Koji Inazu

Characteristics of methoxycarbonylation of aromatic diamine with dimethyl carbonate to dicarbamate using a zinc acetate catalyst

The methoxycarbonylation of aromatic diamines such as 2,4-toluene diamine with dimethyl carbonate using Zn(OAc)2·2H2O as a catalyst is examined to determine the influence of reaction variables on the yields of mono- and di-carbamates. These reactions yield dimethyltoluene-2,4-dicarbamate in 98% yield over 2 h at 453 K. An induction period is observed in the reaction of aromatic amines with dimethyl carbonate, but this induction period is almost completely eliminated by pretreating the catalyst with methanol. The role of methanol is investigated based on infrared absorption measurements, and a mechanism for dimethyl carbonate activation is proposed. Observed differences between the reactivities of aromatic and aliphatic amines for methoxycarbonylation are attributed to differences in the basicities of NH2 groups in these amines.

DETERMINATION OF ATMOSPHERIC NITRO-POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR PRECURSORS AT A HEAVY TRAFFIC ROADSIDE AND AT A RESIDENTIAL AREA IN OSAKA, JAPAN

Concentrations of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) and polycyclic aromatic hydrocarbons (PAHs) in airborne particles collected at two sites, a residential area and a roadside with high traffic density in Osaka, Japan, in summer and winter were quantified. Five nitro-PAHs, 1-nitropyrene (1-NP), 2-nitropyrene (2-NP), 2-nitrofluoranthene (2-NF), 3-nitrofluoranthene (3-NF), and 2-nitrotriphenylene (2-NTP) and five PAHs, pyrene (Py), fluoranthene (Fl), triphenylene (Tp), benzo[k]fluoranthene (B(k)F), and benzo[a]pyrene (B(a)P) were determined by high-performance liquid chromatography with chemiluminescence and fluorescence detection. At both sites, the mean concentration of 1-NP was higher in winter than in summer. On the contrary, the mean concentrations of 2-NF and 2-NP were higher in summer than in winter. Observed 2-NF/2-NP ratio in the range from 0.40 to 16 suggests that 2-NF and 2-NP were dominantly formed via OH radical initiated reaction in the atmosphere. Nitro-PAH and PAH concentrations were generally higher at a roadside area than at a residential area due to extremely higher concentration of particles at a roadside area. 1-NP/B(k)F ratio was higher at a roadside area than at a residential area, while 2-NF/B(k)F, 2-NP/B(k)F, and 2-NTP/B(k)F ratios were higher at a residential area than at a roadside area. The diurnal changes of 2-NF/B(k)F, 2-NP/B(k)F, and 2-NTP/B(k)F ratios were slightly different from those of 1-NP/B(k)F and 3-NF/B(k)F ratios. Thus, the differences in the patterns of nitro-PAHs/B(k)F ratios may be due to the disparity in formation pathways of each nitro-PAH.

Environmental occurrence of nitrotriphenylene observed in airborne particulate matter.

1- and 2-Nitrotriphenylenes were found in the airborne particulate matter extracts collected in central Tokyo between the winter of 1998 and the winter of 1999. In particular, we have identified and quantified nitrotriphenylenes in the airborne particulate matter extracts collected over four consecutive 6-h periods on 2 December 1999. The concentrations of 1- and 2-nitrotriphenylene ranged from 0.04 to 0.44 and from 0.02 to 0.47 ng/m3, respectively, and the concentrations in the airborne particulate matter extracts collected during the 18:00-24:00 h time period were the highest of the four collection periods. 1-Nitropyrene and 2-nitrofluoranthene were also identified and quantified in the four 6-h samples. Although the concentrations of 1- and 2-nitrotriphenylenes were not higher than that of 2-nitrofluoranthene except during the 18:00-24:00 h time period, the concentrations were much higher than that of 1-nitropyrene during the four collection periods. The higher concentrations of 1- and 2-nitrotriphenylenes during the 18:00-24:00 h time period are presumably responsible for the high reactivity of parent triphenylene with NO2/NO3/N2O5, and high stability of 1- and 2-nitrotriphenylenes toward O3 + O2. In addition, the observed isomer distribution of nitrotriphenylenes suggested that direct emission of nitrotriphenylenes is also a source as well as their atmospheric formation.

