Publication Date: 1997
Synthetic Communications (00397911)27(15)pp. 2709-2719
Zn(bipy)3Cl2, Fe(bipy)Cl3, and Fe(tpp)Cl are effective catalysts for silylation of hydroxy groups with HMDS at room temperature in dry CH3CN. High selectivity is observed between primary and secondary hydroxy functional groups. This method absolutely discriminates ether functional groups containing labile hydrogen atoms.
Publication Date: 1998
Journal of Chemical Research - Part S (13645560)(5)pp. 242-243
Sulfonated manganese(in) tetraphenyiporphyrin supported on poly(4-vinylpyridine), Mn(tpps)-PVP, can act as an efficient heterogeneous catalyst for alkene epoxidation and alkane hydroxylation by sodium periodate.
Publication Date: 1998
Journal of Chemical Research (3082342)(12)pp. 820-821
The oxidative decarboxylation of α-aryl carboxylic acids to the corresponding carbonyl derivatives was observed in catalytic systems containing tetrabutylammonium periodate and metallotetraphenylporphyrins (metal = FeIII or MnIII) at room temperature.
Publication Date: 1998
Journal of Chemical Research (3082342)(8)pp. 456-457
The periodate-manganese tetraphenylporphyrin, Mn(tpp)/1O4-, catalytic system is efficient in regenerating the parent carbonyl compounds from oximes and phenylhydrazones at room temperature.
Publication Date: 1998
Chemistry Letters (03667022)(12)
Epoxides are readily obtained in high yields and good selectivities by ultrasonic irradiation of alkenes and sodium periodate in the presence of catalytic amounts of manganese porphyrins supported on polyvinylpyridine and IRA-900 ion-exchange resin.
Publication Date: 1998
Journal of Chemical Research - Part S (03082342)(10)
The oxidation of primary aromatic amines to the corresponding azo derivatives has been observed in catalytic systems containing manganese(III) tetraphenylporphyrin and sodium periodate in the presence of heterocyclic nitrogen bases acting as axial ligands.
Publication Date: 1998
Synthetic Communications (00397911)(3)
Sulfonated manganese(III) tetraphenylporphyrin supported on Amberlite IRA-900 ion exchange resin (MnTPPS-Ad) has been found to be a highly active and stable catalyst for olefin epoxidation and alkane hydroxylation by sodium periodate.
Publication Date: 1998
Chemistry Letters (03667022)(6)pp. 511-512
Zinc heteropolyanion, PZnMo2W9O395-, was found to be an efficient catalyst for alkene epoxidation and oxidation of alkylaromatic compounds with 30% H2O2. Epoxide selectivities in the range of 80 to 100% was observed.
Publication Date: 1998
Journal of Chemical Research - Part S (03082342)(12)
The manganese(III) complex of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin covalently bound to crosslinked chloromethylated polystyrene can act as an efficient heterogeneous catalyst for alkene epoxidation by sodium periodate.
Publication Date: 1998
Journal of Organometallic Chemistry (0022328X)568(1-2)pp. 53-61
The reaction of Li(CH2)4Li with [PtCl2(SEt2)2] yielded an unstable complex, probably [{Pt(CH2CH2CH2CH2)(μ-SEt 2)}2], 1. Complex 1 reacts with bis(diphenylphosphino)methane, dppm, and forms [{Pt(CH2CH2CH2CH2)(μ-dppm)} 2], 2. Complex 2 has been fully characterized using multinuclear NMR and FAB mass spectroscopies and shown to be fluxional in solution. The bright red platinacyclopentane complex [Pt(CH2CH2CH2CH2)(bpy)], 3, in which bpy=2,2′ bipyridyl, has been prepared by reaction of 1 with bpy. In a comparative kinetic study, it was demonstrated that at different temperatures, EtI reacted 2.2-2.6 times faster with the platina(II)cyclopentane complex 3 than with the dimethyl analogue [PtMe2(bpy)].
Publication Date: 1999
Microchemical Journal (0026265X)(2)pp. 302-310
The construction performance characteristics and applications of a new polymeric membrane coated on graphite electrode with high selectivity toward salicylate are reported. The electrode was prepared by incorporating aluminum phthalocyanine chloride into a plasticized poly(vinyl chloride) membrane. The influence of several variables was investigated to optimize the potentiometric response of the electrode and to maximize the selectivity for salicylate over potentially interferent anions. Calibration plots with Nernstian slopes for salicylate were observed, -59 ± 1 mV/decade, over a linear range of more than four decades of concentration (5 × 10-6 to 1 × 10-1 M salicylate) with good precision and low detection limit. The electrode is highly selective toward salicylate over several inorganic and organic anions. Response time of the electrode is ≤30 s over the entire concentration range. The electrode was successfully applied to the determination of salicylate in pharmaceutical preparations and biological samples, © 1999 Academic Press.
