手性的控制：不对称有机催化——2021年诺贝尔化学奖成果简析

 2021年诺贝尔化学奖授予德国化学家Benjamin List和苏格兰裔美英籍化学家David MacMillan，以表彰他们在不对称有机催化领域的贡献。介绍了该诺奖工作的源头创新点和背景。阐述了手性化学、手性催化剂和不对称有机催化，及其对手性的控制。概括了有机催化和催化剂的类别。介绍了中国科学家和华人科学家在有机不对称催化领域的重要贡献，并对该领域的发展、研究现状和未来进行了展望。     

难降解有机废水的高级氧化技术

介绍了处理难降解有机废水的湿式(催化)乳化、超临界水(催化)乳化、光化学(催化)乳化、化学(催化)乳化、固定化细胞及基因工程等高级乳化处理技术的反应机理、特点及应用，这类处理技术应用于一般生物处理难以奏效的有机工业废水处理。     

吸附、催化燃烧法治理有机废气的研究

介绍了试验工艺流程、主要设备、控制方法及试验结果．采用蜂窝状活性炭吸附浓缩，小风量热空气脱附催化燃烧的工艺，完成了处理风量25000～30000m3／h含苯系物废气的工业试验．研究结果表明：对苯系物吸附净化效率在90％左右，排放浓度＜100mg／m3，达到国家排放标准；用催化燃烧排放的热废气对蜂窝状活性炭脱附再生安全、有效、节能；催化燃烧过程可利用自身燃烧热进行或只耗少量电能；在国内首次实现工业微机对该工艺自动控制，解决了手工操作难以实现的控制过程，数据采集方便，准确．该方法具有设备体积小、耗能低、维修操作方便等特点，是治理低浓度、大风量有机废气的可行办法．     

催化抗体及其在化学中的应用

对一类新的有机反应催化剂－催化抗体作了介绍。它能提高速率１０＾３－１０＾４倍。许多有机反应，甚至那些在一般条件下很难发生的反应都能被特定的抗体所催化，并可进行克量级合成。     

手性二级胺催化的不对称串联反应研究进展

有机催化的不对称串联反应是快速构建复杂分子的重要的方法之一：利用简单易得的原料,在温和的反应条件下,经过简单的操作,高选择性地构建结构复杂的有机分子。近年来,使用手性二级胺催化的不对称串联反应取得了显著的进展,已经成为有机催化领域的一个研究热点。根据手性二级胺催化剂活化模式的不同,从亚胺～烯胺和烯胺一亚胺两种活化模式,对手性二级胺催化的不对称串联反应进行了综述,介绍了该领域最新研究进展。     

湿式催化氧化处理化工集装罐清洗废水的新工艺

介绍了环保领域一种湿式催化氧化处理高浓有机废水的新工艺，该处理工艺是在一定温度条件下，在填充固体专用催化剂的反应器中，利用氧化剂对高浓度工业有机废水中的COD、氨、氰等污染物进行催化氧化分解的深度处理，使之转变为CO2、N2和水等无害成分，同时脱臭、脱色及杀菌消毒，从而达到净化处理有机废水的目的。     

金属有机化合物在有机合成中的应用

本文介绍了有机镁,有机锂,有机铜在有机合成中的应用以及过渡金属催化的高选择性有机合成反应。     

新型高级氧化技术在污水处理中的应用

为了能够对污水中有毒难生物降解的有机污染物进行更加有效的处理，采用了一种V-O型高级催化氧化技术，通过试验初步探讨了其催化机理、催化性能和活性及其影响因素。试验结果表明，在自制的6种催化剂中，V-O／SiO2／N2显示了较好的催化性能和活性；其催化机理为催化剂和臭氧反应。生成了氧化性极强的羟基自由基；催化臭氧化时间、催化剂用量、进气臭氧浓度、体系pH值等因素均对降解产生一定的影响。研究结果为该技术在环境保护领域的应用前景提供了可靠的理论根据。     

有机小分子催化不对称环氧化

光学活性的环氧化合物是有机合成的重要原料.不对称环氧化反应可以使潜手性的烯烃转化为带有手性碳的环氧化合物,这个反应在医药、农药、香料等合成上具有重要的意义.有机小分子催化烯烃的不对称环氧化是一种高效,绿色的光学活性环氧化合物的合成方法,目前该类反应主要是通过手性酮和手性亚胺盐来催化实现的.文章介绍了该类反应的催化机理,并概述了这两类有机小分子催化的不对称环氧化反应的研究进展.     

非水介质中酶促反应的研究进展

主要分析了在非水介质中酶促反应的几个重要影响因素；介绍了非水介质中酶催化反应在有机反应中的应用和非均相的低共熔酶促反应技术，论述了固定化酶在有机溶荆中的应用。     

The advent and development of organocatalysis

The use of small organic molecules as catalysts has been known for more than a century. But only in the past decade has organocatalysis become a thriving area of general concepts and widely applicable asymmetric reactions. Here I present my opinion on why the field of organocatalysis has blossomed so dramatically over the past decade.     

