Shoichi Kikkawa

Studies of organometallic compounds The five-membered ring structure of organotin containing dicarboxylic esters☆

Abstract Bis[(1,2-dialkoxycarbonyl)ethyl]tin dihalides (II) were synthesized by the direct method; the reaction between tin foil and dialkyl halosuccinates in the presence of accelerators. Besides the main products, [(1,2-dialkoxycarbonyl)ethyl] tin hydroxydibromide (III) was obtained as by-product. It was considered that (II) had two stereoisomers with a six-coordination containing 2 five-membered ring structures in which the oxygen atom of the CO at the γ-position with respect to the tin atom was coordinated to the tin atom. These isomers could be isolated with appropriate solvents and the by-products (III) on the basis of IR or NMR spectra, had the five-coordination with tridentate ligand in which the CO group at the γ-position was coordinated to the tin atom and another CO group in the β-position formed a hydrogen bond to the OH group. However, only one product (unstable in the air) was obtained by the direct reaction between other dialkyl halodibasic acid esters and tin foil. The properties of the direct reaction products were compared with those of hydrostannation of the unsaturated dicarboxylic ester with tri-n-butyltin hydride and of the subsequent bromination. The brominated products were considered to have the five-membered ring structure with the CO at the γ-position coordinated to the tin atom, also on the basis of IR and NMR spectra. In view of these observations, it is concluded that those coordinations where the CO at the γ-position coordinates to the tin atom must be caused by the electronegativity of the attached halogen atoms.

Hydrocracking of Athabasca asphaltene over ZnCl2-KCl-NaCl melts with or without an additive of some transition metal chlorides

Abstract Hydrocracking of Athabasca asphaltene over molten salts has been studied at 400 °C for 1 h at an initial hydrogen pressure of 9.8 M Pa. The hydrocracking over ZnCl2-KCl-NaCl produced 57.0 wt% of pentanesolubles (PS), 4.7 wt% of benzene-solubles (BS) and 22.7 wt% of gases together with 15.6 wt% of coke. These melts containing NiCl2 and CuCl, respectively, were examined, the former exerting a little better influence on reducing the coke yield. A small amount of coke (3.7%) and a higher conversion attained with ZnCl2-KCl-NaCl-MoCl5 suggested excellent properties of MoCl5 for the hydrocracking of asphaltene. The sulphur contents of the PS and BS were lowest with melt catalysts containing MoCl5. A compound-type separation of each pentane-soluble showed that in the presence of melt catalyst, monoaromatic and diaromatic contents increased greatly at the expense of polyaromatics and polar materials. The trend of catalytic activity of each melt for hydrocracking of asphaltene was found to be quite different from that for the decomposition reaction of tetrahydrothiophene in a continuous flow system.

Studies on low temperature structure of infinite-layered superconductor Sr1−xLaxCuO2 (0 ≤ x ≤ 0.12)

Abstract Low temperature structure was investigated on infinite-layered Sr 1− x La x CuO 2 (0 ≤ x ≤ 0.12, La-IL) superconductor by X-ray absorption fine structure (XAFS), X-ray diffraction (XRD) and Raman spectroscopy. XAFS showed that CuO bond distance slightly expanded with lowering temperature down to 20 K, and the expansion was remarkable below T c(onset) = 43 K. Tetragonal lattice parameters shrank with lowering temperature but the shrinkage of the a -parameter seemed to be almost saturated below T c(onset) . Resonance Raman peaks were observed at 151 cm −1 and 304 cm −1 in the La-doped samples, although the ideal IL structure should be Raman inactive. The peak intensities increased with lowering temperature. The variation may be related to the change observed with both XAFS and XRD in local structure with temperature. It is assumed that the CuO 2 plane may buckle with shifting oxygen ion positions above and below the CuO 2 plane, as reported in another electron-doped superconductor Nd 2− x Ce x CuO 4 (T′-214).

XANES study on electron doped infinite-layer Sr1−xLaxCuO2 (0 ≤ x ≤ 0.12) and (Sr1−yCay)0.9La0.1CuO2 (0 ≤ y ≤ 0.20) superconductors

Abstract X-ray absorption near-edge spectroscopy (XANES) was applied to study electronic structure of infinite-layer (IL) superconductors Sr 1− x La x CuO 2 and (Sr 1− y Ca y ) 0.9 La 0.1 CuO 2 . The 1s–4p ∗ (π) transition for Cu3d 10 was intensified with increasing La 3+ content x . This is the first spectroscopic evidence for the electron doping in the present system.

