Direct uranium extraction from dihydrate and hemi-dihydrate wet process phosphoric acids by liquid emulsion membrane

A new liquid emulsion membrane (LEM) process for uranium extraction from either dihydrate 28-30% P₂O₅ (DH) or hemi-dihydrate 42-45% P₂O₅ (HDH) wet process phosphoric acid is proposed. In this process, the organic component of the LEM is composed of a synergistic mixture of 0.1M di-2-ethyl hexyl phosphoric acid (DEHPA) and 0.025M trioctyl phosphine oxide (TOPO) with 4% Span 80. The internal or the strip acid phase is composed of 0.5M citric acid. The prepared LEM was proved to be stable in 42-45% P₂O₅ acid concentration range and can, therefore, be applied to the phosphoric acid produced by the hemi-dihydrate process. After breakdown of the loaded emulsion, the uranyl citrate in the internal strip phase is separated by adding methanol followed by its calcination to the orange oxide. Most of the reagents used are recycled. The proposed process is characterized by simplicity, practically closed operation cycle in addition to lower capital and operating costs.     

Synthesis of norfloxacin analogues catalyzed by Lewis and Brönsted acids: An alternative pathway

An alternative synthetic pathway to prepare norfloxacin analogues is presented. Three Lewis acids (CeCl₃·7H₂O, AlCl₃·6H₂O, ZnCl₂) and one Brönsted acid (TsOH) were tested as catalysts in the preparation of 3,4-difluoroacrylate. Cyclization of this acrylate at 55 °C was achieved with the use of Eaton's reagent (P₂O₅/MeSO₃H) a known Brönsted acid. The fluoroquinolone-boron complex presented high yields on C-7 nucleophilic substitution of the fluorine atom by different heterocyclic amines with low, medium and strong nucleophilic character.     

Chlorination and decarboxylation of (heptafluoronaphthalen-2-yl)acetic acid. Synthesis of 2-(dichloromethyl)- and 2-(difluoromethyl)heptafluoronaphthalenes

Decarboxylation of (heptafluoronaphthalen-2-yl)acetic acid in DMF in the presence of NaHCO₃ gave 2-methylheptafluoronaphthalene, and treatment with PCl₅ on heating afforded dichloro(heptafluoronaphthalen-2-yl)acetic acid. Decarboxylation of the latter in DMF led to the formation of 2-(dichloromethyl)-heptafluoronaphthalene which was converted to 2-(difluoromethyl)heptafluoronaphthalene by heating with cesium fluoride.     

Salts of maleic and fumaric acids with oxine: the role of isomeric acids in hydrogen‐bonding patterns

Both maleic and fumaric acid readily form adducts or complexes with other organic molecules. The 1:1 adduct formed by quinolin‐8‐ol (oxine) with maleic and fumaric acid are salts, namely 8‐hydroxyquinolinium hydrogen maleate, C₉H₈NO⁺·C₄H₃O₄⁻, (I), and 8‐hydroxyquinolinium hydrogen fumarate, C₉H₈NO⁺·C₄H₃O₄⁻, (II). The cations and anions of both salts are linked by ionic N⁺—H...O⁻ hydrogen bonds. The maleate salt crystallizes in the space group P2₁2₁2₁, while the fumarate salt crystallizes in P. The maleic and fumaric acids in their complex forms exist as semimaleate and semifumarate ions (mono‐ionized state), respectively. Classical N—H...O and O—H...O hydrogen bonds, together with short C—H...O contacts, generate an extensive hydrogen‐bonding network. The crystal structures of the maleate and fumarate salts of oxine have been elucidated to study the importance of noncovalent interactions in the aggregation and interaction patterns of biological molecules. The structures of the salts of the Z and E isomers of butenedioic acid (maleic and fumaric acid, respectively) with quinolin‐8‐ol are compared.     

Isopoly-molybdic acids

From the measurements of conductivity, diffusion coefficient etc., Jander indicated the presence of several isopoly-anions of molybdenum under different pH conditions. He and subsequent workers in the field dealt with solutions only. In the present work one free molybdic acid, and one ammonium acid molybdate were isolated in solid condition at pH 4.6 and 2. On analysis, their compositions were found to be H₄Mo₃O₁₁ and NH₄H₅Mo₆O₂₁ (or (NH₄)₂H₄Mo₇O₂₄) respectively.     

