Photoreaction of 2′-chloro-4-R-benzanilide: synthesis of 2-(4-R-phenyl)-1,3-benzoxazole and 9-R-phenanthridin-6(5H)-one (R=H, CH3, CH3O)

The UV photolysis of 2′-chloro-4-R-benzanilides in acetonitrile solution under nitrogen atmosphere leads to the formation of intramolecular photocyclization products (9-R-phenanthridin-6(5)-one, 20–30%), along with the minor photoreduction, photo-Fries, and intramolecular photosubstitution products. The photoreaction of 2′-chloro-4-R-benzanilide in acetonitrile solution containing 10% of water or aqueous sodium hydroxide however gives 2-(4-R-phenyl)-1,3-benzoxazole as a major product (30%) along with the photoreduction, photo-Fries and intramolecular photocyclization products.     

Activity concentrations of 210Po in the soft parts of cockle (Anadara granosa)at Kuala Selangor, Malaysia

Polonium-210 has been measured in the soft parts of Anadara granosa purchased at Kuala Selangor, West Coast of Malaysia in August 2001, April 2002 and September 2002. It is shown that ²¹⁰Po is non-uniformly distributed within cockles of various sizes (i.e., 2.5, 3.0, 3.5 and 4.0 cm of shell length) and the concentration of ²¹⁰Po in the soft parts of cockle was significantly different (p<0.05) due to sampling date. The highest value was observed in the smallest cockle with a shell length of 2.5 cm (411.6±26.16 Bq/g dry wt.). It is clear that there is an allometric relationship between ²¹⁰Po activity concentration and individual cockle weight. This may reflect on the differences of metabolic rate and growth age of cockles. The mean activity concentration of ²¹⁰Po measured in Kuala Selangor filtered water were 1.75±0.17, 0.79±0.08 and 1.13±0.20 Bq/kg for August 2001, April 2002 and September 2002, respectively. The yield concentration factors for ²¹⁰Po in the soft parts of cockles varies from 27.3^. 10³ to 106.9^. 10³. This revised version was published online in July 2006 with corrections to the Cover Date.     

Use of spectroscopy of gamma-radiation from the inelastic scattering of reactor fast neutrons for elemental analysis

Gamma-spectra of stainless-steel and soil samples have been measured to study the potentialities of using spectroscopy of γ-radiation from the inelastic scattering of reactor fast neutrons for element analysis of various materials. Contents of iron, chromium, nickel, manganese, silicon and titanium in stainless steel, and those of silicon, iron, aluminium, magnesium, calcium, sodium, titanium, carbon and oxygen in soil have been determined by comparing the spectra of the samples with those of specially prepared mixtures of elements. The distinguishing features, advantages, and limitations of this method are discussed.     

Hygrometric Determination of Water Activities and Osmotic and Activity Coefficients of NH4Cl–LiCl–H2O at 25°C

The mixed aqueous electrolyte system of ammonium and lithium chlorides has been studied by the hygrometric method at 25°C. The relative humidities of this system are measured at total molalities from 0.3 to 6 mol-kg^{– 1} for different ionic-strength fractions y of NH₄Cl with y = 0.33, 0.50, and 0.67. The data obtained allow the deduction of new water activities and osmotic coefficients. The experimental results are compared with the predictions of the ECA (extended composed additivity) law proposed in our previous work. The Zdanovskii–Stokes–Robinson (ZSR), the Robinson–Stokes (RS), Reilly–Wood–Robinson (RWR), the Pitzer, and the Lietzke–Stoughton (LS II) models are also compared with our results. Predictions made using these models are, in general, consistent with our results. From these measurements, new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic-strength fractions.     

An efficient procedure for the synthesis of coumarin derivatives using TiCl4 as catalyst under solvent-free conditions

The ability of titanium(IV) chloride as a catalyst to promote the Pechmann condensation reaction with a range of phenols and β-keto esters is described.The reaction was carried out by addition of TiCl₄ to a mixture of the phenol and the β-keto ester with thorough stirring in the absence of a solvent and represents an improvement on the classical Pechmann conditions. The yields of coumarins obtained via this novel protocol were significantly higher than those using the conventional method and the reaction duration was reduced to a few minutes or even a few seconds.     

