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161.
An ionic crystal K2[Cr3O(OOCC2H5)6(H2O)3]2[alpha-SiW12O40] x 3H2O (1a) is synthesized by the complexation of a Keggin-type polyoxometalate of [alpha-SiW12O40]4- with K+ and a macrocation of [Cr3O(OOCC2H5)6(H2O)3]+. Compound 1a possesses both hydrophilic and hydrophobic channels in the crystal lattice. The 3 mol mol(-1) of the water of crystallization in 1a resides in the hydrophilic channel. The water of crystallization is removed by the evacuation at 303 K to form the guest-free phase 1b with small changes in the lattice lengths (+/-0.2 A). The water sorption profile is reproduced by the single rate constant. Therefore, the water sorbed probably resides in the hydrophilic channel. Compound 1b sorbs various kinds of polar organic molecules, and the amounts of < or = C3 alcohols are comparable to or larger than that of water, while chlorocarbons with no hydrogen-bonding ability and nonpolar molecules are excluded. Thus, 1b showed the amphiphilic sorption property. The states of the polar organic molecules sorbed in 1b have been quantitatively investigated using ethanol as a probe molecule. The IR, NMR, and single-crystal X-ray diffraction studies combined with the sorption kinetics reveal that ethanol molecules are mainly sorbed into the hydrophilic channel at P/P0 < or = 0.5, while the sorption into the hydrophobic channel is dominant at P/P0 > or = 0.6. Thus, it is demonstrated that ethanol molecules enter both hydrophilic and hydrophobic channels of 1b. 相似文献
162.
Hitoshi Yamaguchi Sinji Itoh Shukuro Igarashi Kunishige Naitoh Ryosuke Hasegawa 《Fresenius' Journal of Analytical Chemistry》1998,362(4):395-398
Total reflection X-ray fluorescence (TXRF) analysis after the separation of matrix element was studied for the determination
of trace impurity elements (Ca, Sc, V, Cr, Mn, Fe, Co, Ni and Zn) in high purity copper. Matrix copper was removed by electrolysis
(0.2 A, 8 h) of a nitric acid solution. A 10 μL aliquot of the remaining solution of the electrolysis was dropped on a silicon-wafer
sample-carrier and dried in a vacuum. This was repeated five times and the precipitate of five 10 μL-aliquots was analyzed
by TXRF using a W-Lβ beam with an incident angle of 0.05 °. TXRF analytical values were obtained by using relative sensitivity
factors of the analytes to the internal standard element (Pd). Detection limits of the analytes ranges from 0.077 ng for Zn
to 0.785 ng for Ca.
Received: 25 December 1997 / Revised: 30 March 1998 / Accepted: 2 April 1998 相似文献
163.
Kobayashi S Matsubara R Nakamura Y Kitagawa H Sugiura M 《Journal of the American Chemical Society》2003,125(9):2507-2515
In the presence of a catalytic amount of Cu(OTf)(2)-chiral diamine 3e complex, N-acylimino esters reacted with silyl enol ethers to afford the corresponding Mannich-type adducts in high yields with high enantioselectivities. A wide variety of silyl enol ethers derived from ketones, as well as esters and thioesters, reacted smoothly. In the reactions of alpha-substituted silyl enol ethers (alpha-methyl or benzyloxy), the desired syn-adducts were obtained in high yields with high diastereo- and enantioselectivities. Several intermediates for the synthesis of biologically important compounds were prepared using this novel catalytic asymmetric Mannich-type reaction, and at the same time, absolute and relative stereochemical assignments were made. In addition, it has been revealed that alkyl vinyl ethers reacted with N-acylimino esters in the presence of a catalytic amount of the Cu(II) catalyst to give the corresponding Mannich-type adducts in high yields with high enantioselectivities. This is the first example of catalytic asymmetric Mannich-type reactions with alkyl vinyl ethers. The reaction mechanism, structure of chiral catalyst-electrophile complexes, and transition states of these catalytic asymmetric reactions were assumed based on X-ray crystallographic analysis of the Cu(II)-chiral amine complex, PM3 calculations, and FT-IR analyses, etc. Finally, (1R,3R)-N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)dodecanamide (HPA-12, 1), a new inhibitor of ceramide trafficking from endoplasmic reticulum to the site of sphingomyerin (SM) synthesis, has been synthesized efficiently using the present Mannich-type reaction as a key step. The synthesis involved three steps (two-pot), and total yield was 82.9%. 相似文献
164.
Takaki K Koshoji G Komeyama K Takeda M Shishido T Kitani A Takehira K 《The Journal of organic chemistry》2003,68(17):6554-6565
Intermolecular hydrophosphination of alkynes with diphenylphosphine is catalyzed by a Yb[bond]imine complex, [Yb(eta(2)-Ph(2)CNPh)(hmpa)(3)], to give alkenylphosphines and phosphine oxides after oxidative workup in good yields under mild conditions. This reaction is also applicable to various carbon[bond]carbon multiple bonds such as conjugated diynes and dienes, allenes, and styrene derivatives. Regio- and stereoselectivity and the scope and limitation of the present reaction clearly differ from those of the corresponding radical reaction. Instead, the reaction takes place through insertion of alkynes to a Yb[bond]PPh(2) species, followed by protonation. In fact, the Yb[bond]phosphido complex, [Yb(PPh(2))(2)(hmpa)(3)], is obtained from the imine complex and phosphine, which exhibits similar catalyst activity for the hydrophosphination. The empirical rate law is nu = k[catalyst](2) [alkyne](1)[phosphine](0) at least under the standard conditions. 相似文献
165.
