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81.
Tricyclo[3.3.1.1]decanone azine ( adamantanone azine ) reacts with 4-substituted 1,2,4-triazoline-3,5-diones under elimination of diazo adamantane to give a 1,3-dipole ( “azomethinimine” ), which on treatment with dipolahophiles affords the [ 2 + 3] -cycloadducts. The reaction is compared with singlet oxygen oxidation. 相似文献
82.
Mitsuru Ueda Hiroya Sugita Masaki Sato 《Journal of polymer science. Part A, Polymer chemistry》1986,24(5):1019-1026
A convenient method for the synthesis of poly(benzoxazole)s of high molecular weights has been developed. These polymers were prepared readily by direct polycondensation of aromatic dicarboxylic acids containing phenyl either structure with 3,3′-dihydroxybenzidine dihydrochloride using phosphorus pentoxide/methanesulfonic acid (PPMA) as condensing agent and solvent. Polycondensations proceeded fast and was completed within 5 h at 140°C and produced poly(benzoxazole)s with inherent viscosities up to 4.6 dL/g. Model compound work was performed in detail to demonstrate the feasibility of the reaction for polymer formation. The thermogravimetry of the aromatic poly(benzoxazole)s showed 10% weight loss in air and nitrogen at 450–505°C and 465–535°C, respectively. 相似文献
83.
Whenp-toluidine is added to an aqueous solution of CTAB, a remarkable increase of viscosity is accompanied by a spectacular elasticity. We detected the existence of extremely elongated rod-like micelles in electron micrographs. SAXS measurements indicate a closely packed array of cylindrical rod-like micelles, brought about when solutions flow through a thin capillary. A scattering maximum ofd=160 Å almost corresponds to the distance between the nearest neighbours of the cylindrical rod-like micelles. This value agrees with the diameter measured on electron micrographs. The second broad peak (d=75 Å) is assigned to a subsidiary maximum of the shape function of the cylinder with infinite length. 相似文献
84.
Synthesis of diphenyl cucurbit[6]uril (CB[6]) has been achieved via co-oligomerization of diphenyl glycoluril and unsubstituted glycoluril. The unsymmetrically substituted CB[6], Ph(2)CB[6], was further converted to a rotaxane incorporating bis(dinitrophenyl)spermine. [reaction: see text] 相似文献
85.
[structure: see text] Absolute stereochemistry of amphidinolides G (1) and H (2), potent cytotoxic 27- and 26-membered macrolides, respectively, isolated from a marine dinoflagellate Amphidinium sp., was determined by X-ray diffraction analysis, synthesis of a degradation product (3) of 2, and interconversion between 1 and 2. 相似文献
86.
M. J. Musmar M. Robert Willcott Gary E. Martin Robert T. Gampe Masatomo Iwao Milton L. Lee Ralph E. Hurd Leroy F. Johnson Raymond N. Castle 《Journal of heterocyclic chemistry》1983,20(6):1661-1669
Development of successively higher field nmr spectrometers has facilitated the study of increasingly more complex molecules, although smaller molecules such as phenanthro[3,4-b]thiophene still offer very substantial assignment problems because of the highly congested nature of their 1H- and 13C-nmr spectra. Assignments of such spectra, if they are to be unequivocal, frequently require the utilization of two-dimensional nmr spectroscopic techniques. Total assignments of the 1H- and 13C-nmr spectra of phenanthro[3,4-b]thiophene are reported. Assignments were based on a conventional high resolution 500 MHz 1H-nmr spectrum, autocorrelated two-dimensional 1H-nmr spectra (COSY), two-dimensional 1H-13C chemical shift correlation spectra and a modified version of autocorrelated 13C-13C double quantum coherence two-dimensional nmr spectroscopy. From NOE measurements, a separation of 1.99 Å between H1 and H11 was computed, suggesting that phenanthro[3,4-b]thiophene has a pronounced helical conformation in solution. 相似文献
87.