Optical sensor for sulfur dioxide based on fluorescence quenching

A series of potential indicator dyes is evaluated for use in the development of optical sensors for measuring sulfur dioxide in gaseous samples. Rhodamine B isothiocyanate is selected on the basis of relative sensitivity to dynamic quenching by sulfur dioxide and oxygen. A solid-state fluorometer is described for monitoring the sulfur dioxide induced fluorescence quenching of sensing membranes composed of silicone and rhodamine B isothiocyanate. A modulated blue LED is coupled with the lock-in detection of a photodiode detector to provide high signal-to-noise ratios. The limit of detection is 0.114+/-0.009% for sulfur dioxide in a carrier stream of nitrogen gas. Selectivity measurements indicate no interference from several common gases (HCl, NH(3), NO, and CO(2)). Oxygen alters the sensor response when comparing signals for sulfur dioxide in 0, 20 and 100% oxygen environments.     

Lithiation of 2-Alkyl-3-amino- and 2-Alkyl-3-(methylamino)-4(3H)-quinazolinones(1)

3-Amino-2-methyl-4(3H)-quinazolinone has been doubly lithiated, on nitrogen and in the 2-methyl group, with n-butyllithium. The lithium reagent thus obtained reacts with a variety of electrophiles (D(2)O, benzophenone, cyclohexanone, cyclopentanone, acetophenone, benzaldehyde, tetraisopropylthiuram disulfide (TITD)) to give the corresponding 2-substituted derivatives in very good yields. Reactions of the dilithio reagent with 2 molar equiv of methyl iodide or phenyl isocyanate give disubstituted derivatives. Double lithiation of the 2-ethyl and 2-propyl analogues have been achieved using LDA, and subsequent reactions with most electophiles are then similar. In the reaction of the dianion of the 2-ethyl compound with TITD, deamination from position 3 takes place with the formation of the 2-substituted derivative. In reactions with prochiral ketones, the dianion of the 2-ethyl compound gives very high diastereoselectivity. Lithiation and subsequent reactions of 3-(methylamino) analogues take place in a similar manner, thus providing access to a range of substituted 3-(methylamino)-2-alkyl-4(3H)-quinazolinones by a general procedure. Lithiation of 3-(dimethylamino)-2-ethyl-4(3H)-quinazolinone did not take place under similar conditions. Lithiation of 3-amino-2-unsubstituted-4(3H)-quinazolinone was also unsuccessful.     

Membranes obtained by preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene–perfluorovinyl ether)

Some properties of the membranes obtained by preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene-perfluorovinyl ether) copolymer (PFA) films have been investigated. The dimensional change caused by grafting and swelling behavior, water uptake, electrical conductivity, and mechanical properties of the grafted films were found to increase as the grafting proceeds. The influence of the preparation conditions (such as preirradiation dose, monomer concentration, grafting temperature, and film thickness) on those properties was studied. These properties were found to be dependent mainly on the degree of grafting regardless of grafting conditions, except at higher monomer concentration (>40 wt %). The electric conductivity and mechanical properties for the membranes obtained at higher AAc concentrations were lower than those obtained at lower ones. Analysis by x-ray microscopy of the grafted films revealed that the grafting begins at the part close to the film surface and proceeds into the central part with progressive diffusion of monomer to give finally homogeneous distribution of the electrolytes in the whole bulk of the polymer. The membranes show good electrochemical and mechanical properties which make them acceptable for practical use as cation-exchange membranes.     

Atomic absorption spectrometric and potentiometric microdetermination of the nitro and nitroso groups in organic compounds

New simple, rapid, accurate, and selective methods are described for microdetermination of the nitro and nitroso groups in organic compounds. These are based on reduction with cadmium metal and 0.05 M HCl whereby 6 and 4 equivalents of the cadmium ions are released per nitro and nitroso groups, respectively. The cadmium ions are measured by atomic absorption spectrometry at 228.8 nm, potentiometrically by titration with EDTA using the cadmium ion selective electrode, and visually by EDTA titration using Eriochrome Black T indicator. Results with an average recovery of 98% and a mean standard deviation of 1.3% are obtainable and no interferences are caused by many nitrogen, oxygen, and sulfur functional groups.     

A simplified sampling technique for use with the Weisz ring oven: application to qualitative analysis of some gold and silver alloys

Up to 100 microg of sample can be collected from gold or silver alloys by rubbing the specimen with the ground hemispherical tip of a 4-mm Pyrex glass rod. Gold alloys are then dissolved in potassium cyanide solution containing hydrogen peroxide; silver alloys are exposed to vapours of nitric acid. Procedures for transfer, ring oven separation and identification of alloy constituents in the sample solutions are described.