Stereocontrolled organocatalytic synthesis of prostaglandin PGF2α in seven steps

Prostaglandins are hormone-like chemical messengers that regulate a broad range of physiological activities, including blood circulation, digestion and reproduction. Their biological activities and their complex molecular architectures have made prostaglandins popular targets for synthetic organic chemists for over 40 years. Prostaglandin analogues are widely used as pharmaceuticals and some, such as latanoprost, which is used to treat glaucoma, have become billion-dollar drugs. Previously reported syntheses of these compounds are quite lengthy, and every chemical step costs time and energy, generates waste and is accompanied by material losses. Using a new bond disconnection, here we report a concise synthesis of the most complex prostaglandin, PGF2α, with high levels of control of relative and absolute stereochemistry, and fewer steps. The key step is an aldol cascade reaction of succinaldehyde using proline organocatalysis to create a bicyclic enal in one step and an enantiomeric excess of 98%. This intermediate bicyclic enal is fully primed with the appropriate functionality for attachment of the remaining groups. Access to this bicyclic enal will not only render existing prostaglandin-based drugs more affordable, but will also facilitate the rapid exploration of related chemical structures around the ubiquitous five-membered ring motif, such as potentially therapeutic prostaglandin analogues.     

Engineering the third wave of biocatalysis

Over the past ten years, scientific and technological advances have established biocatalysis as a practical and environmentally friendly alternative to traditional metallo- and organocatalysis in chemical synthesis, both in the laboratory and on an industrial scale. Key advances in DNA sequencing and gene synthesis are at the base of tremendous progress in tailoring biocatalysts by protein engineering and design, and the ability to reorganize enzymes into new biosynthetic pathways. To highlight these achievements, here we discuss applications of protein-engineered biocatalysts ranging from commodity chemicals to advanced pharmaceutical intermediates that use enzyme catalysis as a key step.     

Combined use of an alkene and a phosphine as a nucleophilic catalyst system for the cyanosilylation of carbonyl compounds

The catalytic potential of carbon nucleophiles has seldom been disclosed due to their reactivity toward carbon electrophiles to form stable carbon-carbon bonds, which are too strong to be cleaved for the expected catalytic cycles. We have developed an efficient catalytic cyanosilylation of carbonyl compounds with an in situ generated alkene/phosphine adduct, which is tuned not to couple with a carbonyl compound or an electron-deficient alkene under the reaction conditions when its nucleophilicity is translated into catalytic activity. In the presence of 3 mol% of methyl acrylate and 3 mol% of triphenylphosphine, a broad range of alkyl, alkenyl, and aryl ketones and aldehydes undergo cyanosilylation reaction with trimethylsilyl cyanide at room temperature to yield structurally diversified cyanohydrin silyl ethers in excellent yields. By using methyl acrylate/triphenylphosphine as a highly effective nucleophilic catalyst system for the cyanosilylation of carbonyl compounds, this study demonstrates a new concept for the development of useful organocatalysis utilizing the nucleophilicity of alkene/phosphine adducts generated in situ.     

The spatial distribution and sedimentary processes of organic matter in surface sediments of Nam Co, Central Tibetan Plateau

In this study,67 surface sediment samples collected from Nam Co in central Tibet were analyzed for total carbon,total organic carbon and total nitrogen,and 51 of these samples were also analyzed for n-alkanes.The origin and spatial distribution of organic matter were then investigated using these proxies,and the control factors responsible for the spatial distribution patterns and paleolimnological significance were discussed.The results indicated that the origin of organic matter in surface sediment of Nam Co is consistent with the sources of n-alkanes,which were primarily submerged plants,followed by terrestrial plants,and then aquatic algae and bacteria.The organic matter in surface sediments of the lake showed typical spatial variability.Because of the great influence of underwater topography,river inputs and water quality,the spatial distribution of organic matter is enriched from the source to the deposit center.This spatial variability of organic matter in the lake indicates that the sediments in different areas have different sensitivities to environmental changes,which is important to reconstruction of paleoenvironments and paleoclimate using lake sediment cores.     

