bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Pyrimidines, Thienopyrimidines and Pyrazolopyrimidine
Authors: El‐Dean Ade L. M. Kamal , Abdel‐Moneam Maisa E.
Published: May 2015

5‐Ethoxycarbonyl‐4‐methyl‐2‐phenylpyrimidin‐6(1H)‐thione (3), which was prepared from the reaction of ethyl β‐aminocrotonate 1 with benzoyl isothiocyanate (2) in refluxing acetone, was reacted with halo compounds to give S‐alkyl derivatives 4a‐h. Treatment of compounds 4a‐c with sod. ethoxide cyclized into thienopyrimidine 10a‐c. Hydrazinolysis of compound 3 gave hydroxypyrazolopyrimidine derivative 6. Also the latter compound was obtained upon heating compound 4a with hydrazine hydrate under neat conditions, but when compound 4a refluxed with hydrazine hydrate in ethanol the corresponding carbohydrazide 5 was produced.
Novel Cyanine Dyes: Synthesis, Characterization and Photosensitization‐Structure Correlation
Authors: Shindy H. A. , El‐Maghraby M. A. , Eissa F. M.
Published: May 2015

Novel furo, thieno and pyrrolo[2,3‐b]pyrazole cyanine dyes were synthesized. The structure‐photosensitization properties correlation of the dyes were examined in 95% ethanol solution by absorption spectroscopy. The chemical structure of the starting biheterocyclic compounds and their derived cyanine dyes were confirmed by elemental analysis, IR and 1H NMR spectroscopy.
Synthesis of 2,2′‐Biflavanones from Flavone via Electrolytic Reductive Coupling
Authors: Chen Arh‐Hwang , Cheng Chieh‐Yuan , Chen Chia‐Wen
Published: May 2015

Flavone (1) was easily reduced by using the electrochemical method to give two hydrodimers of 2,2′‐biflavanone(racemate) (5a) and 2,2′‐biflavanone(meso) (5b) and one reductive product of flavanone (6). Their yields were dependent on the nature of electrodes, the kinds of supporting electrolytes and the reaction temperature. They were found to afford higher yields of 2,2′‐biflavanone(racemate) (5a) and 2,2′‐biflavanone (meso) (5b) (32.4% and 24.8%, 35.8% and 13.4%, respectively,) in the reaction conditions of Pb(‐)/C(+)‐H2SO4‐7F/mol and C(‐)/C(+)‐H2SO4‐5F/mol.
CeCl3/Sm System Induced Reductive Cleavage of the Se‐Se Bond in Diaryl Diselenides: A Novel Method for the Synthesis of β‐Selenoesters and β‐Selenonitriles
Authors: Li Xue , Zhang Songlin , Wang Yulu , Zhang Yongmin
Published: May 2015

The Se‐Se bond in diselenides was reduced by CeCl3/Sm system to produce selenolate anions, which react with α,β‐unsaturated esters or α,β‐unsaturated nitriles to afford β‐selenoesters and β‐selenonitriles, respectively.
1,3‐Dicyclohexylcarbodiimide, an Effective Activating Agent for H‐Phosphonate Chemistry
Authors: Padiya Kamlesh J. , Mohe Nikhil U. , Patil Prashant S. , Pal Ravindra R. , Salunkhe Manikrao M.
Published: May 2015

1,3‐Dicyclohexylcarbodiimide (DCC) has been exploited as an activating agent for nucleoside‐H‐phosphonates in the solution as well as solid phase synthesis of oligonucleotide and is effective in terms of speed and coupling efficiency.
Mononuclear Iron(III) and Manganese(III) Complexes with Substituted Salicylaldimine Ligands: Structure, Magnetic Properties, and Catalytic Activity of Olefins‐Epoxidation
Authors: Cheng Sheng‐Chuan , Chang Cheng‐Wei , Wei Ho‐Hsiang , Lee Gene‐Hsiang , Wang Yu
Published: May 2015

Two mononuclear manganese(III) and iron(III) complexes with substituted salicylaldimine ligands, [MnL(H2O)2]Cl·H2O (1) and [FeL(H2O)(Cl)]CH3CN (2) [H2L = N,N′‐(1,1‐cyclohexane)bis(3‐methoxysalicylaldimine)] were prepared and characterized. The X‐ray crystal structure shows that 1 and 2 centers are six‐coordinate with distorted octahedral geometry. In 1, the hydrogen bonding of water molecules form a quasi one‐dimensional chain structure. The temperature dependence of magnetic susceptibility measurements for complexes of 1 and 2 was analyzed in terms of the zero‐field splitting (D) spin‐Hamiltonian formula with D = 2.0 cm−1 for 1 and J = 7.5 cm−1, and D = 0.01 cm−1 for 2, respectively. The complexes of 1 and 2 activate the epoxidation of cis‐stilbene or α‐methylstyrene by NaOCl. With 1 the epoxides were produced in 75% yield with cis:trans = 12:88 from cis‐stilbene and 82% from α‐methylstyrene, and with 2 the epoxides were produced in 43% with cis:trans = 30:70 from cis‐stilbene and 71% from α‐methylstyrene.
Synthesis and Crystal Structure of Tristropocryptands
Authors: Shindo Kimio , Wakabayashi Hidetugu , Kurihara Teruo , Zhang Luo‐Chenz , Ebata Keisuke , Sakurai Hideki , Nozoe (The Late) Tetsuo
Published: May 2015

Treatment of benzo[b]cyclohepta[e][1,4]oxazines (4) with 1.2 equiv. of tris(2‐aminoethyl)amine (13) in methanol at 80 °C gave 1,4,12,15,18,26,31,39‐octaazapentacyclo[13.13.13.05,11.019,25.032,3]pentetraconta‐4,6,8,10,18,20,22,24,31,33,35,37‐dodecacenes (14), armed tropocoronands (15), and tropopodands (16). The structure of tristropocryptand 14a was determined by the X‐ray diffraction method.
Optical Properties of Host(SBA‐15)‐guest(AgI) Composite Materials
Authors: Kamalakar G. , Zhai Q.‐Z. , Hwang Dennis W. , Chien Shu‐Hua , Yang Yi‐Han , Lin Jin‐Dong , Chen Yit‐Tsong , Hwang Lian‐Pin
Published: May 2015