Multi-component hydrogen-bonding salts formed between imidazole and aromatic acids: Synthons cooperation and crystal structures

Imidazole base was crystallized with different aromatic carboxylic acids 2,4-dihydroxybenzoic acid, 5-chlorosalicylic acid, and 1,8-naphthalic acid, affording three new binary molecular organic salts of [(C 3 H 5 N 2 + )·(C 7 H 5 O 4 )] (1), [(C 3 H 5 N 2 + )·(C 7 H 4 O 3 Cl )] C 7 H 5 O 3 Cl (2), and [(C 3 H 5 N 2 + ) (C 12 H 7 O 4 )] (3). Proton transfer occurs from the COOH of carboxylic acid to nitrogen of imidazole in all complexes (1-3), leading to the hydrogen bond N-H…O in all structures. To our knowledge, the recognition pattern between the carboxylic acid group and imidazole (acid-imidazole synthon) is less well-studied so far. The cooperation among COOH, COO and imidazolium cation functional groups for the observed hydrogen bond synthons is examined in the three structures. Generally, the strong N-H…O and O-H…O hydrogen bonds define supramolecular architecture and connectivity within chains, while weaker C-H…O hydrogen bonds play the dominant role in controlling the interactions between layers in these novel organic salts. Thermal stability of these compounds has been investigated by thermogravimetric analysis (TGA) of mass loss.     

S‐((Phenylsulfonyl)difluoromethyl)thiophenium Salts: Carbon‐Selective Electrophilic Difluoromethylation of β‐Ketoesters, β‐Diketones,and Dicyanoalkylidenes

S‐((Phenylsulfonyl)difluoromethyl)thiophenium salts were designed and prepared by a triflic acid catalyzed intramolecular cyclization of ortho‐ethynyl aryldifluoromethyl sulfanes. The thiophenium salts were found to be efficient as electrophilic difluoromehtylating reagents for introduction of a CF₂H group to sp³‐hybridized carbon nucleophiles such as of β‐ketoesters and dicyanoalkylidenes. The (phenylsulfonyl)difluoromethyl group can be readily transformed into CF₂H under mild reaction conditions. Enantioselective electrophilic difluoromethylation was also achieved in the presence of bis(cinchona) alkaloids.     

Sorption of strontium and lanthanum on polyantimonic acid and two phosphatoantimonic acids

The sorption of strontium and lanthanum on antimonic acid (HAP) and on two phosphatoantimonic acids, H₃Sb₃O₆(PO₄)₂ (RH3) and H₅Sb₅O₁₂(PO₄)₂ (RH5) were studied by three types of measurements: kinetics of fixation, distribution coefficients at trace level and sorption capacity. A 2H⁺/Sr²⁺ or 3H⁺/La³⁺ exchange stoichiometry and an affinity order of HAP>RH5>RH3 for Sr and RH3>HAP>RH5 for La were observed. The fixation kinetics is very fast for RH3. For HAP and RH5, there is a fast step followed by a slow diffusion-controlled step. The results are interpreted by comparing the chemical compositions and crystal structures of the three sorbents. Applications to radioactive waste treatment are discussed.     

S‐((Phenylsulfonyl)difluoromethyl)thiophenium Salts: Carbon‐Selective Electrophilic Difluoromethylation of β‐Ketoesters, β‐Diketones,and Dicyanoalkylidenes

S‐((Phenylsulfonyl)difluoromethyl)thiophenium salts were designed and prepared by a triflic acid catalyzed intramolecular cyclization of ortho‐ethynyl aryldifluoromethyl sulfanes. The thiophenium salts were found to be efficient as electrophilic difluoromehtylating reagents for introduction of a CF₂H group to sp³‐hybridized carbon nucleophiles such as of β‐ketoesters and dicyanoalkylidenes. The (phenylsulfonyl)difluoromethyl group can be readily transformed into CF₂H under mild reaction conditions. Enantioselective electrophilic difluoromethylation was also achieved in the presence of bis(cinchona) alkaloids.     

