Mechanisms of methane C-H bond activation by soluble methane monooxygenase (sMMO) are discussed. Widely-believed oxygen rebound mechanism for alkane hydroxylation by sMMO is critically reexamined. We suggest a two-step concerted mechanism for the hydroxylation of methane on the basis of our theoretical studies by means of a hybrid density-functional method. The activation of methane C-H bond by intermediate Q of sMMO which is suggested to involve a high valent Fe₂ (μ-O)₂ diamond core is found to occur through the formation of the Q (CH₄) complex with an Fe-C bond and Fe-II bonds, followed by a concerted H atom abstraction via a four-centered transition state. Methyl migration via a three-centered transition state successively occurs within the complex leading to the formation of product methanol. Our proposed mechanism for the conversion of methane to methanol is able to explain the important experimental results of kinetic isotope effect and inversion of stereochemistry. The two-step concerted mechanism sheds new light on recent experimental results which are inconsistent with the widely-accepted radical mechanism.

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Since Li₂O-TeO₂ glasses have unique properties such as high densities, high refractive indexes, large dielectric constants and transmittance in a wide infrared wavelength region, much scientific attention has been focused on the glasses from the standpoint of its technological utilizations. In spite of their usefulness, little diffraction work has been done about the short range structure of Li₂O-TeO₂ glasses. The structure of 15 mol%Li₂·O.85 mol%TeO₂ and 25 mol%Li₂·75 mol%TeO₂ glasses was analyzed by an X-ray diffraction technique. Interpretation of the radial distribution function was performed on the basis of the correlation method. The following conclusions were obtained from the present study; (1)Two kinds of Te-O bond lengths of 0.18 nm and 0.20 nm are in TeO₄ trigonal bipyramid. (2) As network forming units, the TeO₄ trigonal bipyramids and TeO₃ trigonal pyramids are observed. The former units are thought to be transformed, via the transient species of polyhedra with non-bridging oxygens, into the latter units with increasing Li₂ contents. (3) The lone pairs of electrons on Teatoms do not contribute to the network formation.

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Hydrogenation of santonin C (2), an isomer of santonin, over Pd-C in aqueous alkaline solution afforded a new tetrahydrosantonin (THS) 4 with a cis-decalin skeleton, which was epimerized by HCl0₄ to 9methyl isomer 5. Reduction of 4 with NaBH₄ afforded two new hexahydrosantonins (HHS) 6 and 7, whereas the reduction of 5 gave 8 and 9. THS 5 was assigned as what Cocker did as 4. Accordingly 9 corresponded to what Cocker assigned as 7.
Stereochemistries of THSs and HHSs were fully studied.

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The products from electroreduction of phosphonium and arsonium salts in acetonitrile containing supported electrolyte were traced by ³¹P-NMR spectra and liquid chromatography. (Methoxycarbonylmethyl)triphenylphosphonium bromide gave the corresponding ylide by hydrogen abstraction along with triphenylphosphine. Benzyltriphenylphosphonium bromide gave mainly stilbene as the oxidation products of nonstabilized ylide besides triphenylphosphine and triphenylphosphine oxide. The corresponding arsonium salts were reduced and gave mainly triphenylarsine. The electroreduction of phosphonium and arsonium salts under the presence of substituted benzaldehydes gave the olefins from Wittig reactions. The ylide formations could be considered as a competitive reactions with the radical cleavage of a substituent on the phosphonium or arsonium salt forming triphenylphosphine and arsine.

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The photochromism of porphyrin caused by putting on and off hydrogen chloride, which is generated by the photodegradation of solvent, is investigated. The effect of solvent and porphyrin substituent on the photochromism is surveyed and 50% 2-chloroethanol in ethyl acetate is found to be suitable as solvent from the viewpoints of the quick generation of hydrogen chloride by irradiation and the facile abstraction of hydrogen chloride from the porphyrin hydrochloride salt on heating, 5, 10, 15, 20-tetrakis (4-trifluoromethylphenye)porphyrin (CF₃TPP) being fitted because of its light resistance. The photochromic system consisted of CF₃TPP and 50% 2-chloroethanol reveals to be stable to the repeated putting on and off hydrogen chloride.

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Poly (vinylidene fluoride) (PVdF) in some ketones (such as acetone, ethyl methyl ketone, cyclohexanone, and so on) converts to thermoreversible gel at room temperature. Gelation of PVdF/ketone system takes place through crystallization of polymers taking the conformation TGTG. from random statistical coils. In this study, gelation process of PVdF/cyclohexanone system was examined by both dilatometry and Fourier transform infrared (FT-IR) measurements using four samples with different molecular weights. A range of weight-average molecular weight is from 30.7×10⁴ to 82.7×10⁴.
It was found from FT-IR spectra that the conformation TGTG was formed slowly in a solut ion with increasing molecular weight. According to the analysis of dilatometry experiments by the Avrami equation, the Avrami plot for each sample was divided into two linear regions with different slopes: one is the primary crystallization region with a steep slope; the other is the secondary crystallization region with an easy slope. Avrami exponents (n) in the primary crystallization region were approximately 2.9<n <3.6, and became smaller with increasing molecular weight. On the contrary, gelation time became longer with decreasing molecular weight.

