Transformed steroids

The approaches to the synthesis of various 16,17-disubstituted pregna-4,9-dien-3,20-diones from the corresponding 9-derivatives with labile epoxide, dioxolane, and oxathiolane ringsD have been studied. The transformation has been found to proceed efficiently when the 9-sulfinic esters are used at the intermediate stage and then elimination of sulfinic acid by TsOH/SiO₂ is carried out.For part 193, see ref. 7.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 983–986, May, 1993.     

电感耦合等离子体原子发射光谱专家系统中谱线激发模型

阐述了ＩＣＰ－ＡＥＳ专家系统中ＡＥＳ电离和激发模型的基本原理，研究了模拟中应用ｎｏｎ－ＬＴＥ理论的正确性以及所需的支持数据库。利用Ｂｏｌｔｚｍａｎｎ曲线，讨论了Ｂｏｌｔｚｍａｎｎ温度的测量值随能级激发能变化的现象，并与类似条件下的经验Ｂｏｌｔｚｍａｎｎ曲线进行对比，证明了专家系统中ＡＥＳ电脑和激发模型可靠性。     

In vitro nitrosation of ephedrine in the presence of cyclodextrins

-, and -cyclodextrin and heptakis-2,6-di-O-methyl--cyclodextrin enhance the nitrosation rate of l-ephedrine if the nitrosation assay procedure (NAP test) is applied. During this reaction with -cyclodextrin a solid inclusion compound of -cyclodextrin andN-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 -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 -nucleation effect of pigments, the ratio (H ₁+H ₂)/(H ₃+H ₄) was suggested.     

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

The conformation of various basic poly (-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-structure in the reversed micelles at low w_ovalue (w_o=[H₂O]/[AOT]). Similarly to poly(L-lysine), poly(L-ornithine) takes an ordered structure in the aqueous solution containing AOT and-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-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-(4,4bipyridine)ruthenium(II) and cyclohexyldiamine-N,N,N,N-tetraacetatocobaltate(III) has been studied in unsubstituted and substituted -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^th CSC Congress, Sherbrooke, Quebec, May 30–June 3, 1993, honoring Professor Donald Patterson on the occasion of his 65^th 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 - 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 - 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^I ortho-benzosemiquinolate complexes, or (Ph₃P)₄Pt leads to tetrahydrodigermane, C₆F₅H₂GeGeH₂C₆F₅. X-ray analysis has confirmed thetrans-arrangement of the C₆F₅-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^–1) in the IR spectrum is probably associated with nonequivalence of the hydrogen atoms in the molecule.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 315–318, February, 1994.