Alain Guy

Cloud point extraction : An alternative to traditional liquid-liquid extraction for lanthanides(III) separation

Cloud point extraction (CPE) was used to extract and separate lanthanum(III) and gadolinium(III) nitrate from an aqueous solution. The methodology used is based on the formation of lanthanide(III)-8-hydroxyquinoline (8-HQ) complexes soluble in a micellar phase of non-ionic surfactant. The lanthanide(III) complexes are then extracted into the surfactant-rich phase at a temperature above the cloud point temperature (CPT). The structure of the non-ionic surfactant, and the chelating agent-metal molar ratio are identified as factors determining the extraction efficiency and selectivity. In an aqueous solution containing equimolar concentrations of La(III) and Gd(III), extraction efficiency for Gd(III) can reach 96% with a Gd(III)/La(III) selectivity higher than 30 using Triton X-114. Under those conditions, a Gd(III) decontamination factor of 50 is obtained.

Rapid Synthesis of New DNMT Inhibitors Derivatives of Procainamide

DNA methyltransferases (DNMTs) are responsible for DNA methylation, an epigenetic modification involved in gene regulation. Families of conjugates of procainamide, an inhibitor of DNMT1, were conceived and produced by rapid synthetic pathways. Six compounds resulted in potent inhibitors of the murine catalytic Dnmt3A/3L complex and of human DNMT1, at least 50 times greater than that of the parent compounds. The inhibitors showed selectivity for C5 DNA methyltransferases. The cytotoxicity of the inhibitors was validated on two tumour cell lines (DU145 and HCT116) and correlated with the DNMT inhibitory potency. The inhibition potency of procainamide conjugated to phthalimide through alkyl linkers depended on the length of the linker; the dodecane linker was the best.

Selective synthesis of 1,1′-binaphthalene derivatives by oxidative coupling with TiCl4

Abstract Oxidative coupling of naphthalene compounds with TiCl 4 in nitromethane under mild conditions gives symmetrical 1,1′-binaphthyls in good yields. The method is particularly useful when applied to substrates with electron donating groups.

Selective Strontium Removal from a Sodium Nitrate Aqueous Medium by Nanofiltration - Complexation

In aqueous medium, selective complexation increases the ionic separation by nanofiltration. The combination of nanofiltration and complexation can be applied to the nuclear effluents treatment. To separate radioelements from a sodium salt medium, poly(acrylic acid) is associated to the FILMTEC NF 70 membrane. Effects of transmembrane pressure, pH, ligand concentration and ionic strength on salts retention are described, and the complexation constants are estimated. Finally, to reach the objectives, a strontium two-stages concentration by nanofiltration-complexation with a control of retentate salinity is investigated in a nonactive solution case.

Lipophilic polythiamacrocycles as palladium extracting agents

Abstract Six new lipophilic thiacrown ethers ( 1 – 6 ), abbreviated as 2-octyl-9S3, 2-octyl-10S3, 2-octyl-12S4, 6-octyl-14S4, 3-octyl-16S4 and dioctyl-18S6, were synthesized starting from different dithiols and dihalides. Cs2CO3 is used for the cyclizations. The extraction behavior of palladium (II) from nitric acid media with these reagents in chloroform has been studied in terms of extraction equilibrium constants Kex. The influence of parameters such as lipophilicity brought by alkyl chains, macrocyclic cavity size and number of sulfur donor atoms on the extraction behavior was investigated.

Halogenation regioselective en serie aromatique—II: Chloration des naphtols et de leurs ethers a l'aide de reactifs mettant en jeu des interactions du type donneur-accepteur

Abstract The regiospecific chlorination of naphthols by hexachlorocyclohexadienones as selective chlorinating reagents is described. The selectivity attained is better than that which we have obtained with phenol derivatives and confirms the importance of the donor-acceptor interaction between the reagent and the naphthol during the chlorination.

Regioselective synthesis of N-functionalized 12-membered azapyridinomacrocycles bearing trialkylcarboxylic acid side chains

Abstract Selective protection of primary amine moieties of diethylenetriamine by 2-nitrophenylsulfonyl chloride followed by alkylation of the central N atom generates functionalized disulfonamide building blocks. When reacted with 2,6-bis(bromomethyl)pyridine following the Richman–Atkins methodology, such compounds yield the corresponding pyridine-containing azamacrocycles. Smooth removal of the N-sulfonyl groups provides versatile azamacrocyclic intermediates with transannular secondary amine functions. Subsequent N-alkylation regioselectively leads to tri N-functionalized 12-membered azapyridinomacrocycles bearing a sequence of N-acetate and N-propionate side chains.

Selective ring-opening reaction of styrene oxide with lithium azide in the presence of cyclodextrins in aqueous media

Abstract Regioselective ring-opening of racemic styrene oxide was achieved by lithium azide in the presence of β-cyclodextrin in aqueous media. Kinetic resolution of racemic epoxide was observed and 1-phenyl-2-azido-ethanol was obtained with 78 % ee.

Selective Separation of Lanthanides with Phenolic Resins: Extraction Behavior and Thermal Stability

Catechol, resorcinol, and their admixtures with 8-hydroxyquinoline were converted into polymeric resins by alkaline polycondensation with formaldehyde. The resins were characterized by FTIR spectroscopy, moisture regain, ion-exchange capacity, and distribution coefficient (D) for Eu3+. Thermogravimetric analysis of the polymer samples was studied, and the effect of the sorption of metal ions on their thermal stability was evaluated. Complexation of Eu3+ to the resins was modeled based on metal ion charge neutralization. The selective uptake of Eu3+ from aqueous solutions containing La3+ was investigated, and the ionoselectivities of the resins were compared. The incorporation of 8-hydroxyquinoline in the molecular matrix of the phenolic resins is shown to exert a significant influence upon the competitive sorption of La3+ and Eu3+, leading to their intragroup separation. The separation factors obtained by phenolic ion-exchange resins from aqueous solutions indicate ion-specific resins can be developed for the specific separation of actinide ions from nuclear waste.

Radiolytic products study of dicyclohexano-18-crown-6, a selective extractant for nuclear fuel reprocessing

The radiolytic products of the DCH18C6 obtained after γ-irradiation have been determined, and the seven main structures have been separated and analyzed. The radiolytic product yields range from about 0.01 to nearly 0.3 molecules per 100 eV absorbed by the DCH18C6 at an energy of 3290 kGy. From the viewpoint of radiation decomposition rate, the DCH18C6 presents a considerable resistance and its radiolytic products have little or no extraction power.