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Phenyl-modified silica gels were derived from a mixture of triethoxy (phenyl) silane and tetraethoxysilane. The fluorescence spectra and lifetime of pyrene were measured in silica gels. The fluorescence spectra and lifetime changed with an increase in phenyl content and became constant above ≈ 20 mol%of triethoxy (phenyl) silane. The fluorescence band of phenyl groups also showed a change from a monomer one to an excimer one above ≈ 20 mol% of phenyltriethoxysilane. Similarly the vibrational frequencies of infrared bands due to the siloxane network were shifted above ≈ 20 mol%. These results were explained by the structural changes of phenyl-modified silica gels induced by the bulky phenyl groups.

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A four-stage filter pack method (F₀: PTFE, F₁: polyamide, F₂: 6%K₂CO₃+2% glycerol impregnated and F₃: 5 % phosphoric acid +2 % glycerol impregnated filters) was used to sample the atmosphere for determination of gas (SO₂, HNO₃, HCl, NH₃) and particulate matter (SO₄^2-, NO₃^-, Cl^-, Na⁺, NH₄⁺, K⁺, Ca²⁺, Mg²⁺) concentrations. The average concentrations of SO₂, H NO₃, HCl, NH₃ gases and SO₄^2-, NO₃^-, Cl^-, Na⁺, NH₄⁺, K⁺, Ca²⁺ and Mg²⁺ particles were 76.2 (1.83), 27.3 (0.66), 31.8 (0.76), 115 (2.76), 52.3, 47.7, 45.1, 34.4, 121, 9.4, 20.5 and 6.2 nmol/m³ (ppb: 20 °C), respectively.
The gases and particulate matter concentrations were multiplied by dry deposit ion velocities for various surfaces (bare soil, farmland, deciduous forest, coniferous forest) from the literature to estimate dry deposition. The coniferous forest received the greatest dry deposition of SO₄^2- and NO₃^-. The average amounts of dry deposition of SO₄^2- and NO₃^- estimated with data from a Wet/Dry collector were 0.692 and 0.601 molm^-2/month, respectively, smaller than the average amounts obtained with the inferential method. The contribution of dry deposition to total deposition was greater for gaseous species than for particulate matter. In the coniferious forest, the SO₄^2- and NO₃^- contributions to total dry deposition were 59 and 77%, respectively. Forest damage cannot be fully evaluated by wet deposition measurements alone; estimate of dry deposition of HNO₃ to coniferous forests will advance our understanding of forest damage by acidic deposition.

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An automatic monitor has been developed for measuring formaldehyde in air using a sensitive tape for formaldehyde. It is based on the color change of the tape by reaction with formaldehyde. The tape containing silica gel and impregnated with a processing solution containing hydroxylamine sulfate, Methyl Yellow (pH indicator; pH 2.9-4.0, red-yellow), glycerol and methanol was found to be a highly sensitive means of detecting formaldehyde and maintained stable sensitivity. When an air sample including formaldehyde was exposed to the tape, the color of the tape changed from yellow to red. The degree of color change was proportional to the concentration of formaldehyde at a constant sampling time and flow rate, and it could be recorded by measuring the intensity of reflecting light (555nm). The tape could be used to detect down to 0.08 ppm (WHO standards) of formaldehyde with a sampling time of 30min and a flow rate of 100 mL/min. Reproducibility tests showed that the relative standard deviation of response (n=10) was 3.8% for 0.1 ppm formaldehyde. The monitor is simple, specific, operated automatically and recommended for both laboratory and field operation.

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Adsorption-desorption phenomena of sodium dodecyl sulfate and sodium dodecylbenzenesulfonate at a mercury electrode were studied by a flow injection method with measuring differential capacity-time curves. Adsorption of sodium dodecyl sulfate at -0.2 V is irreversible, while that at the potential more negative than -0.4 V is reversible. Adsorption of sodium dodecylbenzenesulfonate is irreversible at the potential more positive than -0.8 V. It is reversible at the potential more negative than -1.0 V. From these results, adsorption models for the two surfactants were proposed.

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Non-ligated Nickel (II) chloride-catalyzed cross-coupling between aryl Grignard reagents and aryl halides has some merits for industrial application. 1) Toxic and expensive phosphines are not needed and 2) the absence of organic ligands makes the treatment of the reaction mixture easier: The extraction with water is enough to separate the product from the catalyst. We examined the problems for the industrial scale application of the NiCl₂-catalyzed cross-coupling reaction for the production of 3-chloro2-methylbiphenyl, an intermediate for pyrethroid insecticides, from 2, 6-dichlorotoluene and bromobenzene.
The undesired formation of bis (magnesium chloride) from 2, 6-dichlorotoluene can be avoided by using excess 2, 6-dichlorotoluene. The unreacted 2, 6-dichlorotoluene can be recovered by distillation after the reaction. Homo-coupling of Grignard reagents can be suppressed by the purge of oxygen from the reaction system.

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