Extraction of Am(III) from different acid media by di-2-ethyl hexyl phosphoric acid containing phosphorous pentoxide

The extraction of Am(III) from nitric, hydrochloric, oxalic, phosphoric and hydrofluoric acids was studied using 0.4F di-2-ethyl hexyl phosphoric acid (HDEHP) containing 0.1M phosphorous pentoxide (P₂O₅) in dodecane/xylene. The extraction with pure 0.4F HDEHP was found to be negligible from all the media studied. However, the presence of a small amount of P₂O₅ in it increased the extraction substantially. The distribution ratios of Am(III) obtained for HDEHP - P₂O₅ mixture 3M nitric acid containing different concentrations of oxalic acid/phosphoric acid/hydrofluoric acid are in the order of 200-250. The same for 3M hydrochloric acid is very high (800). These distribution ratios are sufficiently high for the quantitative extraction of Am(III) from all the acid media studied. Different reagents such as ammonium oxalate, sodium oxalate, oxalic acid, hydrofluoric acid, sodium carbonate and potassium sulphate were explored for the back extraction of Am(III) from 0.4F HDEHP + 0.1M P₂O₅ in dodecane/xylene. Of these, 0.35M ammonium oxalate and 1M sodium carbonate were found to be most suitable. The back extraction of Am(III) was also attempted with water and 1M H₂SO₄, HNO₃, HClO₄ and HCl solutions after allowing the extracted organics to degrade on its own. It was found that more than 90% of Am could be back extracted with these acids. Using this method more than 90% of Am(III) was recovered from nitric acid solutions containing calcium and fluoride ions.     

Adenosine hypodiphosphate ester,an analogue of ADP: analysis of the adenine–hypodiphosphate interaction mode in hypodiphosphate nucleotides and adenine salts

Adenosine diphosphate (ADP) plays a crucial role in cell biochemistry, especially in metabolic pathways and energy storage. ADP itself, as well as many of its analogues, such as adenosine hypodiphosphate (AhDP), has been studied extensively, in particular in terms of enzymatic activity. However, structural studies in the solid state, especially for AhDP, are still missing. An analogue of ADP, i.e. adenosine hypodiphosphate ester, has been synthesized and characterized in the crystalline form as two hydrated sodium salts of 2′:3′‐isopropylideneadenosine 5′‐hypodiphosphate (H₃AhDP, C₁₃H₁₉N₅O₉P₂ for the neutral form), namely pentasodium tetrakis(2′:3′‐isopropylideneadenosine 5′‐hypodiphosphate) tetracosahydrate, 5Na⁺·3C₁₃H₁₈N₅O₉P₂⁻·C₁₃H₁₇N₅O₉P₂²⁻·24H₂O or Na₅(H₂AhDP)₃(HAhDP)·24H₂O, (I), and sodium tetrakis(2′:3′‐isopropylideneadenosine 5′‐hypodiphosphate) pentadecahydrate, Na⁺·C₁₃H₂₀N₅O₉P₂⁺·2C₁₃H₁₈N₅O₉P₂⁻·C₁₃H₁₉N₅O₉P₂·15H₂O or Na(H₄AhDP)(H₃AhDP)(H₂AhDP)₂·15H₂O, (II). Crystal structure analyses of (I) and (II) reveal two nucleoside hypodiphosphate ions in the asymmetric units with different ionization states of the hypodiphosphate unit and adenine base. For all AhDP nucleotides, the same anti conformation about the N‐glycosidic bond and similar puckering of the ribose ring have been found. AhDP geometry and interactions have been compared to ADP nucleotides deposited in the Cambridge Structural Database. The adenine–hypodiphosphate interactions, identified as defining nucleotide self‐assembly, have been analysed in model systems, i.e. the adenine (Ade) salts of hypodiphosphoric acid, namely bis(adeninium) hypodiphosphate dihydrate, 2C₅H₆N₅⁺·H₂P₂O₆²⁻·2H₂O or (AdeH)₂(H₂P₂O₆)·2H₂O, (III), and bis(adeninium) hypodiphosphate, 2C₅H₆N₅⁺·H₂P₂O₆²⁻ or (AdeH)₂(H₂P₂O₆), (IV).     