Publication Date: 1999
Synthetic Communications (00397911)(12)
Conversion of various epoxides to the corresponding thiiranes is achieved by thiourea in the presence of tin(IV) meso-tetraphenylporphyrin with excellent yields under non-aqueous conditions.
Publication Date: 1999
Journal of Chemical Research (3082342)(6)pp. 370-371
Iron(III) 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, Fe(TF5PP)Cl, is a new catalyst for the conversion of epoxides to the corresponding thiiranes in the presence of ammonium thiocyanate in excellent yields.
Publication Date: 1999
Journal of Chemical Research - Part S (13645560)(12)pp. 722-723
Sulfonated manganese(III) tetraphenylporphyrin supported on Amberlite IRA-400 ion-exchange resin (MnTPPS-Ad), can act as an efficient heterogeneous catalyst for alkene epoxidation and alkane hydroxylation by sodium periodate in the presence of imadazole.
Publication Date: 1999
Analyst (32654)(9)pp. 1319-1322
Iron(III) and manganese(III) tetraphenylporphyrins were explored as electroactive materials for preparing polymeric membrane-based sensors selective to histamine. The membranes, incorporating 30% poly(vinyl chloride) (PVC), 60% dioctyl phthalate (DOP), and 10% iron or manganese tetraphenylporphyrin, coated on the surface of graphite electrodes, exhibited near-Nernstian responses in the concentration range from 1 x 10-6 to 1 x 10-1 mol dm-3 with detection limits of about 5 x 10-7 mol dm-3 histamine, and response times of < 30 s. The electrodes show high selectivity towards histamine over several amino acids and common inorganic anions and can be used in a wide pH range. They were applied to the determination of histamine in synthetic serum samples.
Publication Date: 1999
Analytical Letters (32719)(14)pp. 2737-2750
Thiocyanate selective electrodes were prepared by incorporating cobalt and manganese phthalocyanines into plasticized ploy(vinyl chloride) membranes which were directly coated on the surface of graphite electrodes. A calibration plot with Nernstian slope for thiocyanate was observed over a linear range of five decades of concentration (1x10-6-1x10-1 M). The electrode has a fast response time, very low detection limit (5x10-7 M thiocyanate), is easy to prepare, and could be used for over a month. The proposed sensor revealed good selectivity for thiocyanate over several anions and could be used over a wide pH range. Applications of the electrode to the potentiometric titration of silver ion with thiocyanate and determination of thiocyanate in urine samples are reported.
Publication Date: 1999
Analytical Chemistry (32700)(13)pp. 2502-2505
The construction, performance characteristics, and application of a polymeric membrane coated on a graphite electrode with unique selectivity toward histidine are reported. The electrode was prepared by incorporating chloro (5, 10, 15, 20-tetraphenylporphyrinato) manganese-(III) [Mn(TPP)Cl] into a plasticized poly(vinyl chloride) membrane. The influences of membrane composition, pH, and foreign ions were investigated. Calibration plots with near Nernstian slopes for histidine were observed, -55.4 mV/decade, over a linear range of four decades of concentration (1 x 10-5 to 1 x 10-1 M). The electrode has a detection limit of 5 x 10-6 M histidine and shows high a fast response time of about 1 min. The electrode shows high selectivities high toward histidine over several amino acids and common inorganic anions.
Publication Date: 1999
Analytica Chimica Acta (00032670)402(1-2)pp. 137-143
Thiocyanate-selective electrodes based on nickel and iron phthalocyanines are described. The electrodes were prepared by incorporating the ionophores into plastisized poly(vinyl chloride) membranes, which were directly coated on the surface of graphite electrodes. The resulting electrodes demonstrate near-Nernstian responses over a wide linear range (5x10-7-0.1M) thiocyanate. The electrodes have a fast response time, submicromolar detection limits (5x10-7M thiocyanate) and could be used over a wide pH range of 3-10. The influences of lipophilic cationic and anionic additives on the response properties of the electrodes were investigated. The proposed sensors revealed high selectivity for thiocyanate over a number of common inorganic and organic anions. Highest selectivity was observed for the electrode based on iron phthalocyanine in the presence of sodium tetraphenylborate as a lipophilic anionic additive. Application of the electrodes for determination of thiocyanate in urine samples is reported. Copyright (C) 1999 Elsevier Science B.V.
Publication Date: 1999
Electroanalysis (10400397)(18)pp. 1340-1344
The response characteristics of a new solvent-polymeric membrane electrode with unique selectivity and detection limit toward SCN- ion are reported. The electrode is prepared by incorporating (octabromotetraphenylporphyrinato)manganese(III) chloride into a plasticized PVC-membrane. The resulting sensor exhibits anti-Hofmeister selectivity pattern with high specificity for thiocyanate over other anions, including lipophilic inorganic anions. The electrode has a linear dynamic range between 1.0 and 4.8 × 10-7M, with a Nernstian slope of 58.3±0.8mV/decade and a detection limit of 3.2 × 10-7M. The electrode can be used for at least 3 months without any considerable divergence in potential. It was used as an indicator electrode in potentiometric titration of SCN-1 ion and in direct determination of thiocyanate in urine samples.
