醇腈酶:生物与化学的结合点

辞腈酶是用途较广的一类酶,在植物体内抵御微生物侵袭方面起着重要作用。在化学工业,醇腈酶用于合成手性氰醇的生物催化剂。氰醇是合成β-氨基醇类,α-羟基酮类及酸类化合物的重要生物活性物质,这些化合物又是精细化工、制药和农用化学品领域的重要原料和中间体。研究人员已经利用蛋白质工程和定点突变技术来改变各种醇腈酶的活性位点和底物特异性等。许多重组醇腈酶业已在大肠杆菌,啤酒酵母和甲醇酵母中成功表达。     

醇腈酶在不对称催化合成氰醇中的应用

醇腈酶在化学合成中催化碳碳键的形成,其产物氰醇可以转化成多种重要的手性医药和农药中间体.从天然产物中可以提取能产生R和S两种构型氰醇的醇腈酶.通过基因重组和在微生物宿主体内过量表达,实现了醇腈酶的工业化生产.对醇腈酶作为催化剂用于不对称催化氢氰酸和羰基化合物反应生成氰醇类手性化合物的工业化应用进行了介绍.     

酶催化合成手性氰醇的研究进展

手性氰醇是一类重要的手性药物与农药中间体,并能够转化成具有不同官能团的光学活性中间体,在手性药物的合成中具有极其重要的地位。本文从氰醇醛缩酶的来源、酶催化合成手性氰醇的条件因素等几个方面系统介绍了手性氰醇的酶催化合成研究进展以及手性氰醇的应用。     

新手性试剂(1R,2S)-2-氨基醇的合成

采用格氏试剂C6H13MgBr和C10H2MgBr对光学活性O-TMS保护的(R)-氰醇的氰基加成,随之用NaBH4对亚胺化合物立体诱导还原氢化,以98%的de值合成了两个新的手性试剂(1R,2S)-2-氨基醇,产率分别达到59%和62%.并通过X射线单晶结构分析法测定了分子结构和晶体结构.     

醇腈酶催化合成手性氰醇的研究进展

概括了不同来源醇腈酶的结构及其催化合成手性氰醇的立体构型.举例证实醇腈酶能够催化除天然底物外的多种底物的羟氰化反应,有广泛的应用价值,并对醇腈酶在手性药物合成中的应用作了介绍.     

醇类酶催化合成双氧水工艺概述

双氧水的早期工业生产采用电解法,六十年代起蒽醌法得以发展并成为世界范围内双氧水生产的主要方法。与此同时,国内外生产者开发了多种双氧水生产新方法,这其中包括氢、氧元素直接合成法,氧阴极还原法,燃料电池法等,醇类酶催化氧化法是八十年代国外研究的一种制备双氧水的最新工艺方法。该方法采用生物发酵技术由低     

脂肪酶和醇腈酶在有机合成中的应用

有机相酶催化反应常用于高附加值产品的合成。脂肪酶是有机合成中一种重要的工具酶，可以催化酯交换反应。脂肪酶催化的酯的氨解反应已经用于手性酰胺的合成，烷氧羰基化也广泛应用于一些天然化合物的化学选择性修饰。以前在有机合成中很少实用的裂合酶如(R)-醇腈酶在合成具有旋光性的氰醇中的应用也开始引起人们的关注。     

他汀类药物关键中间体(3R,5S)-6-羟基-3,5-O-亚异丙基-3,5-二羟基己酸甲酯的合成

设计并合成了他汀类降血脂药物关键中间体(3R,5S)-6-羟基-3,5-O-亚异丙基-3,5-二羟基己酸甲酯,此路线不须要金属有机试剂和极低的反应温度,整条路线总产率20%.     

生物催化生产手性环氧氯丙烷的研究进展

手性环氧氯丙烷(ECH)是一种高价值的手性合成子,在合成β-肾上腺素阻遏剂、维生素、费洛蒙等手性物质方面具有重要的作用。手性环氧氯丙烷的合成方法有化学法和生物法。化学法选择性差,重金属催化剂污染严重;生物法选择性较好,且环境友好。本文介绍了卤醇脱卤酶和环氧化物水解酶生产手性ECH的研究进展,并对其发展前景作了简要展望。     

微波消解-ICP-OES法测定黑芝麻中的18种矿质元素

采用HNO3/H2O2湿法微波消解制样,利用全谱直读电感耦合等离子原子发射光谱法(ICP-OES),全面详细地分析测定了黑芝麻中的矿质元素,共检出Ca、P、S、Mg、K、Al、Si、Fe、Na、Zn、Se、Sr、Cu、Mn、Ba、B、Ti、Cr等18种矿质元素,RSD值在1.21%～10.1%,其中13种元素在5%以内。黑芝麻中所含人体常量元素Ca、P、S、Mg、K、Na等的质量分数分别为1.79%,1.08%,0.59%,0.43%,0.41%和0.009 1%;微量元素Fe、Zn、Se、Cu、Mn、B、Cr、Sr、Si、Al等的含量分别为18.6,4.55,3.87,1.74,1.62,0.91,3.21,78.8,125.8 mg/100 g,未检出Pb、Hg、Cd、As以及Ni、Co、Mo等元素。     

