bluuebunny/crossref_metadata_2025 huggingface dataset:
Epoxy Type Inhibitors of Cholesterol Esterase, Acetylcholinesterase, and Butyrylcholinesterase
Authors: Lin Gialih , Kao Bing‐Hong
Published: May 2015

Epoxy type inhibitors, 3‐t‐butylphenyl 3‐1,2‐epoxybutyl ether (1), 3‐t‐butylphenyl 3‐1,2‐epoxyhexyl ether (2), and 2‐naphthyl 3‐1,2‐epoxyhexyl ether (3) are synthesized as the active site‐directed inhibitors of cholesterol esterase, acetylcholinesterase, and butyrylcholinesterase. All epoxy compounds are characterized as the time‐independent inhibitors for all three enzymes from the stopped‐time assay. Further, all epoxy compounds are characterized as the competitive inhibitors for all three enzymes from the Lineweaver‐Burk plots. The inhibition constants (Ki) of cholesterol esterase for compounds 1‐3 are 320 ± 40, 190 ± 20, 130 ± 20 μM, respectively. The Ki values of acetylcholinesterase for compounds 1‐3 are 490 ± 20, 141 ± 5, 200 ± 30 μM, respectively. Values of Ki of butyrylcholinesterase for compounds 1‐3 are 250 ± 30, 26 ± 4, 120 ± 20 μM, respectively. Compound 2 is the most potent inhibitor for butyrylcholinesterase probably because the compound mimics most the natural substrate, butyrylcholine.
Selective Monolithiation of 1,1‐Dibromoferrocene Applied to the Synthesis of New Unsymmetrical 1,1‐Disubstituted Ferrocenyl Ligands
Authors: Dong Teng‐Yuan , Ho Pei‐Hau , Chang Chung‐Kay
Published: May 2015

A novel convenient method for preparing unsymmetrical 1,1′‐disubstituted ferrocenyl ligands by using the readily accessible 1,1′‐dibromoferrocene as a precursor is described. The method is of interest for modifying the chelating ferrocenyl ligands in view of the growing influence of homogeneous catalysis in organic synthesis, manipulation of materials and production of high optical yield.
Conformational Analysis of Biphenyl Derivatives. I. A Novel Steric Constant from the Internal Rotation Rate of 2,2′‐Bis‐(N‐Substituted Carbamoylmethyl)Biphenyl by Means of Dynamic NMR
Authors: Lin Gialih , Hwang Ching‐Ing , Chouhwang Ju‐Yueh , Tsai Hou‐Jen
Published: May 2015

A novel scale of steric substituent constant EsD is defined from the correlation of the logarithms of the internal rotation rate (kr) at 393 K with Hancock (Esc) steric constant by means of dynamic NMR. In the inhibition of Pseudomona species lipase by 2,2′‐bis‐(N‐substituted carbamoylmethyl)biphenyls (1‐8), the logarithms of bimolecular rate constants are multiply correlated with both the Taft substituent constant σ* and EsD.
Molecular Distance‐Edge Vector (μ) and Chromatographic Retention Index of Alkanes
Authors: Liu Shushen , Liu Hailing , Xia Zhining , Cao Chenzhong , Li Zhiliang S.
Published: May 2015

A new method of quantitative structure‐retention relationship (QSRR) is proposed for estimating and predicting gas chromatographic retention indices of alkanes by using a novel molecular distance‐edge vector, called μ vector, containing 10 elements. The QSRR model (Ml), between the μ vector and chromatographic retention indices of 64 alkanes, was developed by using multiple linear regression (MLR) with the correlation coefficient being R = 0.9992 and the root mean square (RMS) error between the estimated and measured retention indices being RMS = 5.938. In order to explain the equation stability and prediction abilities of the M1 model, it is essential to perform a cross‐validation (CV) procedure. Satisfactory CV results have been obtained by using one external predicted sample every time with the average correlation coefficient being R = 0.9988 and average RMS = 7.128. If 21 compounds, about one third drawn from all 64 alkanes, construct an external prediction set and the 43 remaining construct an internal calibration set, the second QSRR model (M2) can be created by using calibration set data with statistics being R = 0.9993 and RMS = 5.796. The chromatographic retention indices of 21 compounds in the external testing set can be predicted by the M2 model and good prediction results are obtained with R = 0.9988 and RMS = 6.508.
Determination of Mercury and Thallium in Seawater by Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry
Authors: Liu Hung‐Wei , Jiang Shiuh‐Jen
Published: May 2015

Electrothermal vaporization inductively coupled plasma mass spectrometry (ETV‐ICP‐MS) has been applied to the determination of Hg and Tl in seawater samples. Various modifiers were tested for the best signal of these elements. After preliminary studies, 0.3% EDTA, 0.1%m/vTAC and 1% v/v HCl were added to the sample solution to work as the modifier. Since the sensitivities of Hg and Tl in various seawater matrices and aqueous standard solutions were quite different, standard addition method and isotope dilution method were used for the determination of Hg and Tl in these seawater samples. This method was applied to the determination of Hg and Tl in NASS‐4 and CASS‐3 reference seawater samples and seawater samples collected from the Kaohsiung area. Results obtained by isotope dilution method and method of standard additions agreed satisfactorily. Detection limits were in the range of 5‐15 and 0.4‐0.5 ng l−1 for Hg and Tl in seawater, respectively, with the ETV‐ICP‐MS method. The precision between sample replicates was better than 18%) for all the determinations.
Thermal Degradation Studies of Complexes of a Derivative of Phenhomazine (Dibenzo[b,f][1:5]diazocine‐6:12‐Dione (PHZD)) by Thermoanalytical Techniques
Authors: Saeed‐ur‐Rehman  , Arshad Muhammad , Ahmad Masood , Masud Khalid , Ghani Abdul , Arshad Nasima , Qureshi Ammad Hussain , Ghauri Sohail Akhtar
Published: May 2015

Some of the bis‐complexes of a derivative of phenhomazine (dibenzo[b,f][1:5]diazocine‐6:12‐dione; PHZD) with Ni(II), Cu(II), Co(II), Cd(II), Zn(II) and Hg(II) of the general formula M(PHZD)2X2 [where X = C1, Br and I], were prepared and identified. These complexes have been characterised on the basis of elemental analysis, and spectroscopic, magnetic and conductance data. The thermal mode of decomposition and thermal stability of these complexes was investigated on the basis of the respective thermal curves in a static air atmosphere. The thermoanalytical investigations indicate that these complexes undergo two‐step changes as temperature is raised, except for Cd(II) and Hg(II) complexes, with the formation of metal oxides as end product. The degradation mechanism of the complexes has also been proposed.
Synthesis and Spectral Behaviour of Some New Uninuclear Pyrimidine 2[2(4)]‐Mono(Tri)‐Methine Cyanine Dyes
Authors: Shindy H. A. , El‐Aal R. M. Abd , Koraiem A. I. M.
Published: May 2015

