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关键词： Chemical benchmarking   Flowback and Produced Waters   High-resolution mass spectrometry   Hydraulic fracturing   Matrix effects   Non-target screening  

摘要： Hydraulic fracturing (HF, a.k.a. fracking) is a method of unconventional oil and gas extraction that has allowed the United States to become a leader in natural gas production. However, HF operations generate large quantities of flowback and produced waters (FPW) that require proper disposal. FPWs are wastewaters that contain a complex mixture of chemical additives, salts, and other unknown chemicals. Many chemical additives are semi-polar to polar organic chemicals that can be transported in water resources and are potentially toxic to aquatic life or other organisms. To minimize the risks that chemical additives pose to the environment and human health, it is critical that researchers understand the chemical composition of FPWs and the persistence of chemical additives during the wastewater treatment process to prevent the release of harmful chemicals into the environment. Assessing the organic chemical composition of FPWs and the persistence of organic chemicals in wastewater treatment is complicated by many factors. For example, conventional methods of analysis are focused on the detection or assessment of a single chemical or a small class of chemicals, but over one thousand chemicals have been disclosed as HF additives and many others are undisclosed or unanticipated. FPWs are produced for years after HF operations are completed and it is unclear how the organic chemical composition changes over time. Furthermore, the high levels of salts in FPWs alter the detection and quantification of organic chemicals in FPWs. Screening methods capable of detecting and assessing the persistence of a wide range of chemicals are required to determine the composition of FPWs and identify proper methods of disposal. The overarching goals of this dissertation were to: (1) characterize the semi-polar to polar organic composition of FPWs and develop a method to quantify additives used in HF fluids; (2) characterize the temporal abundance trends of known and unknown constituents w

关键词： 有机化学   仿生邻醌催化剂   有氧氧化反应  

摘要： 氧化反应是有机合成中最基础的反应之一。考虑到使用当量氧化剂带来的成本和污染等问题，以氧气为终端氧化剂的有氧氧化反应被认为是一类绿色的氧化反应。有氧氧化过程普遍存在于生物体中，所涉及的种类繁多氧化还原酶为发展高效有氧氧化化学催化剂提供了蓝本。受生物体醌酶的辅酶结构启发，化学家设计出了一系列小分子仿生邻醌氧化催化剂。但该类催化剂仍只适用于胺类的氧化反应，催化机理方面也存在诸多争议。如何设计发展高效广谱的仿生邻醌催化剂，揭示其催化机制和规律仍是当前研究的挑战性难题。围绕上述问题，本论文利用本组已发展的邻醌催化剂，进一步开拓了其在醇类有氧氧化方面的应用，并研究了其催化机制，主要研究进展包括:　　(1)利用胺氧化中原位产生的亚胺中间体实现了伯胺α位的氧化官能化反应。在温和的条件下，使用邻醌催化剂以氧气作为终端氧化剂实现了苯并咪唑、苯并恶唑和喹喔啉三种杂环的高效合成。　　(2)通过实验和理论计算，研究揭示了邻醌催化剂氧化伯胺、仲胺和叔胺的反应机制。在关键的脱氢步骤，伯胺经历与铜胺氧化酶类似的共价转氨化机制，而仲胺和叔胺则是通过非共价的直接负氢转移发生反应。此外，胺类底物可以作为碱加速邻醌催化剂的氧化再生。　　(3)受到新近发现的以稀土元素为中心金属的甲醇脱氢酶XoxF-MDH的启发，成功发展了稀土金属碘化镧与邻醌的仿生催化体系。该有氧氧化体系能够高效地氧化伯醇与仲醇，具有底物范围广、催化效率高和条件温和等优点。控制实验和光谱数据表明邻醌通过单电子还原得到的镧-半醌自由基阴离子物种是真正的活性氧化物种，该活性物种通过联动的O-H/C-H氢转移过程来实现醇类的氧化脱氢反应。底物的脱氢与得失电子均发生在半醌自由基阴离子上，三价镧作为路易斯酸不参与底物氧化的过程，而是与单电子还原后的产物碘三负离子协同促进活性催化物种的循环。