Publication Date: 2000
Synthetic Communications (00397911)30(13)pp. 2365-2374
Epoxides can be cleaved in a regio- and stereoselective manner with alcohols, acetic acid and water in the presence of catalytic amounts of bismuth(III) chloride, affording the corresponding β-alkoxy and β-acetoxy alcohols and diols in high yields.
Publication Date: 2000
Journal of Chemical Research - Part S (13645560)(11)pp. 515-517
Alkens are transformed to their corresponding epoxides in high yields and with high selectivity by ultrasonic irradiation and sodium periodate in the presence of catalytic amounts of manganese porphyrin supported on Amberlite IRA-400 ion-exchange resin (MnTPPS-Ad).
Publication Date: 2000
Electroanalysis (10400397)12(11)pp. 863-867
A potentiometric method has been developed for determination of 2-mercaptobenzimidazole (MBIM) and-2-mercaptobenzothiazole (MBTH) based on cobalt phthalocyanine (CoPc) modified carbon-paste electrode. We show that the CoPc-modified electrode acts as a catalyst for the electrooxidation of MBIM and MBTH, lowering the overpotential of the reaction by 250 to 400mV, compared to the unmodified electrode. The faster rate of electron transfer results in a near-Nernstian behavior of the modified electrode and makes it a suitable potentiometric sensor for potentiometric detection of these sulfhydryl compounds. The potential response of the electrode to the sulfhydryl compounds has a linear dynamic range between 1 x 10-6 and 3.6 x 10-3 M with a near Nernstian slope of 50 to 54 mV/decade of concentration and a detection limit of 5 x 10-7 M. The electrode retains its full activity for at least a month. The potentiometric response mechanism toward sulfhydryl compounds is discussed and a mechanistic model for the electrode response is given.
Publication Date: 2000
Analytical Chemistry (32700)(5)pp. 956-962
New salicylate-selective electrodes based on aluminum(III) and tin(IV) salophens are described. The electrodes were prepared by incorporating the ionophores into plasticized poly(vinyl chloride) (PVC) membranes, which were directly coated on the surface of graphite electrodes. These novel electrodes display high selectivity for salicylate with respect to many common inorganic and organic anions. The influence of membrane composition and pH and the effect of lipophilic cationic and anionic additives on the response properties of the electrodes were investigated. The electrode based on- aluminum salophen, with 32% PVC, 65.8% plasticizer, and 2.2% ionophore, shows the best potentiometric response characteristics and displays a linear log [Sal-] vs EMF response over the concentration range 1 x 10-6-1 x 10-1 M in phosphate buffer solutions of pH 7.0, with a Nernstian slope of -59.2 mV/decade of salicylate concentration. Highest selectivity was observed for the membrane incorporating 38.8% PVC, 57.3% plasticizer, 2.6% Sn(salophen), and 1.3% sodium tetraphenylborate. The electrodes exhibit fast response times and micromolar detection limits (~1 x 10-6 M salicylate) and could be used over a wide pH range of 3-8. Applications of the electrodes for determination of salicylate in pharmaceutical preparations and biological samples are reported.
Publication Date: 2001
Journal of Chemical Research - Part S (03082342)(9)
Tin(IV) tetraphenylporphyrin perchlorate, Sn(IV)(tpp)(ClO4)2, catalyses the efficient reaction of epoxides with acetone to give the corresponding 1,3-dioxolanes in good yields.
Publication Date: 2001
Journal of Industrial Pollution Control (discontinued) (09702083)17(1)pp. 67-73
The photoassisted oxidation of water containing paramethyl thiophenol (PMTP) was investigated, over a heterogeneous catalyst of TiO2 (anatase/rutile) in a photocatalytic reactor. The effect of some physical and chemical parameters such as irradiation time, amount of TiO2, flow of O2 and pH were studied in order to optimise the process. Carbon dioxide an d sulphate ion yield measurements indicte that almost complete minzeralization occurs in the final phase of oxidation.
Publication Date: 2001
Iranian Journal Of Chemistry And Chemical Engineering (10219986)20(2)pp. 66-74
A flow injection method is reported for the determination of ascorbic acid based on amperometric detection, using a cobalt(II) phthalocyanine (CoPc) modified graphite-epoxy electrode. The amperometric response was evaluated with regard to pH, ionic strength of the electrolyte, flow rate of the carrier solution, injected sample volume and conditioning time of the electrode. The limit of detection was 0.013 mM (50 μL, injected), and the calibration plot was linear in the ranges of 0.025-1.0 mM (correlation coefficient, r =0.9989, n =6) and 1.0-10 mM (r = 0.9997, n=5). The relative standard deviation for the measurement of ascorbic acid at several concentrations was ≤ 1%. The modified electrode was found to retain its full response inflowing streams for several days of operating time. The results of ascorbic acid quantification in fruit juices and vitamin tablets are reported.