Nanoclusters AgI have been prepared in the channels of SBA‐15 molecular sieve host, and the host‐guest nanocomposite materials were prepared by a heat diffusion method. The (SBA‐15)‐AgI host‐guest nanocomposites were characterized by powder X‐ray diffraction analysis, nitrogen adsorption‐desorption isotherms at 77 K, and solid‐state diffuse reflectance absorption spectra. The decrease in surface area, pore diameter, and pore volume showed the existence of silver iodide clusters in the channels of SBA‐15 host. X‐ray diffraction illustrates that the framework of the SBA‐15 remained in the host‐guest composites of (SBA‐15)‐AgI. As the guest loading decreases, a blue‐shift was observed in the diffuse reflectance spectra. This shows that the guest existed in the channels of SBA‐15 and a quantum confinement effect emerged. The photoluminescence (PL) spectra show that the PL at ∼2.38 eV, associated with the hydrogen‐related species, decreases substantially after the loading of AgI in SBA‐15. The decrease of the PL indicates the reduction of the hydrogen concentration on the pore surface of SBA‐15 after the loading of AgI guest. The intensity decrease of the self‐trapped exciton (STE) band at 2.76 eV also suggests a hindrance for generating the excitons upon adding the AgI guest into the SBA‐15 host.
Evaluation of Natural Porous Crab Shell Powder Used for the Enrichment of Sulfur Compounds from Gaseous Samples
Authors: Sye Wen‐Fa , Chen Yen‐Chun , Wu Shang‐Fei
Published: May 2015

A glass liner of a PTV injector packed with porous crab shell powder (50–100 mesh) was used to enrich the trace concentrations of sulfur components in natural gas, then the sulfur gases were thermally released according to a programmed temperature from the crab shell powder trap and re‐collected in a PLOT‐column head cooled with liquid nitrogen. The sulfur compounds were revolatilized and directly transferred to the system of PLOT‐column gas chromatography/flameless sulfur chemiluminescence detector for analysis. The characteristics of natural crab shell powder as an adsorbent have been presented. The sulfur gaseous compounds known to cause nuisance odors in natural gas were determined. The application of a porous crab shell powder trap for the analysis of sulfur compounds from gaseous samples has been proved to be useful.
Regioselective Photoamination of 2‐Styrylthiophenes with Ammonia
Authors: Ho Jinn‐Hsuan , Ho Tong‐Ing
Published: May 2015

Photoinduced electron transfer from the singlet excited state of 2‐styrylthiophenes (1a‐1f) to p‐DCB (p‐dicyanobenzene) has been proposed from the negative value of ΔGET (the free energy of the electron transfer) calculated by the Rehm‐Weller equation. This leads to the formation of radical cations of 1a‐1f and a radical anion of p‐DCB. The p‐nitro derivative 1g can not result in the radical cation due to the positive ΔGET value which results from the unfavorable singlet excitation energy (E0,0) and oxidation potential. Regioselective amination by ammonia to the radical cations of 1a‐1e has occurred to afford 1‐amino‐1‐aryl‐2‐(thien‐2‐yl)ethanes (2a‐2e) in reasonable yields (50–90%). The regioselectivity arises from the attack of ammonia at the localized positive charge on C‐1 of the ethene bond of the radical cations of 1a‐1e.
Preparation and Properties of 2‐(9′‐Carbazolyl)‐3‐(8″‐hydroxy‐2″‐Quinolinyl)Acrylonitrile Derivatives
Authors: Xu Peng‐Fei , Chow Tahsin J. , Lin Richard , Lu Ta‐Jung
Published: May 2015

The E and Z‐isomers of the titled compound were synthesized by condensation of 2‐carboxaldehyde‐8‐alkyloxyquinoline and N‐cyanomethylcarbazole, followed by hydrolysis. The alkoxy protection groups in 3b‐c can be cleaved either in acid or in base to yield 3a. All compounds exhibit blue/green luminescence, which may be used as emitting materials in the fabrication of light‐emitting diodes. Crystal diffraction analyses were performed for 3a‐E, 3d‐Z, and 4‐Z, while the results indicated the presence of a common structural feature among these molecules. The rings of quinoline are co‐planar with the double bond of acrylonitrile, forming a major conjugated chromophore. The carbazole group is twisted along the N(9″)‐C(2) bond away from the major plane with a large dihedral angle. The major conjugated chromphore was found to be responsible for the spectral properties of these compounds. Protonation of the quinoline in these compounds red‐shifted their absorption bands substantially.
The Intramolecular Diels‐Alder Reactivity of N‐Phenyl‐1,2‐Propadienyl Phosphinic Acid Amides and Related O‐Phenyl Esters
Authors: Himbert Gerhard , Ruppmich Martin , Knöringer Heinz
Published: May 2015

The P‐phenylpropa‐1,2‐dienyl phosphinic amides 4a‐h, the corresponding phosphinates 4i‐k and the (1‐phenylpropa‐1,2‐dienyl) phosphonic diamide 4l, whose amide N‐atoms resp. ester O‐atoms wear unsubstituted or substituted benzene nuclei, were formed by [2,3] sigmatropic rearrangement of the corresponding (2‐alkynyloxy)phosphine derivatives 3a‐l. Heating the solutions of 4a‐l led in some cases to decomposition (see 4a‐c), but in other cases to the tricycles 5d‐l, which were formed by Intramolecular Diels‐Alder (IMDA) reaction between the second allenic double bond as dienophile and the benzenic π‐system as diene.
Study of Reactions of Triiodide and Alizarin Red S with Some Important Phenothiazines. Development of an Indirect Titrimetric and a Spectrophotometric Method for the Assay of Phenothiazine Derivatives
Authors: Farhadi Khalil , Savojbolaghi Amir Karimi , Maleki Ramin
Published: May 2015

The reactions of a triiodide ion and alizarin red S with some N‐substituted phenothiazine drugs have been studied for the development of two simple, rapid, sensitive and accurate indirect titrimetric and extractive‐spectrophotometric methods for determining these drugs. Spectroscopic studies and chemical analysis showed that the protonated forms of phenthiazines, (PhenH2)2+, react with triiodide ions forming highly stable and insoluble ion pair products as (PhenH2)(I3)2. Formation of ion association complexes have been applied to the development of an indirect visual titrimetric method for the determination of chlorpromazine hydrochloride (CPH), trifluoperazine hydrochloride (TFPH), fluphenazine hydrocholoride (FPH) and promethazine hydrochloride (PMH) over the range 10−5–10−2 M. The extractional‐spectrophotometric method is based on the formation of (1:1) ion‐association complexes between drugs and alizarin red S as chromogenic reagents in acidic citrate buffer that are extractable into chloroform with an absorption maximum at 425 nm. The effect of different factors such as organic solvents, pH, and reagents concentration, were studied. CPH, TFPH and FPH can be determined over the range 9–57, 14–77 and 7–71 ppm, respectively. The proposed methods were applied for the analysis of the studied drugs in pure forms and their commercial preparations. Results are in good agreement with those obtained by official methods.
Oxidation of Stereo‐regular Poly(styrene‐co‐4‐methylstyrene) by Cobalt(II) Acetate Tetrahydrate/Sodium Bromide Catalyst
Authors: Chen Yu‐Pin , Hong Jin‐Long
Published: May 2015

