S. Lazar

Removal of two textile dyes from aqueous solutions onto calcined bones

Abstract The adsorption of textile dyes such as Direct Red 75 and Direct Red 80 onto calcined bone was studied for their removal from aqueous solutions. The adsorption of Direct Red 75 and Direct Red 80 occurred by studying the effects of adsorbent amount, dye concentration, contact time, pH media and temperature. The adsorption rate data were analyzed using the intraparticle diffusion model, pseudo first order and the pseudo second order kinetic models to determine adsorption rate constants. The isotherms of adsorption data were analyzed by various adsorption isotherm models such as Langmuir, Freundlich and Tempkin. All results found concluded that calcined bone could be effectively employed as an effective new low cost adsorbent for the removal of textile dyes from aqueous solutions.

A Selective Removal of Benzyl Protecting Groups in Arylphosphate Esters with Bromotrimethylsilane

Abstract Bromotrimethylsilane (BTMS) is shown to be an effectively selective reagent for the debenzylation of dibenzyl arylphosphate esters to give the corresponding arylphosphate acids and does not affect other functional groups also present in the molecular structure.

Synthesis and biological activity of the phosphate and sulfate esters of naloxone and naltrexone

Abstract Prodrugs of the two opiate antagonists naloxone and naltrexone, in particular the 3-monophosphate, 3-triphosphate, 3-monosulfate and 3,14-disulfate esters, have been synthesized and evaluated for: i) their ability to bind opioid receptors in vitro ; and ii) their stability in both space and time upon entrapment into ex vivo human red blood cells (RBC). We find that, unlike the other esters, the mono- and triphosphate esters of naloxone and naltrexone retain high (in the nmol range) affinities especially for μ- and κ-opioid receptors. Owing to their hydrophilic nature, the two esters could possibly help in certain types of pharmacological experiments. Moreover, upon entrapment into human RBC, the triphosphate esters of naloxone and naltrexone display considerable ex vivo intracellular stability.

Synthesis of New Compounds Containing the 2,3-dihydro-1, 4-dioxino[2,3-b]pyridine Heterocyclic System as a Substructure:

2,3-Dihydro-spiro[1,4]dioxino[2,3-b]pyridine-3,3′-pyrrolidine (8A) and 2,3-dihydro-spiro[1,4]dioxino[2,3-b]pyridine-3,4′-piperidine (9A) have been synthesized from 2-chloro-3-pyridinol. The corresponding 2,3′ (8B) and 2,4′ (9B) isomers were obtained via the Smiles rearrangement, while 9B was also selectively synthesized from 2-nitro-3-pyridinol. The separation of the isomers A and B under the sulfamide form was carried out by flash column chromatography. Subsequent transformations of the corresponding dioxinopyridine derivatives were described.

Simultaneous determination of inorganic anions and methyl and ethylphosphonic acids by anion exchange chromatography using evaporative light scattering detection

Anion exchange chromatography with evaporative light scattering detection was investigated for the direct and simultaneous analysis of methyl and ethylphosphonic acids and inorganic anions in aqueous media. The chromatographic system made up of a Dionex IonPac AS4A-SC column and an aqueous mobile phase containing NH4HCO3 25 mM (pH 7.8) allows the resolution of the two phosphonic acids in less than 10 minutes without coelution of chloride, phosphate, and sulfate. This methodology has been successfully applied to the direct analysis of aqueous matrix containing low levels of phosphonic acids and high levels of inorganic anions (chloride 1700 mg/L, phosphate 1000 mg/L, or sulfate 1200 mg/L) without any baseline perturbation and matrix pretreatment. Quantitative analysis of phosphonic acids is achieved with a good correlation coefficient, and a 200 ng (200 μL of 1 mg/L) detection limit of MPA or EPA is obtainable.

Synthesis of an artificial phosphate bio-isostere of glucotropaeolin

Abstract A synthetic sequence was devised to produce phospho-glucotropaeolin 6 , the first representative of phosphate bio-isosteres of naturally-occurring glucosinolates with a view to enzymatic studies.

New eco-friendly animal bone meal catalysts for preparation of chalcones and aza-Michael adducts

Two efficient reactions were successfully carried out using Animal Bone Meal (ABM) and potassium fluoride or sodium nitrate doped ABMs as new heterogeneous catalysts under very mild conditions. After preparation and characterization of the catalysts, we first report their use in a simple and convenient synthesis of various chalcones by Claisen–Schmidt condensation and then in an aza-Michael addition involving several synthesized chalcones with aromatic amines. All the reactions were carried out at room temperature in methanol; the chalcone synthesis was also achieved in water environment under microwave irradiation. Doping ABM enhances the rate and yield at each reaction. Catalytic activities are discussed and the ability to re-use the ABM is demonstrated.ResultsFor Claisen–Schmidt the use of ABM alone, yields never exceeded 17%. In each entry, KF/ABM and NaNO3/ABM (79-97%) gave higher yields than using ABM alone under thermic condition. Also the reaction proceeded under microwave irradiation in good yields (72-94% for KF/ABM and 81-97% for NaNO3/ABM) and high purity. For aza-Michael addition the use of ABM doped with KF or NaNO3 increased the catalytic activity remarkably. The very high yields could be noted (84-95% for KF/ABM and 81-94% for NaNO3/ABM).ConclusionThe present method is an efficient and selective procedure for the synthesis of chalcones an aza-Michael adducts. The ABM and doped ABMs are a new, inexpensive and attractive solid supports which can contribute to the development of catalytic processes and reduced environmental problems.

Separation of benzodioxinic isomers in LC. A molecular modeling approach for the choice of the stationary phase

Seven couples of position isomers on the aromatic ring of benzodioxinic compounds had to be separated. The tries made on classical systems in gas chromatography or liquid chromatography did not allow the separation. We have studied the structures of solutes by molecular modeling. Many molecular descriptors (lipophilic, electronic and steric) were calculated. Our objective was to compare the relative difference between the isomers in term of lipophilicity, electronic and steric properties and design the chromatographic system where these interactions are dominant. From these results, the porous graphitic carbon stationary phase was chosen and allowed a good separation of all the products.

Isocratic conditions for analysis of inorganic anions by ion exchange chromatography with evaporative light scattering detection

Different volatile carboxylic acids and sublimate salt have been investigated as ion competitors to optimize the separation of four common anions (phosphate, chloride, nitrate, and sulfate) by Ion Exchange Chromatography (IEC) with Evaporative Light Scattering Detection (ELSD) on a Hamilton PRP-X100 (100 × 4.1 mm ID) column. We evaluated the effect of temperature on the response of inorganic anions by ELSD. The latter is especially strong for chloride and nitrate but for sulfate and phosphate the detector response remains essentially temperature-independent in the temperature range studied.

Synthesis of enantiomerically pure 7-hydroxy-2-substituted-2,3-dihydro-1,4-benzodioxin derivatives

Abstract A rapid and simple procedure for the preparation of the two pure enantiomers of 7-hydroxy-2-substituted-2,3-dihydro-1,4-beniodioxin derivatives is described.