New unsymmetrical 2[2(4)]‐mono‐and tri (substituted tri)‐methine cyanine dyes incorporating 1,2,5,6‐tetrahydro‐4,6‐diaryl pyrimidine (pyrimidinium‐1‐yl salt)‐2‐one were prepared. Structural determination was carried out by elemental analysis, IR and 1H NMR spectral data. The spectral behaviour of all the synthesized cyanines was examined in 95% ethanol.
Synthesis of Propylene Diblock Copolymers via Metallocene and Borane Chemistry
Authors: Jiang George J , Hwu Jyh Ming , Lee Sheau Fang , Hsu Ming Tsunh
Published: May 2015

An isotactic chain end unsaturated polypropylene was prepared by the homogeneous metallocene catalyst Et(Ind)2ZrCl2 with MAO. Herein, the chain end unsaturated polypropylene proceeded the hydroboration reaction to prepare borane‐containing polypropylene. The borane‐containing polypropylene could be transformed to hydroxyl‐terminated polypropylene, PPOH. And then the polypropylene‐nylon 6 diblock copolymer, PP‐b‐NY6, was synthesized from telechelic PPOH by converting this prepolymer with toluene diisocyanate and using the resulting materials as macroactivators for anionic caprolactam polymerization. Meanwhile, this investigation used borane‐containing polypropylene and oxygen to produce free radicals at the chain end on the polypropylene. Experimental results indicate that the free radical is an effective initiator for the polymerization of methyl methacrylate to produce diblock PP‐b‐PMMA. The block copolymers are characterized by IR, NMR, and DSC analyses. The diblock copolymer is a good compatibilizer for polymer blends.
Phytochemical and Pharmacological Studies on Chinese Changzhu
Authors: Ding Hsiou‐Yu , Wu Yang‐Chang , Linc Hang‐Ching
Published: May 2015

In addition to twelve known compounds including triterpenoids, steroids, sesquiterpenoids and polyacetylenes, a new natural product, hinesolone was isolated from the rhizhome of Atractylodes chinensis (Compositae). The structure of hinesolone was elucidated on the basis of spectral evidence. Of the isolated compounds, only β‐Eudesmol showed a diuretic effect on S.D. rats.
New Meroditerpenoids from a Taiwanese Marine Sponge Strongylophora Durissima
Authors: Shen Ya‐Ching , Hung Meng‐Chieh , Prakash Chaturvedula V. S. , Wang Jeh‐Jeng
Published: May 2015

In addition to strongylophorines 1 (3), 2 (4), 3 (5) and 8 (6), two new meroditerpenoids named strongylophorines 9(1) and 11 (2) were isolated from a Taiwanese marine sponge Strongylophora durissima. The structures of the new compounds were established by spectral methods and chemical derivatizations.
Remarkably Fast Deprotection of Semicarbazones and Tosylhydrazones Under Mild, Neutral and Solvent‐Free Conditions
Authors: Bandgar Babasaheb P. , Makone Sangita S.
Published: May 2015

Rapid and selective regeneration of carbonyl compounds from their semicarbazones and tosylhydrazones was carried out using hexamethylenetetramine‐bromine (HMTAB) and N‐bromosuccinimide (NBS). Good to excellent yields, mild, neutral and solvent‐free conditions are important features of this method.
Ultrafast Reaction Dynamics in Different Environments
Authors: Flachenecker Günter , Materny Arnulf
Published: May 2015

We review recent work done on the femtosecond time‐resolved investigation of the influence of solvation on elementary molecular and reaction dynamics of solvated molecules. Using the photo dissociation reaction of I2 and NaI molecules as models, the solvation effect is studied for varying environments. By adding inert gases (He, Ar, N2) at pressures ranging from 0 to 3000 bar, the dynamics is studied starting from isolated molecules, going steadily to solvent‐like conditions. Clearly different reaction behaviour can be found when comparing I2 and NaI. While I2 molecules predissociate due to the collisions with the surrounding gas particles and afterwards recombine due to the caging effect, NaI is stabilized in its adiabatic potential well formed by the first excited electronic state and the ionic ground state. I2 is also embedded in a solid matrix, formed by a crystalline porosil. For I2 in both cases the recombination dynamics is studied by varying the probe wavelength. The experimental data are discussed using a theoretical model. For I2 in a high pressure gas environment, geminate primary and secondary recombination can be detected; in the porosils also nongeminate processes contribute on a very short time scale.
Interplay of Exciton Transfer and Relaxation
Authors: Barvík Ivan , Macek Jan
Published: May 2015

We have contrasted several methods which can be obtained from the Tokuyama‐Mori approach only by serious approximations treating exciton transfer as well as relaxation in the simplest model, namely symmetric molecular dimer. We have solved dynamical equations of motion for the density matrix p of the exciton interacting with a bath. The bath has been simulated by phonons in an infinite linear chain. An exciton‐phonon interaction has been taken as the local, linear and weak one. The exciton transfer runs in microscopic “SLE like” models without (mSLE) and with (mSLEr) relaxation slower and, on the other hand, in the Redfield (RE) model with the secular approximation quicker than in the Tokuyama‐Mori (TM) model. Relaxation between extended states + and ‐ is for models mSLEr and RE quicker than in the TM model.
Vibrational Motion of Electron Donor‐Acceptor Complexes Time‐Resolved by Femtosecond Fluorescence Spectroscopy
Authors: Rubtsov Igor V. , Yoshihara Keitaro
Published: May 2015

