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81.
Polymerization of acrolein(AL) in the presence of imidazole(Im) has been investigated in tetrahydrofuran or methanol below room temperature. The polymers obtained, white or pale yellow powders, were found to be composed of vinyl polymer with one Im group attached and having an aldehyde side chain, of which 70–80 mole % of the aldehyde revealed bridge structure. The number-average molecular weight (M n) of these polymers was determined to be in the range of 317 to 691. The rate of polmerization Rp was expressed by the equation, R + k[Im] [AL]2. The addition of water or dimethyl sulfoxide accelerated the polymerization reaction, while the presence of benzaldehyde or N,N'-dimethylformamide decreased Rp. The structure of addition products in the initial polymerization step was confirmed by IR and NMR spectra, and the observations of polymerization system was carried out by UV and NMR spectra. The polymerization mechanisms were discussed on the basis of these results. 相似文献
82.
Natsuki Yamashita Atsuhito Tadokoro Eiichiozu Toshihisa Maeshima Ion C. Baianu Lun-Shin Wei 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1223-1239
The anionic polymerization of acrolein (AL) with N, N-dimethylamino-propylacrylamide (DMAPA) in the presence of water was investigated in tetrahydrofuran, benzene, and ethanol at 0°C in a nitrogen atmosphere. The resulting polymers were found to be essentially vinyl polymers with one DMAPA attached and an aldehyde side chain. From observations of the polymerization process by 1H NMR, we find that polymerization was initiated by the hydroxyl anion formed in the thermodynamic equilibrium between the amine of DMAPA and water. The hydrogen transfer reaction of DMAPA was caused by the propagating poly-AL anion. On the other hand, the monomer reactivity ratios and the Q2-e2values of DMAPA were determined by the free-radical copolymerization of styrene (St, M1) with DMAPA and AIBN as initiator. 相似文献
83.
Eiichi Ozu Natsuki Yamashita Toshihisa Maeshima Ion C. Baianu Lun-Shin Wei 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1637-1653
N-(Butyl-3-one)imidazole acts as an initiating adduct which is formed in the anionic polymerization of methyl vinyl ketone (MVK) induced by imidazole (Im) and is directly formed from Im and the MVK monomer. The kinetics of the anionic homopolymerization of MVK and acrylamide (AAm) under argon in the presence of the adduct were investigated in tetrahydrofuran (THF). The rate of polymerization for the MVK system is expressed as Rp = k[Adduct] [MVK], where k = 3.1 × 10?6 L/(mol·s)in THF at 30°C. The overall activation energy, Ea , was found to be 5.34 kcal/mol. The Rp for the AAm system is expressed as Rp = k[Adduct] [AAm], where k = 6.8 × 10?6 L/(mol·s) in THF at 30°C, with Ea 7.78 kcal/mol. The mechanism of the polymerization induced by the initiator adduct is discussed on the basis of these results. 相似文献
84.
85.
Hideaki Murasugi Dr. Shohei Kumagai Dr. Hiroaki Iguchi Prof. Dr. Masahiro Yamashita Dr. Shinya Takaishi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(42):9885-9891
Crystal structures of a series of organic–inorganic hybrid gold iodide perovskites, formulated as A2[AuII2][AuIIII4] [A=methylammonium (MA) ( 1 ) and formamidinium (FA) ( 2 )], A′2[I3]1−x[AuII2]x[AuIIII4] [A′=imidazolium (IMD) ( 3 ), guanidinium (GUA) ( 4 ), dimethylammonium (DMA) ( 5 ), pyridinium (PY) ( 6 ), and piperizinium (PIP) ( 7 )], systematically changed depending on the cation size. In addition, triiodide (I3−) ions were partly incorporated into the AuI2− sites of 3 – 7 , whereas they were not incorporated into those of 1 and 2 . Such a difference comes from the size of the organic cation. Optical absorption spectra showed characteristic intervalence charge-transfer bands from AuI to AuIII species, and the optical band gap increased as the size of the cation became larger. 相似文献
86.