Formation of 2-nitrofluoranthene in gas-solid heterogeneous photoreaction of fluoranthene supported on oxide particles in the presence of nitrogen dioxide

Abstract Heterogeneous reaction of fluoranthene (FL) supported on eight kinds of inorganic particles has been investigated in the presence of NO 2 both under photoirradiation and in the dark to simulate atmospheric transformations of FL. In the air containing 10 ppm NO 2 , 2-nitrofluoranthene (2-NF), the most abundant nitroarene found on airborne particles, was produced under photoirradiation for the first time in a laboratory heterogeneous system while the reaction did not proceed in the dark in 24 h. The maximum yield of 2-NF ranged from 7.9% for FL supported on CaO to 1.2% on Fe 2 O 3 . The other NFs identified in the photoirradiated sustem were 1- and 7-NFs with maximum yields varying with the kind of support material. This isomer distribution was quite different from that reported for electrophilic substitution and similar to that for radical reaction. Also the degraded percentage of FL in the reaction for 4 h was dependent on the support material in the range from 20.9% on graphite to 79.5% on TiO 2 , respectively. The presence of O 2 in the reaction atmosphere caused promotion of 2-NF formation and suppression of 7-NF formation. Both 3- and 8-NFs, reported to exist in vehicle exhaust particles, were formed only in trace amounts for all the photoirradiated systems.

Mutagenic nitrated benzo[a]pyrene derivatives in the reaction product of benzo[a]pyrene in NO2-air in the presence of O3 or under photoirradiation.

In order to clarify the contribution of nitrated products to the direct-mutagenic activity of products of the reactions of benzo[a]pyrene in NO2-air under various conditions, heterogeneous reactions of BaP deposited on filter in the air containing 10 ppm of NO2 have been conducted in dark or under photoirradiation. The reaction products have been analyzed by gas chromatography and mutagenicity of the products fractionated by preparative HPLC was assayed for Salmonella typhimurium strains TA98 and YG1024 in the absence of S9 mix. 3,6-dinitrobenzo[a]pyrene and 1,3-dinitrobenzo[a]pyrene, which are strong direct-acting mutagens, largely contributed to the total direct-acting mutagenicity of the dark reaction products in NO2-air. On the other hand, both the dark reaction in the presence of O3 and the photoreaction in NO2-air resulted in the formation of much smaller amounts of nitrobenzo[a]pyrenes than that observed in the dark reaction in the absence of O3. These results show that the contribution of other direct-acting mutagens to the total direct-acting mutagenicity of the products in these reactions should be considered. Benzo[a]pyrene lactones were identified in a highly mutagenic fraction of the products of the dark reaction in the presence of O3 and photoreaction and a nitrobenzo[a]pyrene lactone was also identified in a highly mutagenic fraction of the dark reaction products in the presence of O3. Nitrated oxygenated benzo[a]pyrene derivatives such as nitrobenzo[a]pyrene lactone were considered to largely contribute to direct-acting mutagenicity of the products of the dark reaction in the presence of O3 and photoreaction.

Effect of Methanation of Active Carbon Support on the Barium-Promoted Ruthenium Catalyst for Ammonia Synthesis

The effect of the induced methanation of hydrogen-treated active carbon (HTAC) support on the structural change and then catalytic activity over Ba-promoted Ru/HTAC catalysts (Ba(NO3)2 and RuCl3 were precursors) for ammonia synthesis was investigated. It was found that a moderate degree of the methanation of HTAC support increased the catalyst surface area and pore volume significantly rather than destroyed the porous structure. But the methanation of carbon support might accelerate the growth of Ru particles, which finally led to the low activity. We suggested that both the dechlorination temperature (refer to the reductive dechlorination of RuCl3 to form Ru on HTAC) and the hydrogenolysis temperature (refer to the hydrogenolysis of Ba(NO3)2 on Ru/HTAC) have binary effects on the catalytic activity, respectively. On the one hand, the dechlorinating effect and the hydrogenolysis effect increased with the increase of H2 treatment temperature. On the other hand, simultaneously the methanation degree of the support increased too in above both processes. The performance of the catalyst was the combined result of the interaction of the amount of residual chlorine, Ru particle size, and the active promoter component. A respective control of the methanation degree during the catalyst preparation and activation processes was suggested to be necessary for the practical use of the promoted Ru/C catalyst.

COMPARISON OF PAHS, NITRO-PAHS AND OXY-PAHS ASSOCIATED WITH AIRBORNE PARTICULATE MATTER AT ROADSIDE AND URBAN BACKGROUND SITES IN DOWNTOWN TOKYO, JAPAN

Atmospheric polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs and oxy-PAHs are emitted from primary sources. Some nitro-PAHs and oxy-PAHs can also arise from secondary formation in the atmosphere. To assess the relative importance of these sources, the polycyclic aromatic compound (PAC) concentrations were determined at a roadside (Roadside site) and on a rooftop (Urban Background site) in downtown Tokyo Japan. The concentrations of PAHs, 1-nitropyrene and oxy-PAHs at the Roadside site were higher than those at the Urban Background site, while 2-nitrofluoranthene levels were the same at both sites. However, the mean ratios of concentrations at the Urban Background site to the Roadside site were in the order 1,8-naphthalic anhydride>9,10-anthraquinone>PAHs or 1-nitropyrene or acenaphthenequinone or benzanthrone. This suggests that in addition to vehicle emissions, a considerable fraction of some of the oxy-PAHs studied originates from another source, which might be secondary formation by atmospheric PAH degradation, and this contribution varied among the oxy-PAHs.