关键词： 高校   有机化学   教学  

摘要： 问题、项目任务教学法可以有效规避传统教学弊端,逐步提升教学效率。要大力推广这种教学措施,培养学生自主学习的意识和能力。帮助学生尽可能的积累到更多知识、可在实践中把理论知识与实践结合起来。

关键词： Chemistry   Science education  

摘要： The undergraduate organic chemistry course is a prerequisite course for many students who plan to pursue careers in chemistry and chemical engineering. It also serves those students who wish to pursue professional careers in medicine, dentistry, and veterinary sciences. Previous research on student learning in organic chemistry shows that students struggle to understand ideas such as acid-base reactions and structure-property relationships which are foundational concepts on which more complex concepts are built. Furthermore, the typical organic chemistry course emphasizes students use of the electron-pushing formalism to represent how bonds are formed and broken in chemical reactions. Expert organic chemists use this formalism to represent predicted reaction mechanisms that explain the formation of products. Numerous studies have characterized student difficulties using electron-pushing mechanisms in an expert-like way as well as associating underlying chemical principle with the representations. We suggest that deep understanding of chemical reactions and their underlying chemical principles can be developed by engaging students in causal mechanistic explanation as part of a transformed organic chemistry course that emphasizes students using their knowledge of electrostatics, structure-property relationships, and energy to engage in explanation of chemical phenomena. Our goal is to engage students in as specific type of explanation called in casual mechanistic explanation which includes reasoning about the underlying causal factors in conjunction with the underlying entities and their activities that bring the phenomenon about. The studies reported here use a qualitative approach to elicit student’ written explanations and drawn reaction mechanisms for various chemical reactions. Students were sampled at multiple time points over the course of their two-semester organic course to investigate how student reasoning changes overtime. Students participants were enrolle

关键词： 高中有机化学   大学有机化学   衔接  

摘要： 伴随着新课程教育改革的延伸,科学价值观已然成为当前教学当中非常重要的组成部分。有机化学是高中及大学化学教学过程中的重要组成部分,学习有机化学部分思考问题的方法、解决问题的角度能够较好服务于自然学科的学习。基于此,本文将对高中有机化学与大学有机化学的衔接进行探讨,从有机化合物的结构、反应及合成等三个方面探讨有机化学的内容特点,并提出了强化高中有机化学与大学有机化学的衔接的建议。

关键词： 有机化学   趣味性   策略  

摘要： 有机化学作为我国高校专业培养体系内的重要内容,但由于其课程性质使然,其理论内容难免晦涩难通.对此,若想有效有机化学课堂效益,教师必须要着力在教学手段上做出改变、创新,通过趣味教学法,来有效提高我国高校有机化学课堂教学的生动性及吸引力,活跃课堂氛围,引导学生自主参与到课堂学习中,共同致力打造高效有机化学课堂.对此,本文就高校有机化学课堂中趣味性教学的应用策略展开深入探讨.

ISBN: (纸本)9787122362636

关键词： 有机化学   案例式教学法   运用  

摘要： 有机化学是高中化学课程的重要部分之一,但由于有机物种类多、结构复杂、学生对官能团理解不够,再加之传统教学模式单调,导致学生的综合水平普遍不高。因此,本文重点探讨案例式教学法在有机化学教学中的运用,并分析该教学法对学习有机化学的积极作用。

关键词： 微课   有机化学   课堂教学  

摘要： 在化学教学过程中,有机化学是十分重要的一课.为了提升有机化学的课堂教学质量,教师可以采用微课教学的方式,利用微课来弥补传统教学中存在的缺点和不足,本文就此进行了相关的阐述和分析.

ISBN: (纸本)9787040542011