Hamada Fumio Kondo Yoshihiko Ito Riko Suzuki Iwao Osa Tetsuo Ueno Akihiko 《Journal of inclusion phenomena and macrocyclic chemistry》1993,16(3):273-281
The crystal structure of thiamine iodide sesquihydrate has been determined by X-ray diffraction methods as a host-guest model for coenzyme-substrate interactions. The asymmetric unit contains two chemical units. Both the thiamine molecules A and B, which are crystallographically independent, assume the usualF conformation and have a disordered hydroxyethyl side chain. An iodide anion (or a water molecule) bridges the pyrimidine and thiazolium rings of molecule A (or B) by forming a hydrogen bond with the amino group and an electrostatic contact with the thiazolium ring to stabilize the molecular conformation. In the crystal the thiamine molecules self-associate to form a pipe-like polymeric structure, in which four thiamine hosts surround an iodide guest and hold it through C(2)-H...I hydrogen bonds and thiazolium...I electrostatic interactions. Crystal data: C12H17N4OS+·I– · 1.5 H2O, monoclinic,P21/c, a=12.585(2), b=25.303(5), c=12.030(2) Å, =115.15(1)°,V=3468(1) Å3,Z=8,D
c=1.606 g cm–3,R=0.045 for 3328 observed reflections.
Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP. 82156 (13 pages). 相似文献
88.
Scale-up of wet granulation in a vertical high shear mixer was conducted. Pharmaceutical excipient powders composed of lactose, cornstarch and micro-crystallinecellulose, and hydroxypropylcellulose as a binder were mixed together and then granulated with purified water under various operating conditions and vessel scales. A novel internal stress measurement system was developed and stress of normal and tangential directions that granules received from the agitator blade during the granulation was continuously measured. The results indicated that granules received stress mainly from the tangential direction, which also showed the largest value near at the vessel wall. The effects of the agitator tip speed and the centrifugal acceleration on the measured stress was investigated. It was found that the tip speed of the agitator blade could be the main factor for the granule growth. The physical properties such as strength, size distribution and compressibility of granules prepared by changing the operating conditions and the vessel scales were evaluated and the scale-up characteristics of high shear granulation were investigated experimentally. The results showed that these physical properties had linear correlations with the tip speed. It was finally concluded that the scale-up of high shear granulation could be well conducted by means of the tip speed of the agitator blade. 相似文献
89.
Danuta Frackowiak Mamoru Minuro Iwao Yamazaki† Naoto Tamai† Yoshihiko Fujita 《Photochemistry and photobiology》1989,50(4):563-570
–Time-resolved fluorescence spectra in the ps time range were measured on phycobilisome (PBS) embedded in poly(vinyl alcohol) films. The cyanobacterium Tolypothrix tenuis was used as a source of PBS because the pigment composition and the structure of the PBS are well defined. Isotropic PBS in the unstretched film and PBS uniaxially oriented in the stretched film were investigated. Diameters of PBS hemidiscs were oriented parallel to the film-stretching direction. The time-resolved fluorescence spectra of the unstretched sample and of the two polarized components in the stretched samples showed several differences in the rise and decay. The delay time, estimated from the time span between the maximum laser pulse and maximal intensity of the phycocyanin and allophycocyanin fluorescence, was much longer than that reported in the aqueous media. This suggests occurrence of a higher thermal deactivation of PBS in polymer film than in aqueous media. The excitation energy transfer from excited phycocrythrin to allophycocyanin was more efficient in the unstretched than in the stretched samples, and it was greater in the parallel polarized component of the stretched sample than in the perpendicular component. The present results are in agreement with a previous suggestion which states that there are two independent pathways of excitation energy transfer in PBS and that there is more than one final emitter of fluorescence. The molecules taking part in various pathways of energy transfer differ in their orientation within PBS. 相似文献
90.
Tabushi Iwao Kuroda Yasuhisa Yamada Masahiko Sera Takashi 《Journal of inclusion phenomena and macrocyclic chemistry》1988,6(6):599-603
Deuterium relaxation times ofd- andl--d-tryptophan included in -cyclodextrin derivatives were directly measured by deuterium NMR spectroscopy. The results showed that the molecular motion of the tryptophan molecule was strongly restricted even in the cavity of unmodified -cyclodextrin and the additional recognition groupings — ammonium and carboxylate — on -cyclodextrin did not affect the molecular motion of tryptophan, though the association constants were significantly enhanced.Deceased on March 22, 1987. 相似文献