The excited‐state dynamics of several electron donor‐acceptor complexes were studied by a femtosecond fluorescence up‐conversion technique. The spontaneous fluorescence decay of the complexes contains an oscillatory component superimposed with an ultrafast decay component. The oscillatory component was assigned to the out‐of‐plane vibration of the acceptors (tetracyanoethylene (TCNE), chloranil, fluoranil) having b3u symmetry. The time‐dependent fluorescence spectrum for the TCNE ‐ hexamethylbenzene (HMB) complex was reconstructed from the fluorescence dynamics at different wavelengths and the fluorescence peak‐shift correlation function was obtained. The ultrafast relaxation of the fluorescence peak position is superimposed with the oscillatory component. The main component of the spectral relaxation of 115 fs is attributed mainly to the intramolecular vibrational energy redistribution process in both donor and acceptor parts of the complex. The oscillatory behavior of the fluorescence peak position demonstrates the modulation of the transition frequency during the vibrations. The time dependence of the mean transition moment was constructed. It oscillates with the same frequency (155 cm−1), which is an indication of the non‐Condon transition. Thus, two mechanisms are observed to be responsible for the oscillations: the modulation of the transition frequency and the modulation of the mean transition moment by the vibrational motion.
Ultrafast Anisotropy Measurements on Charge Transfer Dynamics in Plastocyanin
Authors: Nakashima Satoru , Seike Kazushige , Nagasawa Yutaka , Okada Tadashi , Sato Maki , Kohzuma Takamitsu
Published: May 2015

Using a blue copper protein, plastocyanin, we have studied protein dynamics associated with optical excitation of the charge‐transfer band of plastocyanin by ultrafast pump‐probe measurements. In this study we show the first clear evidence of a coherency of the protein motion that is induced by the charge‐transfer reaction. The formerly observed low‐frequency vibrational mode (33 cm−1) is attributed to the coherent motion of the protein by the anisotropy measurement. In this charge‐transfer reaction, not only stochastic process, but coherent motion of protein is revealed to play a key role in the reaction.
Solvent Dependent Ultrafast Ground State Recovery Dynamics of Triphenylmethane Dyes
Authors: Nagasawa Yutaka , Ando Yoshito , Okada Tadashi
Published: May 2015

We have studied ground state recovery dynamics of triphenylmethane dyes, brilliant green and malachite green, by a single wavelength pump‐probe spectroscopy at 635 nm with a time‐resolution of 33 fs. The recovery of the ground state dependeded on solvent viscosity and also on solute molecular size. We observed a plateau or a rise component in the signal which indicates an intermediate state. The rise time also showed solvent viscosity dependence even in the ultrafast time domain, although no solute dependence was observed. It is suggested that the lack of solute dependece indicates that only small conformational change is involved in the initial process.
Ultrafast Fragmentation and Vibrational Dynamics of Triatomic Hetero‐ and Homonuclear Alkali Metal Clusters
Authors: Rosendo‐Francisco Porfirio , Lupulescu Cosmin , Baptist Bernd , Vajda ŠTefan
Published: May 2015

The one‐color femtosecond pump and probe spectroscopical technique was employed to study the fragmentation kinetics and vibration dynamics of the dissociative excited states of alkali trimer clusters K2Na, K3 and Na2K located in the spectral region between 730 and 840 nm. The electronically excited states were populated by a pump pulse via one‐photon absorption. The temporal evolution of the excited state was then monitored by ionizing the particle at a variable delay with a two photon transition. The lifetimes of the predissociated excited states strongly depend on the excitation wavelengths: 2.8‐5.1 ps for K2Na, 7.5‐9.8 ps for K3, and 2.5‐5.8 ps for Na2K. Furthermore, the dominant fragmentation channels were identified as well. In the case of the Na2K trimer a clear wavepacket dynamics with an oscillation period of about 490 fs was observed at an excitation wavelength of 770 nm. In the case of the K3 and K2Na trimers, no pronounced oscillatory ion signal indicative of a vibrational dynamics was observed at the applied wavelength region.
Formation of Bacteriochlorophyll Anion Band at 1020 nm Produced by Nuclear Wavepacket Motion in Bacterial Reaction Centers
Authors: Yakovlev A. G. , Shuvalov V. A.
Published: May 2015

Formation of a nuclear wavepacket on the potential energy surface of the primary electron donor P* induced by 30‐fs excitation of pheophytin‐modified Rhodobacter sphaeroides R‐26 reaction centers leads to a reversible and irreversible appearance of the state P+BA− monitored by the measurements of the 1020‐nm band which is characteristic of the radical anion band of bacteriochlorophyll monomer BA−. The reversible appearance of the state P+BA− is characterized by two (130 and 320 cm−1) vibration modes and related to the creation of maximal value of the Franck‐Condon factor when the wavepacket is near an intersection of the P* and P+BA− potential energy surfaces. The irreversible formation of the state P+BA− with a time constant of 3 ps is accompanied by oscillations with frequencies of 9 and 33 cm−1. These results show that the nuclear vibration modes (9 and 3 3 cm−1) on the P* potential energy surface have near their bottom the intersection with the P+BA− surface as well. The electron transfer time between P* and BA was estimated to be in the range of 700 fs. This is larger than the wavepacket intersection time for the 130 cm−1 mode (∼100 fs) and comparable with that for the 33 cm−1 mode (∼600 fs). Therefore the reversible electron transfer with small amplitude can be observed for the 130 cm−1 mode, while the irreversible one is allowed for the 33 cm−1 mode that is probably important for the primary charge separation.
Models of Ultrafast Energy and Electron Transfers in Bacterial Reaction Centers
Authors: Hayashi Michitoshi , Yang Tzyy‐Schiuan , Liang Kuo‐Kan , Chang Chung‐Hung , Lin Sheng Hsien
Published: May 2015

In this paper, we present a microscopic model to describe the spectroscopy and dynamics for photosynthetic bacterial reaction centers (RCs). In this model, we propose eight vibrational modes and their Huang‐Rhys factors for different electronic energy states, and the couplings between the electronic states. As applications, we have constructed steady state and ultrafast time‐resolved spectra for the mutant RC of Rhodobacter (Rb.)sphaeroides R26. Our model can also treat the temperature effect on the spectroscopy and dynamics of RCs.
Homogeneous Line‐Width of Optical Transitions and Multiple Electron‐LO‐Phonon Scattering in Quantum Dots
Authors: Král Karel , Khás Zdenk , Lin Chung‐Yi , Lin Sheng‐Hsien
Published: May 2015

The optical line‐shape of electronic transitions due to the polar electron‐LO‐phonon interaction in semiconductor quantum dots is studied. The mechanism of the finite optical line‐width is based on the multiple electron‐LO‐phonon scattering. The influence of the higher order corrections beyond the self‐consistent Hartree‐Fock approximation to the electron‐phonon part of the electronic self‐energy is estimated quantitatively. The problem is studied within the two‐level model of a single electron interacting with the system of longitudinal optical phonons of the whole bulk sample of the polar semiconductor. The influence of the higher order corrections is demonstrated on the line‐shape of the optical transitions, the temperature dependence of the line‐width and on the dependence of the line‐width on the size of the quantum dot.
Excited State Coherent Vibrational Motion in Deoxymyoglobin
Authors: Lambry Jean‐Christophe , Vos Marten H. , Martin Jean‐Louis
Published: May 2015

