In vitro nitrosation of ephedrine in the presence of cyclodextrins

<img src="/content/w35lt05106l26l48/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-, and <img src="/content/w35lt05106l26l48/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-cyclodextrin and heptakis-2,6-di-<i>O</i>-methyl-<img src="/content/w35lt05106l26l48/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin enhance the nitrosation rate of l-ephedrine if the nitrosation assay procedure (NAP test) is applied. During this reaction with <img src="/content/w35lt05106l26l48/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin a solid inclusion compound of <img src="/content/w35lt05106l26l48/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin and<i>N</i>-nitrosoephedrine precipitates. Solubilities and stabilities of inclusion compounds of the cyclodextrins with ephedrine and nitrosoephedrine, respectively, explain especially the catalytic effects of some cyclodextrins on ephedrine.Part of the PhD thesis of V. Wedelich, Freie Universität Berlin, 1985.     

Reaction of Grignard Reagents with Diethyl Perfluoroacyl (1-Cyanoethyl)phosphonates. Synthesis of Perfluoroalkylated α,β-Unsaturated Nitriles with Predominant Z-Selectivity

ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｃｅｎｔｌｙｍｕｃｈａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎｄｅｖｏｔｅｄｔｏｔｈｅｓｙｎｔｈｅｓｉｓｏｆα ,β ｕｎｓａｔｕｒａｔｅｄｎｉｔｒｉｌｅｓｓｉｎｃｅｔｈｅｙａｒｅｉｍ ｐｏｒｔａｎｔｓｔｒｕｃｔｕｒａｌｆｅａｔｕｒｅｏｆｓｅｖｅｒａｌｎａｔｕｒａｌｌｙｏｃｃｕｒｒｉｎｇｂｉ ｏｌｏｇｉｃａｌｌｙａｃｔｉｖｅｃｏｍｐｏｕｎｄｓ .1,2 Ｔｈｅｉｎｔｒｏｄｕｃｔｉｏｎｏｆｆｌｕｏ ｒｉｎｅｏｒｔｒｉｆｌｕｏｒｏｍｅｔｈｙｌｇｒｏｕｐｉｎｔｏｂｉｏｌｏｇｉｃａｌｌｙａｃｔｉｖ…     

Nucleation of the β-modification of isotactic polypropylene

The effects of the organic pigments C.I.P. RED 177 and C.I.P. Yellow 83 as nucleating agents on the crystallization of polypropylene were studied by DSC. The anthraquinone pigment exerted a significant effect, resulting in structural modifications with lower melting point, and particularly the <img src="/content/l4l423494051gl11/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-modification. The DSC curves exhibit four transition regions, with the following temperature intervals: I. 415–417 K, II. 423–425 K, III. 430–432 K and IV. 438–439 K. For evaluation of the <img src="/content/l4l423494051gl11/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-nucleation effect of pigments, the ratio (<img src="/content/l4l423494051gl11/xxlarge916.gif" alt="Delta" align="BASELINE" BORDER="0"><i>H</i> <sub>1</sub>+<img src="/content/l4l423494051gl11/xxlarge916.gif" alt="Delta" align="BASELINE" BORDER="0"><i>H</i> <sub>2</sub>)/(<img src="/content/l4l423494051gl11/xxlarge916.gif" alt="Delta" align="BASELINE" BORDER="0"><i>H</i> <sub>3</sub>+<img src="/content/l4l423494051gl11/xxlarge916.gif" alt="Delta" align="BASELINE" BORDER="0"><i>H</i> <sub>4</sub>) was suggested.     

Conformational studies of basic poly (α-amino acid)s in reversed micelles

The conformation of various basic poly (<i><img src="/content/l628p405k20j60v5/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"></i>-amino acid)s was investigated by CD measurements in aqueous solutions containing bis (2-ethylhexyl)sodium sulfosuccinate (AOT) as well as in the AOT reversed micelles. The addition of AOT into an aqueous solution of poly(L-lysine) induces the conformational transition from coil to ordered structure, followed by aggregation. On the other hand, poly(L-lysine) assumes<i><img src="/content/l628p405k20j60v5/xxlarge914.gif" alt="Bgr" align="BASELINE" BORDER="0"></i>-structure in the reversed micelles at low w<sub>o</sub>value (w<sub>o</sub>=[H<sub>2</sub>O]/[AOT]). Similarly to poly(L-lysine), poly(L-ornithine) takes an ordered structure in the aqueous solution containing AOT and<i><img src="/content/l628p405k20j60v5/xxlarge914.gif" alt="Bgr" align="BASELINE" BORDER="0"></i>-structure in the reversed micelles. In this case, however, these ordered structures are not so stable, compared with that of poly(L-lysine). Poly(L-arginine) undergoes the conformational transition from coil to helix by addition of AOT into the aqueous solution. Further addition of AOT allows transformation into<i><img src="/content/l628p405k20j60v5/xxlarge914.gif" alt="Bgr" align="BASELINE" BORDER="0"></i>-structure. Copoly(L-lysyl-L-leucine) with 63% leucine residue was shown to take a stable helical conformation even in pure water. In the reversed micelles, however, this ordered structure is significantly changed probably because the hydrophobic interaction among the leucyl residues is lowered in the reversed micelles.     