Phosphorus pentoxide supported on silica gel and alumina (P2O5/SiO2, P2O5/Al2O3) as useful catalysts in organic synthesis

Phosphorus pentoxide supported on silica gel or alumina (P₂O₅/SiO₂, P₂O₅/Al₂O₃) has been used in many organic transformations as versatile solid catalysts. These catalysts have received considerable attention as an inexpensive, eco-friendly, highly reactive, easy to handle and non-toxic acid catalyst for various organic transformations, affording the corresponding products in excellent yields and high selectivity. In this review, some applications of these catalysts in organic reactions are discussed.     

Photofragmentation of alpha-oxocarboxylic acids in aqueous solution. An EPR study. Formation of semidione radicals by decarboxylative substitution of alpha-oxocarboxylic acids by acyl radicals--II. Oxaloacetic acid (oxosuccinic acid).

Abstract— –On in situ photolysis (Λ= 250–400 nm) of aqueous oxaloacetic acid solutions, between pH 5 and 10, the radicals ^-O₂CCH₂C(O^->=C(O⁺)CH₂CO₂^- and ^-O₂CCH₂C(OH)CO₂ are identified. With acetone present, CH₂CO₂, CH₃C(OH)CO^-₂, CH₃C(O^-)=C(O)CH₂CO₂ and -O₂CCHCOCO₂ are also observed. CO₂ and CO are identified as reaction products. The experimental results are explained in terms of α-cleavage of the electronically excited keto-isomer dianion of oxaloacetic acid to yield O₂CCH₂CO and CO₂^-. ^-O₂CCH₂CO adds to the keto-isomer of oxaloacetic acid and to pyruvic acid, which is formed from oxaloacetic acid by thermal decarboxylation, to yield ^-O₂CCH₂C(O^-)= C(O^-)CH₂C0^- and CH₃C(O^-)=C(O)CH₂CO^-₂, respectively, via a decarboxylase substitution reaction. CH₂CO₂ is derived from ^-O₂CCH₂CO by decarbonylation. CO₂^- is scavenged by oxaloacetic acid and pyruvic acid to yield O₂CCH₂C(OH)CO₂ and CH₃C(OH)CO₂^-, respectively.     

Synthesis and Properties of Inorganic Triphosphate Crystal Hydrates

Abstract

The polycrystalline samples and single crystals of crystal hydrates of inorganic triphosphates with ring-like and chain-like anion structured were synthesized: lithium and sodium cyclotriphosphates, sodium and ammonium chain triphosphates, and double salts of chain triphosphoric acid (ammonium-potassium, ammonium-magnesium, ammonium-manganese). The crystallization field of the double salt of variable composition (NH₄,K)₃H₂P₃O₁₀ ·xH₂O (NH₄ :K=0.23–3.60; x=0.8–1.5) from aqueous solutions was established. Synthesis of Na₅P₃O₁₀ · 6D₂O crystals has been performed by the interaction of the high temperature form Na₅P₃O₁₀ (I) with D₂0. At 20°C and relative humidity RH < 70–80% the (NH₄) ₅P₃O₁₀·2H₂O crystals lose their transparency and generate different crystalline products depending on RH value: (NH₄)₅P₃O₁₀ at RH=0% or (NH₄)₅P_{3 10} · H₂O at RH=32%. The (NH₄) ₅P₃ O₁₀ · H₂O crystals are stable at RH < 60–70%, at RH=80% they absorb water and transform into (NH₄) ₅P₃O₁₀ · 2H₂0. In the latter case a characteristic picture is registered: on active sites situated on the (NH₄) ₅P₃O₁₀ · H₂O crystal face the appearance and epitaxial growth of (NH₄) ₅P₃O₁₀ · H₂O crystals is observed. For some single crystals the character of dehydration localization has been shown to correlate with space arrangement of phosphate groups in crystal structure. On the basis of the obtained results a model of dehydration front propagation in crystals has been suggested.     

Reactions of dimethyl(dimethylsulphoxide)pentamethylcyclopentadienyl-rhodium and -irridum with acids

The complexes [C₅Me₅MMe₂(Me₂SO)] (Ia, M = Rh; Ib, M = Ir) react with p-toluenesulphonic acid in acetonitrile to give [C₅Me₅MMe(Me₂SO)(MeCN)]⁺, (II), and with trifluoroacetic acid to give first [C₅Me₅MMe(Me₂SO)(O₂CCF₃)] and then [C₅Me₅M(Me₂SO)(O₂CCF₃)₂]. Complexes II react with halide (X^?) to give the halomethyl complexes [C₅Me₅MMe(X)(Me₂SO)]. The IR, far-IR, ¹H and ¹³C NMR spectra are all in agreement with structures proposed.     

