Convenient and High-Yielding Preparations of Mono(5-carboxy-2-ethylpentyl) Phthalate and its Ring-Deuterated Isomer – The “Third” Major Metabolite of Bis(2-ethylhexyl) Phthalate

The synthesis of an oxidative major metabolite of bis(2-ethylhexyl) phthalate is described. The target molecule and its ring-deuterated isomer were obtained via acylation of the appropriate -hydroxy benzyl ester or the corresponding carboxylate with phthalic anhydride or phthalic anhydride-d₄. All transformation steps proceed with high yields.     

A Novel Dimeric Eremophilane from Ligularia virgaurea spp. oligocephala

A novel dimeric eremophilane, ligulolide B, was isolated from the alcoholic extract of the whole plant of Ligularia virgaurea spp. oligocephala. The structure was elucidated by various spectroscopic methods including intensive 2D NMR techniques （^1H-^1H COSY, gHMQC, gHMBC and ^1H-^1H NOESY） and HR-ESI-MS.     

Convenient and High-Yielding Preparations of Mono(5-carboxy-2-ethylpentyl) Phthalate and its Ring-Deuterated Isomer – The “Third” Major Metabolite of Bis(2-ethylhexyl) Phthalate

Summary. The synthesis of an oxidative major metabolite of bis(2-ethylhexyl) phthalate is described. The target molecule and its ring-deuterated isomer were obtained via acylation of the appropriate -hydroxy benzyl ester or the corresponding carboxylate with phthalic anhydride or phthalic anhydride-d₄. All transformation steps proceed with high yields.     

Monophthalates with Oxidized C5-Carbon in the Ester Chain: A Simple Synthetic Access to Two Major Metabolites of Bis-(2-ethylhexyl)-phthalate

Summary.  The synthesis of two oxidized metabolites of bis-(2-ethylhexyl)-phthalate is described. The target structures were obtained by esterification of the appropriate alcohol carrying a protected hydroxy group with phthalic anhydride, followed by deprotection and further oxidation. Received February 26, 2002. Accepted March 6, 2002     

(2-Ethyl-5-oxo-hexyl) Methylthiomethyl Phthalate as By-product of the Swern Oxidation: Improved Synthesis of Ring-deuterated Major Metabolites of Bis(2-ethylhexyl) Phthalate

Summary. Two ring-deuterated major metabolites of bis(2-ethylhexyl) phthalate were obtained in excellent yields by means of an improved oxidation procedure. The by-product of their interconversion by Swern oxidation is elucidated and a possible mechanism of its formation is proposed.Received February 27, 2003; accepted March 3, 2003 Published online July 28, 2003     

Eigenvalues of a statistical mechanics matrix

We consider the problem of finding the spectrum of an n × n matrix which arises in the study of a certain model of long-range interactions in a one-dimensional statistical mechanics system. Our analysis exhibits a curious resemblance of the suitably normalized distribution of eigenvalues to the Marčenko–Pastur law in the limit n → ∞.     

Many years of experiences in internal quality control in the toxicological analysis of biological material in the field of occupational medicine

Summary Toxicological analysis in blood and urine for biological monitoring of occupationally exposed persons must be carried out in the Federal Republic of Germany under an internal and external quality control scheme. The results of many years of experiences with 5 commercially available control specimens (1 blood, 1 serum, 3 urine samples) from three companies for internal quality assurance are presented. Precision and accuracy were evaluated by comparison of our results with the data of the initial period (within day precision of the methods) and the assigned values. Over years the commercially available control specimens show good comparable results. Except in a few cases, there was a good agreement between our results and the assigned values. An expected worldwide increase of the importance of biological monitoring makes the availability of control specimens for everyday use a prerequisite in effective internal quality control. This is especially valid for the determination of organic compounds, e.g. solvents and pesticides in blood and urine samples.