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681.
芳香烃作为城市大气臭氧(O3)和二次有机气溶胶(SOA)的重要前体物, 由于其对大气二次污染、气候变化及人体健康具有重要影响, 因此芳香烃氧化机理研究成为当前大气环境化学领域最具挑战的热点研究之一. 本文综述了芳香烃氧化机理的研究成果, 详细讨论了它们与OH自由基在高低氮氧化物条件下的各反应通道和影响因素, 重点关注近年来芳香烃氧化反应研究中的新发现和新理论. 芳香烃的大气氧化反应起始由OH自由基主导, 根据其反应产物主要分为醛通道、酚通道、双环RO2通道和环氧化物通道. 随着形成多羟基化合物、烷氧自由基环氧化、双环过氧自由基分子内氢转移、醛类化合物氢转移、CO-loss生成低碳产物等新理论的提出, 对芳香烃氧化的理解虽然有所提高, 但反应过程仍存在碳质量不守恒和自由基不闭合的问题, 导致对后续O3和SOA形成机制的认识还十分有限. 理论计算和实验室模拟是目前芳香烃氧化机理研究的主要手段. 质谱法和光谱法是芳香烃氧化产物最常用的测量技术, 在线质谱技术尝试从分子水平上捕捉示踪性中间产物的转化, 对揭示芳烃氧化机理具有重要作用. 随着示踪物测量技术的发展, 特别是色谱-质谱联用技术为中间产物的精准测量和芳香烃氧化机制的完善开拓了新方向. 在此基础上, 厘清芳烃氧化中的碳平衡和自由基收支等关键科学问题、探究实际大气中芳香烃的环境效应有望成为未来该领域的重点研究方向. 相似文献
682.
683.
Dr. Massimo Serra Prof. Marco Terreni Dr. Eric Bernardi Prof. Lino Colombo 《European journal of organic chemistry》2023,26(5):e202201394
After the first synthesis reported in 1994, azabicycloalkane amino acids have raised increasing interest, becoming one of the most important classes of constrained dipeptide mimics. Their incorporation into peptidomimetic structures allowed the obtainment of a wide range of biologically active compounds. Over the years, different research groups have worked at the development of synthetic strategies to gain these rigid dipeptide surrogates, nevertheless, methods affording functionalized and “easy-to-functionalize” derivatives are quite less described. The presence of a derivatizable azabicycloalkanone core could allow the introduction of chemical modifications aimed to improve the pharmaceutical properties of a biologically active compound without the need for redesigning its chemical synthesis. This account has collected and critically surveyed relevant approaches to the synthesis of functionalized azabicycloalkane amino acids, focusing the attention on the period of 2010 to the present. Moreover, recent applications of these compounds in drug discovery will be discussed. 相似文献
684.
Si-Yu Wang Zhong-Wei Zhang Liu Yuan Prof. Dr. Yi Jin Dr. Cong-Hai Zhang Prof. Dr. Jun Lin 《European journal of organic chemistry》2023,26(3):e202201268
An efficient and simple procedure for the preparation of 2-pyridinone is reported. The obtained products contained various bicyclic 2-pyridinones and multi-substituted 6-amino-2-pyridinones. This approach employed 3-hydroxy-2-aryl acrylate and nitro ketene aminal as substrates, and the corresponding 2-pyridinones were obtained in good to excellent yields. This method may be used for the synthesis of bicyclic 2-pyridinones, as well as multi-substituted complex 2-pyridinones. 相似文献
685.
Owing to increasing demand for Panax notoginseng-based medicines and health products, establishing a fast, simple, and reliable assay to analyze the chemical differences between its root and rhizome is important. Although previous studies showed that the chemical and biological differences between the root and rhizome of P. notoginseng seem to be small, efforts should be taken to investigate such differences to ensure the safety and efficacy of the products. This work describes a holistic approach that combines characteristic fingerprinting using ultra-high performance liquid chromatography-tandem mass spectrometry parent ion scanning with charged aerosol detection and targeted separation by online heart-cutting two-dimensional liquid chromatography, to identify and evaluate characteristic markers allowing differentiation of the root and rhizome. A total of five potential markers chikusetsusaponin L5, ginsenoside Rb2, stipuleanoside R2, malonyl-ginsenoside Rb1, and malonyl-ginsenoside Rd, were identified and confirmed by comparing chromatographic retention time, the accurate mass of molecular weight, and the fragments of secondary MS with the available reference materials. The results showed that all five markers were 2.8–7 times higher in content in the rhizome than in the root. 相似文献