14C-labelled propoxur metabolic studies on Anopheles Stephensi from the south coast of Iran

¹⁴C-Propoxur (Baygon^®) was synthesized through the reaction of o-isopropoxyphenol with methyl isocyanate –¹⁴C. The product was isolated chromatographically on Florisil and crystallized from carbon tetrachloride. The purity and structure were confirmed using infrared spectra, melting point, co-chromatography on Florisil column, and silica-gel G thin layer chromatography. The purity was found to be at least 99%. The rate of absorption and other characteristics of¹⁴C-propoxur resistance inAnopheles Stephensi from the south coast ot Iran was investigated. The mortality of strain adults was 100% after a one hour exposure when 1 ppm¹⁴C-propoxur was used. Moreover, the mortality was not changed when a lower concentration (5 ppm) was used. On the other hand, the absorbance of¹⁴C-propoxur in several strains ofA. Stephensi has been determined. The identity and TLC characteristics of products formed after 1 and 2 hours exposure, respectively, to¹⁴C-propoxur have also been investigated.     

Synthesis of 1-14C-17-iodoheptadecanoic acid

1,16-Diiodohexadecane was obtained by reaction of 1,16-hexadecanediol and potassium iodide. The¹⁴C-label was introduced into the 1,16-diiodohexadecan using a substitution reaction which replaced one of the terminal iodine with¹⁴C-cyanide. Hydrolysis and HPLC purification of 1-¹⁴C-17-iodoheptadecanoic acid yielded a product with a radiochemical yield of 17% and a specific activity of approx. 1850 MBq mol^–1.     

Partial molar volumes of sodium chloride solutions at 200 bar,and temperatures from 175 to 350°C

High precision densities of sodium chloride solutions at a constant pressure of 200 bar and temperatures between 175°C and 350°C have been measured by a mercury displacement technique. The densities have been converted to apparent molar volumes. The apparent molar volumes decrease with increasing temperature and decreasing concentration whereas the concentration effect increases with temperature. Standard partial molar volumes range from 8.0 cm³-mol^–1 at 175°C to –600 cm³-mol^–1 at 350°C. The results indicate the applicability of the unextended Debye-Hückel limiting law up to concentrations of 0.02 mol-kg^–1.     

Study on the production of formaldehyde-14C by direct reduction of14CO2 with LiAlH4

A vial technique was developed for the synthesis of formaldehyde-¹⁴C from¹⁴CO₂ in an ether solution of lithium aluminium hydride. The yield of formaldehyde (40–50%) was achieved by optimization of the reaction parameters.     

Degradation studies of14C labelled p-fluorophenylacetic acid prepared by exchange reaction

Carbon-14 labelled p-fluorophenylacetic acid was prepared by heating its sodium salt with¹⁴CO₂ at 325 °C. The labelled acid after isolation from the reaction mixture was degraded by reaction with sodium azide. From the radioactivity measurements it was observed that no scrambling of¹⁴C had taken place and the acid could be designated as carboxyl-¹⁴C.Paper presented at the DAE Symposium on Nuclear Chemistry and Radiation Chemistry in February 1988 at Bombay, India.     

Biosynthesis of brevicolline

Conclusions 1. When DL-[2^–14C] tryptophan, sodium [2^–14C] pyrotartrate, sodium [¹⁴/C]-formate, and universally labeled L-[¹⁴C] glutamic acid were introduced through the root system intoCarex brevicollis DC, active brevicolline was obtained.2. Tryptophan and sodium pyrotartrate are precursors of the -carboline moiety of the brevicolline molecule, and sodium formate is a precursor of the N-methyl grouping.3. The introduction of universally labeled L-glutamic acid does not lead to an unambiguous indication of the role of this precursor in the biosynthesis of brevicolline.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 1, pp. 39–43, 1969     

Determination of total chlorine in waste oil

Summary A simple method has been developed to determine the concentration of organic chlorine in waste oil. The determination is based on the conversion of organic chlorine to inorganic chloride by reaction with sodium biphenyl followed by extraction with nitric acid and a mixture of nitric acid and water. The concentration of chloride is determined by direct potentiometry with an ion-selective electrode. The limit of determination amounts to 3·10^–5 mol·l^–1 chloride ions with a standard deviation of 3.5%. Different samples of waste oil have been analyzed and the results have been compared to those obtained by combustion in a H₂/O₂ flame followed by potentiometric titration with silver nitrate.     

Utilization of Chromatographic and spectroscopic techniques to study the oxidation kinetics of selenomethionine

Ion-exchange LC and spectroscopic supporting techniques have been successfully used to study the kinetics and mechanism of oxidation reactions of selenomethionine (SeMet). Oxidation of selenomethionine with both cyanogen bromide (CNBr) and hydrogen peroxide (H₂O₂) proceeds through a stable intermediate which undergoes cyclization and C-Se bond cleavage to form 2-amino-4-butyrolactone. This stable intermediate was identified by IR spectroscopy as methionine dihydroxy selenide. The CH₃-Se moiety of SeMet formed methyl selenic acid upon reaction with H₂O₂ and methyl selenocyanate (CH₃SeCN), characterized by GC-MS, for the reaction with CNBr. Both reactions were of apparent first order with respect to the concentration of SeMet. A rate constant (k₁)of 4.0×10^–3 s^–1 for the reaction of SeMet with HO and 4.0×10^–3 s^–1 for the reaction with CNBr were determined at a temperature of 22°C. Oxidation of methionine (Met) gives disparate kinetics and oxidation products from SeMet. Thus the differential rate method can be utilized to quantitatively separate SeMet in biological samples in the presence of much higher concentrations of Met.     

