New chiral dopants having a chiral ring structure were designed and synthesized. The materials investigated here are three-membered ring compounds such as cyanocyclopropanes, fluorocyclopropanes, (trifluoromethyl)cyclopropanes, and difluorocyclopropanes, five-membered ring compounds such as γ-lactones, tetrahydrofurans, and 2-oxazolidinones, six-membered ring compounds such as 1, 3-dioxanes and 1, 3-dioxan-2-ones, and 1, 3-diols which form a sixmembered ring through intramolecular hydrogen bonding. The ferroelectric liquid crystal mixtures doped with one of these compounds exhibited high spontaneous polarization (Ps).

View full abstract

Electric potential of graphite during intercalation of sulfuric acid by chemical oxidation was found to increase in stepwise to positive direction, and reflect the change in stage structure of graphite intercalation compounds with sulfuric acid (H₂SO₄-GICs). It was shown that the intercalation behavior of sulfuric acid into graphite by the chemical oxidation method could be followed by in-situ measurement of electric potential.
From the potential change, the intercalation p rocess of sulfuric acid by the chemical oxidation method was found to be fundamentally the same as that by electrochemical one. The intercalation reaction is divided into two processes; one is charging process of host carbon layers corresponding to the potential increase and another is transformation process of stage structure in GICs showing the plateau on the potential curve.
The potential increase of graphite in sulfuric acid soluti on by the chemical oxidation process was limited by the equilibrium potential of redox reaction of oxidant used, which is determined on the activities of each chemical species in the solution. Effects of dilution of sulfuric acid on the formation of H₂SO₄-GICs could be explained in term of the balance between the upper limit of saturated potential in the chemical oxidation and the onset potential for each stage structure.
The intercalation behavior of sulfuric acid by the chemical oxidation process depended strongly on the structure and the texture of host carbon materials. The effect of host carbon materials on the potential change during the chemical intercalation could be explained on the basis of competition of reaction rates between the charging of carbon layers and the stage transformationlin the gallery.

View full abstract

The reactions between photoexcited benzophenone and several aromatic amines were studied by a time-resolved ESR technique in different kind of micellar solutions (SDS, CTAB and Brij 35) at room temperature. The systems of benzophenone(BP)/N, N-dimethylaniline and BP/N, N-diethylaniline showed the formation of an emissively spin-polarized benzophenone anion radical in all micellar solutions. The systems including N-methyl- and N-ethylanilines showed mainly the benzophenone ketyl radical with emissive spin-polarization in SDS and CTAB micellar solutions, and the benzophenone anion radical in Brij 35. The systems including aniline yielded an emissively spin-polarized aniline N-centered radical in all the micelles. All the emissive spin-polarization observed is explained by the triplet mechanism of CIDEP. These experimental results lead to the conclusion that such micellar environments and/or interfaces promote a function of charge separation and prohibit a back charge transfer of a transient charge transfer complex or a radical-ion pair formed immediately after photolysis, when amines have low ionization potentials.

View full abstract

SO, removal activity of a commercially PAN-ACF, FE-300 was examined at 100 °C in its repeated use by regenerating it at a temperature range of 400-1000 °C, using model flue gas containing 1000 ppm SO, . The particular ACF showed an excellent removal activity after the heat treatment at 800 °C (FE-300-800) providing a breakthrough time of 5.1 h. However its activity was so much reduced in the second successive runs to be 50% of the first run, when its ACF was regenerated before the successive are at 500 °C, where adsorbed SO₂ was completely recovered.
High temp erature of 800 °C regenerated more the activity, although the breakthrough time was still 4.5 h in the second run, and decreased steadily in the successive runs. Such regeneration provoked a large carbon loss by evolving CO, and CO after the recovery of SO₂.
The activity was almost completely regenerated when the ACF was treated with NH 3 at 500 °C after the complete recovery of SO₂. NO was found reduced with NH₃ at 500 °C over the ACF after the recovery of SO₂, exhibiting a conversion of 60% recovery of SO₂ adsorption ability. Reduction with NH₃ for the recovery of SO, adsorption led to no carbon loss at the regeneration. The role of oxygen functional groups introduced by oxidative adsorption and desorption of SO₂ are discussed for the oxidative adsorption of SO2 in the successive runs.

View full abstract

Since thermal conversion of carbon tetrachloride into tetrachloroethylene is an endothermic reaction, it is necessary that the reaction is performed at high temperatures such as 750 °C. On the other hand, the reaction of carbon tetrachloride with 1, 2-dichloroethane in the presenc e of oxygen is an exothermic reaction and possibly proceeds at lower temperatures.
We examined the reaction of EDC or 1, 2-dichloropropane with CTC in the presence of oxygen with an oxychlorination catalyst and obtained the following results.
( 1 ) The reaction of EDC with CTC to PCE proceeded at about 400 °C over supported CuC12-KC1 catalyst.
( 2 ) DCP was also converted into PCE under the similar reaction conditions.

