Facile conversion of [1-<Superscript>14</Superscript>C]lauronitrile to [1-<Superscript>14</Superscript>C]lauric acid under microwave irradiation

Summary A highly efficient and an optimized synthesis of [1-¹⁴C]lauric acid with high specific activity (50 mCi/mmol) is described. [1-¹⁴C]lauric acid was prepared from [1-¹⁴C]lauronitrile, in 2 minutes with a mixture of concentrated hydrochloric acid: propionic acid (1: 2 v/v) under microwave irradiation, in quantitative yield.     

A convenient method for <Superscript>14</Superscript>C-labeling of <Emphasis Type="Italic">N</Emphasis>-(2-oxo-5-phenyl-2,3-dihydro-1H-benzo[e][1,4]diazepin-3-yl)-1H-pyrrole-2-carboxamide-[carboxy-<Superscript>14</Superscript>C] as CCK-A antagonist

N-(2-oxo-5-phenyl-2,3-dihydro-1H-benzo[e][1,4]diazepin-3-yl)-1H-pyrrole-2-carboxamide-[carboxy-¹⁴C] was prepared as part of a five-step sequence from pyrrol-2-carbonitrile-[cyano-¹⁴C] as a key synthetic intermediate which has been synthesized from 2-bromopyrrole and zinc [¹⁴C]-cyanide in the presence of tetrakis (triphenylphosphine)palladium.     

A facile preparation of ammonium [<Superscript>14</Superscript>C]thiocyanate

Summary An attractive and simple method has been developed for the preparation of ammonium [¹⁴C]thiocyanate from [¹⁴C]thiourea which eliminates the necessity of handling highly hazardous potassium [¹⁴C] cyanide. [¹⁴C]thiourea was isomerized to ammonium [¹⁴C]thiocyanate by heating the aqueous solution of thiourea (12%) in a sealed tube at 160 °C for 24 hours. The product formed was purified by silica-gel column chromatography. A radiochemical yield of 92.7% was obtained based on [¹⁴C]thiourea. The specific activity of the product obtained was 53.3 mCi/mmol (1.97 GBq/mmol) and the radiochemical purity was greater than 99%. This method has not been reported so far for the production of this labeled compound.     

An improved method for the preparation of [<Superscript>14</Superscript>C]thiourea of high radiochemical purity

Summary An improved method for the preparation of [¹⁴C]thiourea of high radiochemical purity is described. [¹⁴C]thiourea is prepared by the barium cyanamide route and is purified by vacuum-sublimation. The labeled product showed ammonium [¹⁴C]thiocyanate as a radiochemical impurity in the range of 2-4%. This was further purified by silica-gel column chromatography to get the product having more than 99% radiochemical purity.     

A facile synthesis of 4,6-dimethoxy-[2-<Superscript>14</Superscript>C]-2-methylsulphonylpyrimidine

Summary 4,6-dimethoxy-2-methylsulphonylpyrimidine is a key intermediate for the synthesis of pyrithiobac-sodium, a selective herbicide for cotton plant. ¹⁴C labeled pyrithiobac-sodium is required for studying the translocation and metabolism in cotton plants. It was prepared by oxidation of 4,6-dimethoxy-[2-¹⁴C]-2-methylmercaptopyrimidine with H₅IO₆/CrO₃ in ethyl acetate at room temperature to give 4,6-dimethoxy-[2-¹⁴C]-2-methylsulphonylpyrimidine in high yields.     

Synthesis of a <Superscript>14</Superscript>C analogue of N-(3,5-dichlorobenzyl)-4-(fluoromethoxy) benzene carboximidamide-[carboxy-<Superscript>14</Superscript>C] as NR2B-selective NMDA receptor antagonist

N-(3,5-Dichlorobenzyl)-4-(fluoromethoxy) benzenecarboximidamide labeled with carbon-14 was prepared from 4-hydroxy-benzonitrile-[cyano-¹⁴C].     

A facile synthesis of racemic carboxyl <Superscript>14</Superscript>C-labeled phenylglycine under microwave irradiation

We report here a facile synthesis of racemic carboxyl ¹⁴C labeled phenylglycine. Toluene was brominated in presence of manganese dioxide to give benzyl bromide (>98%), which on cyanation with K¹⁴CN followed by acid hydrolysis under microwave enhanced conditions gave [1-¹⁴C]-2-phenyl ethanoic acid. The latter on α-bromination followed by amination with liquid ammonia furnished a racemic mixture of the title compound with a yield >90% with respect to K¹⁴CN. The racemic mixture was resolved using L(+) tartarate to give D and L phenylglycine.     

