Regio- and Stereoselective Reactions of 17-Phenyl-18,19,20-trinorprostaglandin F(2)(alpha) Isopropyl Ester

Novel prostaglandin F(2)(alpha) derivatives, functionalized at C13 and C14, have been prepared. 17-Phenyl-18,19,20-trinorprostaglandin F(2)(alpha) isopropyl ester [(15S)-1] and its epimer [(15R)-1] were stereoselectively epoxidized, using Sharpless conditions, to produce each of the four diastereomeric epoxides (15S)-2, (15S)-3, (15R)-2, and (15R)-3. Treatment of the four epoxides with LiOH stereospecifically-produced the pentahydroxy substituted analogues 12 and 13. Alternatively, epoxides 2 and 3were allowed to react with thiophenolate ion. The attack of the sulfur nucleophile on the epoxide occurred at either C13 or C14 depending on the stereochemistry of the epoxide and of C15.     

On-line enzymatic reaction,extraction, and chromatography of fatty acids and triglycerides with supercritical carbon dioxide

Supercritical carbon dioxide can be utilized both as an introduction solvent in capillary SFC and as a reaction medium; both possibilities are illustrated in this study. An off-line SFE unit was modified for on-line SFE-SFC. To facilitate rapid depressurization of the extraction cell and to prevent memory effects, a 6-port valve was installed at the outlet line of the extraction unit. An increased background signal was obtained when PEEK polymer was used in the construction of the extraction vessel; when stainless steel was used, the blanks improved. The synthesis of methyl esters and butyl esters of fatty acids from triglycerides in edible fat was examined using an immobilized lipase as a catalyst in on-line SFE-SFC. As a result of 30 minutes reaction – extraction time, high yields of fatty acid esters were obtained at a pressure of 150 bar and a temperature of 50°C.     

Analysis of aerosols at the bosporus bridge of Istanbul

Air samples collected at the second Bosporus bridge of Istanbul which carries a heavy traffic load between Asia and Europe, were analyzed for 22 elements by the INAA method. Pb, Cd and Fe concentrations in the samples were determined by AAS. Iron concentrations were used as a cross check between the two methods. In order to define the enrichment factors for the elements in the bridge area, a sample collected from our university campus which can be considered as a rural site, was also analyzed. Differences were observed especially for Br, Al, Mg, Ti, Cu and Na between the two sites. Based on the results of the samples from the bridge, we got a value of 0.58(16) for the Br/Pb-ratio.     

Synthesis and photophysics of one mononuclear Mn(III) and one dinuclear Mn(III,III) complex covalently linked to a ruthenium(II) tris(bipyridyl) complex

The preparation of donor (D)-photosensitizer (S) arrays, consisting of a manganese complex as D and a ruthenium tris(bipyridyl) complex as S has been pursued. Two new ruthenium complexes containing coordinating sites for one (2a) and two manganese ions (3a) were prepared in order to provide models for the donor side of photosystem II in green plants. The manganese coordinating site consists of bridging and terminal phenolate as well as terminal pyridyl ligands. The corresponding ruthenium-manganese complexes, a manganese monomer 2b and dimer 3b, were obtained. For the dimer 3b, our data suggest that intramolecular electron transfer from manganese to photogenerated ruthenium(III) is fast, k(ET) > 5 x 10(7) s(-)(1).     

On the construction of least favourable pairs of distributions

Summary Convex programming techniques were used by Witting and Krafft in [4] in order to reduce a testing problem for composite hypotheses to one for simple hypotheses. This is realized in terms of least favourable pairs of distributions, which represent the solution of the dual of a suitable program. Without further assumptions on the hypotheses, however, the results, derived that way (cf. Baumann [1], Österreicher [6] and Kusolitsch and Österreicher [5]), are of less practical impact. This is due to the fact that in this case the least favourable pairs depend on the level of the testing problem. Conditions avoiding this, were given by Huber and Strassen in [3]. These conditions make use of 2-alternating capacities in the sense of Choquet. The present paper offers a rather general principle of constructing the least favourable distribution in the case, when one of the two hypotheses is simple. This method works also for the local variation model and the Prohorov neighbourhood model in the case of monotone likelyhood ratio. For simple cases—subsuming the gross error model and the total variation model, for which the solution was given by Huber in [2]—a least favourable pair is obtained by using the mentioned technique of construction two times successively.     