Direct Sulfonylation of Aromatic Rings with Aryl or Alkyl Sulfonic Acid Using Supported P2O5/Al2O3

Direct sulfonylation of aromatic rings with aryl or alkyl sulfonic acid supported P₂O₅/Al₂O₃ (w/w 50%) under heterogeneous conditions in short reaction time and high yields.     

SIFT studies of the reactions of H3O+, NO+ and O+2 with a series of volatile carboxylic acids and esters

We report the results of a selected ion flow tube (SIFT) study of the reactions of H₃O⁺, NO⁺ and O⁺₂ with some nine carboxylic acids and eight esters. We assume that all the exothermic proton transfer reactions of H₃O⁺ with all the acid and esters molecules occur at the collisional rate, i.e. the rate coefficients, k, are equal to k_c; then it is seen that k values for most of the NO⁺ and O⁺₂ reactions also are equal to or close to k_c. The major ionic products of the H₃O⁺ reactions with both the acids and esters are the protonated parent molecules, MH⁺, but minor channels are also evident, these being the result of H₂O elimination from the excited (MH⁺)1 in some of the acid reactions and an alcohol molecule elimination (CH₃OH or C₂H₅OH) in some of the ester reactions. The NO⁺ reactions with the acids and esters result in both ion-molecule association producing NO⁺M in parallel with hydroxide ion (OH⁻) transfer with some of the acids, and parallel methoxide ion (CH₃O⁻) and ethoxide ion (C₂H₅O⁻) transfer as appropriate with some of the esters. The O⁺₂ reactions proceed by dissociative charge transfer with the production of two or more ionic fragments of the parent molecules, the different isomeric forms of both the acid and the ester molecules resulting in different product ions.     

Acid-Mediated Specific α,α-Diarylation And A-Monoarylation Reactions Of Pyruvic Acid With/Without Decarbonylation

Pyruvic acid (3) was found to be arylated chemoselectively at the a-ketocarbonyl carbon in P₂O₅-MsOH affording decarbonylative α,α-diarylated products 5, decarbonylative a-monoarylated compounds 6, or non-decarbonylative α,α-diarylated adducts 7 depending on the reactivity of arenes (4a-g), in contrast to Lewis acid-catalyzed reaction of its acid chloride (2).     

Darstellung und Untersuchung von Difluormethylsubstituierten Aminen

Preparation and Investigation of Difluoromethyl-substituted Amines N-Methyl- ( 6a ), N-ethyl-bis(difluoromethyl)-amine ( 6b ), and tris(difluoromethyl)-amine ( 7 ) were prepared by fluorination of the corresponding chloro compounds ( 2a , 2b , 5 ) with antimony(III) fluoride. The reaction of N-methyldiformamide ( 1a ) with carbonylfluoride led under special conditions to the already unknown α,α-difluorodimethylformamide ( 8 ). 6a , 6b , and 7 were proven to be molecules with covalent carbon-fluorine bonds. By reaction of 6a with antimony(V) or boron(III) fluoride a fluoride ion could be split off from a difluoromethyl group. The vibrational spectrum of 7 was assigned and supported to a plane configuration of the NC₃ skeleton and C_3h molecular symmetry.     

Preparation and biodistribution of 131I-labeled graphene quantum dots

Uranium sorption from commercial phosphoric acid was carried out onto kaolinite and metakaolinite. The different factors affecting uranium adsorption have been investigated. The obtained results show that, the sorption process is applicable for the high strength phosphoric acid, 40% P₂O₅, and diluted phosphoric acid, 20% P₂O₅, but it preferred to the diluted phosphoric acid. The kinetic models applied to the sorption rate data were evaluated for Lagergren first order and the pseudo second order models. From the results, the uranium sorption from commercial phosphoric acid, 40% P₂O₅, onto kaolinite and metakaolinite was found to occur through physical sorption process.