5%氟虫脲悬浮剂润湿分散剂的筛选

分别采用流点法和激光粒度测定法对5%氟虫脲悬浮剂润湿分散剂进行筛选,综合对比2种方法的筛选结果,优选出5%氟虫脲悬浮剂润湿分散剂为GYD08-W10(苯乙烯磺酸盐聚合物-聚氧乙烯氧丙烯醚嵌段共聚物质量比2:1).实验结果表明:流点法筛选周期短,操作简单,但结果重复性差;激光粒度测定法实验周期长,仪器昂贵,但结果准确、重复性好.     

水性体系颜料用高分子分散剂的研究

讨论了聚合物分散剂的相关结构和特点,研究了丙烯酸酯类聚合物分散剂的实验室合成方法及其性能。     

Synthesis and Structural Elucidation of NSC Auxiliary Dispersing Agents

The synthesis, characterization, structural elucidation, and application of the dispersant (NSC) obtained from condensation of β-naphthalene sulphonic acid and formaldehyde are described. The one pot process from naphthalene, sulphuric acid, and formaldehyde leads to reproducible condensate products with n = 13 and 14 naphthalene nuclei. The ¹H and ¹³C NMR spectra were recorded in D₂O (representative spherical shape) and DMSO (representative rod-like shape). Bleaching leads to the recovery of excellent super pure material.     

Synthesis of Quinazolinones from Alcohols via Laccase‐Mediated Tandem Oxidation

This paper describes the synthesis of quinazolinones via a tandem reaction using the laccase‐mediator system under mild conditions. The procedure involved the laccase‐catalyzed oxidation of alcohols to the corresponding aldehydes, followed by cyclocondensation with isatoic anhydride and a number of amines to afford 2,3‐dihydroquinazolin‐4(1H)‐ones, which were further oxidized to quinazolinones in useful yields. The use of an enzyme as the catalyst, O₂ as an environmentally friendly oxidant, and a citrate buffer as the green solvent represents a novel and efficient approach for the one‐pot synthesis of quinazolinones.

     

Single‐Biocatalyst Synthesis of Enantiopure d‐Arylalanines Exploiting an Engineered d‐Amino Acid Dehydrogenase

A practical and efficient biocatalytic synthesis of aromatic d ‐amino acids has been developed, based on the reductive amination of the corresponding α‐keto acids via a recombinant whole cell system composed of an engineered dehydrogenase and cofactor recycling apparatus. The reaction was shown to give excellent enantioselectivity (≥98%) and good yields at the preparative scale across a broad range of substrates. Additionally, the structure of the variant enzyme was solved to allow rationalisation of the observed reaction rates. The engineered whole cell catalyst was also used to mediate the production of d ‐phenylalanine derivatives from racemic mixtures and cheaper l ‐amino acids by combining it with an enantiocomplementary deaminase.

     

高分子分散剂在抗静电涂料中的应用研究

研究了分散剂种类及其用量对自制抗静电涂料的粘度、分散稳定性及涂层电阻的影响,确定了合适的分散剂及其最佳用量。     

Total Synthesis of Capsaicin Analogues from Lignin‐Derived Compounds by Combined Heterogeneous Metal,Organocatalytic and Enzymatic Cascades in One Pot

The total synthesis of capsaicin analogues was performed in one pot, starting from compounds that can be derived from lignin. Heterogeneous palladium nanoparticles were used to oxidise alcohols to aldehydes, which were further converted to amines by an enzyme cascade system, including an amine transaminase. It was shown that the palladium catalyst and the enzyme cascade system could be successfully combined in the same pot for conversion of alcohols to amines without any purification of intermediates. The intermediate vanillylamine, prepared with the enzyme cascade system, could be further converted to capsaicin analogues without any purification using either fatty acids and a lipase, or Schotten–Baumann conditions, in the same pot. An aldol compound (a simple lignin model) could also be used as starting material for the synthesis of capsaicin analogues. Using L ‐alanine as organocatalyst, vanillin could be obtained by a retro‐aldol reaction. This could be combined with the enzyme cascade system to convert the aldol compound to vanillylamine in a one‐step one‐pot reaction.

     

3种流动分散剂在丁基橡胶胶料中的应用研究

对比研究流动分散剂RL16,WB16和AC617对丁基橡胶胶料性能的影响.结果表明:3种流动分散剂均能提高胶料的流动性和填料的分散性,RL16和WB16的改善效果优于AC617;加入RL16和WB16的胶料焦烧时间和t90有所延长,硫化胶的100％和300％定伸应力减小,拉断伸长率增大,而AC617对硫化胶的物理性能影响较小;加入RL16和WB16的硫化胶耐热空气老化性能和耐压缩永久变形性能有所下降,影响程度略高于AC617.     

