Massoud Hojjatie

Extraction of selected tervalent lanthanides with N-phenylacylhydroxamic acids

Abstract the extraction behavior of certain tervalent lanthanides into chloroform solutions containing various N-phenylacylhydroxamic acids is reported. The ligands include N-o-methylphenyl-m-trifluoromethylbenzohydroxamic acid (MPFBHA), N-m-trifuloromethylphenyl-o-methylbenzohydroxamic acid (FPMBHA), N-o-methylphenylbenzohydroxamic acid (MPBHA), N-phenyl-o-methylbenzohydroxamic acid (PMBHA), N-o-methylphenyl-p-tertbutylbenzohydroxamic acid (MPBBHA), and N-phenyl-p-tert-butylbenzohydroxamic acid (PBBHA). Of the N-phenylacylhydroxamic acids mentioned, only PBBHA was found suitable to extract the lanthanides under the experimental conditions used. The selected lanthanides, namely La, Pr, Eu, Ho, and Yb, were all found to extract with PBBHA as self-adducts of the form LnL3 · 2 HL, where L and HL denote the ligand anion and neutral ligand, respectively. The extraction constants and separation factors for the lanthanides with PBBHA were evaluated. It is possible that steric hindrance prevents the lanthanides from extracting with MPFBHA, FPMBHA, MPBHA, PMBHA, or MPBBHA.

Liquid-liquid extraction and spectrophotometric determination of palladium with 2-mercaptobenz-amide

Abstract 2-Mercaptobenzamide (MBA) was investigated as a reagent for the extraction of palladium. The palladium complex of MBA was extracted into tributyl phosphate (TBP). The pKa of the ligand was 5.45 with the stability constant of the palladium complex β2=107.1. The composition of the complex in TBP was Pd:MBA:TBP=1:2:2. Addition of sodium chloride accelerated the rate of extraction. Various interfering ions could be masked with EDTA; Ag(I), Au(III), Os(VIII), Se(IV), Te(IV) etc. interfered. The molar absorptivity was 1.59×104 l mol−1 cm−1; 1–35 μg Pd could be determined at pH 6.0.

The effect of substituents on the extraction behavior of hydroxamic acids

Abstract The extraction behavior of several alkyl-substituted hydroxamic acids in chloroform solution with several metal ions is described. Among the N-phenylacylhydroxamic acids used, those with o-alkyl substituents on either the phenyl or acyl ring generally do not extract metals, apparently because of steric problems at the O=CNO− chelation site. An improved synthesis of substituted hydroxamic acids is reported.

Electron Transfer from Thioethers

Abstract Oxidation of thioethers is greatly facilitated by neighboring group participation by carboxylate, alcohol, and thioether moieties.

Extraction of lanthanides with 8-quinolinol in the presence of 6-amino-4,4′-(5-nonyl)-2,2′-bipyridine

Abstract 6-Amino-4,4′-(5-nonyl)-2,2′-bipyridine (ADNBP) is studied for adduct formation in combination with 8-quinolinol (HQ) for lanthanide extractions. Ytterbium, praseodymium and lanthanum are extracted as mixed complexes, LnQ 3 · ADNBP. 8-Quinolinol did not form self-adducts in these systems under the given conditions. Extractabilities are enhanced dramatically by ADNBP.

A Short and Convenient Synthesis of 5-Alkyl Substituted 8-Hydroxyquinolines

Abstract 5-Chloro-8-methoxyquinoline undergoes rapid and reversible lithium-halogen exchange reaction with alkyllithiums to yield 5-alkyl substituted derivatives indirectly, whereas the reaction with phenyllithium is slower and 5-alkyl substituted compounds are formed by the direct addition of alkyl halides.