Molecular structure and conformation of gaseous bromoacetyl chloride and bromoacetyl bromide as determined by electron diffraction

Bromoacetyl chloride and bromoacetyl bromide are studied by gas phase electron diffraction at nozzle-tip temperatures of 70°C and 77°C, respectively. Both compounds exist as mixtures of anti and gauche conformers. The mole fraction anti, with uncertainties estimated at 2σ, was found to be 0.474(0.080) for bromoacetyl chloride and 0.615(0.069) for bromoacetyl bromide. The results for the distance (r_a)and angle (∠α) parameters, with parenthesized uncertainties of 2σ including estimated uncertainty in the electron wave length and correlation effects are as follows: (1) bromoacetyl chloride, r(C-H) = 1.086(0.062) Å, r(CO) = 1.188(0.009) Å, r(C-C) = 1.519(0.018) Å, r(C-Cl) = 1.789(0.011) Å, r(C-Br) = 1.935(0.012) Å, ∠C-CO = 127.6(1.3)°, ∠C-C-Cl = 111.3(1.1)°, ∠C-C-Br = 111.0(1.5)°, ∠H-C-H = 109.5°(assumed), $\text{}\text{?}$/o (gauche torsion angle relative to 0° for the anti form) = 110.0°(assumed); (2) bromoacetyl bromide, r(C-H) =1.110(0.088) Å, r(C=O) = 1.175(0.013) Å, r(C-C) = 1.513(0.020) Å, r(CO-Br) = 1.987(0.020) Å, r(CH₂-Br) = 1.915(0.020) Å, ∠C-CO = 129.4(1.7)°, ∠CH₂-CO-Br = 110.7(1.5)°, ∠CO-CH₂-Br = 111.7(1.8)°, ∠H-C-H = 109.5°(assumed), ∠ø (gauche torsion angle relative to 0° for the anti form) = 105.0°(assumed). The structural results are discussed in connection with the structures of related molecules.     

Determination of D- and L-amino acids in biological samples by two-dimensional column liquid chromatography

Summary A two-dimensional, column liquid chromatographic system is used for the determination of the D- and L-enantiomers of amino acids in biological samples. Separation of the amino acids is first on ion-exchange column by gradient elution with a sodium citratesodium chloride buffer. Enantioseparation is by subsequent injection of 3 l heart-cuts of the individual amino acids onto a second column with a chiral crown ether stationary phase. Finally, fluorescence detection is after post-column labelling of the amino acids using ano-phthalaldehyde-2-mercaptoethanol reagent solution. The high separation power and selectivity of the system allow processing of complex samples with hardly any additional treatment and the determination of small quantities of D-amino acids in the presence of excess L-form. Applicability of the system is illustrated by the determination of D- and L-aspartate, serine, glutamate and alanine in various complex biological samples, such as protein hydrolysates, urine and biotechnological and food samples. Data are given on detectability, repeatability and linearity.     

Spectrothermal studies of 1,10-phenanthroline complexes of Co(II), NI(II), Cu(II) and Cd(II) orotates

The 1,10-phenanthroline (phen) complexes of Co(II), Ni(II), Cu(II) and Cd(II) orotates were synthesized and characterized by elemental analysis, magnetic susceptibility, spectral methods (UV-vis and FTIR) and thermal analysis techniques (TG, DTG and DTA). The Co(II), Ni(II), Cu(II) and Cd(II) ions in diaquabis(1,10-phenanthroline)metal(II) diorotate octahedral complexes [M(H₂O)₂(phen)₂](H₂Or)₂·nH₂O (M=Co(II), n=2.25; Ni(II), n=3; Cu(II) and Cd(II), n=2) are coordinated by two aqua ligands and two moles of phen molecules as chelating ligands through their two nitrogen atoms. The monoanionic orotate behaves as a counter ion in the complexes. On the basis of the first DTG_max, the thermal stability of the hydrated complexes follows the order: Cd(II), 68°C 68°C     

The molecular structure of gaseous 2-cyclopentene- 1,4-dione as determined by electron diffraction

The molecular structure of gaseous 2-cyclopentene-1,4-dione has been studied by electron diffraction. The molecule is planar to within the experimental error. The results obtained for some of the more important parameters with estimated uncertainties of 2σ are r(C-H) = 1.093 Å (0.013), r(C0) = 1.208 Å (0.002), r(CC) = 1.341 Å (0.005), r(CH-CO) = 1.493 Å (0.005), r(CO-CH₂) = 1.525 Å (0.005), ∠CC-C = 110.4° (0.3), ∠CH-CO = 124.9° (1.1), ∠CC-H. = 118.7° (5.8), ∠H-C-H = 113.2° (8.7) l(C-H) = 0.0853 A (0.0113), l(CO) = 0.0428 Å (0.0021), l(CC) = 0.0448 Å (0.0037) and l(C-C) = 0.0561 Å (0.0029). The structure is discussed in connection with the structures of related molecules.     

Trimethylsilylcyanid als Umpolungsreagens,VI. Anionische 1,4- O→C-Silylgruppen-Umlagerung

Trimethylsilyl Cyanide — A Reagent for Umpolung, VI. Anionic 1,4-O→C-Silyl Group Rearrangement The adducts 6 from substituted acroleins 5a – f and trimethylsilyl cyanide form the anions 6 _A on deprotonation at −78°C, which are silylated by trimethylsilyl chloride to 7 or (and) 8 in positions 3 or (and) 1. On warming up to room temperature, 6a _A and 6b _A undergo smoothly 1,4-O→C-silyl group rearrangements to form 13a _A and 13b _A which can be trapped by silylation. 6c – d _A decompose on warming up. Triethylsilyl instead of trimethylsilyl groups decelerate the rearrangement appreciably. Structure and configuration of the different products are determined.