Studies on local structure of infinite-layered (Sr1−yCay)1−xLaxCuO2 (0 ≤ x ≤ 0.12, 0 ≤ y ≤ 0.20) superconductor

Abstract Local structure of infinite-layered superconductor (Sr1−yCay)1−xLaxCuO2 (0 ≤ x ≤ 0.12, 0 ≤ y ≤ 0.20) was investigated by studying the Extended X-Ray Absorption Fine Structure (EXAFS). The results showed that both the Sr1−xLaxCuO2 (0 ≤ x ≤ 0.12) and (Sr1−yCay)0.9La0.1CuO2 (0 ≤ y ≤ 0.20) systems have local structure consistent with the expected from the ideal infinite-layer structure at room temperature, without obvious deviation of oxygen ions from the CuO2 plane.

Tetragonal LaN and its new LaBN ternary reaction product prepared under high pressure

Abstract Two kinds of new nitrides related to rocksalt LaN were obtained. One is a tetragonal LaN prepared by nitriding of La metal after heating at 1223K in vacuum. It has lattice parameters of a = 0.5284 nm, c = 0.5357nm and c a = 1.074 . The other is an La-B-N ternary compound obtained under high pressure of 2.5GPa at 1773K. Its X-ray diffraction pattern could be indexed with an orthorhombic lattice having lattice parameters of a = 0.3 756 nm, b = 1.3037 nm and c = 1.6327 nm. The crystal structure was assumed to be a composite of LaN layers with interleaving boron atoms.

Magnetic and Interface Characterization Of Rf-Sputter Deposited Multilayered and Granular Fe/A1N Films

Several kinds of iron nitrides with various amounts of nitrogen have been reported. Both Fe16N2 and Fe4N are interesting magnetic materials because of their large saturation magnetization and small coercivity. The saturation magnetization value gradually decreases with increasing nitrogen content.1 These nitrides are also superior both in mechanical hardness and chemical stability in comparison to α-Fe, but easily decompose, releasing nitrogen above several hundred °C. Other elements such as Zr, Ti have been added to increase their thermal stability.

Diels-Alder Reaction of Vinyl Chloride with Butadiene

塩化ビニルとブタジエンとのディールス・アルダー反応を,反応温度165℃,反応時間4時間程度の条件で過剰の塩化ビニルの存在の下に行なうと, 約26 % の収量で4 - クロルシクロヘキセン- 1 (I) を生じるが, 同時に4 - ビニルシクロヘキセン- 1 (II) やシクロオクタジエン- 1, 5, ジビニルシクロブタン, シクロヘキサジエン- 1, 4 などを同伴することを知った。過剰の塩化ピニルを用いると,これに比例してIのIIに対する生成比が増加し,また適当な溶媒や,各種のラジカル禁止剤を用いると,Iの生成率が増加する。溶媒としてベンゼンを用い,同時に少量のヒドロキノンを禁止剤として用いてジエン反応を行なうと,ブタジエンのIへの転化率は約33 % , I とII とを合した総転化率は約85 % に達した。

Dealkylation of Tar Oil in the Presence of the Alumina Catalyst -Effects of the Pressure and the Temperature

タール油中のメチルナフタリン,ジメチルナフタリン留分を,高圧水素の存在下に,各種触媒を用いて脱メチルさせる際,触媒としては,活性アルミナ(以下アルミナと略称),ヨウ素が比較的有効で,アルミナ触媒を用いて550℃で60分間処理した場合には,40wt%前後のナフタリンが得られた。本研究では連続式高圧反応装置を用い,主として実験計画法に従って,反応温度,反応圧力,滞留時間等の反応条件と,ナフタリン収率その他の特性値との関係を検討した。その結果,アルミナ触媒を用いてタール油の220～260℃ 留分を原料とした実験において,反応温度600～650℃,反応圧力30～50kg/cm2,滞留時間20～30secの作業条件の範囲内では,温度,圧力は高い程,ナフタリン収率が向上することを認めた。

Catalysts to Produce Naphthalene by Dealkylation of Tar Oil Fraction

クレオソート油の有効利用をはかるため, 加圧水素下に粗メチルナフタリン, 粗ジメチルナフタリン, ナフタリン油,ソルベー油等高温タールの諸留分を試料油とし, 各種触媒とともに400～550℃に10～180分間加熱して脱アルキル化反応を行わせ, 各種条件とナフタリン収量との関係, とくに触媒の比較検討を主眼として検討を加えた。著者らの試みた範囲内ではヨウ素,アルミナ等の触媒が比較的良好で反応温度は500～550℃ 付近が適当と思われた。反応時間,反応圧力,水素初圧等の影響は明瞭に認めるにはいたらなかったが,反応温度に到達するまでの加熱速度や冷却速度,あるいは反応温度の均一な管理などの諸条件とも深い関係があるのではないかと思われる。今回の実験においては,ナフタリンの最高収率は粗メチルナフタリン留分に対して22.0%,粗ジメチルナフタリン留分に対して24.0%,ナフタリン油に対して22.8%,ソルベー油に対して27.1%であった。