Chemical modification on the stereo‐regular poly(styrene‐co‐4‐methylstyrene) (sPS‐PMS) was attempted in this study. Metallocene copolymerization of styrene (St) and 4‐methylstyrene (MSt) was performed by using η5‐pentamethylcyclopentadienyl‐titanium(IV)tributoxide (Cp*Ti(OBu)3)/methylaluminoxane (MAO)/tri‐iso‐butylaluminum (TIBA) catalyst in the bulk state. Cobalt(II) catalyst was then applied to oxidize the benzylic methyl group on the MSt units of the resulting sPS‐PMS copolymer. Both aldehyde and carboxylic acid in the oxidized products were resolved by the FTIR and 1H NMR. The oxidized sPS‐PMSs exhibit a low and a high‐temperature Tg and Tm corresponding to the transitions in the amorphous and the crystalline regions. Hydrogen‐bond and polar interactions between the aldehyde and carboxylic acids tend to interrupt the regular chain packing of the oxidized sPS‐PMS, resulting in the lowering of Tm with oxidation level. The oxidized sPS‐PMS showed better adhesion to glass fiber than pure sPS‐PMS copolymer as evaluated from the respective SEM fractured micrographs.
Synthesis and Photophysical Properties of Hetero‐Bischelated Complexes of Rhodium(III) Containing Phenyl‐Pyridin‐2‐Ylmethylene‐Amine
Authors: Lee Jen Rong , Lung Jin Wang , Huang Wen Liang
Published: May 2015

Three new hetero‐bischelated rhodium (III) complexes ofcis‐[Rh(PA)(L)Cl2]Cl (where PA = phenylpyridin‐2‐ylmethylene‐amine; L = 2,2′‐bipyridine, 2,2′‐dipyridylamine and 1,10‐phenanthroline) have been successfully prepared and characterized. Each complex shows high intensity bands in the UV region, and these are assigned to spin‐allowed π‐π* transitions. The medium‐intensity absorption band profile in the lower energy region can be explained by convolution of spin‐allowed CT and d‐d* transitions. The emission spectra at low temperature (77 K) of these complexes in EtOH/MeOH (4:1 v/v) are virtually identical. They all exhibit a broad, symmetric, and structureless red emission with a microsecond lifetime and hence are assigned as the d‐d* phosphorescence.
Colorimetric Determination of Sulphur Dioxide and Sulphites in Various Environmental Samples
Authors: Chatterjee Sukumar , Pillai Ajai K. , Gupta V. K.
Published: May 2015

Rhodamine‐B has been proposed as a simple and sensitive colorimetric reagent for the estimation of sulphur dioxide in air. The air sample containing sulphur dioxide is passed through the absorbing solution of aqueous potassium iodate and N‐chlorosuccinimide to liberate iodine. The liberated iodine bleaches the pinkish red coloured rhodamine‐B dye, which measured at 555 nm. Beer's law was obeyed in the range of 0.5–5.0 μg, of sulphite per 25 mL (0.02–0.2 ppm) equivalent to 0.4–4.0 μg of sulphur dioxide (0.016–0.16 ppm). The molar absorptivity and Sandell's sensitivity were found to be 4.56 × 105 l mol−1 cm−1 and 0.00017 μg cm−2, respectively. The method has been suitably modified and successfully applied to the determination of sulphites in water after liberation of sulphur dioxide in acidic medium.
Synthesis of Some New 6,8‐Disubstituted 7,8‐Dihydropyrimido[2,3:4,3]pyrazolo[1,5‐a]pyrimidines and 6,7,8‐Trisubstituted Pyrimido[2,3:4,3]Pyrazolo[1,5‐a]Pyrimidine Derivatives
Authors: Ho Yuh‐Wen , Yao Chia‐Tseng
Published: May 2015

Cyclization of 5‐cyano‐1,6‐dihydro‐4‐methyl‐2‐phenyl‐6‐thioxopyrimidine 4 with excess of 85% hydrazine hydrate afforded the 3‐amino‐4‐methyl‐6‐phenylpyrazolo[3,4‐d]pyrimidine 5, which can react with appropriate Mannich base derivatives 13a‐c and chalcones 27a,b to yield the corresponding 6,8‐disubstituted 7,8‐dihydropyrimido[2,3:4,3]pyrazolo[1,5‐a]pyrimidines 15a‐c and 30a,b, respectively. On the other hand, the 6,7,8‐trisubstituted pyrimido[2,3:4,3]pyrazolo[1,5‐a]pyrimidine derivatives 8a‐g, 20a‐e, 36 and 38 were obtained by treatment of compound 5 with appropriate 1,3‐diketones 6a‐g, 3‐dimethylamino‐1‐(substituted)prop‐2‐enones 18a‐e, 3‐aminocrotononitrile 3, and ethoxymethylenemalononitrile 37 under acidic condition, respectively.
Spectrophotometric and Conductometric Studies of Charge Transfer Interaction of 2‐(1H)‐Pyridinethione with π‐Acceptors
Authors: Sayed N. I. Abdel
Published: May 2015

Kinetic studies on the formation of charge transfer complexes of 2‐(1H)‐pyridinethione with π‐acceptors p‐chloranil and p‐bromanil in dipolar aprotic solvent N,N‐dimethylformamide have been carried out spectrophotometrically at various temperatures. The reaction follows an overall third order rate equation, through first order with respect to π‐acceptors and second order with respect to the 2‐(1H)‐pyridinethione. The rates were found to increase with increasing temperature. Activation parameters, ΔH≠ and ΔS≠ have been calculated for the charge transfer complexes. The structure of the products was confirmed by their elemental analysis, IR, 1H NMR and mass spectrometry. Conductometric method has been used to investigate the electron donor‐acceptor complex formation. The stoichiometries of these complexes have been established and their conductance (σP−) and molar conductivity (σM−) values are reported.
Estimation of the Taurocholate to Lecithin Molar Ratio of Mixed Micelles in Taurocholate‐Lecithin Solutions by an Interaction Model and Laser Light‐Scattering Measurements
Authors: Liu Chen‐Lun , Weng Ming‐Shin
Published: May 2015

