Prebiotic Organic Chemistry of Formamide and the Origin of Life in Planetary Conditions: What We Know and What Is the Future

The goal of prebiotic chemistry is the depiction of molecular evolution events preceding the emergence of life on Earth or elsewhere in the cosmos. Plausible experimental models require geochemical scenarios and robust chemistry. Today we know that the chemical and physical conditions for life to flourish on Earth were at work much earlier than thought, i.e., earlier than 4.4 billion years ago. In recent years, a geochemical model for the first five hundred million years of the history of our planet has been devised that would work as a cradle for life. Serpentinization processes in the Hadean eon affording self-assembled structures and vesicles provides the link between the catalytic properties of the inorganic environment and the impressive chemical potential of formamide to produce complete panels of organic molecules relevant in pre-genetic and pre-metabolic processes. Based on an interdisciplinary approach, we propose basic transformations connecting geochemistry to the chemistry of formamide, and we hint at the possible extension of this perspective to other worlds.     

A Step toward Molecular Evolution of RNA: Ribose Binds to Prebiotic Fatty Acid Membranes,and Nucleosides Bind Better than Individual Bases Do

A major challenge in understanding how biological cells arose on the early Earth is explaining how RNA and membranes originally colocalized. We propose that the building blocks of RNA (nucleobases and ribose) bound to self-assembled prebiotic membranes. We have previously demonstrated that the bases bind to membranes composed of a prebiotic fatty acid, but evidence for the binding of sugars has remained a technical challenge. Here, we used pulsed-field gradient NMR spectroscopy to demonstrate that ribose and other sugars bind to membranes of decanoic acid. Moreover, the binding of some bases is strongly enhanced when they are linked to ribose to form a nucleoside or – with the addition of phosphate – a nucleotide. This enhanced binding could have played a role in the molecular evolution leading to the production of RNA.     

Prebiotic Membranes and Micelles Do Not Inhibit Peptide Formation During Dehydration

Cycles of dehydration and rehydration could have enabled formation of peptides and RNA in otherwise unfavorable conditions on the early Earth. Development of the first protocells would have hinged upon colocalization of these biopolymers with fatty acid membranes. Using atomic force microscopy, we find that a prebiotic fatty acid (decanoic acid) forms stacks of membranes after dehydration. Using LC-MS-MS (liquid chromatography-tandem mass spectrometry) with isotope internal standards, we measure the rate of formation of serine dipeptides. We find that dipeptides form during dehydration at moderate temperatures (55 °C) at least as fast in the presence of decanoic acid membranes as in the absence of membranes. Our results are consistent with the hypothesis that protocells could have formed within evaporating environments on the early Earth.     

Physical Organic Chemistry and the Origin of Life Problem: A Personal Perspective

The origin of life (OOL) question might be considered physical organic chemistry’s ultimate challenge, yet despite continuing efforts over close to a century, the problem remains unresolved. In this personal perspective, I discuss some aspects of that challenge, and argue that notwithstanding the general perception that physical organic chemistry is a research area in decline, the discipline was, and continues to be, the most relevant one for tackling the OOL problem. Systems chemistry, a newly emergent branch of physical organic chemistry, which, inter alia, deals with replicating chemical systems and the networks they establish, reveals that physical organic chemistry, though in different guise, is alive and kicking. The broad direction ahead seems illuminated.     

Adsorptive Removal of Organic Acids and Furans from Hydrothermal Treatment Process of Biomass

Abstract

Hydrothermal treatment of plant biomass using subcritical water is one of the pretreatment methods for producing valuable chemicals such as D-glucose for producing bio-alcohol. However, this treatment causes side reactions and produces by-products such as organic acids and furans which may inhibit the production of alcohols in the following step. In this study, the adsorption process is applied to remove by-products from products solution. As adsorbents, Cellufine A-200, A-800, DIAION WA21J, and activated carbon were used. Among them, Cellufine A-200 selectively adsorbed organic acids and activated carbon showed the best adsorption performance for furans. DIAION WA21J adsorbed both organic acids and furans.     

有机硒化合物的合成研究进展

许多有机硒化合物具有生理活性,在医药和添加剂等方面显现出巨大的应用前景。有机硒化合物按照结构可以分为:硒化氨基酸,硒化多糖,肌醇硒酸酯,硒化茶多酚,硒化亚油酸等几大类。本文综述了以上各类有机硒化合物的合成方法。     

半微量有机合成实验装置的设计方案

从反应原理入手,对半微量有机合成实验条件进行系统分析,从而达到有效地设计合成装置的目的,利于教师教学及学生学习,提高教学效果。     

水介质中有机合成反应的研究进展

近年来,水作为有机合成反应介质的报道相继出现。本文综述了水介质中几类有机合成反应的研究进展,这些反应类型包括还原、氧化、取代、加成、缩合、偶联等。     

Hydrothermal synthesis of nano-kaolinite from K-feldspar

Development of sustainable routes for the synthesis of kaolinite in nano-scale (nano-kaolinite) is very significant for producing high quality kaolinite of paper-coating grade in kaolin industry. Duplicating chemical weathering processes in nature, two routes were developed and compared for the synthesis of nano-kaolinite from K-feldspar. Kaolinite of uniform plate-like morphology with thickness of around 14?nm was obtained in this study. Both synthesis routes may lead to the comprehensive utilization of K-feldspar for the synthesis of pure kaolinite for not only high quality paper-coatings but also medical and other uses.     