Magnesium-Potassium Phosphate Matrix for Immobilization of <Superscript>14</Superscript>C

Possibility of using a low-temperature magnesium-potassium phosphate matrix to solve the problem of immobilizing the radioactive wastes containing radioactive carbon (¹⁴C) in the form of calcium carbonate was examined. The physicochemical characteristics of the compounds obtained were determined. Large values of the ultimate compression strength (22 ± 5 MPa), which satisfy the technical requirements for cemented radioactive wastes (no less than 4.9 MPa), were obtained. The minimum carryover of carbon dioxide into the atmosphere in the course of synthesis and in keeping of samples for 14 days was noted: not more than 3 wt % relative to the starting CaCO₃. The leaching rate of carbonate ions from magnesium-potassium compounds by 28th day of contact with air does not exceed 10?9 g cm^?2 day^?1, with this value for the rest of the compound components not exceeding 10^?4 g cm^?2 day^?1. Thus, it was found that the magnesium?potassium phosphate matrix is an alternative to the cementation for solidification of radioactive wastes containing ¹⁴C.     

Gasification characteristics to <Superscript>14</Superscript>CO<Subscript>2</Subscript> of <Superscript>14</Superscript>C radionuclide desorbed from spent resin by phosphate solutions

The removal characteristics of H¹⁴CO₃ ⁻ ions from IRN-150 mixed resin contaminated with ¹⁴C radionuclide and the gasification effects of ¹⁴C radionuclide on ¹⁴CO₂ are investigated in this study. The stripping solutions used for the removal of ¹⁴C from spent resin are NaNO₃, Na₃PO₄, NH₄H₂PO₄, and H₃PO₄. The influence of the stripping solution concentration on the desorption characteristics of an inactive HCO₃ ion into a stripping solution from IRN-150 mixed resin and the gasification of this ion to CO₂ is analyzed. The gasification behavior to CO₂ using NaOH, HNO₃, and HCl was also compared to that of phosphate solution. Spent resin stored in Wolsong nuclear power plant is used to evaluate the gasification characteristics of ¹⁴C radionuclide to ¹⁴CO₂. Gamma radionuclides such as ¹³⁷Cs and ⁶⁰Co in residual striping solutions after desorption experiments are analyzed.     

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.     

Application of an experimental design to optimize a segregation method of <Superscript>129</Superscript>I and <Superscript>14</Superscript>C

In this work, the optimization of a segregation method of ¹²⁹I and ¹⁴C, two long-living radionuclides, main constituents of nuclear radioactive waste, has been developed. To be able to carry out this project, a fractional factorial experimental design was applied using 5 factors and 2 levels by factor (2^5–2). Only 8 experiments were necessary to identify the variables affecting the process, and very good recoveries of both radionuclides were obtained: (94?±?2)% for ¹²⁹I, and (99?±?1)% for ¹⁴C. The segregation of ¹²⁹I was influenced by flow (Q), volume of H₂SO₄ (V_H+), and carriers (CR), while V_H+ and time (t) played a major role in the segregation of ¹⁴C.     

Distribution characteristics of <Superscript>14</Superscript>C and <Superscript>3</Superscript>H in spent resins from the Canada deuterium uranium-pressurized heavy water reactors (CANDU-PHWRs) of Korea

It is regarded that the spent resins from the water purification systems of moderator (MOD) and the primary coolant of the Canada deuterium uranium-pressurized heavy water reactor (CANDU-PHWR) are a unique waste, owing to their high ¹⁴C and gamma-emitting nuclides. In this work, ¹⁴C and ³H contents, anion and cation fractions and the predominant gamma-emitting nuclides of the spent resins from 4 units of CANDUPHWRs, were investigated. Also the chemical species of ¹⁴C of the spent resins were determined. For a simultaneous separation of ¹⁴C and ³H from the spent resins, the wet oxidation-16 wt% H₂SO₄ stripping process was utilized. The ¹⁴C and ³H activity concentration range of the spent resins of the nuclear power plant (NPP), 4 units of all CANDU-PHWR types, was 2.48E5 Bq/g ∼5.33E6 Bq/g, 1.29E5 Bq/g and ∼2.33E5 Bq/g, respectively. Among the analyzed spent resins, the highest ¹⁴C and ³H activity concentration was detected in units 4 and 3, respectively. It was found that more than 92% of the ¹⁴C activity concentration was retained on the anion resin and the predominant chemical species was inorganic ¹⁴C. It was revealed that the anion resin fraction of the spent resins from unit 1 and unit 2, was about 40% and that of unit 3 and unit 4 was around 60%. More than 80% of the total gamma-radioactivity concentration was associated with the cation fraction of the spent resin. The predominant gamma-emitting nuclide of the spent resin for unit 2 was ¹³⁷Cs, a fission product, and that for unit 4 was ⁶⁰Co, a corrosion product.     