Orientational effects of β-cyclodextrins on electron transfer between metal complexes in solution

The kinetics of the electron transfer reaction between pentammine-(4,4<img src="/content/g7719705032l505l/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">bipyridine)ruthenium(II) and cyclohexyldiamine-N,N,N<img src="/content/g7719705032l505l/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">,N<img src="/content/g7719705032l505l/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-tetraacetatocobaltate(III) has been studied in unsubstituted and substituted <img src="/content/g7719705032l505l/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin solutions. The increased ion-pairing and the decreased electron transfer rates that result when the ruthenium complex are encapsulated by cyclodextrins are interpreted in terms of hydrogen bonding between cyclodextrin and the metal complexes markedly stabilizing the ionpair.Presented at the Symposium 76<sup>th</sup> CSC Congress, Sherbrooke, Quebec, May 30–June 3, 1993, honoring Professor Donald Patterson on the occasion of his 65<sup>th</sup> birthday.     

Study of modified silicas by inverse gas chromatography. Part I: Influence of chain length on grafting ratio

Summary Silica has been modified by an esterification reaction using either n-alcohols or <img src="/content/l343436806431220/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-<img src="/content/l343436806431220/xxlarge969.gif" alt="ohgr" align="BASELINE" BORDER="0"> diols. The grafting ratios were evaluated by elemental analysis of carbon or by the weight loss of the grafted silica heated to 700°C. The grafting ratio can be easily fixed by changing the silica to reactant impregnation ratios. In the case of n-alcohols, the grafting ratios do not vary monotonously with the number of carbon atoms of the grafts and the density of the grafted layer is 25% higher for <img src="/content/l343436806431220/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-<img src="/content/l343436806431220/xxlarge969.gif" alt="ohgr" align="BASELINE" BORDER="0"> diols than for n-alcohols. This observation needs further investigation.     

Synthesis and structure of 1,1′-bis(pentafluorophenyl)tetrahydrodigermane

Dehydrogenation of pentafluorophenylgermane in the presence of catalytic amounts of a Wilkinson complex, certain Rh<sup>I</sup> <i>ortho</i>-benzosemiquinolate complexes, or (Ph<sub>3</sub>P)<sub>4</sub>Pt leads to tetrahydrodigermane, C<sub>6</sub>F<sub>5</sub>H<sub>2</sub>GeGeH<sub>2</sub>C<sub>6</sub>F<sub>5</sub>. X-ray analysis has confirmed the<i>trans</i>-arrangement of the C<sub>6</sub>F<sub>5</sub>-cycles at the Ge atoms. The Ge-Ge bond length is 2.394(1) Å. The doublet pattern of the band due to the Ge-H bonds (v 2090 and 2104 cm<sup>–1</sup>) in the IR spectrum is probably associated with nonequivalence of the hydrogen atoms in the molecule.Translated from<i>Izvestiya Akademii Nauk. Seriya Khimicheskaya</i>, No. 2, pp. 315–318, February, 1994.     

β-Tricarbonyl compounds. I. 2,4-Disubstituted 1,3-cyclopentanediones

Summary Stable enolic isomers of 2-aroyl-4-aracyl-1,3-cyclopentanediones such as<b>3</b> and<b>4</b> were prepared by condensation of aryl methyl ketones and diethyl maleate using an excess of sodium ethoxide (Aryl=C<sub>6</sub>H<sub>5</sub>, 4-C<sub>6</sub>H<sub>4</sub>CH<sub>3</sub>, 4-C<sub>6</sub>H<sub>4</sub>Br and 4-C<sub>6</sub>H<sub>4</sub>Cl).<hr><blockquote><img src="/content/l644017943185534/xhuge946.gif" alt="beta" align="MIDDLE" BORDER="0">-Tricarbonyl Verbindungen. I. 2,4-Disubstituierte 1,3-Cyclopentandione</blockquote><blockquote>Zusammenfassung Stabile Enol-Isomere von 2-Aroyl-4-aracyl-1,3-cyclopentandionen wie<b>3</b> und<b>4</b> wurden durch Kondensation von Arylmethylketonen und Diethylmaleat mit einem Überschuß von Natriumethoxid dargestellt (Aryl=C<sub>6</sub>H<sub>5</sub>, 4-C<sub>6</sub>H<sub>4</sub>CH<sub>3</sub>, 4-C<sub>6</sub>H<sub>4</sub>Br und 4-C<sub>6</sub>H<sub>4</sub>Cl).</blockquote>     

Synthesis of some sulfur-containing pyrido[1,2-α]pyrimidines

4-Methylthiopyrido[1,2-α]pyrimidin-2-one and 2-hydroxypyrido[1,2-α]pyrimidine-4-thione derivatives were synthesized by the addition of<em>N</em>-(4-R-pyrid-2-yl)acetoacetamides (R = H, Me) to CS<sub>2</sub> under phase-transfer conditions followed by the alkylation of the reaction products with Mel. The molecular structure of 3-acetyl-4-methylthiopyrido[1,2-α]pyrimidin-2-one is established by X-ray analysis.     

Rates of convergence of α-stable random motions

The rate-of-convergence problem in the central limit theorem is considered for <img src="/content/t303928l71006674/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-stable distributions on the noncommutative group of motions in <img src="/content/t303928l71006674/xxlarge8477.gif" alt="Ropf" align="BASELINE" BORDER="0"><sup>d</sup>. The method used here is based on the theory of probability metrics.