绿色水处理剂的研究与应用分析

绿色环保技术的开发与发展是可持续发展的一项重要内容,也是21世纪世界各国所关注的焦点.传统的环境治理工艺技术具有化学药品和能源消耗大、容易造成二次污染等缺点,这也促使开展绿色化学研究,开发清洁的治理工艺技术成为当前环境治理领域的热点问题.     

Structure and Activity of NADPH‐Dependent Reductase Q1EQE0 from Streptomyces kanamyceticus,which Catalyses the R‐Selective Reduction of an Imine Substrate

NADPH‐dependent oxidoreductase Q1EQE0 from Streptomyces kanamyceticus catalyzes the asymmetric reduction of the prochiral monocyclic imine 2‐methyl‐1‐pyrroline to the chiral amine (R)‐2‐methylpyrrolidine with >99 % ee, and is thus of interest as a potential biocatalyst for the production of optically active amines. The structures of Q1EQE0 in native form, and in complex with the nicotinamide cofactor NADPH have been solved and refined to a resolution of 2.7 Å. Q1EQE0 functions as a dimer in which the monomer consists of an N‐terminal Rossman‐fold motif attached to a helical C‐terminal domain through a helix of 28 amino acids. The dimer is formed through reciprocal domain sharing in which the C‐terminal domains are swapped, with a substrate‐binding cleft formed between the N‐terminal subunit of monomer A and the C‐terminal subunit of monomer B. The structure is related to those of known β‐hydroxyacid dehydrogenases, except that the essential lysine, which serves as an acid/base in the (de)protonation of the nascent alcohol in those enzymes, is replaced by an aspartate residue, Asp187 in Q1EQE0. Mutation of Asp187 to either asparagine or alanine resulted in an inactive enzyme.     

Novel 1,4‐Substituted‐1,2,3‐Triazoles as Antitubercular Agents

Tuberculosis (TB) remains a pressing unmet medical need, particularly with the emergence of multidrug‐resistant and extensively drug‐resistant tuberculosis. Here, a series of 1,4‐substituted‐1,2,3‐triazoles have been synthesized and evaluated as potential antitubercular agents. These compounds were assembled via click chemistry in high crude purity and in moderate to high yield. Of the compounds tested, 12 compounds showed promising antitubercular activity with six possessing minimum inhibitory concentration (MIC) values <10 μg mL^?1, and total selectivity for Mycobacterium tuberculosis (Mtb) growth inhibition. A second set of 21 compounds bearing variations on ring C were synthesized and evaluated. This second library gave an additional six compounds displaying MIC values ≤10 μg mL^?1 and total selectivity for Mtb growth inhibition. These compounds serve as an excellent starting point for further development of antitubercular therapies.     

3种流动分散剂在EPDM胶料中的应用研究

研究流动分散剂RL20,WB42和AC617对EPDM胶料性能的影响.结果表明:RL20和WB42对胶料流动性的改善效果优于AC617;加入RL20和WB42可以改善填料的分散性,而加入AC617则无明显效果;3种流动分散剂对EPDM胶料硫化特性、硫化胶的物理性能和耐热空气老化性能影响不大,加入RL20和WB42的硫化胶压缩永久变形有所减小,而加入AC617的硫化胶压缩永久变形有所增大.     

Dispersing mechanism of carboxymethyl starch as water‐reducing agent

In this article, by using zeta (ζ) potential analyzer, X‐ray photo spectroscopy, and UV–visible adsorption spectrophotometer, the adsorption characteristics and surface electrochemical properties of carboxymethyl starch (CMS) as water‐reducing agent on cement particles and its effects on the fluidity of cement paste were studied in comparison with traditional naphthalene sulfonic acid–formaldehyde condensates, whose dispersion ability mainly depends on electrostatic repulsive force caused by ζ‐potential. The results indicate that the adsorption conformation of CMS is dendritic, generating strong steric hindrance by branched chains and polar side chains of adsorption layer, and the dispersion capacity of CMS mainly comes from steric hindrance effect rather than electrostatic repulsive force. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Engineering towards Nitroreductase Functionality in Ene‐Reductase Scaffolds

Nitroreductases (NRs) and ene‐reductases (ERs) both utilize flavin mononucleotide cofactors but catalyze distinct reactions. NRs reduce nitroaromatics, whereas ERs reduce unsaturated C?C double bonds, and these functionalities are known to somewhat overlap. Recent studies on the ER xenobiotic reductase A (XenA) from Pseudomonas putida demonstrated the possibility of increasing NR activity with active site modifications. Structural comparison between NRs and ERs led us to hypothesize that active site cavity size plays an important role in determining enzyme functionality. Residues of ER KYE1 from Kluyveromyces lactis were selected to increase the binding pocket size, compensate for hydrogen bonding pattern changes, and eliminate ER activity. Single variants were screened, and promising mutations were combined. Variant F296A/Y275A showed a 100‐fold improvement in NR specific activity over wild‐type, and variant H191A/F296A/Y375A exhibited complete conversion to a NR.     