Femtosecond coherence spectroscopy of deoxymyoglobin has been performed under excitation in the lowest electronic transition (Q band) and probing in the Soret band. Under these excitation conditions, ground state low‐frequency vibrational motions are strongly suppressed with respect to Soret excitation. Evidence is presented for a contribution of excited state vibrational dynamics to the coherent response.
Ultrafast Non‐Adiabatic Curve Crossing and Energy Transfer in the IBr B0+·Ar van der Waals Complex
Authors: Hussain Ahmed N. , Roberts Gareth
Published: May 2015

Photodissociation of the T‐shaped IBr B0+·Ar complex initiated by an ultrafast laser pulse is investigated theoretically by integrating the time‐dependent Schrödinger equation for wavepacket motion in two dimensions. The fragmentation dynamics are explored through calculations of time‐dependent expectation values, electronic state populations and vibrational state probabilities. The focus of this study is on the competition between electronic predissociation of IBr, induced by non‐adiabatic transitions between the bound B0+ and repulsive Y0+ excited states, and vibrational predissociation of Ar from the intact diatomic, mediated by vibrational energy redistribution between intramolecular and van der Waals degrees of freedom. This is facilitated by comparative calculations in which non‐adiabatic curve crossing is either included or artificially disabled. It is found that molecular dissociation to form ground‐state I + Br at energies below the B0+ asymptotic limit takes place over time scales ranging from 200‐500 fs for vibrational levels that are strongly coupled to the Y0+ continuum, to longer than 10 ps for the most metastable levels. Sequential loss of vibrational quanta from IBr B0+ into the van der Waals mode over a 2‐10 ps time scale is significantly disturbed by dissociation of the diatomic moiety: instead of time‐ordered vibrational cooling via consecutively lower‐energy levels, a complex pattern of energy transfer evolves during the lifetime of metastable B0+ vibrational levels until the Ar atom is propelled into the van der Waals continuum. The probabilities of final IBr B0+ vibrational levels are determined, therefore, by the strength of non‐adiabatic transfer to the molecular dissociative continuum in addition to the dynamical coupling of intramolecular and van der Waals modes.
Temporal Contrast of High Intensity Femtosecond UV Pulses
Authors: Osvay Károly , Csatári Márta , Gaál Attila , Ross Ian N.
Published: May 2015

Estimates of temporal pulse contrast ratio to high values can be obtained from significantly lower dynamic range measurements of the pulse spectrum. The effect of non‐compensated third‐order dispersion of a laser system on the pulse contrast is also calculated.
Morphology‐Dependent Resonances in a Dielectric Microsphere and Femtosecond Laser Pulses
Authors: Sbanski O. , Roman V. E. , Kiefer W. , Popp J.
Published: May 2015

Mie‐scattering on microspheres is investigated experimentally and theoretically on a femtosecond timescale. Although the pulse duration is smaller than the particle circumference, morphology‐dependent resonances are excited, leading to a distinct pulse shaping and elongation of the scattered light.
Solvent Extraction Separation of Gold with Cyanex 302 as Extractant
Authors: Sarkar Sunil G. , Dhadke Puroshattam M.
Published: May 2015

A method has been developed for the extraction of gold(III) from hydrochloric solution with Cyanex 302 dissolved in toluene. The extraction was quantitative from 0.005‐8.0 M HCl with 7.5 × 10−4 M Cyanex 302 and an equilibrium period of 3.0 min. Gold(III) from the non‐aqueous phase was stripped with 0.1 MNa2S2O3 and determined spectrophotometrically at 400 nm using stannous chloride method. The method is useful for separation of Au(III) from Cu(II), Ni(II), Pd(II), Pt(IV)and Fe(III) and was extended for the determination of Au(III) in Ayurvedic drug samples.

The method is reproducible with a relative standard deviation of ± 1.0%.
Total Energy Calculations for Silane Dissociative Chemisorption onto Si(100) and Si(111) Surfaces
Authors: Lm Jyh‐Shing , Kuo Yu‐Tzu , Chen Ji‐Cheng , Lee Ming‐Hsien
Published: May 2015

Total energy calculations based on density functional theory in connection with generalized gradient approximation (GGA) and norm‐conserving optimized pseudopotential approximation have been used to investigate the silane chemisorption onto Si(111) and Si(100) surfaces. Firstly, the calculated relaxed surface structure of Si(100)‐(2×2) has a different dangling bonds environment from that of the calculated relaxed surface structure of Si(111)‐(1×1). Secondly, our calculated results indicate that SiH4 chemisorption onto both Si(100)‐(2×2) and Si(111)‐(1×1) surfaces are energetically favorable and they lead to the formation of SiH3 and H adsorbed on the Si=Si dimer, i.e. Si(100)‐(2×2)(SiH3:H) and the surface dihydride SiH2 and 2H, i.e. Si(111)‐(1×1)(SiH2:2H), respectively. Finally, the increase of dangling bond density and the absence of adatom backbond breaking are probably two of the key factors controlling the distinct increase in reaction probability for dissociative chemisorption of SiH4 onto Si(111)‐(7×7) due to Si(111)‐(7×7) ↔ Si(111)‐(1×1) phase transition at surface temperature greater than 800°C.
Reactions of TiCl4 or Ti(O‐i‐Pr)Cl3 with 2,4‐Pentanedione. The Molecular Structures of TiCI3(acac)(THF) and Ti(O‐i‐Pr)CI2(acac)(THF)
Authors: Shao Ming‐Yuan , Ho Yuh‐Chou , Gau Han‐Mou
Published: May 2015

A series of titanium(IV) acetylacetonate (acac) complexes, Ti(acac)Cl3 (THF) (2), [Ti(acac)Cl2(THF)]2 (μ‐O) (3), [Ti(O‐i‐Pr)Cl3(acac)]‐(HNEt3+) (5), and Ti(O‐i‐Pr)Cl2 (acac)(THF) (6), were prepared from reactions of TiCl4 or Ti(O‐i‐Pr)Cl3 with 2,4‐pentanedione (Hacac) in CH2Cl2 or THF with or without the presence of NEt3. The x‐ray structural analyses were carried out on complexes 2 and 6. Complex 2 crystallizes in the monoclinic P21/n space group with a = 8.664(1) Å, b = 11.859(1) Å, c = 14.320(1) Å, β = 103.94(1)°, R = 0.0571, Rw = 0.0620, and G of = 1.10. Complex 6 crystallizes also in the monoclinic P21/n space group with a = 9.074(2) Å, b = 11.499(2) Å, c = 16.549(4) Å, β = 101.96(2)°, R = 0.0492, Rw = 0.0671, and Gof= 1.49. Based on the solid state structures of complexes 2 and 6, the relative bonding order of −O‐i‐Pr > Cl− > acac− THF is established.
Electron Impact Mass Spectra of 3‐Aryl‐3‐hydroxyl‐2,2,4,4‐tetramethylcyclobutanones and Related Compounds
Authors: Lin Shaw‐Tao , Lin Wen‐Chung , Chao Richard Yung‐Ho , Huang Ching‐Liang
Published: May 2015

