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51.
Yoshiyuki Tanaka Makoto Arakawa Yohei Yamaguchi Chieko Hori Masahiro Ueno Takeyuki Tanaka Tatsushi Imahori Yoshinori Kondo 《化学:亚洲杂志》2006,1(4):581-585
A metal‐free acetylide was observed by using NMR spectroscopy. Metal‐free acetylides are closely related to reactive intermediates (carbanions) in solution; therefore, they have been regarded as unobservable species. However, we generated this highly reactive and unstable species through the deprotonation of phenylacetylene by using the strong nonmetallic phosphazene base tBu‐P4. In the presence of tBu‐P4, the J coupling between the ethynyl carbon and hydrogen nuclei (1JC,H) of phenylacetylene disappeared; this indicates the deprotonation of the alkyne terminal. Furthermore, a large low‐field shift (approximately 90 ppm) of the alkyne carbon resonance was observed. We concluded that we have observed a metal‐free carbanion with a formal charge on an sp‐hybridized carbon atom for the first time. 相似文献
52.
Hirota J Satomi Y Yoshikawa K Takao T 《Rapid communications in mass spectrometry : RCM》2003,17(5):371-376
Epsilon -N,N,N-trimethyllysine (K(me3)) is a component of a number of proteins and plays an important role in the expression of their biological functions. Trimethylation, which causes an incremental increase in mass of 42.0470 Da from that of the corresponding MH(+) ion, cannot be distinguished from the acetylation (+42.0106 Da), which also occurs on epsilon-amino groups of Lys or alpha-amino groups in many proteins, without high-accuracy mass measurement which is accurate to within the second decimal place. MALDI-MS and MS/MS have been applied for the analyses of post-translational modifications of histone H3, which is known to contain both multiple acetylation and methylation sites in its sequence. During the measurements of the modified peptides, a novel fragmentation which involves the loss of trimethylamine from K(me3) was found. This characteristic fragmentation, which was observed to produce ions separated by 59 Da from the conventional precursor ion or sequence ions, would be useful for probing K(me3) units in the sequence. 相似文献
53.
Uekawa N Kajiwara J Kakegawa K Sasaki Y 《Journal of colloid and interface science》2002,250(2):285-290
An ethanol solution of Ti-peroxy compounds was prepared from the ethanol solution of titanium isopropoxide (Ti(O-iPr)4) and H2O2. Heating of the ethanol solution of the Ti-peroxy compounds at 348 K formed a Ti-peroxy gel, and heat treatment of the gel at 348 K for more than 6 h formed gels that consisted of anatase nanoparticles. The diameter of the anatase nanoparticles increased from 9 to 15 nm as the heating time increased from 6 to 48 h. According to the results of the N2 adsorption measurement, the anatase nanoparticles had micropores, and the specific surface area (SBET) was in the range of 254 to 438 m2/g. The particle size, lattice strain, specific surface area, and photocatalytic activity of the anatase nanoparticles can be regulated by the heating time of the Ti-peroxy gel at 348 K. 相似文献
54.
Yoshihiko Ito Yoshinori Inubushi Toru Sugaya Takeo Saegusa 《Journal of organometallic chemistry》1977,137(1):1-9
Reaction of carboxamides with Cu2O in the presence of t-butyl isocyanide gave new chelated copper(I) complexes, which probably are formed by the insertion of t-butyl isocyanide into the coppernitrogen bond of copper(I) amide isonitrile complexes, which were initially produced from the carboxamides and Cu2Ot-butyl isocyanide complex. The same chelated copper(I) complexes were prepared more readily by the reaction of the corresponding N-trimethylsilyl-carboxamides with Cu2Ot-butyl isocyanide complex. Reactions of the copper(I) complexes thus obtained with alkylating agents, such as alkyl halides, alkyl tosylates and triethyloxonium tetrafluoroborate, also were described. 相似文献
55.
The reaction of ortho-alkynylated benzaldehydes 1 with allyltrimethylsilane under the Pd(OAc)2-CuCl2 catalyst system gave the isochromene derivatives 2 together with the chlorinated products 3. When the reaction was conducted in the presence of half equiv of H2O, the formation of 3 was suppressed and 2 was obtained in good to high yields. When the reaction of 1a was carried out with trimethylsilylcyanide instead of allylsilane, the cyano group-substituted isochromene 9 was obtained in 94% yield. 相似文献
56.