Chikashi Shinagawa Yusuke Morikawa Shin-ichi Nishimura Hiroshi Ushiyama Atsuo Yamada Koichi Yamashita 《Journal of computational chemistry》2019,40(1):237-246
Na2FePO4F is a promising cathode material for a Na-ion battery because of its high electronic capacity and good cycle performance. In this work, first principle calculations combined with cluster expansion and the Monte Carlo method have been applied to analyze the charge and discharge processes of Na2FePO4F by examining the voltage curve and the phase diagram. As a result of the density functional theory calculation and experimental verification with structural analysis, we found that the most stable structure of Na1.5FePO4F has the P21/b11 space group, which has not been reported to date. The estimated voltage curve has two clear plateaus caused by the two-phase structure composed of P21/b11 Na1.5FePO4F and Pbcn Na2FePO4F or Na1FePO4F and separated along the c-axis direction. The phase diagram shows the stability of the phase-separated structure. Considering that Na2FePO4F has diffusion paths in the a- and c-axis directions, Na2FePO4F has both innerphase and interphase diffusion paths. We suggest that the stable two-phase structure and the diffusion paths to both the innerphase and interphases are a key for the very clear plateau. We challenge to simulate a nonequilibrium state at high rate discharge with high temperature by introducing a coordinate-dependent chemical potential. The simulation shows agreement with the experimental discharge curve on the disappearance of the two plateaus. © 2018 Wiley Periodicals, Inc. 相似文献
87.
Katsuya Maeyama Kenji Yamashita Shugo Maeda Noriyuki Yonezawa Shunichi Aikawa Yasuhiko Yoshida 《合成通讯》2013,43(23):4158-4170
Optically active aromatic ether ketone macrocycles containing 2,2′-dimethoxy-1,1′-binaphthyl-6,6′-diyl moieties were synthesized through electrophilic aromatic substitution reaction and stepwise nucleophilic aromatic substitution reactions. Structures of the resulting macrocycles were confirmed by NMR and matrix assisted laser desorption/ionization time of flight (MALDI-TOF) mass measurements. 相似文献
88.
Yamashita M Yamamoto Y Akiba KY Hashizume D Iwasaki F Takagi N Nagase S 《Journal of the American Chemical Society》2005,127(12):4354-4371
Pentacoordinate and tetracoordinate carbon and boron compounds (27, 38, 50-52, 56-61) bearing an anthracene skeleton with two oxygen or nitrogen atoms at the 1,8-positions were synthesized by the use of four newly synthesized tridentate ligand precursors. Several carbon and boron compounds were characterized by X-ray crystallographic analysis, showing that compounds 27, 56-59 bearing an oxygen-donating anthracene skeleton had a trigonal bipyramidal (TBP) pentacoordinate structure with relatively long apical distances (ca. 2.38-2.46 A). Despite the relatively long apical distances, DFT calculation of carbon species 27 and boron species 56 and experimental accurate X-ray electron density distribution analysis of 56 supported the existence of the apical hypervalent bond even though the nature of the hypervalent interaction between the central carbon (or boron) and the donating oxygen atom was relatively weak and ionic. On the other hand, X-ray analysis of compounds 50-52 bearing a nitrogen-donating anthracene skeleton showed unsymmetrical tetracoordinate carbon or boron atom with coordination by only one of the two nitrogen-donating groups. It is interesting to note that, with an oxygen-donating skeleton, the compound 61 having two chlorine atoms on the central boron atom showed a tetracoordinate structure, although the corresponding compound 60 with two fluorine atoms showed a pentacoordinate structure. The B-O distances (av 2.29 A) in 60 were relatively short in comparison with those (av 2.44 A) in 59 having two methoxy groups on the central boron atom, indicating that the B-O interaction became stronger due to the electron-withdrawing nature of the fluorine atoms. 相似文献
89.
The straightforward methodology for the construction of chiral arene-fused-piperidine motifs using a highly enantioselective addition of 2-trityloxymethylaryllithiums to cyclic and acyclic nitroalkenes has been developed. The versatility of the process was highlighted by the first asymmetric synthesis of a dopamine D1 full agonist, A-86929. 相似文献
90.
Knöevenagel-type reaction between diketene and aldehydes proceeded in the presence of Ti(O-i-Pr)4. This reaction proceeded via titanium enolate derived from Ti(O-i-Pr)4 and diketene. As for the stereoselectivity of the products, E-isomers were produced predominantly in the case of aromatic aldehydes. 相似文献