The mass spectra of 3‐aryl‐3‐hydroxyl‐2,2,4,4‐tetramethylcyclobutanones and their related compounds were studied. The arylcyclobutanones and their ketal forms demonstrate similar fragmentation patterns but with different observed common peaks, i.e., [M‐70]+ and 114 amu, as the base peaks for compounds arylcyclobutanones and their ketal forms, respectively. 1‐Aryl‐2,2,4‐trimethyl‐1,3‐pentadiones, obtained from hydrolysis of cyclobutanones, gave either 43 amu or [Ar‐CO]+ as the peaks, depending on the substituents on the benzene ring. These compounds are good examples of how the relative ionization potentials of the possible fragments govern the observed mass spectra.
Heterocyclic Fused Rings with Bridgehead Nitrogen Atoms: Synthesis of [1,2,4]triazolo[1′,5′:4,3][1,4]oxazepino[5,6‐b]pyrazole Derivatives
Authors: Sayed Samia M.
Published: May 2015

Novel [1,2,4]triazolo[1′,5′:4,3][1,4]oxazepino[5,6‐b]pyrazole derivatives have been synthesized using pyrazolo‐4‐carboxylic acid 1 as starting material is reported.
Behaviour of Some Activated Nitriles Toward Barbituric, Thiobarbituric Acids and 3‐Methyl‐1‐Phenylpyrazol‐5‐One
Authors: Madkour H. M. F. , Mahmoud M. R. , Nassar M. H. , Habashy M. M.
Published: May 2015

The effect of some active methylene containing heterocyclic compounds, namely barbituric, thiobarbituric acids and 3‐mehtyl‐1‐phenylpyrazol‐5‐one on α‐cyano‐3,4,5‐trimethoxycinnamonitrile and ethyl α‐cyano‐3,4,5‐trimethoxycinnamate 1a,b was investigated. The structure of the new products was substantiated from their IR, 1H NMR and mass spectra.
Novel One‐Pot Synthesis of Pyrazolo[3,4‐b][1,4]oxazines
Authors: Raslan M. A. , El‐Latif F. M. Abd , Otto H. H. , Sadek K. U.
Published: May 2015

A simple route for the synthesis of pyrazolo[3,4‐b][1,4]oxazines by the reaction of pyrazole‐4‐oxime derivatives 1 with active methylene reagents has been reported.
Evaluation of the Concentration and Enantiomeric Purity of Selected Free Amino Acids in Chinese Fermented Soy Beans
Authors: Chen Shushi
Published: May 2015

The total concentration and enantiomeric composition of two selected amino acids (leucine, phenylalanine) in eight different Chinese fermented soy beans were determined after their derivatization with N‐benzoyl chloride using HPLC system coupled with UV detector. In comparison, fermented soy beans tended to be relatively higher in both the total concentration and enantiomeric composition than raw soy beans. In most samples, phenylalanine was analyzed to have a higher percentage of D‐enantiomer and lower total concentration than leucine. The level of total concentration for examined amino acids was found irrelevant to the storage conditions (e.g., stored in dry or wet form). However, samples preserved in wet form (i.e., soaked in sauce) were likely to have higher percentage of D‐enantiomers (D‐phenylalanine, D‐leucine). In some cases the relative amounts of D‐phenylalanine and D‐leucine exceeded 20% of the individual amino acids. No significant racemization of N‐benzoyl derivatized amino acids was detected at room temperature. However, the elevation of surrounding temperature caused an increase in the percentage of D‐enantiomers.
Flow Binding Assay Using Sequential Injection Analysis for Bioprocess Monitoring
Authors: Shu H.‐C , Lmg Y.‐C.
Published: May 2015

A sequential injection analysis system (SIA) using a small column of immobilized concanavalin A (Con A) reacting with horseradish peroxidase (HRP) as a model system was developed to demonstrate the feasibility of flow binding assay for bioprocess monitoring and control. The selection of liquid drive and immobilized supports is justified. System performance was evaluated on three assay formats: a direct binding assay, competitive binding assay, and sandwich‐binding assay. In direct binding assay, immobilized Con A mounted in the SIA system was used to determine the concentration of HRP. The competitive binding assay using a free carbohydrate, methyl‐D‐mannopyranoside to provide competitive binding situation gives more complex calibration curves and decreased precision at higher concentrations. The sandwich‐binding assay did not work well. Direct binding assay is recommended to be the best choice based on sensitivity and precision viewpoints. The total time for one assay cycle ranges from 5 ∼ 8 min, depending on the conditions. The current SIA system is fully computerized and yields rapid and reliable system performance. The potential of using SIA‐based flow binding assay on the area of bioprocess monitoring is promising.
Continuous Analysis of Urea in Blood by Immobilized Urease Using a Conductive Biosensor
Authors: Shu Hun‐Chi , Wu Ning‐Ping
Published: May 2015

Urea in blood from a patient undergoing dialysis was continuously monitored using immobilized urease reactor with a conductivity meter. A linear response of urea in the range between 5 to 50 mM with the throughput of 15 samples h−1 was obtained. Urea measured with this biosensor shows a good correlation with the chemical analysis method. A good operational stability for on‐line monitoring during dialysis and the promising storage stability of the urea reactor were found. At 4, and 25°C, no significant activity loss was detected in the urease reactor throughout the 50 weeks storage time. At 37°C, no activity decline was observed before 20 weeks. However, after 50 weeks storage, no activity in the reactor can be detected.
A New Method for the Preparation of Para‐Substituted Benzohydroxamic Acids
Authors: Dhuru Sameer P. , Salunkhe Manikrao M.
Published: May 2015

