Asymmetric Aldol Reaction of Thiazole‐Carbaldehydes: Regio‐ and Stereoselective Synthesis of Tubuvalin Analogues

The first organocatalytic enantioselective approach to precursors of tubuvaline (pre‐Tuv) is presented employing a prolinamide‐catalyzed aldol reaction of easily accessible thiazole‐carbaldehyde with methyl isopropyl ketone “on water” in excellent yield as well as regio‐ and enantioselectivities. The analogues of pre‐Tuv were achieved using an L ‐proline‐catalyzed direct asymmetric aldol reaction of substituted thiazole‐carbaldehydes with acetone. A direct and flexible approach to the tubavaline (Tuv) core of tubusylins has been established employing the reductive amination of the pre‐Tuv species. The key aldol reaction should greatly expand the potential of this strategy to the synthesis of natural product tubulysins and a range of analogues.

     

粘胶亚麻混纺纱线的前处理工艺实践

粘胶和亚麻虽然同属纤维素纤维，但由于其含杂量及耐高温浓碱性能不同，给粘胶亚麻混纺纱线的前处理带来困难。为了兼顾两种纤维，又能有效地去除杂质、提高润湿性和白度、增强可染性，经过工艺试验和实践，采用轻煮重漂工艺，取得了良好的结果。     

活性白土对变压器油的吸附脱色

利用活性白土对变压器油进行脱色处理，探讨了吸附温度、吸附时间以及活性白土添加量对脱色效果的影响，通过色度仪、分光光度计对油品的颜色进行分析。通过红外光谱、扫描电镜、热重分析对吸附前后的白土结构进行表征。结果表明，活性白土对变压器油具有优良的脱色效果，当活性白土的添加量（w）为5%、吸附温度为90 ℃、吸附时间为1.5 h时，变压器油的色号可从9号降至1号，其透光率达到90%以上，且其击穿电压提高了56.64%，介质损耗因数下降了18.81%，水质量分数下降了25.69%。     

脱墨浆生产线白水特性及其回用对浮选和漂白的影响

本文介绍了瑞典一个脱墨浆车间不同取样点白水的特性，及其用于浮选和漂白试验时对漂白效果的影响。     

日照木浆有限公司污水处理工艺设计

本文阐述了日照木浆有限公司污水处理工艺设计采用的技术方法、工艺参数与工艺流程,并对其先进独特性、处理效果进行了介绍.     

机械活化-还原扩散法制备Fe-WC粉末

以人造黑钨矿和石墨为原料,采用机械活化 还原扩散法制备Fe WC复合粉末。运用X 线衍射、差热分析和电子探针等对产物进行分析。结果表明以机械活化还原扩散法制备Fe WC是可行的,球磨具有明显的细化晶粒、活化物料的作用。球磨时间小于8h时,反应物料只有部分发生反应,在180V强度下球磨后经退火可得到金属Fe(Mn)和WC的复合粉末,还原反应表观活化能随球磨时间的延长而明显下降     

Determination of Al(III) activation conditions for white bentonite used for cottonseed oil bleaching by robust design

The optimum Al(III) activation conditions for white bentonite (Ordu, Turkey), used as a bleaching agent for cottonseed oil, were investigated. AlCl₃–clay suspension was hydrolyzed in situ using NaOH to investigate possible pillars. Five controllable factors that mainly affect the activation process were specified as initial AlCl₃ concentration (F1), OH^?/Al³⁺ molar ratio (F2), NaOH volumetric flow‐rate (F3), cation‐exchange temperature (F4) and thermal treatment temperature (F5). Each factor was examined at four levels by using a robust (Taguchi) design to determine optimum activation conditions. The response variable of each experimental run was taken as bleaching efficiency, which is defined in terms of absorbance at 420 nm. The effect of desired levels of factors to the system response was compared using the signal‐to‐noise (S/N) ratio. An importance factor (IF) was suggested in order to compare the affectability of each factor to the response variable by using the integrated area under the S/N ratio curves. The most important factor affecting bleaching efficiency was F5, followed in sequence by F2 > F1 > F4 > F3. The availability of Al? O species after activation in the clay crystal structure was determined by FTIR analysis. The optimum levels of each factor for Al³⁺ activation of clay were F1 5 meq g^?1 clay, F2 2.0, F3 1200 mL h^?1, F4 25 °C and F5 700 °C. Copyright © 2005 Society of Chemical Industry     

Oxygen bleaching systems in domestic laundry

The oxidative bleaching process plays a key role in removing unwanted stains from laundry. This review covers methods of generation of active oxygen bleaching species, their activation and application. In addition, the requirements for commercially acceptable oxygen bleach products are discussed.     

二苯乙烯苯并(口恶)唑荧光增白剂(OB-1)合成方法研究

以对甲基苯甲腈为原料，经氯化、环化、缩合三步反应合成了荧光增白剂双苯并恶唑二苯乙烯(OB—1)．通过对化合物的元素分析、红外光谱以及在DMF中紫外吸收光谱的测定，确定了目标分子．经HPLC测定，产品纯度大于99%。     

死髓变色前牙的激光漂白治疗临床评价

目的:探讨激光冠内漂白治疗死髓牙变色的治疗作用。方法:漂白基本操作同激光活髓牙变色的漂白操作程序。先将牙龈及口唇有效防护,将漂白药物放在唇舌两面并同时封入根冠内。结果:所有牙齿的灰暗变色均有3～5级的色度提高。平均治疗次数为3.4±0.75,脱色85％以上的占89％。结论:牙齿创伤和牙髓分解是冠内变色的常见原因,激光冠内漂白是治疗这种变色的有效手段。