Phase-mineral and chemical composition of coal fly ashes as a basis for their multicomponent utilization. 4. Characterization of heavy concentrates and improved fly ash residues

The phase-mineral and chemical composition of heavy concentrates (HCc) and improved fly ash residues (IFAs) recovered from five fly ashes (FAs) produced in four large Spanish thermo-electric power stations was characterized. The HCs were separated by sink-float separation in bromoform, while the IFAs are residues after the isolation of ceramic cenosphere, salt, magnetic, char and heavy concentrates. The HCs recovered are in the range 0.02–0.28% and their phase-mineral composition (in decreasing order of significance) commonly includes aluminosilicate glass, hematite, magnetite, larnite, quartz, periclase, mullite, corundum, lime, char, melilite, rutile, plagioclase, wollastonite, ferrian spinel, and anhydrite. Numerous accessory minerals of Ba, Ce, Cl, Cr, Cu, F, Fe, La, Mn, P, Pb, Th, Ti, Y, and Zr, are also typical components of HCs. These fractions are enriched in As, Ca, Cr, Cu, Gd, Mg, Mn, Mo, Fe, Ni, Pb, S, Se, Ti, V, Zn, and Zr in comparison with the FAs. The IFAs isolated are in the range 71.5–97.1% and their phase-mineral composition (in decresing order of significance) normally includes aluminosilicate glass, mullite, quartz, char, kaolinite, plagioclase, cristobalite, wollastonite, hematite, anhydrite, K-feldspar, melilite, and corundum. The contents of most elements in IFAs are similar to FAs as Ag, Ba, Cl, Cs, Ge, Mo, S, Sb, and Sc are significantly depleted in these residues. The IFAs have an improved composition in comparison with the FAs because they are: more homogeneous and finer-grained products; abundant in pozzolan and inert constituents; and depleted in harmful components. Some genetic features, properties, possible environmental concern, and potential utilization directions related to the HCs and IFAs are described. A basis for the advanced, multicomponent, wasteless, and environmentally safety utilization of various FAs is also discussed.     

应用ICP-MS同时测定矿泉水中22种微量金属

研究结果表明应用ICP-MS可以同时测定饮用天然矿泉水中的Li、Be、B、Al、Ti、V、Cr、Mn、Co、Ni、Cu、Zn、Ge、As、Se、Sr、Mo、Ag、Cd、Sb、Ba、Pb、等微量金属元素.ICP-MS法具有快速、准确、处理简单、干扰少等优点.     

一种具有混合侧链的苯并菲类盘状液晶材料的合成及其液晶性能的表征

本研究采用邻苯二酚、溴代正戊烷和乙酰氯为原料合成了以苯并菲为基元的盘状液晶化合物2,6,10-三乙酯基-3,7,11-三戊氧基苯并菲,化合物的结构采用核磁手段1HNMR进行鉴定。采用偏光显微镜POM和DSC手段对该种化合物的相行为进行了研究,并且与合成过程中的中间体2,3,6,7,10,11-六戊氧基苯并菲的相行为进行了比较。     

Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in Surface Sediments from the Upper Reach of Huaihe River

Based on the available toxicity data and the concentrations of polycyclic aromatic hydrocarbons (PAHs) in 16 surface sediments from upper reach of Huaihe River, overlapping areas of probability density curves and margin of safety (MOS₁₀) were used to estimate the ecological risk of eight PAHs to aquatic organisms. The results indicated that the overlapping areas of Pyr, Nap, Fla, Ant, Phe, Ace, BaP, and Flu were 0.38, 0.29, 0.16, 0.11, 0.07, 0.03, 0.03, and 0.01, respectively. The risk of Pyr was the highest while that of Flu was the lowest. The overlapping area of ΣPAH₈ was 0.72, higher than that of any individual PAHs due to their joint effect. The calculated MOS₁₀ for Nap, Ace, Flu, Phe, Ant, Fla, Pyr, and BaP were 6.86, 5.42, 19.0, 2.72, 0.93, 0.75, 0.03, and 63.0, respectively. The probabilities of Nap, Ace, Flu, Phe, and BaP surpassing the 10th percentile value of the toxicity data were 0.07%, 0.30%, 0.05%, 1.97%, and 0.01%, respectively, suggesting minimal risk to aquatic organisms. However, the probabilities of Ant, Fla, and Pyr exceeding this value were 11.3%, 12.9%, and 64.8%, indicating potential risks. Among the individual PAHs, the ecological risk from Pyr was the highest, followed by Fla, Ant, Phe, Ace, Nap, Flu, and BaP. Additionally, the combined ecological risk of ΣPAH₈ in the upper reach of Huaihe River was significantly higher than that of any individual PAH alone, which the probabilities of ∑PAH₈ in excess of the 10th percentile of the toxicity data were 99.4%.     

