Chiral reactions in heterogeneous catalysis (1975-1999)

The preparation of pure chemical compounds has been one of the most rapid growth areas in chemistry over the last decade with heterogeneous catalysis being recognised as providing new possibilities. A number of different strategies have been developed to obtain enantioselectivity through heterogeneous catalysis: the use of chiral species to modify the solid surface; the grafting of a chiral catalytic complex on a solid - the so called heterogenised homogeneous catalyst - and homogeneous formation of a chiral complex before reaction at the solid surface. Because the interaction between functional groups is complex, the influence the surface has on reaction mechanisms is, so far, not well developed. Hydrogenation reactions have dominated the field with α- or β-ketoesters being the preferred substrates and nickel modified by tartaric acid and platinum modified by cinchona alkaloids as preferred catalytic systems with modified zeolites playing a crucial role. Some examples of the leading groups are in Switzerland (Blaser and Baiker), Japan (Nitta, Osawa, Izumi and Harada), USA (Sachtler, Augustine), United Kingdom (Webb, Wells, Thomas, Catlow, Hutchings and Whyman) and the Netherlands (Sheldon).In spite of the present hyper-activity the use of metal catalysts to effect asymmetric reactions is not new with Schwab in Germany and Lipkin and Stewart in the USA active in the 1930s. In 1995 at the ChiCat Symposium both Reisse and Ghosez suggested that those in catalysis should “not reinvent wheels that organic chemists had laboured over many years” and “that goals already achieved by organic chemists will not be easy to obtain through heterogeneous catalysis”. We await future developments with much anticipation! This revised version was published online in July 2006 with corrections to the Cover Date. This revised version was published online in July 2006 with corrections to the Cover Date.     

为人民提供安全食品--北京食品安全宣言(2005)

“国以民为本，民以食为天，食以安为先。”食品安全问题是事关国计民生和人们身体健康的重大问题。随着我国经济社会的发展，食品安全在继续重视粮食数量安全的同时，其质量安全问题已日益凸现出来。种植养殖、生产加工、市场流通、餐饮消费等方面存在的问题还相当突出，食源性疾病数量不断上升，恶性食品污染事件接二连三，     

典型煤炭燃料在民用解耦炉中的燃烧实验研究

实验对比研究了烟煤块状半焦及烟煤型煤等煤炭燃料在民用解耦炉中燃烧时的污染物排放特性和炊事能力,并基于解耦测试炉对烟煤型煤的特征尺寸进行优化,验证了解耦炉具对不同种类民用煤炭燃料的适应性。结果表明,民用解耦燃煤炉具特有的结构特征和通风方式有利于NOx和CO的同时减排。若在解耦炉中燃烧烟煤洁净型煤,可进一步实现对SO2和颗粒物(PM)的有效控制。型煤尺寸对炉具污染物排放影响显著,尺寸优化后的烟煤洁净型煤在解耦炉中稳定燃烧时NO, SO2, CO和PM的平均排放浓度按基准氧含量9vol%折算后,分别低于190, 300, 380和30 mg/m3,炊事功率可达1.65 kW。     

国内日化产品涨价的思考

论述了国内日化产品的涨价原因、成本消化和是否涉嫌行业垄断。对外资品牌和本土品牌进行了简要分析。介绍了政府对日化产品涨价的态度。同时,指出了日化行业今后的机遇和挑战。     

谈谈设计阶段控制水泥工程造价的措施

对过去十年我国水泥的供需状况和价值变化的原因进行对比分析，预测了未来的水泥价值走势。     

Removal of Hazardous Anions from Aqueous Solutions by La(lll)- and Y(lll)-lmpregnated Alumina

Abstract

New adsorbents, La(III)- and Y(III)-impregnated alumina, were prepared for the removal of hazardous anions from aqueous solutions. A commercially available alumina was impregnated with La(III) or Y(III) ions by the adsorption process. The change in the surface charge due to the impregnation was measured by acid/base titration. The adsorption rate and the capacity of the alumina for La(III) and Y(III) ions were determined. The adsorption characteristics of the La(III)- and Y(III)-impregnated alumina and the original alumina for fluoride, phosphate, arsenate and selenite ions were analyzed under various conditions. The pH effect, dose effect, and kinetics were studied. The removal selectivity by the impregnated alumina was in the order fluoride > phosphate > arsenate > selenite. The impregnated alumina has been successfully applied for the removal of hazardous anions from synthetic and high-tech industrial wastewaters.     