The taurocholate (TC) to lecithin (L) molar ratio (K) and molecular weight of mixed TC‐L micelles coexisting with simple TC micelles were determined by employing laser light‐scattering measurement and an interaction model of mixed and simple micelles. When the nonmixed micellar taurocholate (NMTC) concentration was greater than 25 mM, the K value and molecular weight of mixed TC‐L micelles were ∼ 4.3 and ∼ 20,000 daltons, respectively, at an L concentration of 6 mM, and ∼ 2.0 and ∼ 35,000 daltons at L concentrations of 12 mM and 21 mM. A quantitative model of the formation of simple TC micelles and mixed TC‐L micelles indicated that, when the NMTC concentration was greater than 25 mM, mixed TC‐L micelles were unstable at low L levels because of low concentrations of L monomers.
Sensitive Determination of Zinc(II) in Real Samples Using a Poly(4‐vinylpyridine)/Mercury Film Electrode
Authors: Zen Jyh‐Myng , Tsai Dong‐Mung , Yang Hsueh‐Hui
Published: May 2015

A poly(4‐vinylpyridine)/mercury film electrode (PVP/MFE) was applied for the determination of trace amounts of zinc ion by square‐wave anodic stripping voltammetry. The PVP/MFE shows better mechanical stability, higher sensitivity, and enhanced resistance to common ions and surface‐active compounds than conventional mercury film electrodes. Various experimental parameters affecting the performance of the PVP/MFE in Zn(II) determination were optimized. Under the optimized conditions, the PVP/MFE shows a linear response up to 50 μg l−1 with a detection limit (S/N = 3) of 1.7 μg l−1. The practical applicability of the electrode was evaluated through the analytical estimation of Zn(II) in various real samples.
Nitrile Hydrolysis of 4‐Cyanopyridinepentaammineruthenium(III) Complex
Authors: Yeh Joyce , Liu Kwery , Lien Ming‐Huei , Yeh Andrew
Published: May 2015

The nitrile ligands undergo hydrolysis to amides under mild conditions when Ru(NH3)5NCR2+ (R = 4‐py, 4‐pyCH3+ and CH=CHCN) complexes are oxidized to Ru(III). The rate of hydrolysis of Ru(NH3)5NCpy3+ increases with the increase in acid concentration as a result of the protonation of the pyridyl nitrogen. The kinetic results yield the rate constant of the hydrolysis for Ru(NH3)5NCpyH4+ complex as 0.12 s−1 at μ = 1.0 M HCl/LiCl, greater than that of a deprotonated species by nearly two orders of magnitude. The enormous increase in rate for the protonated complex arises mainly from the increase in electron withdrawing power due to protonation which will decrease the electron density on the nitrile carbon and make it easier for the nucleophilic attack of the water molecule.
Total Synthesis of (±)‐Abieta‐8,11,13‐trien‐7β‐ol
Authors: Zhang Cheng‐Lu , Bie Ping‐Yan , Peng Xuan‐Jia , Pan Xin‐Fu
Published: May 2015

The first total synthesis of (±)‐abieta‐8,11,13‐trien‐7β‐ol (1) was accomplished, in which α‐cyclocitral was used as the A ring synthon, and triphenylphosphonium chloride (9), which was obtained from m‐bromobenzyl alcohol (4) via five steps, as the C ring synthon. The reduction of another natural organic compound (±)‐abieta‐8,11,13‐trien‐7‐one (2) with LiAlH4 gave exclusively the title compound 1.
Heterocyclic Spiro‐Compounds from Tandem Cascade Reaction of Alkyl Azides and Methyl Vinyl Ketone
Authors: Yang Chia‐Hsi , Lee Lang‐Tong , Wang Yu
Published: May 2015

Tandem cascade reaction of one molecule of alkyl azide and four molecules of methyl vinyl ketone gives a heterocyclic compound having an 1,4‐diazepine fused to a pyrazoline and spiro‐linked to a dihydropyran. The tandem cascade reaction is composed of an intermolecular [3+2] dipolar cycloaddition to give a triazoline, an isomerization to a diazo compound, another intermolecular [3+2] dipolar cycloaddition to give a pyrazoline, a Michael addition, dehydration, and a [4+2] cycloaddition.
Synthesis of Galanthamine Analogs as Acetylcholinesterase Inhibitors via Intramolecular Heck Cyclization
Authors: Liang Pi‐Hui , Hsin Ling‐Wei , Pong Sung‐Ling , Hsu Chia‐Huei , Cheng Chen‐Yu
Published: May 2015

A novel approach towards the construction of the galanthamine skeleton was demonstrated by the Pd‐catalyzed cyclization of N‐[2‐(1,4‐dioxa‐spiro[4,5]dec‐7‐en‐8‐yl)‐ethyl]‐2‐iodo‐4‐methoxy‐N‐methyl‐benzamide (23), with formation of the benzazepine ring and creation of a quaternary carbon.
Theoretical Investigation of the Spin‐dependent Exciton Formation Rates in Polymeric Light‐emitting Diodes
Authors: Shuai Zhigang , Yin Shiwei , Chen Liping , Ye Aijun , Beljonne David , Brédas Jean‐Luc
Published: May 2015

First, a brief review is given of recent experimental and theoretical progress in the determination of the spin‐dependent exciton formation rates in electroluminescent π‐conjugated polymers. We then describe our recent development of the coupled‐cluster equation of motion method and present its application to the theoretical study of singlet and triplet exciton formation rates and polymer light‐emitting diode quantum efficiency. It is found that, in general, singlet excitons can be formed with a higher yield than triplet excitons. The underlying mechanism is still a matter of debate. Here, we explore the role of inter‐chain charge‐bond correlation effects.
Theoretical Study on the Formation Mechanism of Resonance States for the Na + I2 → Na+ + I2− System
Authors: Cai Zhengting , Ma Wanyong , Sun Xiaomin , Feng Dacheng , Zhang Donghui
Published: May 2015

An extended LCAC‐SW (linear combination of arrangement channels‐scattering wavefunction) quantum scattering dynamic method combined with ab initio quantum chemical calculations has been used to study the formation mechanism of the resonance states for the ion‐pair formation reaction Na + I2 → Na+ + I2−. Resonance energy and resonance width or lifetime for the first resonance peak were calculated. Resonance can be identified to Feshbach resonance, and the physical interpretation has been given.
Theoretical Study on the Decomposition of NO via Dimer in the Presence of Cu
Authors: Sun Yueming , Zhang Yuan , Cao Ainian , Liu Juzheng
Published: May 2015