View full abstract

4, 4'-Dimethylbenzil shows four n→π* transitions at 381.0, 358.5, 338.0 and 330 nm in EPA (ether: isopentane: ethanol=5: 5: 2) at 101 K. From configuration analysis, it is found that 381.0 and 358.5 nm bands can be assigned to the n→π* transitions localized separately on the two benzoyl moieties, and the 338.0 and 330 nm bands to the n-, 27-* transitions, having intramolecular CT characters, from the n orbital of the oxygen atom to the 7r* orbital belonging to the different benzoyl moiety. The 232.5 nm band, observed in the PE(polyethylene)film at 101 K, has mixed natures of the n→π* transition with intramolecular CT character and the nearby intense π→π* one. The polarized absorption spectrum, measured in the stretched PE film at 101K, shows that the intense, π→π*band, appearing in the wavelength region 250-320 nm, is composed of the three electronic bands at 293, 278.5 and 272 nm, whic h can be assigned to the S₅←S₀, S₇←S₀ and S₈←S₀ transitions, respectively. Splitting features of the above mentioned n→π* transitions indicate that the two n orbitals interact significantly. The n orbital also interacts with the 7r orbital belonging to the different benzoyl moiety.

View full abstract

Epoxidation of olefins with sodium bromite was st udied in the alkaline aqueous solution. The epoxidation proceeded effectively at room temperature in the presence of small amount of copper ion. No epoxidation occurred without copper ion. It is considered that copper ion is reacted with sodium bromite to give unstable copper(II)bromite. Reaction of epoxidation is proposed as follows.
_??_

View full abstract

4-Alkoxy-6-amino-2 H-1, 3, 5-thiadiazine-2-thiones 5 J were prepared by the reaction of N'-cyano-O-alkylisourea [4] with carbon disulfide in the presence of potas sium hydroxide, f ollowed by acidification. Thiadiazine [5 a] (R=Et) rearranged into 6-ethoxy-1, 3, 5-triazine-2, 4(1 H, 3 H)-dithione [9] in ethanolic sodium hydroxide, whereas yielded dimethyl N-a(cyanoimino)ethoxymethyljimidodithiocarbonate [3 ] by the reacti on of methyl iodide in the presence of potassium hydroxide. Heating of 5 in water resulted in the hydrolysis at 4-position of thiadiazine ring and N'-(alkoxycarbonyl)thioureas [10] were obtained.
6-Amino-4-(substituted amino)-1, 3, 5-2 H-thiadiazine-2-thione 1 could b e obtained by the reaction of [5 a] with amines, and the reactivity of [1] was also investigated.

View full abstract

As an extension of our synthetic investigation on heterocycles using silicon reagents, preparation of perfluoroalkyl-1 H-benzo[ c ]quinolizin-1-onesw as studied. An addition-cyclization reaction of perfluoro(2-methyl-2-pentene) [ 2 ] with a 2-quinolylmethyl carbanion generated from 2-(trimethylsilylmethyl)quinoline [3 a] in the presence of a catalytic amount of tetrabutylammonium fluoride (TBAF) afforded 3-pentafluoroethyl-2-trifluoromethyl-1 Hbenzo[c ]quinolizin-1-one [6 a] in 36% yield, accompanied with the corresponding adduct [4 a] and E/Z alkenes [5 a] (1, 29 and 11% yields, respectively). These intermediate compounds [4 a] and E/Z-[5 a] were effectively transformed into the final product [6 a] on heating in wet xylene. An equilibrium constant K_E-Z for E-Z isomerization of [5 a] was 2.44 in refluxing dry tetrahydrofuran (THF) and the calculated ΔG_E→Z was 2.5 x 10³ J⋅ K^-1mol^-1. Under the optimized conditions ([3]:[2]: [KF] =1: 3: 1; at -5°C for 3 h in THF, then refluxed for 6 h in xylene after quenching with water and replacement of the solvent), the reaction of [3a] or the methyl- or chloro-substituted analogs gave the corresponding 1 Hbenzo[c ]quinolizin-1-one derivatives [6a]-[6e] in 93 (substituent R =H), 92 (R =6-CH_, ), 83(R = 8 -CH₃), 90(R =8-Cl), 86%, (R =10-Cl) yields, respectively, and 5-methyl-3-pen tafluoroethyl2-trifluoromethyl-1 H-benzo[ c ]quinoxalizin-1-one [6 f] in 35% yield.