Yoshiko Okada Shinobu Kishi Yasuko Shishido Masako Kato 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):m171-m173
Dichloro(4,4′‐dipentyl‐2,2′‐bipyridine‐κ2N,N′)platinum(II), [PtCl2(C20H28N2)], adopts a discrete π–π stacking structure, where the alkyl chains are located in a random manner. In contrast, dichloro(4,4′‐diheptyl‐2,2′‐bipyridine‐κ2N,N′)platinum(II), [PtCl2(C24H36N2)], forms a layer structure comprised of alkyl chain layers and paired coordination sites, as observed for analogous complexes with longer alkyl chains. 相似文献
166.
Masayuki Kitamura Noritaka Usami Takamasa Sugawara Kenrato Kutsukake Kozo Fujiwara Yoshitaro Nose Toetsu Shishido Kazuo Nakajima 《Journal of Crystal Growth》2005,280(3-4):419-424
The floating zone technique was employed to grow multicrystalline Si with controlled grain boundary configuration. Purposely designed bi-crystals were utilized as seed crystals to investigate the effect of the tilt angle from the perfect twin boundary on the growth behavior. When the growth was initiated from a bi-crystal with a Σ3 twin boundary, no particular change took place on the grain boundary configuration during growth. On the other hand, the decrease of the tilt angle during growth was observed when the growth was initiated from a bi-crystal with a tilted boundary from Σ3. This was accompanied by the appearance of new crystal grains. The reduction of the total interface energy would be a possible driving mechanism for this phenomenon. 相似文献
167.
Noriyuki Kuramoto Yuichi Shishido Katsutoshi Nagai 《Journal of polymer science. Part A, Polymer chemistry》1997,35(10):1967-1972
Thermosensitive and redox-active polymers were prepared by copolymerization of N-ethyl- or N,N-diethylacrylamides with vinylferrocene (VFc). LCST (lower critical solution temperature) of the aqueous copolymer solution was decreased by increasing the ferrocene content in the copolymer. The oxidation of ferrocene led to a significant increase in LCST due to the transition from hydrophobic to hydrophilic character of the ferrocene moiety in the copolymer. The ferrocene content in the copolymer increases with increasing differences between the LCST's of the oxidation and reduction states. The transition could be made reversible by redox reaction using L -ascorbic acid as an oxidant and cerium sulfate as a reductant. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1967–1972, 1997 相似文献
168.
A novel tandem [2 + 2] cycloaddition-Dieckmann condensation via ynolate anions is described. Ynolate anions are useful for the formation of reactive beta-lactone enolates via a pathway not involving the enolization of the corresponding beta-lactones. The [2 + 2] cycloaddition of ynolate anions with delta- or gamma-keto esters, followed by Dieckmann condensation, gives bicyclic beta-lactones, which are easily decarboxylated to produce synthetically useful 2,3-disubstituted cyclopentenones and cyclohexenones in one pot. This tandem reaction was applied to a novel, one-pot synthesis of highly substituted naphthalenes. 相似文献
169.
Shinji Watanabe Osamu Shishido Miki Murata Yuzuru Masuda 《Macromolecular rapid communications》1998,19(1):75-77
Polymer microspheres with mercapto groups were synthesized by polycondensation of 1,6-dibromohexane and 1,3-propanedithiol in the presence of a polystyrene latex and a nonionic surfactant. The sulfur content of the obtained particles is comparable with the one calculated according to the feed ratio, which shows that the polycondensation proceeds quantitatively in the particles. A higher molar ratio of dithiol against dibromide used in the polycondensation results in microspheres with higher mercapto group content. 相似文献
170.
Osamu Nishizawa Hideki Misaka Ryosuke Sakai Toyoji Kakuchi Toshifumi Satoh 《Journal of polymer science. Part A, Polymer chemistry》2008,46(22):7411-7418
The copolymerization of ethylene (E) and norbornene (NB) was investigated using the commercially available and inexpensive catalyst system, cyclopentadienylzirconium trichloride (CpZrCl3)/isobutyl‐modified methylaluminoxane (MMAO), at a moderate polymerization temperature in toluene. For the CpZrCl3 catalyst system activated by aluminoxane with a 40 mol % methyl group and a 60 mol % isobutyl group (MMAO), the quantities of the charged NB and the polymerization temperature significantly affected the molecular weights, polydispersities, and NB contents of the obtained copolymers and the copolymerization activities in all the experiments. As the charged NB increased and thereby the NB/E molar ratio increased, the NB content in the copolymer increased and reached a maximum value of 71 mol %. The CpZrCl3/MMAO ([Al]/[Zr] = 1000) catalyst system with the [NB] of 2.77 mol L?1 and ethylene of 0.70 MPa at 50 °C showed the highest activity of 1690 kg molZr?1 h?1 and molecular weight of 21,100 g mol?1. The 13C NMR analysis showed that the CpZrCl3/MMAO catalyst system produced the E‐NB random copolymer with a number of NB homosequences such as the NN dyad and NNN triad. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7411–7418, 2008 相似文献