The interaction between NO molecules and copper atoms has been studied at the B3LYP/Lanl2DZ level. The results show that the NO molecules can be stably adsorbed on the adjacent Cu atoms to form the co‐adsorption configurations and the dimer‐adsorption configurations. The relative energies indicate that the structure of NO adsorbed on the Cu with N‐down is more stable than any other structure in the NO co‐adsorption models, and the NO atop adsorption is less stable than the others. On the other hand, the N‐N bond is strengthened, while the N‐O bond is weakened in the NO dimer adsorption models. It indicates that the formation of NO dimer is propitious to the NO direct decomposition on the copper surface. The intermediates of NO decomposing to N2O or N2 via dimer on the copper surface are found. The calculation results reasonably explain that the NO can be directly decomposed via the dimer configurations on the adjacent Cu atoms.
Theoretical Study of Photosynthetic Light‐Harvesting Processes: Application of Time‐Dependent Density Functional Theory
Authors: Hsu Chao‐Ping
Published: May 2015

We review recent progress in the area of theoretical investigations of light‐harvesting processes. The application of time‐dependent density functional theory (TDDFT) in the calculation of excitation energy transfer coupling factor will be emphasized. The effect of a dielectric environment can be obtained through a response theory based on TDDFT formalism. As an example of applicability of TDDFT, the role of a transition forbidden S1 state of carotenoid in a light‐harvesting complex LH2 is discussed in detail. The applicability of TDDFT to states with charge‐transfer character is also discussed with a few examples in the literature. Finally we briefly review works on the applications of TDDFT for excitations in chlorophylls and bacteriochlorophylls.
Unified Semiclassical Theory for the Nonadiabatic Transition
Authors: Zhu Chaoyuan
Published: May 2015

Unified semiclassical theory for general two‐state nonadiabatic transition is discussed by demonstrating an important quantity that represents a type of nonadiabatic transition. This quantity is essentially defined by the rotation angle which determines transformation between diabatic and adiabatic representation, and it runs from unity to infinity continuously. The unified semiclassical formula is numerically demonstrated, especially in the high energy range where the transition probability is sensitive to the type of nonadiabatic transition. The present semiclassical theory can be incorporated with the framework of the Tully's fewest‐switches trajectory surface hopping method to deal with nonadiabatic transitions in multi‐dimensional systems.
Stability and Unfolding Mechanism of the N‐terminal β‐Hairpin from [2Fe‐2S] Ferredoxin I by Molecular Dynamics Simulations
Authors: Liu Hsuan‐Liang , Lin Yuan‐Ming
Published: May 2015

The stability and unfolding mechanism of the N‐terminal β‐hairpin of the [2Fe‐2S] ferredoxin I from the blue‐green alga Aphanothece sacrum in pure methanol, 40% (v/v) methanol‐water, and pure water systems were investigated by 10 ns molecular dynamics simulations under periodic boundary conditions. The β‐hairpin was mostly in its native‐like state in pure methanol, whereas it unfolds dramatically following the ‘zip‐up’ mechanism when it was placed in pure water. Both interstrand and inside‐turn hydrogen bonds account for the stability of the β‐hairpin in its native‐like conformation, whereas hydrophobic interactions among nonpolar side chains are responsible for maintaining its stable loop‐like intermediate structures in 40% (v/v) methanol‐water. Reducing solvent polarity seems to increase the stability of the β‐hairpin in its native‐like structure. Methanol is likely to mimic the partially hydrophobic environment around the N‐terminal β‐hairpin by the subsequent α‐helix.
Phase Chemistry Investigation on Cr(NO3)3‐Met‐H2O System
Authors: Chen San‐Ping , Gao Sheng‐Li , Hu Rong‐Zu , Shi Qi‐Zhen
Published: May 2015

The solubility property of the ternary of Cr(NO3)3‐Met‐H2O has been investigated in the whole concentration by the phase equilibrium method, and the phase diagram has been constructed. From the phase diagram, the congruently soluble complexes Cr(Met)(NO3)3·2H2O (D) and Cr(Met)2(NO3)3·2H2O (E) have been prepared and characterized by chemical analysis, elemental analysis, IR and TG‐DTG. Their combustion energies have been determined by a RBC‐type I precision rotating‐bomb calorimeter, and their standard enthalpies of formation, Δf, Hθm, have been calculated as (‐1842.01 ± 2.13) kJ·mol−1 and (‐1136.16 ± 4.45) kJ·mol−1, respectively.
Rapid Solvent Extraction of Tin(IV) with High Molecular Weight Amine from Hydrochloric Acid Solution
Authors: Sargar B. M. , Anuse M. A.
Published: May 2015

A novel method has been developed for the solvent extraction of tin(IV) from 8 M hydrochloric acid with 4% N‐n‐octylaniline. Tin(IV) from the organic phase was determined spectrophotometrically with pyrocatechol violet at 550 nm. Extraction was found to be quantitative in the range of 7–10 M hydrochloric acid. When the concentration of N‐n‐octylaniline was varied from 0.05–20% in xylene, it showed that optimum concentration was > 3%. Amongst diluents like benzene and xylene, toluene was found to be an effective diluent. Effect of shaking time, concentration of metal ion, and salting out agents was studied.

Tolerance limits of various diverse ions were determined by masking interfering cations. Tin(IV) was separated from associated elements in its binary mixture with Se(IV), Sb(III), Bi(III), Pb(II), Au(III), Cu(II) and Zn(II) and from its ternary mixtures with Sb(III), Bi(III) and Cu(II), Au(III). The proposed method was applied for separation and determination of tin(IV) in tin bearing alloys and foodstuffs.
Vapor‐Phase Reaction of Citronellal over Mesoporous Molecular Sieves MCM‐41 and Zeolites
Authors: Shieh Dong‐Lin , Tsai Chia‐Chun , Chen Chih‐Wei , Ko An‐Nan
Published: May 2015

