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71.
Nikitina L. E. Dieva S. A. Plemenkov V. V. Lodochnikova O. A. Gubaidullin A. T. Kataeva O. N. Litvinov I. A. 《Russian Journal of General Chemistry》2001,71(8):1161-1164
7,7-Dimethyl-2,10-epoxybicyclo[3.1.1]heptane obtained by treatment of (-)--pinene with peroxybenzimidic acid has configuration. 相似文献
72.
Ryabov AD Otto S Samuleev PV Polyakov VA Alexandrova L Kazankov GM Shova S Revenco M Lipkowski J Johansson MH 《Inorganic chemistry》2002,41(16):4286-4294
Structural and mechanistic aspects of orthoplatination of acetophenone and benzaldehyde oximes by the platinum(II) sulfoxide and sulfide complexes [PtCl(2)L(2)] (2, L = SOMe(2) (a), rac-SOMePh (b), R-SOMe(C(6)H(4)Me-4) (c), and SMe(2) (d)) to afford the corresponding platinacycles cis-(C,S)-[Pt(II)(C(6)H(3)-2-CR'=NOH-5-R)Cl(L)] (3, R, R' = H, Me) have been investigated. The reaction of acetophenone oxime with sulfoxide complex 2a in methanol solvent occurs noticeably faster than with sulfide complex 2d due to the fact that the sulfoxide is a much better platinum(II) leaving ligand than the sulfide. Evidence is presented that the orthoplatination is a multistep process. The formation of unreactive dichlorobis(N-oxime)platinum(II) cations accounts for the rate retardation by excess acetophenone oxime and suggests the importance of pseudocoordinatively unsaturated species for the C-H bond activation by Pt(II). A comparative X-ray structural study of dimethyl sulfoxide platinacycle 3b (R = R' = Me) and its sulfide analogue 3e (R = H, R' = Me), as well as of SOMePh complex 3c (R = H, R' = Me), indicated that they are structurally similar and a sulfur ligand is coordinated in the cis position with respect to the sigma-bound phenyl carbon. The differences concern the Pt-S bond distance, which is notably longer in the sulfide complex 3e (2.2677(11) A) as compared to that in sulfoxide complexes 3b (2.201(2)-2.215(2) A) and 3c (2.2196(12) A). Whereas the metal plane is practically a plane of symmetry in 3b due to the H-bonding between the sulfoxide oxygen and the proton at carbon ortho to the Pt-C bond, an S-bonded methyl of SOMePh and SMe(2) is basically in the platinum(II) plane in complexes 3c and 3e, respectively. There are intra- and intermolecular hydrogen bond networks in complex 3b. An interesting structural feature of complex 3c is that the two independent molecules in the asymmetric unit of the crystal reveal an extremely short Pt-Pt contact of 3.337 A. 相似文献
73.
Iminodiacetic acid has been covalently bonded to a bare silica monolith to produce the first reported high-performance monolithic chelating ion exchange column. Using the new column, separation and determination of traces of alkaline earth metal ions (low ppm) in high ionic strength samples (up to 2 M NaCl and KCl brines), could be achieved in under 40 s. At an eluent flow rate of 4 mL min(-1) retention time precision was < 1.2% (n = 9) for Mg(II) and Ca(II), with detector linearity (n = 5) over the range 2-10 mg L(-1) of between R2 = 0.985 and R2 = 0.995. In 1 M KCl and NaCl brine samples, detection limits of 0.2 mg L(-1) were possible. 相似文献
74.
Pavel Šebesta Viktor Dobal Jaroslav Kubát 《Journal of Analytical and Applied Pyrolysis》1982,3(3):263-269
Pyrolysis—gas chromatography of brown coal exhibits additive properties and it is therefore possible to construct the pyrogram of the original coal from the individual pyrograms of the bitumen, humic acids, lignin and humin fractions. The contents of phenols in the pyrograms are typical for all of the above classes except bitumen and are in agreement with the contents of the individual groups in the original coal. The results suggest that the separation does not bring about significant chemical changes in individual brown coal fractions. 相似文献
75.
Berestovitskaya V. M. Litvinov I. A. Efremova I. E. Lapshina L. V. Krivolapov D. B. Gubaidullin A. T. 《Russian Journal of General Chemistry》2002,72(7):1111-1118
Procedures were developed for preparing representatives of a new type of halonitrothiolene 1,1-dioxides: mono- and dihalo derivatives of 2,2,4-tri- and 2,4-dinitro-3-thiolene 1,1-dioxides. An X-ray diffraction study showed that 2,5-dinitro-2,3-dichloro-3-thiolene 1,1-dioxide molecules exist in the crystal as enantiomeric pairs; the five-membered rings have the envelope conformation, with deviation of the sulfur atom from the ring plane; the halogen atom and nitro group at the multiple bond are essentially coplanar with the ring. 相似文献
76.
77.
Yang X Fu YJ Wang XB Slavícek P Mucha M Jungwirth P Wang LS 《Journal of the American Chemical Society》2004,126(3):876-883
The microsolvation of the suberate dianion, -O2C(CH2)6CO2-, with two separate charge centers was studied by photoelectron spectroscopy and molecular dynamics simulation one solvent molecule at a time for up to 20 waters. It is shown that the two negative charges are solvated in the linear suberate alternately. As the solvent number increases, the negative charges are screened and a conformation change occurs at 16 waters, where the cooperative hydrogen bonding of water is large enough to overcome the Coulomb repulsion and pull the two negative charges closer through a water bridge. This conformation change, revealed both from the experiment and from the simulation, is a manifestation of the hydrophilic and hydrophobic forces at the molecular level. 相似文献
78.
V. D. Dyachenko S. G. Krivokolysko V. N. Nesterov V. P. Litvinov 《Chemistry of Heterocyclic Compounds》1996,32(9):1066-1074
By the condensation of an aromatic aldehyde, the anilide of acetoacetic acid, cyanothioacetamide, and Nmethylmorpholine, substituted N-methylmorpholinium 1,4-dihydropyridine-2-thiolates have been synthesized and subsequently used in the synthesis of the corresponding thiones, 2-alkylthiopyridines, thieno[2, 3b]pyridines, and disulfides. X-ray diffraction has been used to establish the structure of 2-allylthio-6-methyl-5phenylcarbamoyl-4-(2-chlorophenyl)-3-cyano-1, 4-dihydropyridine.T. G. Shevchenko Lugansk State Pedagogical Institute, Lugansk 348011. A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, Moscow 117813. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1243–1251, September, 1996. Original article submitted May 13, 1996. 相似文献
79.
K. A. Frolov V. V. Dotsenko S. G. Krivokolysko V. P. Litvinov 《Russian Chemical Bulletin》2005,54(9):2226-2228
Reactions of (Z)-5-benzylidene-2-thiohydantoin with formaldehyde and primary aromatic amines afforded novel derivatives of imidazo[2,1-b][1,3,5]thiadiazine in 50–69% yields.
Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2158–2160, September, 2005. 相似文献
80.
Teplý F Stará IG Starý I Kollárovic A Saman D Vyskocil S Fiedler P 《The Journal of organic chemistry》2003,68(13):5193-5197
A nonphotochemical synthetic route to 3-hexahelicenol is reported. It involves a key [2+2+2] cycloisomerization of CH(3)O-substituted triyne that is readily available from 1-methoxy-3-methylbenzene and 1-bromo-2-(bromomethyl)naphthalene. Further functional group transformations led to 3-CO(2)CH(3), 3-NH(2), 3-PPh(2), and 3-SC(O)N(CH(3))(2) substituted hexahelicenes. 相似文献