: Come J. , Klaubert D. H. , Chen R.
Published: June 2015

A useful one‐pot procedure for preparing certain novel 8‐subsituted guanosine derivatives from 7‐allyl‐8‐thioxoguanosine (2b) has been developed.
Isolation of 24‐Hydroperoxy‐24‐Vinylcholesterol and Fucosterol from the Brown Alga Turbinaria Conoides
Authors: Sheu Jyh‐Horng , Sung Ping‐Jyun
Published: June 2015

A highly cytotoxic hydroperoxysterol 24‐hydroperoxy‐24‐vinylcholesterol (1) and fucosterol (2) were isolated from the brown alga Turbinaria conoides. Compound (1) was transformed into 29‐hydroperoxystigmasta‐5, 24(28)‐dien‐3β3‐ol 3 in chloroform solution at −5–0°C in quantitative yield. The latter compound has been shown to exhibit much stronger cytotoxicity toward cultured spleen lymphocytes stimulated by mitogen concanavalin A than toward normal spleen lymphocytes.
Layered Group(IV) Metal Phosphates as Catalysts for MTBE Synthesis
Authors: Cheng Soofin , Wang Jee‐Ten , Lin Chun‐Liang
Published: June 2015

Layered group(IV) metal phosphates and their phenylsulfonic acid derivatives were used as catalysts for the synthesis of methyl tert‐butyl ether (MTBE) from methanol and isobutene. Because zirconium and titanium phosphates have only moderate acidic strength, relatively high temperatures are required to activate their Brønsted acidic sites. The optimal activity was obtained at ca. 443 K. Their phenylsulfonic acid derivatives, however, demonstrated higher acidic strength by giving much higher activity toward MTBE formation at relatively low temperaures. The catalysts were characterized in terms of their structure, thermal stability, surface area and acidic strength.
Investigation of Substituent Effects on Proton and Carbon‐13 Chemical Shifts of 4‐Substituted Trans‐Stilbenes
Authors: Gahm Kyung‐Hyun , Eng Siew‐Leng , Ho Tong‐Ing , Lin Ying‐Chih
Published: June 2015

Proton and carbon‐13 chemical shifts of para‐substituted stilbenes have been measured. 1H‐1H, 1H‐13C COSY spectra were obtained to analyze unambiguously the chemical shifts of protons and carbons. A long range coupling between 2‐H and α‐H was observed in a 1H‐1H COSY spectrum. The observed chemical shifts have been correlated with Hammett substituent parameters. Among ethenyl protons and carbons, all but the chemical shifts of α‐H show good correlation with both dual substituent parameters and single substituent parameters. In addition to this finding, the excellent linear correlations of C‐l, and 4′‐H of 4‐substituted trans‐stilbenes are also reported. Besides the correlations of chemical shifts with Hammett parameters, a good correlation between the chemical shifts and the calculated charges of position C‐4′ are reported.
Improved Theoretical Spectrum of Quasibound States and Resonances for H2(1∑g+)
Authors: Jiann‐Shing Shyu
Published: June 2015

The most recent ab initio potentials for H2(1∑g+), which include relativistic, adiabatic and radiative corrections, were used to calculate the spectrum of quasibound states. The levels, widths and tunneling permeability of resonant states were also studied by the quantum phase‐shift method. A new set of relevant resonance states for the calculations of atomic recombination of hydrogen is indicated by the present work. In comparison with the previous studies, significant improvements have been found for the resonances.
Micelles of SDS Surfactants in Concentrated NaCl Solutions
Authors: Lo Jin‐Hsiang , Mou Chung‐Yuan
Published: June 2015

We investigated the aggregation behavior of rod‐like micelles of sodium dodecyl sulfate (SDS) in concentrated NaCl solution by quasi‐elastic light scattering (QLS) and viscosity measurement over a range of temperature (25 °C to 50 °C) and NaCl concentration. The reduced viscosity of aqueous SDS in the presence of NaCl has been measured by an Ubbelohde‐type capillary viscometer. We show mean hydrodynamic radius of micelles can be determined from viscosity data. We also determined mean hydrodynamic radius using quasi‐elastic light scattering. Micellar size decreases with increasing temperature, whereas it increases with increasing ionic strength. The results of viscosity and dynamic light‐scattering measurements are interpreted as the extension of length of rod‐like micelles. We compare viscosity and light scattering experimental results.
Syntheses of Mg/Al Multinuclear Bridged Complexes. (II). Reactions of Aluminumtrihalide with Dialkylaminomagnesium
Authors: Chang Chung‐Cheng , Lin Su‐Ching , Tsai Chin‐Ngo , Liu Lin‐Kang
Published: June 2015