The vapor‐phase reaction of citronellal (CTN) at 220 °C and atmospheric pressure has been studied using mesoporous molecular sieves and zeolites in a fixed‐bed reactor. The primary products included isopulegol (IPG), menthone, and pulegol with subsequent reactions to form cyclic hydrocarbons. The CTN conversion and the product selectivity depend on the acidity and the textural property of catalysts. Lewis and/or Brönsted acid sites are essential for catalyzing this reaction. An increase of SiO2/Al2O3 mol ratio diminishes the acid amount of all catalysts and enhances both the surface area and the structural order of MCM‐41. The catalytic activity follows the order of MCM‐41 > HZSM‐5 > Hβ > USY, in accordance with the relative total acid amount except that of MCM‐41. Despite its low acidity, Si‐MCM‐41 exhibits the best catalytic performance due to its uniform mesopores, large surface area and good stability; the CTN conversion and the IPG yield attain 91.9% and 58.6%, respectively, after at least 25 h time‐on‐stream.
An Efficient and Simple Approach to Predict Kovat's Indexes of Polychlorinated Naphthalenes in Gas Chromatography
Authors: Yin Chunsheng , Liu Shushen , Wang Xiaodong , Chen Da , Wang Liansheng
Published: May 2015

Molecular structures of polychlorinated naphthalenes were numerically described with a simple but efficient encoding method. Correspondingly a set of structural parameters were obtained for these compounds and linearly correlated with their gas chromatography retention indexes. A quantitative structure‐retention relationship Model (M1) was developed by using multiple linear regression (MLR) with correlation coefficient R = 0.9880 between the numeric structural codes and the gas chromatography retention indexes of 62 polychlorinated naphthalenes. If the “leave‐one‐out” cross‐validation procedure was employed to construct QSPR model for all samples, the second model M2 with the correlation coefficient being R = 0.9839 was generated. The structural codes of polychlorinated naphthalenes were tested with MLR for estimation and prediction of the GC RI by models M1 and M2, and the results obtained were satisfactory.
The Structure of 2‐[(1S)‐(+)‐10‐camphorsulfonamino]‐6‐aminopyridine in the Solid State and in Solution; Unprecedented Cocrystallization of Four Stereoisomers
Authors: Chen Tsun‐Ren , Wu Ying‐Yann , Chen Jhy‐Der , Keng Tai‐Chiun , Wang Ju‐Chun
Published: May 2015

The solid and solution structures of a new optically active aminopyridine compound, 2‐[(1S)‐(+)‐10‐camphorsulfonamino]‐6‐aminopyridine [(S)‐csaap], 1, are reported. Crystal data: space group P21, a = 8.9729 (5), b = 10.9447 (6), c = 36.693 (2) Å, β = 96.435 (1)°, V = 3580.8 (3) Å3, Z = 8, R1 = 0.0673 and wR2 = 0.1600 with I > 2σ(I). This chiral compound shows an unprecedented cocrystallization of four stereoisomers, which are characterized by X‐ray crystallography and NMR spectroscopy.
Reactions of Polymer‐Supported α‐Selenoaldehydes with Grignard Regents. A Facile Solid‐Phase Stereoselective Synthesis of (E)‐1,2‐Disubstituted Ethenes
Authors: Sheng Shou‐Ri , Huang Xian
Published: May 2015

Polymer‐supported α‐selenoaldehydes easily obtained by reaction of polymer‐supported 4‐(phenylseleno)morpholine with aldehydes react with Grignard reagents to form polymer‐supported β‐hydroxyalkyl selenides, which were treated with thionyl chloride/triethylamine leading to (E)‐1,2‐disubstituted ethenes in good yields.
Preparation of Some Novel, Highly Unstable Chain Conjugated 2H‐Pyran‐5‐carboxylates
Authors: Moorhoff Cornelis M.
Published: May 2015

Aldol condensations of conjugated unsaturated β‐ketoesters and unsaturated aldehydes gave chain conjugated 2H‐pyran‐5‐carboxylates.
Intramolecular [2+2] Photocycloaddition‐Fragmentation: Facile Entry to a Novel Tricyclic 5‐6‐7 Ring System
Authors: Hong Bor‐Cherng , Chen Shang‐Hung , Kumar Ellappan Sampath , Lee Gene‐Hsiang , Lin Kuan‐Jiuh
Published: May 2015

An expeditious route to a novel 5‐6‐7 tricyclic ring system is described. The chemistry capitalizes on an enantioselective glyoxylate‐ene reaction, enzymatic resolution as well as a [2+2] photocycloaddition‐fragmentation.
Insertion Reactions of Carbon Disulfide into Mg‐C and Mg‐N Bonds: Syntheses and Structural Determinations of Mg(S2CY)2(THF)n(Y=NEt2, NiPr2, iPr, Ph) and BrMg(S2CZ)(THF)3(Z=Ph, iPr)
Authors: Chang Chung‐Cheng , Yang Kuo‐Ching , Guo Jeng‐Gong , Huang Leigh‐May , Wang Li‐Chyung , Lee Gene‐Hsiang , Peng Shie‐Ming
Published: May 2015

The insertion reaction of CS2 with Mg(NR2)2 (R= Et, iPr), MgR′2 (R′= Et, Ph) and R″MgBr (R″= iPr, Ph) respectively lead solid products, Mg(S2CNR2)2(THF)n (1: R= Et, n=2; 2: R= iPr, n=1), Mg(S2C′R)2(THF)2 (3: ′R= Et, 4: ′R= Ph), BrMg(S2C″R) (THF)3 (5: ″R= iPr, 6: ″R= Ph) in which the inserted carbon disulfides act as terminal chelating ligands. These compounds were characterized with 1H, 13C NMR, IR spectroscopy, mass spectrometry, elemental analyses, and X‐ray crystallography.
Corrosion Behavior of Carbon Steel in Lithium Bromide Solution
Authors: Huang Nai‐Bao , Liang Cheng‐Hao
Published: May 2015

Weight‐loss tests and electrochemical techniques are used to study the inhibition of BTA and Na2MoO4 either individually or in different combinations for carbon steel in boiling 10.24 mol/L LiBr solution containing 0.07 mol/L LiOH. The result indicates the corrosion of carbon steel is effectively inhibited when BTA or Na2MoO4 is added to the solution individually. The adsorptions of BTA or Na2MoO4 on carbon steel surfaces can be well fitted to a Langmuir adsorption isotherm. The free energy of adsorption of BTA and Na2MoO4 are −45.07 kJ/mol and −40.69 kJ/mol, respectively. The corrosion rate is decreased to the minimal value, which is 8.39 μm/y, when 7.28 × 10−4 mol/L Na2MoO4 and 8.39 × 10−4 mol/L BTA are added to a 10.24 mol/L LiBr solution containing 0.07 mol/L LiOH. The inhibition mechanism of the above mixed inhibitors results from the complemental effect of the compact inner layer film composed of Fe‐BTA and the absorbed MoO42− in small quantity of the active site and the outer layer. The passive film of the coordination compound and the adsorbed MoO42− prevent Br− from absorbing and effectively decrease the corrosion of carbon steel.
Synthesis of Lithiophorite in High Alkaline Conditions
Authors: Yang Deng‐Shiu , Wang Ming‐Kuang , Chang Chia‐Ming , Sheu Hwo‐Shuenn , Hwang Bing‐Joe
Published: May 2015