Selective wet air oxidation of diluted aqueous ammonia solutions over co-precipitated transition metal-aluminium catalysts

Catalytic wet air oxidation of ammonia over a co-precipitated transition metal-aluminium catalyst was investigated. Copper-aluminium (Cu-Al-O) catalyst exhibited the highest activity and N2 selectivity among those prepared from Co, Fe, Mn, and Ni. 50% of 1500 ppm of ammonia could be removed from wastewater of pH 12 at 503 K under 2.0 MPa of air by using 4.0 g of catalyst without formation of toxic nitrogen containing compounds. Cu and Al ions were not found in solution after the reaction. It has been found that the catalytic performance of Cu-Al-O catalyst was strongly dependent on the preparation methods. The co-precipitated Cu-Al-O catalysts showed high N2 selectivity. The presence of CuO is concluded to promote the reaction and CuAl2O4 in bulk phase is needed to stabilize the catalyst.

Prediction of rate constants for the gas phase reactions of triphenylene with OH and NO3 radicals using a relative rate method in CCl4 liquid phase-system.

The kinetics of CCl(4) liquid-phase reactions of ten kinds of polycyclic aromatic compounds (PACs) including triphenylene (TP) with NO(3) radicals have been investigated at 273K by a relative rate method using naphthalene (NA) as a reference compound. The obtained relative reaction rates of the tested PACs to NA in CCl(4) were as follows: 2.57±0.24 (acenaphthene), 2.11±0.30 (2,3-dimethylnaphthalene), 1.21±0.13 (fluoranthene), 0.56±0.07 (fluorene), 1.85±0.19 (1-methylnaphthalene), 1.77±0.12 (2-methylnaphthalene), 0.11±0.03 (1-nitronaphthalene), 1.59±0.23 (phenanthrene), 2.40±0.29 (pyrene), 0.22±0.04 (TP). TP is a semi-volatile PAC with four aromatic rings and it is chemically changed into mutagenic 2-nitrotriphenylene (2-NTP) via the gas-phase OH or NO(3) radical-initiated reactions. On the basis of the relative reactivity of the PACs in the CCl(4) liquid phase-system, the rate constants of the gas-phase reactions of TP with OH and NO(3) radicals at 298 K were predicted to be (8.6±1.2)×10(-12) cm(3) molecule(-1) s(-1) and (6.6±1.5)×10(-29)[NO(2)] cm(3) molecule(-1) s(-1), respectively. Based on the ambient concentrations of TP and 2-NTP and the obtained rate constant for the reaction of TP with OH radicals, the atmospheric loss rate of 2-NTP was also evaluated.

Synthesis and Characterization of Zinc-Doped Amorphous Carbon Films by Plasma-Assisted Organometallic Chemical Vapor Deposition

Zinc (Zn)-doped hydrogenated amorphous carbon (a-C:H) films have been fabricated from zinc acetylacetonate by organometallic chemical vapor deposition (CVD). Zn concentration was controlled by a heated flow controller. Deposited films were Zn-doped hydrogenated oxygenated amorphous carbon films because they consisted of carbon, hydrogen, zinc, and oxide. The maximum concentration ratio of zinc to carbon (Zn/C) was as large as 0.069. Depletion of the film resistivity R was found when Zn concentration CZn increased. Activation energy derived from the relationship between R and CZn changed from 38.2 to 7.1 meV when Zn/C ratio increased from 0.008 to 0.069. Photovoltaic characteristics of a Zn-doped a-C:O:H/n-Si cell also depend on the Zn concentration. Above the ratio of Zn/C=0.019 in the Zn-doped a-C:O:H layer, the polarity relationship of n-Si was inversely proportional against the polarity of the film deposited at the lowest Zn concentration of Zn/C=0.008. The open-circuit voltage and short-circuit current of a device consisting of n-Si and Zn-doped a-C:O:H films were 93 mV and 0.16 µA/W when Zn/C was 0.019, respectively. These results show that organometallic CVD using a solid organometallic complex is a promising method of fabricating metal-doped a-C:H films for electrical applications.