View full abstract

Modified β-cyclodextrin-epichlorohydrin cross-linked polymer having hydrophobic cavities was prepared by the esterification of primary hydroxyl groups of B-cyclodextrin with 3, 4, 5trihydroxybenzoic acid (gallic acid) or 3, 4-dihydroxybenzoic acid (protocatechuic acid) activated by KF in DMF.
By compl exation with iron(III) ion, the polymers became a highly active catalyst for the hydroxylation of benzene with hydrogen peroxide in the range of pH 2-4 at room tempera ture under nitrogen atmosphere (conversion of 85-95%). At the optimum pH of 2.5, both catalysts gave catechol, hydroquinone, and phenol in the yields of 68-73, 7-8, and 10-14%, respectively. No resorcinol was detected in the products. The immobilized catalyst was easily separated from the reaction mixture, and was reused without decrease in catalytic activ ity.

View full abstract

X-Ray absorption effects were studied to carry out the quantitative analysis of various asbestos fibers by using transmission electron microscope (TEM) equipped with energy dispersive spectrometry.
X-R ay intensities ratioed to Si for various standards appeared to have much variation in a diameter 0.1μm than in diameters from 0.5 to 1.0μm under the fixed operating conditions of impinging electron beam. It was possible to calculate absorption correction intensities by the linear regression line on fiber diameter vs. intensity ratio basis when the thickness can not be measured or intensity ratios are not much variable. In the linear regression line of absorption correction factor calculated on the basis of chemical compositions, the slope of Na that has a large mass absorption coefficient increased markedly in the presence of much amounts of Fe such as in crocidolite fiber.
The thickness of each fibe r was found to be smaller than its diameter observed by the TEM.

View full abstract

New chelate resins were prepared by the reaction of a diphenyl phosphonate-formaldehyde resin with polyamine. The adsorption and desorption of gold(III) with the present chelate resin were examined.
The prepa red resin modified with triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine have the high adsorption capacity (2.3 mmol Au/g-resin). Gold(M) is readily adsorbed on the resins as anionic chloro-complexes from hydrochloric acid solution. Adsorption rate of gold(11) is high and the gold(M) was adsorbed effectively by passing gold (III) solution (100 mgdm^-3) through the resin column at SV 600.1-cl. The presence of 0.5moldm-8 KH₂PO₄ at pH 4.2 or 0.2 moldm^-3 HNO₃ and the five-times amount of Cu(10, and Al(III) to gold(III) at pH O.5 do not affect the adsorption efficiency of gold(III). The gold(III) loaded on a column can be eluted with 0.5 moldm^-3 HCl-50 v/v% acetone aqueous solution.
The DPP-PEH resin loading gold(ll) which was treated with NaBH₄ in ethanol can be utilized as a catalyst for hydrogenation of acetylene.

View full abstract

Selective conversion to useful syngas or methane of fuel soots impregnated with KOH was investigated in respect of air pollution or lowering engine efficiency. Reactant soot was prepared from propane gas and light oil fuel by flame incomplete combustion, and gasification, of these soots was performed using flow type reactor (U tube) under atmospheric pressure. Water gas reaction or shift reaction of the KOH-impregnated soots exhibited much higher as well as more stable gas evolution rate on steam-helium mixture stream than that of active carbon granule as reference carbon (550-700 °C). Gasificated products from these soot/KOH by steam were largely H², CO, CO^, and small amount of CH_, (under 1%).
It was found that the light oil-soot interacted strongly with KOH gave higher carbon consumption rate (138 g⋅l^-1⋅h^-1at 650 °C) as compared with that of gasoline fuel-soot (70g⋅l^-1⋅h^-1at 650 °C). Impregnation with KOH caused soot to promote increase in the surfa ce area at elevated temperature and to catalyze water gas reaction. The results presented on the products distribution and the gasification rate suggest that reduction-oxidation cycle of potassium was caused by the contact of carbon with water molecules at the elevated temperature. From the results of water gas reaction on K₂CO₃-impregnated soot and XRD it was infered that the gradual deactivation of KOH in the gasification of soot was due to the formation of K²CO³.

View full abstract

The flammability limits of hydrogen are known to follow characteristic pressure dependence. The relationship between the limit flame temperature and pressure is determined according to the mechanism of flame quenching. In the present study, by using rather small sized vessels (20 mm and 35 mm in diameter), the flammability limits of hydrogen hae been measured at pressures of 1-50 kgf⋅cm^-2. The measurements have also been made to examine the effect of direction of flame propagation; upward, downward and horizontal propagations (Table 1). Pressure dependences of the limit flame temperature were analyzed, using equations which were derived from competitive reaction model and conductive heat loss model, f or upward propagation, and convection model for downward and horizontal propagations, respectively (Tables 2 and 3).
It has been found that the vessel size does not change much the pressure dependence of the lower flammability limits. On the other hand, the direction of flame propagation does change the lower limits, though the way is very similar for the two vessels (Figs.2 and 3). It seems that the mechanism which determines the lower limits of hydrogen is the competition between the chain branching and chain breaking reactions of hydrogen combustion.
As for the upper limits (Figs.4 and 5), the pressure dependence has been found to vary drastically according to the experimental conditions. The mechanism of the propagation limit seems to change for different propagation directions and for different pressure regions. For the lower pressure region, the pressure dependence of the limit flame temperature is well explained by the competitive reaction model. And for the higher pressure region, the heat l oss mechanism seems to be effective for upward propagation, and the convective mechanism seems responsible for both downward and horizontal propagations.