Lithiophorite consists of alternatively stacked MnO6 octahedral sheets and LiAl2(OH)6 octahedral sheets. Its applications in laboratories and industries have been hindered by sophisticated operation procedures, long reaction time, or impurities existing in the final product. We proposed a fast and simple method, mixing birnessite, aluminate and lithium hydroxide together (designated it as the BAL method) in high alkaline conditions (pH > 13), and treating it hydrothermally at 423 K for 6 hours to prepare pure lithiophorite. A specific reaction between lithium cations and aluminate anions plays as a key role in the BAL method. Due to this specific reaction, LixAln(OH)m+z complexed cations can form and penetrate into interlayers of birnessite to replace sodium cations. In high alkaline conditions (pH > 12), LixAln(OH)m+z complexed cations become smaller and are soluble. Thus, the higher alkaline LixAln(OH)m+z complexed cations can penetrate into interlayers of birnessite at a higher rate. Furthermore, impurities, such as lithium intercalated gibbsite (LIG), aluminum oxyhydroxides and aluminum hydroxides are not stable in high alkaline conditions. Consequently, pure lithiophorite can be easily obtained within 6 hours in high alkaline conditions.
Benzolignanoid and Polyphenols from Origanum Vulgare
Authors: Lin Yun‐Lian , Wang Chuen‐Neu , Shiao Young‐Ji , Liu Tzu‐Ying , Wang Wan‐Yi
Published: May 2015

A new dihydrobenzodioxane derivative, origalignanol (10), together with nine polyphenolic compounds, salvianolic acid A (1), salvianolic acid C (2), lithospermic acid (3), apigenin 7‐O‐β‐D‐glucuronide (4), apigenin 7‐O‐β‐D‐(6″‐methyl)glucuronide (5), luteolin, (6), luteolin 7‐O‐β‐D‐glucopyranoside (7), luteolin 7‐O‐β‐D‐glucuronide (8), and luteolin 7‐O‐β‐D‐xylopyranoside (9), were isolated from the aqueous ethanolic extract of the aerial parts of Origanum vulgare for the first time. The structure of new compound 10 was determined on the basis of spectroscopic methods. Compound 5 is probably an artifact formed during the isolation. Compounds 1, 2 and 3 showed strong DPPH radical scavenging activity with an EC50 of 7.2 ± 0.4, 9.6 ± 0.9, and 9.5 ± 0.7 μM, respectively, and protected rat hepatocytes from CCl4‐damage at 100 μM.
Stereoselectivity in Diphos Addition to Molybdenum Complex with Pyridine‐2‐thionate (pyS) and η3‐Methallyl Coordinated Ligands
Authors: Yih Kuang‐Hway
Published: May 2015

The conformational isomers endo‐ and exo‐[Mo{η3‐C3H4(CH3)}(η2‐pyS)(CO)(η2‐diphos)] (diphos: dppm = {bis(diphenylphosphino)methane}, 2; dppe = {1,2‐bis(diphenylphosphino)ethane}, 3) are prepared by reacting the double‐bridged pyridine‐2‐thionate (pyS) complex [Mo{η3‐C3H4(CH3)}(CO)2]2(η1:η2:μ‐pyS)2, 1 with diphos in refluxing acetonitrile. Stereoselectivity of the methallyl, C3H4(CH3), ligand improves the formation of the exo‐conformation of 2 and 3. Orientations and spectroscopy of these complexes are discussed.
Rapid Preparation and Easy Quality Control Procedures for 99mTc‐Tin‐Nano Colloid: A Lymphoscintigraphic Agent
Authors: Rashid Haroon , Shah Syed Qaiser
Published: May 2015

99mTc‐Tin‐nano colloid is a radiopharmaceutical that can be useful in evaluation of the patients with breast cancer. The current method for preparation requires a lengthy boiling water bath procedure, and the recommended quality control procedure is cumbersome and time consuming. Using a microwave oven, the heating time necessary to provide a maximum labeling efficiency has been reduced to 10 second. A new mini paper chromatography (MPC) system has been developed to analyze the radiochemical purity (RCP) of the labeled preparation involving two different developing solvents. The recommended thin layer chromatography (TLC) system involving the use of an Al2O3 coated plate requires an average time for drying and development of 34.5 ± 0.44 min (n = 30) to complete, whereas the new MPC system has an average developing time of 2.1 ± 0.2 min (n = 20). For RCP values the MPC and TLC methods are correlated closely (r = 0.94). The combined use of the microwave oven heating method and over quick quality control system will facilitate the rapid emergency use of 99mTc‐Tin‐nano colloid.
Study on the Impedance Characteristic and Electrocatalytic Activity of Platinum‐Modified Polyaniline Film
Authors: Niu Lin , Li Qiuhong , Chen Xiao , Wei Fenghua , Wang Hao , Zhang Hu
Published: May 2015

The composite electrode of platinum‐modified polyaniline film is formed in 0.5 M H2SO4 + 3 mM H2PtCl6 solution by cyclic potential or constant potential deposition of platinum particles in polyaniline film. To make a comparison, the polyaniline film with the same initial thickness and structure is also treated with the cyclic potential or constant potential polarization in 0.5 M H2SO4 solution. The electrochemical impedance spectroscopy (EIS) of the composite electrode of platinum‐modified polyaniline film is studied in sulfuric acid solution and compared with the EIS of the polyaniline film without platinum dispersion. The results show that the different modes of potential polarization affect greatly the nature and distribution of the platinum particles, instead of the structure of the polyaniline film (matrix). The electrode reaction kinetics and mass transport process parameters involving charge transfer resistance (Rct), double layer capacitance (Cdl), constant phase elements (CPE) and Warburg impedance in platinum substrate/platinum‐modified polyaniline film/solution interface are discussed on the basis of the interpretation of the characteristic impedance spectra and connected to the electrocatalytic activity on the oxidation of methanol molecules.
Juncenolide E, A New Briarane from Taiwanese Gorgonian Junceella Juncea
Authors: Shen Ya‐Ching , Lin Yu‐Chi , Huang Yeh‐Li
Published: May 2015