有机化学考研中取代苯合成考点的分析

对陕西师大有机化学考研中取代苯合成考点进行具体分析,合成中先分析引入了几个新基团,然后根据定位规则分析清楚哪个基团先引入,哪个基团后引入,引入到哪个个位置。在基团引入过程中违背了定位规则,就要互换基团的引入顺序。以2009-2011年三年的取代苯合成考研试题为例,分析了每个题的具体合成过程,使考陕西师大有机化学科目的考生能理解和掌握此考点。     

有机高分子絮凝剂的合成及应用研究进展

有机高分子絮凝剂作为具有优势的一类高分子絮凝剂,目前广泛应用于废水处理工艺中.本文综述了絮凝剂的种类、合成方法及其在废水处理中的应用,絮凝剂的聚合方法主要包括水溶液聚合法、反相乳液聚合法以及反相悬浮聚合法.分析了有机高分子絮凝剂的研究方向.     

Organic geochemistry of the British Kimmeridge clay: 2. Acyclic isoprenoid alkanes in Kimmeridge shale oils

The C15---C20 isoprenoid alkane composition of Kimmeridge Clay shale oils produced by Fischer assay has been examined, and compared with the isoprenoid composition of corresponding bitumens. C16 and C18 isoprenoid alkanes are generally dominant in shale oils, while pristane (C19) and phytane (C20) dominate in bitumens. A significant proportion of the phytane in many shale oils is derived from simple evaporation of free (bitumen) phytane, while free pristane contributes less to shale oil composition. Some shale oil phytane and a large proportion of pristane is kerogen-derived. Certain shale oils contain lower concentrations of isoprenoid alkanes than corresponding bitumens, suggesting that some free alkane is thermally degraded during pyrolysis. Results thus indicate three sources for shale oil isoprenoid alkanes: thermal evaporation of free alkanes (particularly for phytane), kerogen decomposition, and possibly the cracking of higher homologues for C15---C19 alkanes. Kerogen-derived isoprenoids are suggested to arise by thermal desorption of adsorbed free alkane (particularly for phytane) and from C---O and C---C bonded species (excluding phytane) via postulated clay catalysed hydrogenation of initially formed alkenes. Comparison of shale oil and bitumen pristane/phytane ratios allows groups of oil shales to be defined, dependent on source composition, organic carbon content and maturity. Shale oil pristane/phytane ratios can also help to determine depositional environments and source composition, although maturity, shale mineralogy and competing alkene-forming pyrolytic reactions may also affect the ratios.     

活化硼氢化钠在有机合成中的应用

介绍了有机合成反应中NaBH4与添加剂共同作用的反应,其中包括烯烃和炔烃的还原,羧酸的还原,氨基酸及其衍生物的还原,羧酸酯的还原,酰胺的还原,腈基的还原,酰氯的还原,硝基化合物的还原,醛酮的还原等。与LiAIH4的还原相比较,其反应条件更温和,反应过程更安全、易操控、易放大。     

关于有机合成化学课程改革的探讨

从现代有机合成的发展和学生的实际出发,在对有机合成课程的现状进行剖析的基础上,合理处理教材,由浅入深、循序渐进、与时俱进。采取具体措施进行有机合成课程教学改革,启发学生的创造性思维,培养学生提出问题、分析问题、解决问题的能力。     

室温离子液体在有机合成中的应用研究进展

综述了近年来室温离子液体作为绿色溶剂和催化剂在有机合成反应中应用的研究进展,主要有Friedel-Crafts反应,Diels-Alder反应,Heck偶联反应,缩合反应等,为有机合成的绿色化工业应用及研究提供参考。     

表面活性剂在有机电合成中的应用

主要讲述了表面活性剂在有机电合成中的作用和最近的研究情况。将有机电合成分为间接电合成和直接电合成两部分,简单介绍了表面活性剂在间接电合成中的作用和作用机理,着重介绍了表面活性剂在直接电合成中的应用情况、作用机理以及如何选择合适的表面活性剂。最后提出了表面活性剂的研究方向。     

Hydrothermal Carbonization of Biomass: Major Organic Components of the Aqueous Phase

Process waters obtained from hydrothermal carbonization (HTC) of wheat straw, a biogas digestate derived thereof, and four woody biomass feedstocks were quantified regarding the total organic carbon (TOC) and selected organic compounds. HTC runs revealed that TOC loads were largely unaffected by process severity or type of feedstock whereas the C₂–C₆ fatty acids, determined by GC, displayed clear effects of temperature and feedstock. HPLC demonstrated simultaneously the initial increase and subsequent consumption of cellulose‐derived furfural and 5‐hydroxymethylfurfural as well as the increase of the lignin‐derived 2‐methoxyphenol. 2‐Methylbenzofuran, an example for a substance potentially harmful to aquatic biota, was observed in high concentration in the HTC liquor from wheat straw‐based feedstocks.     

信息技术与有机合成化学教学整合的探讨

教育信息化发展必将引起教育的变革,其中信息技术与学科之间的整合是必经环节。论文结合学校实际,主要在教学内容优化、多媒体课件制作、课堂教学、网络资源应用与教学评价等方面,对信息技术与有机合成化学教学整合进行初步探索,并讨论了整合后有机合成化学教学实践中存在的问题。     

三氯氧磷在有机合成及工业生产中的应用

详细介绍了三氯氧磷作为反应试剂、催化剂以及脱水剂等参与的有机反应,并简要介绍了三氯氧磷在工业生产中的应用。     

浅析以连续化实验实施有机化学实验教学的要求

随着通识教育在大学教育中所占比例的提高,专业课及专业基础课的比例在持续下降,这对有机化学的教学提出了新的要求和标准。连续化合成实验是较好的一种实验教学方案,我们根据自身的实际和教学实践总结了利用此方法进行实验教学时在实验内容选择、师生互动、实验室建设和考核方式等方面的一些经验和要求,根据这些要求组织有机化学实验教学具有学时短、经费省、效果好的优点。