Ru(0) complex catalyzed polyaddition New synthesis of poly(alkylenebenzoxazole) and poly(alkylenebenzimidazole)

Summary The reactions of α,ω-diyne, HC≡C(CH₂)_mC≡CH (m = 6 and 8), with 3,3'-diaminobenzidine and with 3,3'-diamino-4,4'-dihydroxybiphenyl in the presence of RU₃(CO)₁₂-PPh₃ catalyst give the corresponding poly(alkylenebenzoxazole)s and poly(alkylenebenzimidazole)s, respectively. The former polymers obtained from the equimolar reaction of the monomers are partly soluble in polar organic solvents such as DMF, DMSO, and NMP, while the poly(benzimidazole)s are soluble in these solvents. GPC measurement shows the molecular weights of the polymers, M _n of 4.8−14.1×10³ and M _w of 6.4−19.7×10³. Received: 24 November 1998/Revised version: 21 December 1998/Accepted: 24 December 1998     

Carbon nanofibers with radially oriented channels

An easy templateless method to synthesize porous carbon nanofibers (CNFs) having radially-oriented mesopores is reported, using selective gasification with nano-sized catalyst particles and hydrogen as the gasification reagent. The gasification generated pores whose size corresponds to that of the catalyst particle used for the drilling. The pores were formed along the graphitic layers, reflecting the structural alignment in the CNFs. The pore size and structure can be controlled by selection of catalyst and gasification conditions.     

Solution Property and Irradiation Effect of Random Copolypeptides Composed of Ala and Pro Residues

Summary Poly(proline) and random copolypeptide composed of Pro and Ala residues were synthesized, and their solution properties and molecular conformation were investigated. Aqueous solutions of the polypeptide were irradiated with γ-rays above the transition temperature. It was shown that the transition temperature of the aqueous solution of the copolypeptide is influenced by Ala-residue content and γ-ray irradiation.     

Radiation grafting of α,β,β-trifluorostyrene onto poly(ethylene-tetrafluoroethylene) film by preirradiation method. II. Properties of cation-exchange membrane obtained by sulfonation and hydrolysis of the grafted film

A Study was made on certain properties of the cation-exchange membranes obtained by the preirradiation grafting of α,β,β-trifluorostyrene (TFS) noto poly(ethylene-tetrafluoroethylene) (ETFE), followed by sulfonation and hydrolysis of the grafted film. Swelling, water uptake, electric conductivity, and transport number of the membranes were measured as a function of ino-exchange capacity. Thermal and chemical stability were also investigated. These properties were found to be mainly dependent on ion-exchange capacity. The stable membrane properties were established due to a homogeneous ion-exchange group distribution in the membrane, as confirmed by x-ray imcroscopy analysis of the membrane cross sections. In addition, the membranes showed good electrochemical, thermal, and chemical properties, and were found to be scceptable for practical use as cation-exchange membranes.     

A corrosion prediction method for weathering steels

Japanese Specification for Highway Bridges [Japan Road Association: Specification for Highway Bridges—I & II, 2002.3] has been revised in 2002, which clearly states that degradation of bridge members, including those of weathering steels, to occur in prolonged period of time must be taken into account at the design stage to realize long term structural durability. To cope with the revised paradigm, SABI chemistry committee in Japan Society of Corrosion Engineers has proposed durable state concept [SABI Chemistry Committee of Japan Society of Corrosion Engineers, in: Proc. 132nd Symposium for Corrosion and Protection, 2001.6.25, p. 3], which is defined as a condition in which corrosion rate of steel is slow enough not to form thick rust [H. Kihira, K. Shiotani, H. Miyuki, T. Nakayama, M. Takemura, Y. Watanabe, Doboku Gakkai Ronbun-shu (J. Japan Soc. Civil Engineers) No. 745/I-65, 2003.10, pp.77-87]. Since corrosiveness of atmosphere differs by location, a corrosion prediction method for both conventional and advanced weathering steels [H. Kihira, A. Usami, K. Tanabe, M. Ito, G. Shigesato, Y. Tomita, T. Kusunoki, T. Tsuzuki, S. Ito, T. Murata, in: Electrochemical Society Proceedings, vol. 99-26, 2000, pp. 127-136] is needed to ensure structural durability for future. Thus, versatile computational scheme for it has been derived through mathematical modeling based upon the durable state concept.     