Application of AMS <Superscript>14</Superscript>C measurements to criminal investigations

¹⁴C variations of atmospheric CO₂ as well as carbonaceous fraction of living materials, such as collagen from tooth and bone, tissue, skin, hair, nail, etc., of modern humans are influenced by ¹⁴C produced artificially by nuclear bomb tests in the atmosphere from late 1950s to early 1960s. By careful investigation of ¹⁴C concentration of tree rings and human body samples formed in this time intervals, we can establish a relationship of their ¹⁴C concentrations with calendar year. By applying this relation to a sample whose ¹⁴C concentration can be measured, we can estimate the formation age of the sample. In addition, sources of the chemicals that were used in some criminal cases can be possibly identified, by their carbon isotope ratios (¹³C/¹²C and ¹⁴C/¹²C). This method of age determination has been applied to a forensic study, i.e., two criminal cases of murder. For each case, by comparing the measured ¹⁴C abundances of several pieces of hair and one tooth (the third molar) from the body with the annual change on concentrations of bomb-produced ¹⁴C, the time of death of the body and the age of the victim were estimated. The estimated values were consistent with the real ones that were revealed by the confession of the real murderers.     

Synthesis of <Emphasis Type="Italic">O</Emphasis>-[2-[<Superscript>18</Superscript>F]fluoro-3-(2-nitro-1<Emphasis Type="Italic">H</Emphasis>-imidazole-1-yl)propyl]tyrosine ([<Superscript>18</Superscript>F]FNT]) as a new class of tracer for imaging hypoxia

For detection of hypoxic tumor tissue, all radiotracers synthesized until now, are based on the concept that cellular uptake is being controlled by diffusion. As a new approach, we chose the concept to have the tracer hypothetically transported into the cells by well known carrier systems like the amino acid transporters. For this purpose, radiosynthesis of O-[2-[¹⁸F]fluoro-3-(2-nitro-1H-imidazole-1yl)propyl]tyrosine ([¹⁸F]FNT]) was carried out from methyl 2-(benzyloxycarbonyl)-3-(4-3-(2-nitro-1H-imidazol-1-yl)-2-(tosyloxy)propoxy) phenyl)propanoate via no-carrier-added nucleophilic aliphatic substitution. After labelling, 81 ± 0.9% of labelled intermediate i.e. methyl 2-(benzyloxycarbonyl)-3-(4-(2-[¹⁸F]fluoro-3-(2-nitro-1H-imidazole-1-yl)propoxy) phenyl)propanoate was obtained at 140 °C. At the end of radiosynthesis, [¹⁸F]FNT was obtained in an overall radiochemical yield of 40 ± 0.9% (not decay corrected) within 90 min in a radiochemical purity of >98% in a formulation ready for application in the clinical studies for PET imaging of hypoxia.     

Synthesis,scope, <Superscript>1</Superscript>H and <Superscript>13</Superscript>C spectral assignments of isomeric dibenzofuran carboxaldehydes

Two isomeric dibenzofuran carboxaldehydes, namely 2-methoxydibenzo[b,d]furan-1-carbaldehyde (4) and 2-methoxydibenzo[b,d]furan-3-carbaldehyde (5), were synthesized. Formylation of 2-methoxydibenzo[b,d]furan (3) with α,α-dichloromethyl methyl ether and tin(IV) chloride gave a mixture of aldehydes 4 and 5 in 95 % yield and in a 35:65 ratio. Their ¹H and ¹³C NMR spectral signals were not sufficiently resolved in CDCl₃ solution to achieve their complete assignment, but this was possible in DMSO-d ₆ with the help of 2D-NMR techniques: NOESY for ¹H–¹H interactions and HSQC and HMQC experiments for ¹H–¹³C correlations. These aldehydes were used in the synthesis of novel β-phenylethylamines and NBOMe derivatives, which are undergoing biological evaluation.     

Extraction of metal ions (Fe<Superscript>3+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript>) using immobilized-polysiloxane iminobis(n-2-aminophenylacetamide) ligand system

A new insoluble solid functionalized ligand system bearing chelating ligand group of the general formula P-(CH₂)₃-N[CH₂CONH(C₆H₄)NH₂]₂, where P represents [Si–O] _n polysiloxane network, was prepared by the reaction of the immobilized diethyliminodiacetate polysiloxane ligand system, P-(CH₂)₃N(CH₂CO₂Et)₂ with 1,2-diaminobenzene in toluene. ¹³C CP-MAS NMR, XPS and FTIR results showed that most ethylacetate groups (–COOEt) were converted into the amide groups (–N–C=O). The new functionalized ligand system exhibits high capacity for extraction and removal of the metal ions (Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) with efficiency of 95–97% after recovery from its primary metal complexes. This functionalized ligand system formed 1:1 metal to ligand complexes.     