Osmotic and Activity Coefficients of CH3SO4Na(aq) and CH3SO4K(aq) at 25°C

The osmotic and activity coefficients of aqueous sodium and potassium methyl sulfates have been determined at 25°C by the isopiestic method, in the molality range from ca.0.2 to 25 and 19 mol-kg^–1, respectively. The results have been discussed in terms of the ion–ion and ion–water interactions on the basis of the Pitzer and Mayorga model and a method developed in our laboratory.     

Kinetics of Chlorohydrination of Allyl Chloride

The chlorohydrination of allyl chloride with chlorine in water was studied at 20–80°C. The effect of the concentration of chloride ions within the range 0–3.6 mol/l on the selectivity of formation of glycerol dichlorohydrins was studied. An equation that relates the selectivity and the concentration of Cl^–was derived, which adequately describes experimental data. The schemes of parallel and consecutive reactions occurring in the system were suggested. The ratios between the rate constants of the following reactions were found: the reactions of chlorine with water and allyl chloride dissolved in water (k ₁/k ₄= 4.1 × 10^–4), the reaction of allyl chloride with hypochlorous acid and the decomposition of hypochlorous acid (k ₂/k ₃= 1.7 × 10³), and the reactions of the allyl chloride–chlorine complex with a water molecule and Cl^–(k ₅/k ₆= 2.9 × 10^–2).     

Kinetics of adsorption and desorption of sodium alkyl sulfates to and from nylon particles

The desorption rate of surfactant ions from nylon particles was investigated at the concentrations below the critical micelle concentration by applying the stopped-flow method. A mixing cell of stopped-flow spectrophotometer was modified with platinum electrodes for electric conductivity detection. The change in electric conductivity with time in the desorption process was monitored by a memory-recorder system. The surfactants used were sodium decyl, sodium dodecyl, sodium tetradecyl, and sodium hexadecyl sulfates. The desorption rate was independent of the surfactant concentration and the rate constants were obtained by applying the first-order reaction scheme. The adsorption rate constants were estimated from the experimental desorption rate constants and equilibrium constants assuming the second-order kinetics. The desorption rate constants were determined to be 1–6 sec^–1 and the adsorption rate constants to be 2–8×10⁴ mol^–1 dm³ sec^–1; the former decreased and the latter increased with increasing number of carbon atoms in alkyl chain of the surfactants.     

Carbon-14 kinetic isotope effect in the decarbonylation of lactic acid[1-14C]

The carbon-14 kinetic isotope effect for the decarbonylation of lactic acid[1-¹⁴C] in sulfuric acid has been measured in the temperature interval of 20–90°C. The experimental values of (k_12C/k_14C) are compared with the theoretical¹⁴C kinetic isotope effect calculated assuming that one carbon-oxygen stretching vibration is lost in the rate-determining step. The discrepancy between experimentally observed temperature dependence of the¹⁴C kinetic isotope effect and the theoretical one is explained by the possible side reactions which change the apparent degrees of decarbonylation and isotopic composition of CH₃CHOHCOOH[1-¹⁴C] used in experiments aiming at the determination of carbon-14 kinetic isotope effect in the decarbonylation process itself.     

Diels—Alder reaction between naphthalene and N-phenylmaleimide under mild conditions

The rate and equilibrium constants for the Diels—Alder reactions between benzene or naphthalene and several dienophiles at 25 °C were calculated from the data on the ionization potentials of dienes and electron affinity energies of dienophiles, as well as the reaction enthalpies. The highest yield of the adduct was predicted for the reaction of naphthalene with N-phenylmaleimide. However, the time of its formation in 50% yield exceeds 30 years. The use of gallium chloride as a catalyst affords the endo-adduct for seven days at room temperature in 30% yield. The rate ((2±0.5)·10–6 L mol^–1 s^–1) and equilibrium constants (5±2 L mol^–1) of the reaction were determined.     

Determination of the hydrothermal degradation products of D-(U-14C) glucose and D-(U-14C) fructose by TLC

The hydrothermal degradation was examined using D-(U-¹⁴C) glucose and D-(U-¹⁴C) fructose. By thin layer chromatography with methylene chloride, tetrahydrofuran (THF), acetic acid −60∶20∶20 as a mobile phase it was, possible to separate and identify the carbohydrates and their reaction products, glyceraldehyde, dihydroxyacetone, methylglyoxal, glycolaldehyde, 5-hydroxymethylfurfural and furfural. Up to 99% of the initial activity was determined by scintillation counting of the TL-chromatograms. A reaction scheme for the hydrothermal degradation of glucose and fructose was obtained from these results.     