A study on the interchangeability of LFG-LPG mixed fuels with LFG quality in domestic combustion appliances

The interchangeabilities of LFG-LPG mixed fuels with respect to application in domestic combustion appliances were investigated. Two kinds of mixed fuels (MF(WI) and MF(HV)) were produced so as to have a Wobbe index (WI) and a heating value (HV) nearly equivalent to those of LNG, respectively. In this study, the qualities of LFG used in making mixed fuels were considered by varying CH₄ volume fraction in the LFG composition from 55% to 30%. The fundamental characteristics were estimated through comparisons of flame temperature, burning velocity, and the stability region of various fuels. It was found that All MF(WI)s have very similar stable flame zones regardless of the LFG quality, and these mixed fuels can substitute CH₄ completely without any modification of the air entrainment device. On the other hand, the stable flame zone of MF(HV) is decreased to a lower fuel flowrate with a decrease of CH₄ percentage in LFG. These fuels can substitute CH₄ with some restrictions and the air inlet device must be adjusted to lower the air flowrate entrained by the fuel jet.     

国内外食品添加剂产业发展状况

详细介绍了食品添剂中增稠剂、乳化剂、甜味剂、着色剂、酶、防腐剂、抗氧剂的市场和未来发展趋势。2013年世界7类食品添加剂的销售额约200亿美元,产量超过500万t。2013年中国23类食品添加剂的总产量为885万t,销售额870亿元。     

(S)-2-(ethyl propionate)-(O-ethyl xanthate)- and (S)-2-(Ethyl isobutyrate)-(O-ethyl xanthate)-mediated RAFT polymerization of vinyl acetate

(S)-2-(Ethyl propionate)-(O-ethyl xanthate) (X1) and (S)-2-(Ethyl isobutyrate)-(O-ethyl xanthate) (X2) were used as the reversible addition-fragmentation chain transfer (RAFT) agents for the radical polymerization of vinyl acetate (VAc). The former showed the better chain transfer ability in the polymerization at 60°C. Kinetic study with both RAFT agents showed pseudo-first order kinetics up to around 85% monomer conversion. Molecular weight of the resulting polymer increased linearly with increase in the monomer conversion up to around 85%. The observed molecular weights calculated from ¹H-NMR spectrum [M_n(NMR)] are close to the corresponding theoretical molecular weights [M_n(theor)]. The corresponding polydispersity index (PDI) of the resulting polymers remained almost constant at around 1.2 up to ∼ 65% monomer conversion and then increased gradually with the further increase in the monomer conversion. Chain-end analysis of the resulting polymers by ¹H-NMR showed clearly that polymerization started with the radical forming out of the xanthate mediator. The negligible homo-chain extension and the hetero-chain extension involving synthesis of poly(VAc)-b-poly(NVP) diblock copolymer were occurred. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A kinetic analysis of the thermochemical conversion of solid fuels (A review)

The overview is focused on methods for the processing of kinetic curves (with and without models). The paper demonstrates that the kinetics of thermochemical conversion of solid fuels can be described by a great number of kinetic processing methods, which lead to inconsistent estimates of kinetic coefficients. They give a rather simple approximation of experimental thermogravimetric curves. However, the kinetic triplet to be determined (activation energy, order of reaction, and preexponential factor) depends on the conditions of thermoanalytical studies and (to a greater extent) on the reactivity of the test fuels.     

(S)-2-(Ethyl propionate)-(O-ethyl xanthate) and (S)-2-(Ethyl isobutyrate)-(O-ethyl xanthate)-mediated RAFT polymerization of N-vinylpyrrolidone

(S)-2-(Ethyl propionate)-(O-ethyl xanthate) (X1) and the newly synthesized (S)-2-(ethyl isobutyrate)-(O-ethyl xanthate) (X2) were used as the reversible addition-fragmentation chain transfer (RAFT) agents for the radical polymerization of N-vinylpyrrolidone (NVP). The former showed the better chain transfer ability in the polymerization at 60 °C. Kinetics study with X1 shows the psuedo-first order kinetics upto 45% monomer conversion. Molecular weight (M _n) of the resulted polymer increases linearly with increase in the monomer conversion upto around 45%. Polydispersity of the corresponding poly(NVP)s increase gradually from 1.2 to 1.9 with increase in the monomer conversion. Chain-end analysis of the resulted polymer by ¹H NMR shows clearly that polymerization started with radical forming out of xanthate mediator. Living nature of the polymerization was confirmed from the successful homo chain extension experiment and also the hetero-chain extension experiment involving synthesis of poly(NVP)-b-polystyrene amphiphilic diblock copolymer.     

Preparation and properties of La(3-x)DyxBWO9 phosphors and La(3-x)DyxBWO9/PMMA composite films

A series of La_(3-x)Dy_xBWO₉ phosphors and La_(3-x)Dy_xBWO₉/PMMA composite films were prepared. The absorption and photoluminescence of phosphors as well as the transmittance and radioluminescence of the composite films were studied. La_(3-x)Dy_xBWO₉ phosphors mainly emit blue light at 486 nm and yellow light at 577 nm when excited at 310 nm, and the phosphors have good thermal stability. La_(3-x)Dy_xBWO₉/PMMA composite films have good transmittance and X-ray radiation properties. The results indicate that La_(3-x)Dy_xBWO₉ phosphors can be used in solid-state lighting devices, and the prepared composite films are expected to be used in fields such as X-ray imaging and radiation detection.     