合成环己酮乙二醇缩酮的催化剂研究进展

评述了近年来国内采用甲烷磺酸盐、对甲苯磺酸、氨基磺酸、强酸性阳离子交换树脂、磺化聚氯乙烯、六水三氯化铁、二水氯化亚锡、五水四氯化锡、四水氯化锰、硫酸铜、水合硫酸铁、十二水合硫酸铁铵、硫酸钛、四水硫酸锆、氯化锆、四水硫酸高铈、水合硝酸镧、活性炭固载硫酸镧、铌酸、树脂固载Lewis酸、壳聚糖硫酸盐、一水硫酸氢钠、碘、磷酸二氢钠、固体超强酸、杂多酸、分子筛和维生素C等固体酸催化合成环己酮乙二醇缩酮的实验结果。研究结果表明,固体酸能够代替硫酸作为合成环己酮乙二醇缩酮反应的催化剂。     

氯碱下游产品建设投资分析(续2)

介绍了20种氯碱下游产品--氯甲苯、氯乙酸、环氧氯丙烷、氯化苄、环氧丙烷、聚偏氯乙烯树脂、氯化聚氯乙烯树脂、氯化聚乙烯、甲基氯硅烷、三氯氢硅、氯化法钛白粉、三氯化磷、4,4'-二苯基甲烷二异氰酸酯、1,4-丁二醇、苯胺、环己酮、气相法白炭黑、甲基异丁基酮、对氨基苯酚、水合肼的市场前景、技术来源与建设投资.     

METAL EXTRACTION FROM NITRIC ACID SOLUTIONS BY (DIPHENYL-PHOSPHINYLMETHYL) PHENYLPHOSPHINIC ACID

ABSTRACT

The extraction of microquantities of Ca, Sr, Ba, Sc, Mn, Co, Cu, Zn, Ga, Cd, In, Pb, Bi, Zr, Hf, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, and U from HNO₃ solutions by (diphenylphosphinylmethyl)phenylphosphinic acid in organic diluents has been studied.

The effect of HNO₃ concentration in the aqueous phase and that of the extractant in the organic phase on the metal extraction are considered. (Diphenylphosphinylmethyl)phenylphosphinic acid possesses an extraordinary affinity for actinides and rare-earth elements. The extractive efficiency and selectivity of this compound toward rare-earth metal ions are compared with those of some multifunctional acidic and neutral organophosphorus extractants.     

全谱直读电感耦合等离子体原子发射光谱测定苦荞麦矿物元素

采用HNO3/H2O2湿法微波消解制样,采用全谱直读电感耦合等离子体原子发射光谱法（ICP-OES）,分析测定了苦荞麦中的矿物元素,共检出P、S、K、Mg、Ca、Si、Al、Fe、Na、Zn、Mn、B、Cu、Se、Ti、Cr、Ba、Sr等18种矿物元素。分析结果的RSD值在0.45%～9.09%之间,其中15种元素在5%以内。苦荞麦中所含P、S、K、Mg、Ca、Na等常量元素的质量分数分别为0.21%、0.21%、0.17%、0.098%、0.019%、0.0017%;微量元素Fe、Zn、Cu、Se、Cr、Si、Mn、B、Ti、Ba、Sr、Al等的含量（mg.kg-1）分别为37.4、16.5、3.67、1.38、0.44、121.6、6.90、4.88、0.63、0.22、0.12、49.9。     

Petrography and geochemistry of the Middle Devonian coal from Luquan, Yunnan Province, China

Coals from Luquan, Yunnan Province, China, have high contents of cutinite and microsporinite, with an average of 55 and 33.5 vol%, respectively, (on a mineral-free basis). The coals are classified as cutinitic liptobiolith, sporinite-rich durain, cutinite-rich durain, and sporinitic liptobiolith. These four liptinite-rich coals are often interlayered within the coal bed section and vary transversely within the coal bed. The vitrinite content varies from as low as 1.6-20.5% (mineral-free basis), and it is dominated by collodetrinite, collotelinite, and corpogelinite. The maceral composition may be attributed to the type of the peat-forming plant communities. Moreover, the Luquan coals are characterized by high contents of volatile matter, hydrogen, and oxygen, and the high values of the atomic hydrogen to carbon ratio as a result of the maceral composition. As compared with the common Chinese coals and the upper continental crust, the Luquan coals are enriched in Li, B, Cu, Ga, Se, Rb, Mo, Ba, Pb, Bi, and U, with averages of 99.9, 250, 111, 24.4, 4.55, 130, 58.8, 1276, 162, 3.85, and 34.1 μg/g, respectively. The SEM-EDX results show that V, Cr, Ga, and Rb occur mainly in clay minerals, and Cu and Pb are associated with clay minerals and pyrite, and Mo and U are mainly in clay minerals and organic matter. Barite and clay minerals are the main carrier of barium. The high B and U contents are probably resulted from deep seawater influence during coal formation.