<Superscript>18</Superscript>F- and <Superscript>11</Superscript>C-labelling of quantum dots with n.c.a. [<Superscript>18</Superscript>F]fluoroethyltosylate and [<Superscript>11</Superscript>C]methyliodide: a feasibility study

Quantum dots functionalized on the outer surface with either amino- or carboxyl functions were labelled with [¹⁸F]fluoroethyltosylate and [¹¹C]methyliodide in order to use the positron emitter-labelled fluorescence agents for multimodality imaging techniques, i.e. fluorescence imaging and positron emission tomography. ¹⁸F-Labelling of both compounds was realized with yields up to 5% as determined by size exclusion chromatography, which is twice as much as reported in literature before [1]. ¹¹C-Labelling of amino- and carboxyl-QDs proceeded with good yields (up to 45 and 35%, respectively) under optimized reaction conditions. In general for both QD-types and both labelling agents the labelling yield increased with the amount of QDs used in the reaction as well as with reaction time and reaction temperature.     

Synthesis,spectral properties,and antimicrobial activity of 2-arilamino-2,4,4,6,6-pentachloro-1,3,5,2λ<Superscript>5</Superscript>,4λ<Superscript>5</Superscript>,6λ<Superscript>5</Superscript>-triazatriphosphines and poly[bis(4-fluorophenylamino)phosphazene]

2-(4-Chloro and 4-fluorophenylamino)-2,4,4,6,6-pentachloro-1,3,5,2λ⁵,4λ⁵,6λ⁵-triazatriphosphinines and poly[bis(4-fluorophenylamino)phosphazene] were synthesized by reactions of 4-fluoroaniline and 4-chloroaniline with 2,2,4,4,6,6-hexachloro-1,3,5,2λ⁵,4λ⁵,6λ⁵-triazatriphosphinin and poly(dichlorophosphazene), respectively, in tetrahydrofuran under argon at ?20°C, followed by heating under reflux. The products were isolated by column chromatography and were characterized by FTIR, NMR (¹H, ¹³C, ³¹P), and mass spectra, termogravimetry, and high-performance liquid chromatography. Antimicrobial activity of the monomeric compounds and polymer against 9 bacteria and 5 yeast cultures was evaluated by the disk diffusion method in dimethyl sulfoxide relative to a number of commercial antibiotics and antifungal agents. Aminophosphazene derivatives exhibited a broad spectrum of activity against both Gram-positive and Gram-negative bacterial with a magnitude comparable to reference antimicrobial agents. The polymeric product turned out to be more potent than the monomeric compounds.     

Hydrogenolysis of 7-phenyltricyclo[4.1.0.0<Superscript>2,7</Superscript>]heptan-1-carboxylic acid. Synthesis of ketones with tricyclo[4.4.0.0<Superscript>2,7</Superscript>]decane and tricyclo[5.4.0.0<Superscript>2,8</Superscript>]undecane skeletons

Hydrogenation of 7-phenyltricyclo[4.1.0.0^2,7]heptane-1-carboxylic acid over Raney nickel occurred in the syn-stereoselective fashion to give anti-7-phenylbicyclo[3.1.1]heptane-exo-6-carboxylic acid. The latter was used to synthesize 4,5-benzotricyclo[4.4.0.0^2,7]dec-4-en-3-one and two isomeric higher homologs, 5,6-benzotricyclo[5.4.0.0^2,8]undec-5-en-3-and-4-ones.     

Determination of <Superscript>3</Superscript>H and <Superscript>14</Superscript>C in the Dry Active Wastes (DAW) generated from the Light Water Reactors (LWR) by a wet oxidation method

³H and ¹⁴C Measurements of the dry active waste (DAW), such as the cotton, paper, and vinyl, generated from a nuclear power plant (NPP) were conducted with wet oxidation using open vessel equipment based on simulation results. The recovery efficiency with the simulated samples was around 93% with a relative standard deviation (RSD) of 1–3%. A liquid scintillation counter (LSC) was used for counting and adjusted to a quenching correction curve. The counting value was evaluated for the minimum detectable activity (MDA), which was found to be about 4 × 10⁻¹ Bq/g for ³H and 2 × 10⁻² for ¹⁴C when approximately 5 g of the samples were measured. The measured DAW samples for the cotton, paper, and vinyl generated from NPP achieved of RSD values of 25, 25, and 60%, respectively, for ³H and 0–50% for ¹⁴C.