Diversity‐Oriented Synthesis of Diol‐Based Peptidomimetics as Potential HIV Protease Inhibitors and Antitumor Agents

Peptidomimetic HIV protease inhibitors are an important class of drugs used in the treatment of AIDS. The synthesis of a new type of diol‐based peptidomimetics is described. Our route is flexible, uses d ‐glucal as an inexpensive starting material, and makes minimal use of protection/deprotection cycles. Binding affinities from molecular docking simulations suggest that these compounds are potential inhibitors of HIV protease. Moreover, the antiproliferative activities of compounds 33 a , 35 a , and 35 b on HT‐29, M21, and MCF7 cancer cell lines are in the low micromolar range. The results provide a platform that could facilitate the development of medically relevant asymmetrical diol‐based peptidomimetics.     

Biocatalysis at Work: Applications in the Development of Sagopilone

For the antitumour agent sagopilone, an epothilone analogue, a large‐scale synthesis was developed to synthesise the active pharmaceutical ingredient for clinical trials, exploring enzymatic and microbial methods to produce chiral building blocks on a multi‐kilogram scale. The three building blocks were identified as key intermediates in the synthesis and needed to be produced with high optical purity in yields higher than those previously published. The improved syntheses of two of these building blocks are detailed herein. For building block A, the chemical research synthesis was abandoned, and a novel chemical route was developed leading to building block A via an enzymatic hydrolysis process. For building blocks C, replacement of a chemical catalytic procedure by a microbial process meant that the development of a new starting material could be avoided, thereby accelerating the development process. For the clinical development process, a human metabolite of sagopilone was required as a reference. To accelerate the synthesis of the metabolite, no chemical synthesis was investigated; rather, we relied solely on oxidoreductases. The human metabolite of sagopilone was synthesised on a multi‐gram scale in a single‐step process using genetically engineered E. coli expressing human cytochrome P450 enzyme 2C19. The integration of enzymatic and microbial processes provided tools that enable the synthesis of highly functionalised intermediates and metabolites.     

Sulfation of Various Alcoholic Groups by an Arylsulfate Sulfotransferase from Desulfitobacterium hafniense and Synthesis of Estradiol Sulfate

Bacterial arylsulfate sulfotransferases (AST) are enzymes that catalyse the transfer of a sulfate group from p‐nitrophenyl sulfate (p‐NPS) to a phenolic acceptor molecule. By screening of the NCBI protein database a gene coding for an AST was found in Desulfitobacterium hafniense. After expression the enzyme was purified and characterised. This AST efficiently sulfates various acceptor molecules (estrone, estradiol, enkephalin and non‐phenolic alcohols) using p‐NPS as sulfate donor. The purified AST has a pH optimum of 9.6, it is stable in the presence of 10% of DMSO, and depending on the conditions it has a melting temperature of up to 47 °C. Surprisingly, and in great contrast to all other known bacterial ASTs, this enzyme was able to use a variety of non‐phenolic alcohols as sulfate acceptor. Because of these properties, this unique enzyme is a promising tool for biotransformation processes, providing a green and simple method to specifically sulfate compounds without need for functional group protection.     

Expanding the Imine Reductase Toolbox by Exploring the Bacterial Protein‐Sequence Space

Recent investigations on imine reductases (IREDs) have enriched the toolbox of potential catalysts for accessing chiral amines, which are important building blocks for the pharmaceutical industry. Herein, we describe the characterization of 20 new IREDs. A C‐terminal domain clustering of the bacterial protein‐sequence space was performed to identify the novel IRED candidates. Each of the identified enzymes was characterized against a set of nine cyclic imine model substrates. A refined clustering towards putative active‐site residues was performed and was consistent both with our screening and previously reported results. Finally, preparative scale experiments on a 100 mg scale with two purified IREDs, IR_20 from Streptomyces tsukubaensis and IR_23 from Streptomyces vidiochromogenes, were carried out to provide (R)‐2‐methylpiperidine in 98 % ee (71 % yield) and (R)‐1‐methyl‐1,2,3,4‐tetrahydroisoquinoline in >98 % ee (82 % yield).