应用铅同位素比值和元素含量分析法识别有机鸡样品真实性

探究了鸡中铅同位素与相关元素在有机养殖和常规养殖中的差异性,以探讨有机鸡样品溯源的可能性。相同品种的鸡分别采用有机养殖和常规养殖2种不同的饲养方式,利用电感耦合等离子体质谱分别对有机鸡和普通鸡样品中的铅同位素比值和相关元素含量进行测定。方差分析结果表明,铅同位素比值²⁰⁴Pb/²⁰⁶Pb和P、Zn、Fe、Mn、Mg、Ca、Cu、Na、K元素含量具有显著性差异(p＜0.05);主成分分析初步表明,Zn、Mn、Mg、Ca、Cu、Na、K为有机鸡和普通鸡样品中的特征无机元素;聚类分析可将鸡样品分为有机养殖和常规养殖两大类,通过判别分析所得模型的初始分组正确率为100.0%,交叉验证正确率为90.0%。利用铅同位素比值(²⁰⁴Pb/²⁰⁶Pb)、相关元素(P、Zn、Fe、Mn、Mg、Ca、Cu、Na、K)含量分析能够对有机鸡进行有效溯源识别,研究结果可为有机鸡的鉴别研究提供新的方法。     

广西森林土壤有机碳储量估算及空间格局特征

准确估算森林土壤有机碳库,研究其空间格局特征是陆地碳循环研究的关键与热点。利用森林资源连续清查样地资料,结合土壤剖面实测数据,估算广西森林土壤有机碳蓄积,分析不同经度、纬度、海拔的土壤有机碳密度的分布特征。研究结果表明:广西森林土壤有机碳 1 852.5 Tg,其中红壤和赤红壤土壤碳约占76.1%,是土壤有机碳储量的重要组成部分。广西森林土壤碳密度为12.13 kg/m²,碳密度低于全国平均水平,地带性土壤有机碳密度大小顺序为黄壤>红壤>赤红壤>砖红壤。森林土壤有机碳密度的空间分布总体上有北部高于南部、四周高于中部的规律。从三向地带性上看,碳密度均呈现出高—低—高的“U型”分布,有机碳密度低值区域主要是受岩溶地区的影响。     

基于地理加权回归模型的土壤有机碳密度影响因子分析

 为深入探讨土壤碳库的空间变异特征、准确评价区域碳库的影响机制,选择内蒙古自治区赤峰市敖汉旗黄花甸子流域为研究对象,基于研究区的实地采样数据,结合遥感与地理信息系统技术,采用地理加权回归模型对土壤有机碳密度及其影响因子进行拟合,探求不同环境因子对土壤有机碳密度影响的空间变异特性。结果表明,研究区土壤有机碳密度在1.91~16.63 kg/m²范围内变化,其平均密度为7.42 kg/m²;各影响因子对土壤有机碳密度的影响程度由高到低依次为海拔 >坡度 >归一化植被指数(NDVI)>与道路或村庄最短距离(DIST);各因子对土壤有机碳的影响随空间位置的变化存在明显的差异,其中海拔、坡度与土壤有机碳密度呈现负相关,而NDVI、DIST 与土壤有机碳密度呈现正相关。     

生产废水清液和二次凝水回用对燃料乙醇发酵的影响

为研究燃料乙醇生产废水回用的可行性,以燃料乙醇生产发酵过程中产生的清液和二次凝水为研究对象,分析其有机酸组成,并研究单一有机酸和经D318离子交换树脂处理前后的清液和二次凝水对酿酒酵母Saccharomyce cerevisiae NJ-2019生长和发酵生产乙醇的影响。结果显示,乙酸、乳酸、丙酸和柠檬酸是清液中的主要有机酸,乙酸和乳酸是二次凝水中的主要有机酸;乳酸和丙酸对酿酒酵母Sc.erevisiae NJ-2019的生长和发酵过程表现出显著抑制作用,其最低抑制浓度分别为7.0g/L和1.0g/L;清液和二次凝水分别直接回用时,清液对乙醇发酵过程的抑制作用更强;去除或者部分去除有机酸能使清液和二次凝水回用时的乙醇产量分别提高10.11%和9.85%。燃料乙醇发酵过程产生的清液和二次凝水具有回用的潜力,有利于实现乙醇生产过程节能减排。     

泥质烃源岩密度分组及有机质赋存类型初探

选取济阳坳陷沙河街组深湖相暗色泥岩为研究对象,通过不同密度ZnBr2重液浮选,将样品分离成多个密度组分,对各组分检测透射光、荧光、X光衍射等,揭示不同组分有机质赋存类型的差异性.分析结果表明,①组分(密度ρ<1.6g.cm-3)以颗粒有机质为主,有机质与矿物无明显紧密结合关系;②,③组分(1.6g.cm-3<ρ<2.2g.cm-3,ρ>2.2g.cm-3)多见无定形有机质分散于细粒矿物相中,呈橙黄-亮黄色荧光,反映有机质与矿物颗粒紧密共生的赋存特征.进一步对不同密度组分有机质分配的研究表明,①组分结合了烃源岩总有机质质量不到1%;②,③组分结合了烃源岩中90%以上质量的有机质.这反映了有机质和矿物颗粒共生的赋存形式在有机质保存中不可忽视的重要地位.