Al2X6Mg[N(C2H5)2]2( X = Cl, Br), A12X4(NR2)2 (R = C2H5, i‐C3H7, X=Cl, Br), AlX3HNR2(R=i‐C3H7) were characterized by means of mass, infrared, and 1H, 13C and 27Al NMR spectra and elemental analyses. The crystal structures of two aluminum complexes, Al2Cl4[N(C2H5)2]2 and AlCl3HN(i‐C3H7)2, were determined by means of single‐crystal X‐ray diffraction, Al2Cl4[N(C2H5)2]2 crystallized in space group Pmcn with unit‐cell dimensions a = 10.577(2), b = 11.799(3) and c = 13.219(4) Å; structure analysis resulted in a final R = 0.043 for 999 observations. AlCl3HN(i‐C3H7)2 crystallized in space group Pcab with unit‐cell dimensions a = 10.545(7), b = 14.630(4) and c = 15.255(2) Å; structure analysis resulted in a final R = 0.041 for 1054 observations. The Al atoms in both structures show a tetrahedral bonding geometry with Al‐N lengths in the range 1.927(3) −1.956(4) A, and Al‐Cl lengths in the range 2.092(3) −2.128(3) Å. The four‐membered ring of Al2N2 in Al2Cl4[N(C2H5)2]2 is almost planar.
Conformational and Configurational Determination in 1,1,4,4‐Tetrafluoro‐2‐Propylidene‐3‐Methyl‐6‐Tert‐Butyl‐1,4‐Disila‐5‐Cyclohexene
Authors: Lee Chi‐Young , Chiang Hui‐Jean , Liu Chao‐Shiuan
Published: June 2015

A complete assignment of the 1H, 13C and 19F NMR spectra of 1,1,4,4‐tetrafluoro‐2‐propylidene‐3‐methyl‐6‐tert‐butyl‐1,4‐disila‐5‐cyclohexene 3, the product of the cycloaddition reaction between tetrafluorodisilacyclobutene 1 and cis, trans‐2,4‐hexadiene mediated by (n5‐C5H5)Mn(CO)3, has been made by means of various 2D NMR chemical shift correlation methods and selective heteronuclear decoupling techniques. An analysis of the three bond 13C‐1H coupling constants and two bond 13C‐19F coupling constants and the molecular modeling results enabled the determination of the conformation and configuration of compound 3. The conformation of 3 provides insight into mechanistic details of the Mn‐mediated cycloaddition.
Synthesis of Several 2‐Azafluorenones and 5H[1]Benzopyrano[3,4‐c]Py Riding‐Ones
Authors: Shiao Min‐Jen , Peng Chin‐Jen , Wang Jy‐Shib , Ma Ying‐Tsun
Published: June 2015

Convenient syntheses of 2‐azafluorenones 5a‐f and 5H[1]benzopyrano[3,4‐c]pyridin‐5‐ones 6a‐b were performed by using intramolecular cyclization of 4‐arylnicotinic acids 4a‐F. 4a‐f were obtained via permanganate oxidation from the corresponding of 4‐arylpyridines 3a‐f in good yields.
Side Reactions in Peptide Synthesis: Failure of Coupling in Solid‐Phase Automatic Synthesis of a Fragment (Sequence 65‐74) of the Acyl Carrier Protein
Authors: Wu Chi‐Yue , Chen Wen‐Chao , Yu Hui‐Ming , Chen Shui‐Tein , Wang Kung‐Tsung
Published: June 2015

Two major side‐products and a desired peptide (each was one‐third) were found in analysis of a synthesized fragment (65‐74) of the acyl carrier protein by a solid‐phase automatic peptide synthesizer. The peptide mixtures were separated and collected by HPLC. Each isolated peptide was characterized via amino‐acid composition analysis, mass spectra and specific peptide‐bond cleavage to prove the sequence. Each by‐product had one amino‐acid missing (72Ile and 73Asn, respectively) from the sequence of ACP(65‐74).