A new method for the preparation of para‐substituted benzohydroxamic acids from para‐substituted benzoic acids by using hydroxylamine hydrochloride in the presence of triphenyl phosphine and N‐bromosuccinimide under mild basic conditions is described.
Synthesis of Two Derivatives of 3,6,9‐tri(carboxymethyl)‐3,6,9‐triazaundecanedioic Acid and the Stabilities of Their Complexes with Ca2+, Cu2+, Zn2+, Dy3+ and Gd3+
Authors: Wang Yun‐Ming , Cheng Tsann‐Hwang , Liu Gin‐Chung
Published: May 2015

Two N‐2‐hydroxy‐1‐phenylethyl and N‐2‐hydroxy‐2‐phenylethyl derivatives of DTPA (3,6,9‐tri(carboxymethyl)‐3,6,9‐triazaundecanedioic acid), DTPA‐H1P = 3,9‐di(carboxymethyl)‐6‐2‐hydroxy‐1‐phenylethyl‐3,6,9‐triazaundecanedioic acid, and DTPA‐H2P = 3,9‐di(carboxymethyl)‐6‐2‐hydroxy‐2‐phenylethyl‐3,6,9‐triazaundecanedioic acid were synthesized. Their protonation constants were determined by Potentiometric titration in 0.10 M Me4NNO3 and by NMR pH titration at 25.0 ± 0.1°C. The formations of lanthanide(III), copper(II), zinc(II) and calcium(II) complexes were investigated quantitatively by potentiometry. The stability constant for Gd(III) complex is larger than those for Ca(II), Zn(II) and Cu(II) complexes with these two ligands. The selectivity constants and modified selectivity constants of the DTPA‐H1P and DTPA‐H2P for Gd(III) over endogenously available metal ions were calculated. Comparing pM values at physiological pH 7.4 assesses effectiveness of these two ligands in binding divalent and trivalent metal ions in biological media. The observed water proton relaxivity values of [Gd(DTPA‐H1P)]− and [Gd(DTPA‐H2P)]− became constant with respect to pH changes over the range of 4‐10. 17O NMR shifts showed that the [Dy(DTPA‐H1P)]− and [Dy(DTPA‐H2P)]− complexes at pH 6.30 had 1.91 and 2.28 inner‐sphere water molecules, respectively. Water proton spin‐lattice relaxation rates of [Gd(DTPA‐H1P)]− and [Gd(DTPA‐H2P)]− complexes were also consistent with the inner‐sphere Gd(III) coordination.
Synthesis of Novel Pyridothienopyrimidines, Pyridothienopyrimidothiazines, Pyridothienopyrimidobenzthiazoles and Triazolopyridothienopyrimidines
Authors: Bakhite Etif Y. A. , Radwan Shaban M. , El‐Dean Adel M. Kamal
Published: May 2015

The reaction of 3‐amino‐4,6‐dimethylthieno[2,3‐b]pyridine‐2‐carboxamide (1a) or its N‐aryl derivatives 1b‐d with carbon disulphide gave the pyridothienopyrimidines 2a‐d, whilst when the same reaction was carried out using N1‐arylidene‐3‐amino‐4,6‐dimethylthieno[2,3‐b]pyridine‐2‐carbohydrazides (1e‐h), pyridothienothiazine 3 was obtained. Also, refluxing of 1b‐d with acetic anhydride afforded oxazinone derivative 4. Compounds 2a and 2b‐d were also obtained by the treatment of thiazine 3 with ammonium acetate or aromatic amines, respectively. When compound 2a was allowed to react with arylidene malononitriles or ethyl α‐cyanocinnamate, novel pyrido[3″,2″:4′,5′]thieno[3′,2′:4,5]pyrimido[2,1‐b][1,3] thiazines 5a‐c were obtained. Treatment of 2b‐d with bromine in acetic acid furnished the disulphide derivatives 6a‐c. U.V. irradiation of 2b‐d resulted in the formation of pyrido[3″,2″:4′,5′]thieno[3′,2′:4,5]pyrimido[2,1‐b]benzthiazoles 7a‐c. The reaction of 2a‐d with some halocarbonyl compounds afforded the corresponding S‐substituted thiopyrido thienopyrimidines 8a‐j. Compound 8b was readily cyclized into the corresponding thiazolo[3″,2″‐a]‐pyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidine 9 upon treatment with conc. sulphuric acid. Heating of 2a,b with hydrazine hydrate in pyridine afforded the hydrazino derivatives 11a,b. Reaction of ester 8c with hydrazine hydrate in ethanol gave acethydrazide 10. Compounds 10 and 11a,b were used as versatile synthons for other new pyridothienopyrimidines 12–15 as well as [1,2,4] triazolopyridothienopyrimidines 16–19.
Heterocyclic Systems Containing Bridged Nitrogen Atom: Synthesis and Antibacterial Activity of 3‐(2‐Phenylquinolin‐4‐yl)/3‐(1‐p‐Chlorophenyl‐5‐methyl‐1,2,3‐triazol‐4‐yl)‐s‐triazolo[3,4‐b]‐1,3,4‐thiadiazine Derivatives
Authors: Hui Xin‐Ping , Dong Heng‐Shan , Xu Peng‐Fei , Zhang Zi‐Yi , Wang Qin , Gong Yan‐Ni
Published: May 2015

The condensation of 4‐amino‐5‐mercapto‐3‐(2‐phenylquinolin‐4‐yl)/3‐(1‐p‐chlorophenyl‐5‐methyl‐1,2,3‐triazol‐4‐yl)‐1,2,4‐triazoles 1a‐b with chloroacetaldehyde 2a‐b, ω‐bromo‐ω‐(1H‐1,2,4‐triazol‐1‐yl)acetophenone 3a‐b, chloranil 4a‐b, 2‐bromocyclohexanone 5a‐b, 2,4′‐dibromoacetophenone 6a‐b and 2‐bromo‐6′‐methoxy‐2′‐acetonaphthone 7a‐b are described. The structures of the compounds synthesized were confirmed by elemental analyses, IR, 1H NMR and mass spectra. The antibacterial activities were also evaluated.
Ene Reaction with Pummerer‐type Reaction Intermediate of α‐(Methylthio)‐N‐methoxy‐N‐methyl Acetamide: A New Synthesis of N‐methoxy‐N‐methyl‐(E,E)‐2,4‐dienamides
Authors: Lin Mei‐Ling , Wang Huey‐Min , Kang Iou‐Jiun , Chen Ling‐Ching
Published: May 2015

