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1.
The double-bond conversion of UV-cured resins prepared from pentaerythritol triacrylate (PETA) was determined by pyrolysis-gas chromatography in the presence of an organic alkali, tetramethylammonium hydroxide (TMAH). The pyrogram of the uncured prepolymer compound, consisting of PETA and a photoinitiator, 2,2-dimethoxy-2-phenylacetophenone, contained specific products reflecting the original acrylate structure, such as methyl acrylate (MA) and methyl ethers of pentaerithritol. Meanwhile, in pyrograms of the UV-cured PETA, the yields of MA considerably decreased. The double-bond conversions of the cured resins, irradiated with various UV dosages, were calculated based on the relative yields of MA among specific products in the pyrograms. The conversions determined by this approach were analyzed by comparing them with those estimated by Fourier-transform infrared spectroscopy. 相似文献
2.
A simple and rapid method for the analysis of trace amounts of gold(III), palladium(II), and platinum(IV) by the combined use of graphite furnace atomic absorption spectrometry and anion-exchange separation was proposed, and successfully applied to the rapid determination of metals in industrial waste solutions obtained from the final process of noble-metal recovery factories, because noble metals can be selectively and quantitatively separated to a high degree by using a small column containing only a 0.7 g-portion of a common anion-exchange resin and a dilute thiourea solution. 相似文献
3.
Bond IA Budding E Conway MJ Fenton KB Fujii H Fujii Z Fujimoto M Hasegawa H Hayashida N Honda M Hotta N Humble JE Kabe S Kasahara K Kifune T Masaike A Matsubara Y Mitsui K Miura Y Mori M Murakami K Muraki Y Nagano M Nakamura K Nakamura T Norris PM Ohashi Y Okada A Saito T Sakata M Sato H Shibata S Shima M Storey JR Tanimori T Teshima M Torii S Uchino K Watase Y Woodhams MD Yamamoto Y Yock PC Yuda T 《Physical review letters》1988,61(20):2292-2295
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The formation of mixed ligand complexes in Ti(IV)-xylenol orange (XO)-H2O2 and Ti(IV)-chromazurol S (CAS)-H2O2 systems was studied by spectrophotometry. The former system gave constant absorbance (λmax = 562 nm) under the condition of [XO]/[Ti(IV)] = 1 in the pH 2–4 region. In the latter system, a distinct maximum at 557 nm was observed when [CAS]/[Ti(IV)] = 4 in the pH range of 4.5–5.2. In both cases, the absorbance at λmax was stable for a long time and proportional to the concentration of hydrogen peroxide. From those facts, the usefulness of the mixtures of Ti(IV)-XO and Ti(IV)-CAS as the colorimetric reagents for the determination of hydrogen peroxide can be expected. The conditions for the use of the Ti(IV)-XO and the Ti(IV)-CAS reagents were examined in detail, and both reagents were found to be available for trace analysis of hydrogen peroxide with high sensitivity. 相似文献
7.
[reaction: see text] Catalytic, enantioselective Mannich-type reactions of alpha-imino esters bearing readily removable substituents on nitrogen are described. Several N-carbamate-protected alpha-imino esters, which are readily prepared from 2-bromoglycine esters using a polymer-supported amine, reacted with silicon enolates to afford the desired adducts in high yields with high enantioselectivity using a copper(II)-diamine complex. Easy deprotection of the product amine and transformation to free alpha-amino acid derivatives have also been demonstrated. 相似文献
8.
[reaction: see text] A conjugated pi-electron compound, 2-aryl-3-silyl-1,3-butadiene, was easily prepared from 1-benzyloxy-3-silyl-2-propyne, bis(iodozincio)methane, and an aryl halide in the presence of nickel catalyst. A subsequent cross-coupling reaction of the product with another aryl halide gave an unsymmetrical 2,3-diaryl-1,3-butadiene efficiently. 相似文献
9.
Krishna Gopal Dongol M. Cristina Melo e Silva Kouki Matsubara Taisuke Matsumoto Shuntaro Mataka Thies Thiemann 《无机化学与普通化学杂志》2003,629(6):945-947
The preparation of two η6‐estra‐1, 3, 5(10), 6‐tetraene tricarbonylchromium complexes 4 and 6 are described. In both cases only one stereoisomer can be isolated, in contrast to other estrane‐tricarbonylchromium complexes, where complexations are non‐stereoselective. X‐ray crystal structural analysis of 4 discloses that only the more sterically hindered β‐facial isomer is formed. It is assumed that the 6, 7‐olefinic moiety exerts a directive influence on the complexation. 相似文献
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