In addition to junceellolides B (3) and C (4), a new briarane, juncenolide E (1) has been isolated from the acetone extract of the red gorgonian Junceella juncea, collected on the southern coast of Taiwan. The structure of juncenolide E was determined by interpretation of MS, COSY, HMQC, HMBC and NOESY spectra.
Kinetic Determination of GA by the BZ Oscillating Chemical System
Authors: Dong Yanjie , Gai Ke , Gong Xinxing
Published: May 2015

A new analytic method for the determination of gibberellic acid (GA) by perturbation causing different amounts of GA on the BZ oscillating chemical system involving the Mn(II)‐catalyzed reaction between L‐alanine, potassium bromate, and malonic acid in the acidic medium is proposed. The method relies on the linear relationship between the change in the oscillating period of the chemical system and the concentration of GA, which is in this work exposed for the first time. The calibration curve is linearly proportional to the concentration of GA over the range 1.0 × 108 −1.0 × 10−6M, where the regression coefficient is 0.9998, and the detection limit is 5.0 × 10−9 M of GA. Some aspects of the potential mechanism of action of GA on the BZ oscillating chemical system are discussed in detail.
A Novel Macrocyclic Nickel(II) and Ferricyanide 1D Zigzag Chain: Synthesis, Crystal Structure, and Magnetic Properties
Authors: Zhao Qihua , Wang Qinghua , Fang Ruibin
Published: May 2015

A novel cyan‐bridged macrocyclic nickel complex [{NiL1}{Fe(bipy)(CN)4}]2·5H2O 1 (L1 = 3,10‐dimethyl‐1,3,6,8,10,12‐hexaazacyclotetradecane, bipy = 2,2‐bipyridine) was synthesized and structurally characterized. The complex exhibits one‐dimensional zigzag chain structures. Each ferrous(II) ion connects two nickel(II) ions using two trans CN− groups, and the remaining CN− groups are terminal. Magnetic measurement shows weak ferromagnetic interaction between the nearest Ni(II) ions through the diamagnetic Fe(II) ion.
Simultaneous Determination of Tin, Nickel, Lead, Cadmium and Mercury in Tobacco and Tobacco Additives by Microwave Digestion and RP‐HPLC Followed by On‐Line Column Enrichment
Authors: Chen Zhangyu , Yang Guang‐Yu , Wang Shuhua , Li Ling , Su Qingde
Published: May 2015

A new method for the simultaneous determination of five heavy metal ions, tin, nickel, lead, cadmium and mercury ions as metal‐tetra‐(2‐aminophenyl)‐porphyrin (T2APP) chelates was developed using reversed‐phase high performance liquid chromatography (RP‐HPLC) equipped with a photodiode array detector and combined with an on‐line enrichment technique. The tin, nickel, lead, cadmium and mercury ions were pre‐column derivatized with T2APP to form color chelates. The Sn‐T2APP, Ni‐T2APP, Hg‐T2APP, Cd‐T2‐APP and Pb‐T2APP chelates can be absorbed onto the front of the enrichment column when they are injected into the injector and sent to the enrichment column [Waters Xterra™ RP18(5μ, 3.9 × 20 mm)] with a buffer solution of 0.05 mol/L pyrrolidine‐acetic acid (pH = 10.0) as mobile phase. After the enrichment had finished, by switching the six‐port switching valves, the retained chelates were back‐flushed by mobile phase and traveling towards the analytical column. These chelates separation on the analytical column [Waters Xterra™ RP18 (5μ, 3.9 × 150 mm)] was satisfactory by gradient elution with methanol (containing 0.05 mol/L pyrrolidine‐acetic acid buffer salt, pH = 10.0) and acetone (containing 0.05 mol/L pyrrolidine‐acetic acid buffer salt, pH = 10.0) as mobile phase. The linearity range is 0.01˜120 μg/L for each metal ion. The detection limits (S/N = 3) of tin, nickel, lead, cadmium and mercury are 4.0 ng/L, 3.5 ng/L, 2.5 ng/L, 3.0 ng/L and 3.0 ng/L, respectively. This method was applied to the determination of tin, nickel, lead, cadmium and mercury ions in tobacco and tobacco additives with good results.
A Spectrophotometric Investigation of the Interaction of Iodine with Dibenzyldiaza‐18‐crown‐6, Aza‐15‐crown‐5 and N‐phenylaza‐15‐crown‐5 in Chloroform Solution
Authors: Shamsipur Mojtaba , Pouretedal Hamid Reza
Published: May 2015

The complex formation reactions between iodine and DBzDA18C6, A15C5 and N‐phenylA15C5 have been studied spectrophotometrically in chloroform solution. In the case of DBzDA18C6 is the resulting 1:2 (ligand…I+)I3−, while, in the case of A15C5 and N‐phenylA15C5 a 2:2 molecular complex of [(ligand)2…I+]I3− type was formed. The spectrophotometric results indicate that gradual release of triiodide ion from its contact ion paired form in the molecular complex into the solution is the rate‐determining step of the reaction. The kinetic rate constants for the complexation reactions were determined at different temperatures, and activation parameters were calculated from Arrhenius and Eyring equations.
Friedel‐Crafts Benzylation of Arenes over Mixed Oxides
Authors: Jadhav Sujit R. , Sawant Manohar R.
Published: May 2015

The replacement of liquid acid catalyst by solid acids for the Friedel‐Crafts reaction of aromatic alkylation is a challenging task. Mixed oxide possessing spinel structures were found to catalyze the Friedel‐Craft benzylation of arenes. It was found that the reaction was very fast at 80 °C, hence the reaction was studied with respect to more substrate. The significant point was even at this temperature monobenzylation, with the para isomer predominating, was achieved. Mixed oxides were prepared by co‐precipitation method and were characterized by XRD technique.
Spectrophotometric Determination and Kinetic Studies of Condensation of Aromatic Aldehydes with 7,9‐Dioxo‐6,10‐dioxaspiro[4.5]decane
Authors: Medien H. A. A. , Zahran A. A. , Erian A. W.
Published: May 2015

The condensation reaction rates of 7,9‐dioxo‐6,10‐dioxaspiro[4.5]decane with aromatic aldehydes in chloroform in the presence of piperidine has been investigated spectrophotometrically at 25–50 °C. The reaction follows overall second order kinetics, first order in each of the reactants and zero order with respect to piperidine. The rate of condensation increases with the presence of electron withdrawing groups on the aromatic ring of the aldehyde. From the dependence of the rate constants on temperature, activation parameters have been calculated. Plot of ΔH# versus ΔS# for the reaction gave a good straight line with an isokinetic temperature of 367.55 K. Based on this reaction, determination often aromatic aldehydes in a concentration range of 2.65–69.2 μg/mL is proposed.