Pummerer‐type reaction intermediate 2 of α‐(methylthio)‐N‐methoxy‐N‐methyl acetamide (1) has been found to react with 1‐alkenes to afford ene adducts 3. N‐Methoxy‐N‐methyl‐(E,E)‐2,4‐dienamides were synthesized from the adducts 3b‐f.
Taxane Diterpenoids from the Root Bark of Taiwanese Yew Taxus Mairei
Authors: Shen Ya‐Ching , Prakash Chaturvedula V. S. , Hung Meng‐Chieh
Published: May 2015

Nineteen compounds including taxumairol R (1), taxinine M (2), taxacin (3), paclitaxel (4), 10‐deacetyltaxol A (5), 10‐deacetyl‐7‐epi‐taxol (6), 7‐epi‐taxol (7), taxol C, 10‐deacetyltaxol C, 7β‐xylosyl‐10‐deacetyltaxol (8), taxamairin A (9), taxinine A, 14β‐hydroxytaxusin (10), 5α‐hydroxy‐7β,9α,10β, 13α‐tetraacetoxy‐4(20), 11‐taxadiene, 1‐dehydroxybaccatin‐VI, 1β‐dehydroxybaccatin‐IV, baccatin IV, baccatin VI and ponasterone A have been isolated and identified from the root bark of Taxus mairei. Among them, compound 1 was a new taxoid and compounds 11 and 7β‐xylosyl‐10‐deacetyltaxol pentaacetate were new derivatives prepared from 14β‐hydroxytaxusin (10) and 8, respectively. Their structures and assignment were established on the basis of 2D‐NMR analysis and chemical methods.
Mechanism of Butane Transformation
Authors: Ishaq Mohammad , Khan Mohammad Arsala , Yashima Tatsuki
Published: May 2015

Catalytic activity and aromatic selectivity of n‐butane transformation were studied over various MFI type zeolites. From the data obtained, a reaction mechanism is suggested for different catalyst systems. It is visualized that in gallium doped catalysts, Ga3+ directly takes part both in cracking and dehydrogenation. The [Ga CH3]2+ and [GaH]2+ species formed during cracking and dehydrogenation require protonic sites for regeneration of Ga3+ species. An alternative mechanism was suggested for dehydrogenation and cracking by Ga3+ without the involvement of protonic sites. However a protonic site would be required for aromatization. In case of gallosilicates a one step mechanism is suggested for cracking and dehydrogenation reaction which does not require the presence of protonic sites in the catalyst system.
Determination of Estrogenic Nonylphenol and Bisphenol a in River Water by Solid‐Phase Extraction and Gas Chromatography‐Mass Spectrometry
Authors: Ding Wang‐Hsien , Wu Chien‐Yi
Published: May 2015

A simple and sensitive method is presented for the analysis of nonylphenol (NP) and bisphenol A (BPA), two well known hormonally active agents (HAAs), in the samples of river water. The method involves extraction of the sample by a graphitized carbon black (GCB) solid‐phase extraction, and determination by an ion‐trap gas chromatography‐mass spectrometry (GC‐MS). The large‐volume injection technique provides high precision and sensitivity for NP and BPA, to quantitation at < 0.05 μg/L in 200 mL of water samples. Recovery of NP and BPA in spiked water samples ranged from 80% to 85%. Relative standard deviations (RSD) of replicate analyses ranged from 1.6% to 6.9%. The concentrations of NP in rivers were in the range between 0.4 to 2.4 μg/L, which were below the threshold concentration (10 μg/L) for vitellogenin induction in fish, but 78%) of water samples from five rivers exceeded the predicted‐no‐effect concentration (PNEC) of 0.7 μg/L as proposed recently. The concentrations of BPA ranged from < 0.05 μg/L to 3.0 μg/L, which all were below the PNEC of 64 μg/L.
Preparation and Characterization of Aluminum Alkoxides and their Application to Ring‐Opening Polymerization of ϵ‐Caprolactones
Authors: Yu Te‐Liang , Huang Ching‐Huei , Yang Liang‐Fu , Ko Bao‐Tsan , Lin Chu‐Chieh
Published: May 2015

The reaction of 2‐methoxybenzyl alcohol with one molar equiv of R2AIX in diethyl ether at 0°C gives [(2‐MeOC6H4CH2‐μ‐O)AlRX]2 (1: R = Et, X = Cl, 2: R = X = Et). In addition, 2,4‐di‐tert‐butylphenol reacts with iBu3Al affording a four‐coordinated aluminum compound [(μ‐2,4‐tBu2‐C6H4O)Al(iBu)2]2 (4). Single crystal X‐ray structure analysis of 4 shows a C2h‐symmetry with a planar Al2O2 core. Ring‐opening polymerization (ROP) of caprolactones initiated by 1, 4 and [(μ‐OCH2C6H4OMe)Al(iBu)2]2 (3) is performed and polyesters with narrow molecular weight distributions were obtained from the “living” ROP of caprolactones. 1H NMR spectroscopic studies of PCL reveal that the initiator of 1 and 3 is through the Al‐OAr function, but the initiator of 4 is through the Al‐ iBu group.
Studies of Adsorption Kinetics and Defects of Self‐Assembled Thiol Monolayers on Gold by Capacitance Plane Plot
Authors: Guo Min , Diao Peng , Tong Ruting
Published: May 2015

The capacitive property of an electrode/electrolyte interface can be described by complex capacitance. The capacitance plane plots (CPPs) of ideal polarized and kinetic controlled electrodes are derived based on the concept of complex capacitance. By using CPPs, the capacitance of electrode/electrolyte interface can be conveniently determined. In this work, CPPs obtained in ac impedance experiments are employed for the first time in studying the kinetics of adsorption process of the thiol monolayer. The coverage of octadecanethiol (ODT) monolayer on gold is examined as a function of adsorption time. The adsorption process of ODT molecules on gold exhibits two distinct phases: an initial rapid step followed by a slow one. The simple Langmuir model best explains our experimental data in the initial adsorption stage. CPPs and cyclic voltammetry (CV) indicate that, in the initial adsorption step, the ODT monolayer contains defects whose number decreases with the increasing of adsorption time.
Synthesis, Crystal Structure and Magnetic Property of Diiron Complex [Fe(phen)3][Fe2OCl6]·2CH3CN
Authors: Yan Bing , Chen Zhi‐Da , Wang Shi‐Xi
Published: May 2015