Direct Use of Benzylic Alcohols for Gold(III)‐Catalyzed S‐Benzylation of Mercaptobenzoic Acids in Water

We demonstrate the gold(III)‐catalyzed direct substitution of benzylic alcohols in water. These atom economic and environmentally benign protocols afford S‐benzylated products in moderate to excellent yields. In contrast, common Lewis or Brønsted acids as catalyst, and organic solvents such as dichloromethane or toluene were ineffective for the S‐benzylation of mercaptobenzoic acids. Water can be an attractive tool for new transition metal‐catalyzed reactions. A Hammett study for the rate constants with various substituted alcohols shows a good correlation (R²=0.97) between the log(k_X/k_H) and the σ⁺ value of the respective substituents. From the slope negative ρ values of 2.35 are obtained, suggesting that there is a build‐up of positive charge in the transition state. Our catalytic system can be performed with the use of only 2 mol% of gold(III) catalyst without any other additives in water, and scaled up to 10 mmol scale (85% isolated yield). Notably, the present method can accomplish the S‐benzylation of unprotected mercaptobenzoic acids, which is chemoselective and leaves the carboxyl group intact. Furthermore, the direct substitution of allylic and propargylic alcohols also proceeded smoothly in good yields.

     

Compositional analysis of deasphalted oils from Arabian crude and their hydrocracked products

The deasphalted oil (DAO) and its hydrocracked products were analyzed by gas chromatograph with an atomic emission detector (GC-AED), time-of-flight mass spectra (TOF-MS) and X-ray diffraction (XRD) to evaluate the product quality and reaction progress in addition to the yields of the products. Carbon GC-AED spectra revealed that carbon species distributions in distillate products were almost same regardless of their yields and reaction conditions. No sulfur species were found in gasoline and kerosene, while significant reduction of sulfur contents was found in gas oil (GO) according to the hydrocracking reaction temperature and liquid-volume hourly space velocity (LHSV). Vacuum gas oil (VGO) was also analyzed by GC, but it showed a large lump of low resolution. TOF-MS and XRD results indicated that the resid in the feed was cracked into smaller molecules in the product resid. These comprehensive analyses about feeds and products from various hydrocracking process could offer basic information for optimizing the process in industry.     

Activated carbon nanofiber produced from electrospun polyacrylonitrile nanofiber as a highly efficient formaldehyde adsorbent

Electrospun polyacrylonitrile (PAN)-based nanofiber with a uniform diameter of ca. 800 nm was carbonized and steam-activated to produce activated carbon nanofiber with tailored microporosity and abundant nitrogen-containing functional groups as highly efficient adsorption sites. A remarkable amount of formaldehyde, a typical indoor pollutant, was adsorbed onto the pore surface of the PAN-based activated carbon nanofibers even at a low concentration (ca. 11 ppm), demonstrating more than twice as long as breakthrough time of formaldehyde adsorption as compared to conventional activated carbon fibers of larger fiber diameter. The tailored shallow microporosity was considered to afford the preferential adsorption of formaldehyde also in a humid environment.     

超临界流体技术在苎麻织物中的应用研究

对影响超临界CO2流体处理苎麻纤维的因素，如温度、压力、时间以及助溶剂进行正交试验，对处理后的苎麻纤维的含杂情况、微结构、机械物理性能和热稳定性等性质作了测试分析。结果表明，超临界CO2流体处理苎麻织物的最佳工艺条件为：工作温度120℃、压力25MPa、时间40min、助溶剂0．1％。该处理可改善苎麻纤维的性能，提高其膨胀性，有利于后续加工，并为其进一步改性打下基础。     

Levels of phthalates and adipates in processed foods and migration of di-isononyl adipate from polyvinyl chloride film into foods

The levels of dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEPHP), di-isononyl phthalate (DINP), di-(2-ethylhexyl) adipate (DEHA) and di-isononyl adipate (DINA) were determined in 50 processed foods (ham and sausage, fried dumpling and shao-mai, fish paste products, croquette and fried fish, bread, noodle, pickles, etc.). DBP, BBP, DEHP, DINP, DEHA, and DINA were contained at nd approximately 47.7, nd approximately 16.6, nd approximately 749, nd approximately 358, nd approximately 57.2 and nd approximately 20,200 ppb, respectively. High-level contamination of DINA was found in fish paste products, croquette and shao-mai, presumably because of migration from plasticized wrapping film using for food packaging. We studied the relationship between DINA migration from wrapped PVC film into fried croquette and its standing time after frying. When the croquette was wrapped immediately after frying, the migration from wrapping film into the croquette was highest (36,400 ng/g). On wrapping after standing for 5 min and 30 min, the migration level was reduced to 1/3.5 and 1/14 of the highest level, respectively.