Synthesis of 2-dichloromethyl-2-methyl [2-14C]-1,3-dioxolane

The labelled compound was prepared by chlorination of [2-¹⁴C]acetone obtained from the barium salt of [1-¹⁴C]acetic acid by pyrolysis. The reaction product 1,1-dichloro [2-¹⁴C]acetone was converted to 2-dichloromethyl-2-methyl [2-¹⁴C]-1,3-dioxolane by condensation with ethylene glycol in the presence of thionyl chloride. Radiochemical yield: 62% based on [1-¹⁴C]acetic acid.     

Glycosylation of Bovine Serum Albumin with D-[<Superscript>14</Superscript>C]-Glucose

Certain parameters of the Maillard reaction between bovine serum albumin (BSA) and D-[¹⁴C]-glucose were investigated.__________Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 275–277, May–June, 2005.     

Investigation of 2-[(<Emphasis Type="Italic">E</Emphasis>)-2-(4-diethylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3H-indolium as a new highly sensitive reagent for the spectrophotometric determination of nitrophenols

A new, simple, rapid, and sensitive spectrophotometric method has been developed for the determination of nitrophenols [picric acid (PA); dinitrophenols (DNP)] in wastewater samples. The method is based on the reaction of nitrophenols with 2-[(E)-2-(4-diethylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3 H-indolium chloride reagent to form the colored ion associates, which are extracted by organic solvents. The molar absorptivity of the ion associates of PA with the investigated reagent ranges from 8.3×10⁴ to 11.3×10⁴ L mol^–1 cm^–1, depending on the extractant. Because only PA is extracted in an acidic medium with the investigated reagent, but both PA and DNP are extracted in an alkaline medium, it is possible to determine both substances in a mixture. Appropriate reaction conditions have been established. The absorbance of the colored extracts obeys Beers law in the range of 0.04–4.58 mg L^–1 PA, 1.0–18.4 mg L^–1 2,4-DNP and 1.2–14.7 mg L^–1 2,6-DNP, respectively. The limit of detections, calculated from a blank test (n=10; P=0.95), are 0.05 mg L^–1 PA, 0.9 mg L^–1 (2,4-DNP), and 1.1 mg L^–1 (2,6-DNP), respectively.     

Incorporation of Glycine Carbon Atoms into Melanoidin Polymers

Incorporation of C atoms of 1-[¹⁴C]-glycine and 2-[¹⁴C]-glycine into melanoidin polymers (>3500 Da) was studied for the reaction of glycine and D-glucose.__________Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 272–274, May–June, 2005.     

Access to 14C-Ring labelled phenothiazines. Synthesis of 2-chlorophenolhiazine-5a,9-14C

Through the use of a recently reported ring expansion reaction, a new route to phenolhiazines has been developed suitable for the preparation of ring labelled derivatives. As an example, the preparation of 2-chloropheno thiazine-5a,9-¹⁴C ( 1 ) is reported. Condensation of cyclohexanone-2-¹⁴C with 2-amino-4-chlorothiophenol gave the spiro-2,3-dihydro-l, 3-benzothiazole 4 which was protected by acetylation ( 5 ). Treatment of 5 with sulfuryl chloride gave the tetrahydro-phenothiazine olefin mixture 6 and 7 which was directly converted to labelled 1 via treatment with DDQ in refluxing benzene followed by hydrolysis of the acetyl group.     

Preparation and evaluation of the homogeneity of milk as a candidate reference material for carbon-14

A pilot project was initiated to study the feasibility of preparing milk as a candidate reference material for ¹⁴C near environmental levels. Two materials, MK-B at natural level of ¹⁴C and MK-C4 at an elevated level, have been prepared from pasteurized 2% dairy milk. MK-C4 was spiked with an appropriate amount of ¹⁴C-methylated casein tracer to achieve the elevated level. Several samples from MK-B and MK-C4 have been analyzed to test the homogeneity of these materials for the distribution of ¹⁴C. The samples were combusted in oxygen under 20 atmospheres pressure using a Parr bomb. The ¹⁴C concentrations were determined by liquid scintillation counting using Carbo-Sorb/Permafluor E⁺ cocktail. The results indicate that these materials are homogeneous with respect to ¹⁴C concentration even in sub-sample sizes of 0.25 g of the freeze-dried material. The precision of our ¹⁴C measurements, as expressed by the % relative standard deviation, is within 5%. The accuracy has been tested by analyzing replicate samples of the IAEA ¹⁴C quality assurance materials, C-3 (cellulose) and C-6 (ANU sucrose) and found to be within 3%. The lower limits of detection are 0.08, 0.05 and 0.02 Bq.g^–1 of carbon for 20 ml of liquid scintillation mixture (Carbo-Sorb/Permafluor E⁺ = 0.67) loaded with up to 0.4 g of carbon from the sample and counted for 3 cycles of 60, 180 and 1000 min each, respectively. Our measurements of ¹⁴C specific activities of MK-B and MK-C4 are 0.26±0.01 and 15.3±0.4 Bq.g^–1 of carbon, respectively.