A Novel Method for Analysis of Xanthate Group Distribution in Viscoses

Analytical monitoring of xanthation in the viscose process along with xanthate group analysis in the viscose material is a long-debated problem in cellulose chemistry. The task is rendered extremely intricate by the lability of the starting material and the harshness of the reaction medium, which adds to a lack of suitable analytical approaches. In a four-years' endeavor in our lab, a method is being developed which allows to analyze the distribution of xanthate groups in viscoses relative to the anhydroglucose units and along the cellulose chain. In a first step the xanthate groups are stabilized by alkylation, which was optimized towards quantitative conversion. In a second step, the remaining free hydroxyl groups are protected by carbanilation, followed by selective removal of the stabilized xanthate groups. Steps two and three thus generate an inverse image of the initial xanthate pattern. In the forth and fifth step, the liberated hydroxyl groups are methylated, and the carbanilates are removed, so that in the overall process the xanthates were replaced by methyl groups. All reaction steps have been comprehensively tested with regard to completeness of conversion and orthogonality of the protecting groups.     

裂解色谱法甲基化试剂碱性对多不饱和脂肪酸降解和异构化的影响

采用最佳比例裂解甲基化试剂,消除了强碱性甲基化试剂对油脂中多不饱和脂肪酸降解和异构化作用的影响。考察了不同比例甲基化试剂的碱性对多不饱和脂肪酸降解和异构化的程度。     

裂解甲基化气相色谱法区别不产色分支杆菌菌群的研究

应用新的气相色谱技术──裂解甲基化法解析了不产色分支杆菌菌群的细胞脂类组分,结果表明,这个方法能对该群７种细菌进行特异性区分。其特点是在高温裂解的瞬间完成酯化反应,长链大分子的支菌酸（５０～８０个碳原子）断裂成脂肪酸碎片Ｃ＿（２４：０）和Ｃ＿（２６：０）流出。裂解甲基化法分析快捷,谱图重现性好,具有推广应用的价值。     

NaBr／KZSM—5催化剂上甲苯甲烷氧化甲基化制苯乙烯和乙苯

在常压固定床连续流动不锈钢反应装置上,对ＮａＢｒ／ＫＺＳＭ－５催化剂系统考察了ＮａＢｒ负载量、反应温度、接触时间对甲苯的转化率、Ｃ８化合物的选择性、Ｃ８化合物的收率的影响。同时,通过吸附ＮＨ３－ＴＰＤ和吸附甲酸－ＴＰＤ对催化剂表面的酸、碱强度及酸、碱量进行了研究。结果发现,ＮａＢｒ负载量、反应条件对反应影响很大,且有一最佳值,同时,通过对催化剂酸、碱考察,发现ＮａＢｒ／ＫＺＳＭ－５催化剂,其中等强度的碱中心和较弱的酸中心的合理匹配是催化剂的活性中心     

1-羟基-5-十二烷氧基-萘LB膜结构和取向的光谱研究

用红外透射,反射光谱及紫外可见吸收光谱方法研究了１－羟基－５－十二烷基－萘ＬＢ膜及溶液状态下的结构,分子取向。研究结果表明分子在溶液中主要是以单体形式存在;在ＬＢ膜中是以聚集体形式存在。     

Multiple Coordination of Metal Atoms to Arenes: The Coordination of Six Ruthenium Atoms to Naphthalene-1,8-diyl in [Ru6(μ6-C10H6)(μ3-PPh)(CO)14]

Six ruthenium atoms are coordinated to the naphthalene-1,8-diyl ligand in the cluster [Ru₆(CO)₁₄(C₁₀H₆)(PPh)] through two Ru−C σ bonds, two η², and two η³ interactions (section of structure depicted on the right). The complex could, therefore, serve as a model for the chemisorption of naphthalene on a step-site on a (111) metal surface.     

Evidence supporting the presence of dissolved dimethylarsinate in the marine environment

Experiments have been carried out to test the commonly held belief that the dissolved dimethylarsenic species present in marine waters is dimethylarsinate. By employing a novel combination of HPLC and cryogenic‐trap hydride generation atomic absorption spectroscopy (HG AA), the sensitivity limitations of conventional in‐line HPLC instrumentation can be overcome, permitting dimethylarsinate to be measured by HPLC at levels below 200 pg cm⁻³. A comparison of results obtained by this procedure with those obtained by direct cryogenic‐trap HG AA demonstrated that much of the dissolved dimethylarsenic present in the mouth of the Beaulieu River estuary (Hampshire, UK) had HPLC retention characteristics consistent with the presence of dimethylarsinate. Copyright © 1999 John Wiley & Sons, Ltd.     

Speciation of volatile mercury species present in digester and deposit gases

Volatile mercury compounds have been speciated in gases evolved from fermentation of sewage sludge as well as municipal waste. The species were trapped by sequential sampling, using a noble‐metal trap in series with an activated‐carbon trap. Thermally desorbed Hg⁰ and (CH₃)₂Hg were separated by GC at 70 °C and detected by cold vapour atomic fluorescence spectroscopy after thermal reduction. The amounts of mercury detected in the sewage gas correspond to concentrations in the range 50–110 ng m⁻³ for both species whereas the deposit gases were found to contain only elemental mercury. Monomethylmercury species could not be positively identified in any of the gas samples. Copyright © 1999 John Wiley & Sons, Ltd.     

Polyaniline doped with different sulfonic acids by in situ doping polymerization

Doped polyaniline (PANI) was synthesized by an “in situ doping polymerization” method in the presence of different sulfonic acids, such as methanesulfonic acid (MSA), p‐methylbenzene sulfonic acid (MBSA), β‐naphthalenesulfonic acid (β‐NSA), α‐naphthalenesulfonic acid (α‐NSA), 1,5‐naphthalenedisulfonic acid (1,5‐NSA), and 2,4‐dinitronaphol‐7‐sulfonate acid (NONSA). Morphology, solubility in m‐cresol, and electrical properties of the doped PANI were measured with the variation of the molecular structure of the selected sulfonic acids. Granular morphology was obtained when the sulfonic acids without a naphthalene ring, such as MSA and MBSA, were used. Regular tubular morphology was obtained only when β‐NSA was used. The tubular morphology can be modified by changing the substitutes, the number, and location of sulfo‐group(SOH) on the naphthalene ring. These results indicated that naphthalene ring in the selected sulfonic acids plays an important role in forming the tubular morphology of the doped PANI by the “in situ doping polymerization” method. All resulting PANI salts were soluble in m‐cresol, with the solubility depending on the molecular structure of the selected dopants. Room‐temperature conductivity for the doped PANI ranges from 10⁻¹ to 10⁰S/cm. Temperature dependence of conductivity shows a semiconductor behavior, and it can be expressed by one dimenson Variable Range Hopping (VRH) model. 1 © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1277–1284, 1999     

2-溴-3-(1H-吲哚-3)-N-甲基马来酰亚胺的合成

以琥珀酰亚胺为起始原料,经过溴化、甲基化后再与吲哚溴化镁加成反应合成了2-溴-3-(1H-吲哚-3)-N-甲基马来酰亚胺,总收率44.8%,其结构经1H NMR和IR确证.