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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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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.
A mild and efficient preparation of 1,3-dioxolanes from epoxides and acetone has been carried out in high to excellent yields under catalysis of potassium dodecatungstocobaltate trihydrate (K5CoW12O40·3H2O) (0.01 molar equiv.).
Journal of Biochemistry, Molecular Biology and Biophysics (10258140)(2)pp. 143-152
The interaction of 5,10,15,20-Tetrakis (N-Methyl-4-Pyridyl) Porphyrin (TMPyP), a water soluble porphyrin, with human serum albumin (HSA) has been investigated in 5 mM phosphate buffer, pH=7.0, at various temperatures by optical absorption spectroscopy. The spectral pattern at various TMPyP/ HSA molar ratios represented three distinct stages in this process. Aggregate formation of TMPyP on HSA at high TMPyP/ HSA molar ratios was designated stage I and aggregate formation of HSA around porphyrin at low TMPyP/ HSA molar ratio was designate stage III. The appearance of an isosbestic point at intermediate TMPyP/HSA molar ratios represented the existence of an equilibrium between the TMPyP:HSA complex and TMPyP:2HSA complex (stage II). Based on the absorption data a binding model has been proposed and used to analyze the binding process at stage(II). The binding constants for formation of TMPyP:2HSA from TMPyP:HSA have been estimated to be 4.9 × 104 and 3.5 × 104 M-1 at 27 and 37°C, respectively. Values of -24.6 kJ/mol and 20.0 J/K were determined for enthalpy and entropy, respectively using the Vont Hoff relation. It was concluded that both entropy and enthalpy changes play important roles in the binding process.
Pollution Research (discontinued) (02578050)20(3)pp. 295-298
2-Mercaptobenzothiazole (MBT) is known as a widespread, toxic and poorly biodegradable pollutant. In this study, the results of photocatalysed degradation of MBT, an industrial pollutant, in aqueous solutions using suspended titanium dioxide are presented. The rate of MBT degradation as a function of pH, amount of TiO 2 and flow of O 2 was investigated and their optimum values were obtained. Carbon dioxide, ammonia and sulphate ion yield measurements indicate that almost complete mineralization occurs in the final phase of oxidation with some indication of benzothiazole-2-sulfonate (BTSO 3) as intermediate.
Salicylate selective electrodes based on oxo(phthalocyanato)-vanadium(IV) [VO(Pc), vanadyl phthalocyanine] and oxo(phthalocyanato)molybdenum(IV) [MoO(Pc), molybdenyl phthalocyanine] are described. The electrodes were prepared by incorporating the ionophores into plasticized poly(vinyl chloride) membranes, which were directly coated on the surface of graphite electrodes. The resulting electrodes demonstrate Nernstian responses over a wide linear range (10-7-10-1 M) salicylate. The electrodes have a fast response time, submicromolar detection limit, and could be used over the pH range of 6-9. The proposed sensors revealed selectivity for salicylate over a number of common inorganic and organic anions. The influence of lipophilic cationic and anionic additives on the response properties of the electrodes was investigated. Highest sensitivity and the widest linear dynamic range were observed for the electrodes in the presence of trioctylmethylammonium chloride as a lipophilic cationic additive. The electrodes were successfully applied to the determination of salicylate in pharmaceutical preparations.
Iranian Journal Of Chemistry And Chemical Engineering (10219986)(1)
A carbon-paste electrode modified with iron(II) phthalocyanine (FePc) was used as a sensitive potentiometric sensor for determination of 2-pyridinethiol (2PT), 2-mercaptoethanol (2ME) and sulfide ion in aqueous solutions. The modified electrode acts as an electrocatalyst for oxidation of these compounds, and lowers the overpotential for oxidation reactions by more than 400 mV, compared to the unmodified electrode. The process was dependent on the pH of the supporting electrolyte. The fast rate of electron transfer results in a near-Nernstian behavior of the modified electrode, and makes it a suitable potentiometric sensor for measurement of these compounds. Calibration studies were performed using potentiometry in oxygen or air saturated stirred solutions; linear responses were obtained over the range of about 1x10-6 to 5x10-3 M (correlation coefficients, r, of ∼0.999, n=8). The modified electrode exhibited a fast response time (< 20 s), good stability, and had an extended lifetime; the standard deviation of slopes, during a period of two months, was 1.7-2.4% (n=10). Appropriate electrochemical and analytical data are presented.