A method to characterise the volatile release of solid recovered fuels (SRF)

A method was developed and successfully applied to characterise the de-volatilisation process of solid recovered fuels (SRF). Following the definitions of the European initiative on SRF standardisation CEN/TC 343, this kind of fuels have to be produced from non-hazardous bio-residues, mixed- and mono-waste streams, and they are designated to be used either in mono- or co-combustion processes. Consequently, SRF are – in most cases – heterogeneous fuel mixtures. The de-volatilisation process was identified as highly relevant due to the nature of fuel: most SRF components do not evolve a char comparable to coal. Furthermore, large particle sizes do not allow the application of common approaches to determine kinetic parameters. The method presented in this paper relies on thermo-gravimetric analysis (TGA). By successful combination with other well-established analytical procedures, the obtainable information towards the de-volatilisation process was largely improved. The method allows a quantification of energy and elemental distribution between volatiles and char during the de-volatilisation process in relation to the particle temperature. The data can be used to compare SRF or SRF components with other “known” fuels such as lignite and biomass. Moreover, the data is suitable as input data for combustion models. Focus of this paper is the analytical procedure including the required calculations. In addition, first results are presented and some ideas towards the use of the results are discussed.     

O-乙基黄原酸丙酸乙酯的工艺优化

对O-乙基黄原酸丙酸乙酯的合成工艺进行改进,以氢氧化钾、二硫化碳、2-溴丙酸乙酯为原料,以无水乙醇为溶剂,经两步反应,成功制备了黄原酸酯链转移剂O-乙基黄原酸丙酸乙酯。对第2步合成利用正交实验探究了反应时间、反应温度、反应物料摩尔比(乙基黄原酸钾与2-溴丙酸乙酯的摩尔比)对反应收率的影响。结果表明,O-乙基黄原酸丙酸乙酯的产率的优化条件是乙基黄原酸钾与2-溴丙酸乙酯的摩尔比1.1∶1,反应时间为12 h,反应温度为55℃。各因素对合成O-乙基黄原酸丙酸乙酯的产率的影响按大小排列分别为:温度>反应物摩尔比>反应时间。两步总收率可达62.2%,远高于文献报道的47.0%。     

O-乙基黄原酸丙酸乙酯的工艺优化

对O-乙基黄原酸丙酸乙酯的合成工艺进行改进,以氢氧化钾、二硫化碳、2-溴丙酸乙酯为原料,以无水乙醇为溶剂,经两步反应,成功制备了黄原酸酯链转移剂O-乙基黄原酸丙酸乙酯。对第2步合成利用正交实验探究了反应时间、反应温度、反应物料摩尔比(乙基黄原酸钾与2-溴丙酸乙酯的摩尔比)对反应收率的影响。结果表明,O-乙基黄原酸丙酸乙酯的产率的优化条件是乙基黄原酸钾与2-溴丙酸乙酯的摩尔比1.1∶1,反应时间为12 h,反应温度为55℃。各因素对合成O-乙基黄原酸丙酸乙酯的产率的影响按大小排列分别为:温度反应物摩尔比反应时间。两步总收率可达62.2%,远高于文献报道的47.0%。     

(E)-2-(2-溴甲基苯基)-2-甲氧亚胺基乙酸甲酯的合成工艺研究

以2-甲基苯甲酸为起始原料,经氯化亚砜酰氯化、氰化钠腈化、甲醇酯化、甲氧胺盐酸盐肟化以及二溴海因溴化后,得到肟菌酯的重要中间体(E)-2-(2-溴甲基苯基)-2-甲氧亚胺基乙酸甲酯,含量90%(GC),总收率56.0%。该合成工艺反应条件温和,工艺简便,原材料成本低,有工业应用价值。     

(S)-(+)-2-(2-萘)-2-N-甲基氨乙醇的合成与表征

以β-萘乙烯为原料,通过烯烃的Sharpless不对称双羟化、环化、开环、催化氢化、甲酰化、还原等6步反应,生成标题化合物,总产率以β-萘乙烯计为39.7%,e.e.值高达97%~99%。对产物进行了质谱、红外光谱、1HNMR和13CNMR表征。     

3(5)-[(4-苄氧基)苯基]-5(3)-(2-呋喃基)-1H-吡唑的合成及结构确证

β-二酮和水合肼反应合成了标题化合物,采用元素分析、IR、1HNMR和ESI-MS对其结构进行了鉴定和分析.由于这种1H-吡唑化合物能形成N-H...N分子间的氢键,因而在ESI-MS图上出现很强的二聚体离子峰[2M]+.