Asao N Takahashi K Lee S Kasahara T Yamamoto Y 《Journal of the American Chemical Society》2002,124(43):12650-12651
The reaction of o-alkynylbenzaldehydes 1 and alkynes 2 in the presence of a catalytic amount of AuCl3 in (CH2Cl)2 at 80 degrees C gave naphthyl ketone products in high yields. The AuCl3-catalyzed formal [4 + 2] benzannulation proceeds most probably through the coordination of the triple bond of 1 to AuCl3, the formation of benzo[c]pyrylium auric ate complex via the nucleophilic addition of the carbonyl oxygen atom, the Diels-Alder addition of alkynes 2 to the auric ate complex, and subsequent bond rearrangement. Similarly, the AuCl3-catalyzed reactions of o-alkynylacetophenone and o-alkynylbenzophenone with phenylacetylene afforded the corresponding naphthyl ketone products in good yields. 相似文献
57.
A perovskite-type BaCu1/3Nb2/3O3 was prepared by high temperature reaction using BaCO3, CuO and Nb2O5. The X-ray powder diffraction pattern of this compound was indexed with the tetragonal cell with the lattice parameters of a=4.0464(4) and c=4.1807(4) Å (c/a=1.033). This compound had the tetragonal perovskite-type structure in which the B site was occupied statistically by Nb and Cu atoms. From high temperature X-ray powder diffraction patterns this compound had a phase transition from the tetragonal to cubic symmetry in the temperature range of 500-600 °C. The P-E and S-E hysteresis loops occurred at room temperature and the apparent maximum in the temperature dependence of the dielectric constant was observed at 520 °C. The temperature dependence of the inverse of magnetic susceptibility exhibited paramagnetic behavior. 相似文献
58.
Summary Selective and sensitive procedures are described for the direct differential pulse polarographic determination of antimony(III), indium(III) and cadmium(II) in propylene carbonate. This method was based on the salting-out extraction of their halide complexes into the solvent from acidic aqueous media. The extracted Sb(III), In(III) and Cd(II) complexes exhibit sharp differential pulse polarographic peaks at –0.21 V, –0.63 V and –0.72 V vs. SCE in salted-out propylene carbonate phases respectively. The lower limits of determination are 5.0g for Sb(III), 0.6g for In(III), and 0.2g for Cd(II) in 10 ml of the organic phase. A number of foreign ions are eliminated through both processes of solvent extraction and polarography using propylene carbonate.
Propylencarbonat als Lösungsmittel für die Fällungs-Extraktion und die nachfolgende Differential-Puls-Polarographie
Zusammenfassung Selektive und empfindliche Verfahren für die direkte Bestimmung von Sb(III), In(III) und Cd(II) in Propylencarbonat mit Hilfe der Differential-Puls-Polarographie wurden beschrieben. Die vorliegende Methode beruht auf der Fällungs-Extraktion der Halogenid-Komplexe aus wäßrig-saurem Medium in das Lösungsmittel. Die extrahierten Komplexe des Sb(III), In(III) und Cd(II) ergeben scharfe Peaks bei –0,21 V, –0,63 V und –0,72 V gegen die Kalomelelektrode in den betreffenden Propylencarbonat-Phasen. Die unteren Grenzen der Bestimmungen liegen bei 5,0g Sb, 0,6g In bzw. 0,2g Cd in 10 ml organischer Phase. Eine Anzahl Fremdionen wird durch die beiden Prozesse der Extraktion und der Polarographie in Propylencarbonat ausgeschaltet.相似文献
59.
60.
Yoshinori Tominaga Mayumi Hara Harumasa Honkawa Akira Hosomi 《Journal of heterocyclic chemistry》1990,27(5):1245-1248
N-Bis(methylthio)methylene-p-toluenesulfonamide ( 1 ) reacted with active methylene compounds such as malononitrile ( 2a ) and, cyanoacetamide ( 2b ) to give the corresponding 3-methylthio-3-p-toluenesulfonylami-nopropenenitrile derivatives 3a,b which were found to be convenient starting materials for the synthesis of 3,5-diaminopyrazole derivatives. Reaction of 3a and 3b with hydrazines gave the corresponding 3,5-diaminopyrazoles 4a-e , key intermediates for the synthesis of 3-aminopyrazolo[3,4-d]pyrimidine derivatives 5a-d . 相似文献