A new diiron complex has been synthesized and characterized by X‐ray single crystal structural analysis: [FeII(phen)3][FeIII2OCl6]·2CH3CN. The complex crystallizes in the monoclinic system, space group C2/c, with lattice parameters a = 21.162(4) Å, b = 15.168(3) Å, c = 14.812(3) Å, β= 112.71 (3)°, V = 4385.8(15) Å3, Dx = 1.543 Mg/m3, Z = 4. The corresponding variable temperature susceptibility measurement shows that there exists an antiferromagnetic interaction in the complex.
Structure Identification of Aporphine Alkaloids by On‐Line Coupling of HPLC‐NMR with Loop Storage
Authors: Tseng Li‐Hong , Braumann Ulrich , Godejohann Markus , Lee Shoei‐Sheng , Albert Klaus
Published: May 2015

The potential of coupling HPLC separation methodology to on‐line high resolution nuclear magnetic resonance (NMR) spectroscopy has been demonstrated with a mixture of nine aporphine alkaloids. A loop storage procedure after separation has facilitated the identification of closely eluted peaks (α = k2/k1 = 1.01 and Δv = 0.37 min = 367 μL). These were collected off‐line and identified by a 1D 1H NMR spectrum. For this purpose an automated procedure has been implemented which includes the use of shaped pulses, multiple solvents suppression and 13C satellite suppression of acetonitrile.
Vapor‐Phase Aldolization of n‐Butyraldehyde to 2‐Ethyl‐2‐Hexenal over Solid‐Base Catalysts
Authors: Zhu Wei‐De , Ko An‐Nan
Published: May 2015

Vapor‐phase aldol condensation of n‐butyraldehyde to 2‐ethyl‐2‐hexenal was studied at 1 atm and 150∼ 300°C in a fixed‐bed, integral‐flow reactor by using NaX, KX, γ‐Al2O3 and Na/NaOH/γ‐Al2CO3 catalysts. Ion exchange of NaX zeolite with potassium acetate solution results in a decrease of crystallinity and apparent lowering of surface area, whereas the basic strength is enhanced. Treatment of γ‐Al2O3 with NaOH and Na causes a large decrease of the surface area but strong enhancement of the catalyst basicity. The catalytic activity on the basis of unit surface area is in the order Na/NaOH/γ‐Al2O3 < KXU < KXW < NaX >γ‐Al2O3, in accordance with the relative catalyst basic strength. The molar ratio of trimeric to dimeric products increases with increasing the reaction temperature and the catalyst basic strength except for Na/NaOH/γ‐Al2O3. Very high selectivity of 2‐ethyl‐2‐hexenal (>98.5%) was observed for reactions over NaX zeolite at 150°C. Based on the FT‐IR and the catalytic results, the reaction paths are proposed as follows: self‐aldol condensation of n‐butyraldehyde, followed by dehydration produces 2‐ethyl‐2‐hexenal, which then reacts with n‐butyraldehyde and successively dehydrates to 2,4‐diethyl‐2,4‐octadienal and 1,3,5‐triethylbenzene. For the reaction over NaX, the calculated Arrhenius frequency factor and activation energy are 314 mol/g·h and 32.6 kJ/mol, respectively.
Envirocats, as Novel Solid‐Supported Catalysts for Friedel‐Crafts Acylation
Authors: Bandgar Babasaheb P. , Kasture Suhas P.
Published: May 2015

The Friedel‐Crafts acylation reactions of substituted benzenes with acid chloride or anhydrides proceeded smoothly in the presence of a catalytic amount of novel solid‐supported reagents such as EPZG, EPZ10, EPIC and EPZE. These catalysts are reusable and environmentally friendly.
Efficient Synthesis of 1,2,3,4,6‐Penta‐O‐acetyl‐L‐idopyranose
Authors: Hung Shang‐Cheng , Chen Chien‐Sheng
Published: May 2015

An efficient synthesis of 1,2,3,4,6‐penta‐O‐acetyl‐L‐idopyranose 2 from 3,5‐O‐benzylidene‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose in five steps in 45% overall yield via hydroboration of enol ether, hydrolysis of L‐idofuranosyl sugar and acetolysis of 1,6‐anhydro‐β‐L‐idopyranose as key steps is described here.
Sesquiterpenes from Ligularia Fischeri
Authors: Wang Wen‐Shu , Zhu Qi‐Xiu , Gao Kun , Jia Zhong‐Jian
Published: May 2015

Phytochemical investigation of the whole plant of Ligularia fischeri afforded two new sesquiterpenes 11‐hydroxy‐eremophil 1(10)‐en‐2,9‐dione (1); and 1β,11‐dihydroxy‐eremophil‐9‐ene (2); four known compounds (‐)‐4β,7α‐aromadendranediol (3); 1β,6α‐dihydroxyeudesm‐4(15)‐ene (4); Teucdiol A (5); Teucdiol B (6). The new compound structures were elucidated by spectroscopic methods including 2D‐NMR techniques.
An Efficient Synthetic Method and Single Crystal Structure of a 2:3 Adduct of Cyclohexyl Isocyanide and Dimethyl Acetylenedicarboxylate
Authors: Cheng Fong‐Yu , Sung Kuangsen , Lee Gene‐Hsiang , Wang Yu
Published: May 2015

An efficient synthetic method and single crystal structure of a 2:3 adduct of cyclohexyl isocyanide and dimethyl acetylenedicarboxylate are described.
Macrocyclic Polyether Phase Transfer Catalysts for Free Radical Polymerization of Acrolein
Authors: Hsu Hui‐Ping , Shih Jeng‐Shong
Published: May 2015

Macrocyclic polyethers, e.g., crown ethers and cryptands, were prepared and employed as phase transfer catalysts for free radical polymerization of acrolein, a vinyl monomer, with persulfates (S2O82–) as initiators. The catalytic abilities of various macrocyclic polyethers as catalysts for the free radical polymerization of acrolein were found to be in the order: benzo‐15‐crown‐5 > dibenzo‐18‐crown‐6 > 12‐crown‐4 > 15‐crown‐5 > 18‐crown‐6 > cryptand‐22 with sodium persulfate (Na2S2O8) as initiator. Sodium persulfate proved to be a better initiator than ammonium persulfate or potassium persulfate with benzo‐15‐crown‐5 as a catalyst. Effects of solvents and temperature on the catalytic polymerization were also investigated. The polymerization rates in various solvents were in the order: dioxane > benzene > acetonitrile > acetone > dichloromethane > hexane > water. Comparison between bulk polymerization and solution polymerization was also made. Higher polymerization rate was observed at higher temperature. The molecular weights of polyacrolein and the conversion of monomer in reaction period were determined with gel permeation chromatography and ultra‐violet spectrophotometry, respectively. Concentration effects of crown ether and initiator were also investigated and discussed.