View full abstract

The complex formation of elemental mercury with α-, β-, and r-cyclodextrins (CDs) has b een studied in the excess of CD in aqueous medium at 25 °C. Solubility and volatilization methods were used to determine formation constants. The former method gave 4.5 dm^3⋅mol^-1and the latter 6 dm³mol^-1 for the 1: 1 (α-CD: Hg) complex formati on. Both methods did not show any complex formation of Hg with β- and γ-CDs.

View full abstract

Uptakes of Cu²⁺, Pb²⁺ and Zn²⁺ on various synthetic hydrotalcite (HT-0O₃, HT-SO₄, HTCl and HT-NO_, ) were investigated in Cu(NO₃)₂, Pb(NO₃)₂, Pb(NO₃)₂ and Zn(NO₃)₂ aqueous solution (each conc.: 2000 mgdm-3). Hudrotalcite has a pronounced activity for the uptakes of Cu²⁺, Pb²⁺ and Zn²⁺. Amounts of Cu²⁺, Pb²⁺ and Zn²⁺ removed by HT-0O₃ are about 1.7 mmol Cu/g, 1.0 mmol Pbfg -and 1.2 mmol Zn/g. In a mixed solution of Cu²⁺, Pb²⁺ and Zn²⁺ (the concentration of each ions: 20 mmoldm^-3), the order of activity for the uptak es of each ions on HT-0O₃, HT-SO₄, HT-Cl and HT-NO, are Pb>Cu>Zn, Cu>Pb>Zn, Pb>Cu>Zn and Cu>Pb>Zn. When the HT-0O₃ was immersed into the Pb(NO₃)₂ solution, a part of the Me-, OH- and CO₃- of HT-CO₃ (Mg₆Al₂(0F1)₁₆CO₃4 H₂0) dissolve into the solution. The dissolved OH- and CO₃2- causes the Pb²⁺ to precipitate as Pb₃(OH)₂ (CO₃)₂ on the surface of the HT-CO₃.

View full abstract

When the oxidation of 3-substituted 4'-methylazobenzene and 4'-substituted 4-methyl azobenzenes was carried out with hydrogen peroxide in acetic acid, two kind of isomers which differ the relative position of oxygen atom on nitrogen atoms were obtained in almost equimolar amounts.
_??_
β, α-Isomeric conversion of these 4-methylazoxybenzene deriva tives took place in the reaction of β-isomers with chromium(VI) chloride in acetic acid.
_??_
When Y is hydrogen, X are Cl, NO₂ and I and also X is hydrogen, X are NO₂, I and Br, respectively.

View full abstract

The alumina thin films with sponze-like surface structure were prepared by the sol-gel method using a 1, 3-butanediol solution of aluminium nitrate. The film usually produced by the spin-coating method and calcined at 500 °C (100 nm thick) has the homogeneous flat surface. However, the additional hot-water treatment at 100 °C for 2 h and calcination at 500 °C changed the surface texture to the sponze-like surface (Fig.3). The film was found to be covered with fibrillay particles of 50-100 nm in length and ca.5 nm in width which were composed of fine -Al₂O₃r particles with the mean size of ca.5 nm (Fig.4). The pores constructed by the aggregate of the fibrillay particles were observed in the range of 100-, 200 nm in diameter by SEM.

View full abstract

Synthesis of highly pure dipivaloylmethane (Hdpm) chelates of Tantalum(V) was investigated. The chelates were synthesized by the reaction of the ligands with Tantalum pentachlcride using anhydrous solvents under high purity argon gas atmosphere.
[Ta(dpm)₄]Cl was syntesized as a new source material for p reparation of Ta₂O₅ thin films by MOCVD. [Ta(dpm)₄]Cl was in good agreement with the calculated value in the results of ICP and elemental analysis, and was confirmed by FT-IR, ₁H-NMR, ₁₃C-NMR, and TGDTA. Vaporization of impurities was not found in TG measurement. The tantalum complex vaporized in the range of 220 to 360 °C without residue.
[Ta(dpm)₄]Cl proved to be superior in volatility and purity for the MOCVD source material.

View full abstract