- 首页
- 产品推荐个人精选服务科研辅助服务教育大数据服务行业精选服务学科系列服务产品服务
- 期刊大全
- 充值
- 会员
- 职称材料
- 首页
- 产品服务
- 知识脉络
- 期刊大全
- 充值
- 会员
- 职称材料
智能检索
二次检索
任意字段
在结果中检索
在结果中去除
暂无数据
共
58
条结果 ，以下是1
-
20条
1 / 3
已选:0 清除
批量下载
批量引用
相关度
摘要： 丙二酸二乙酯(Diethyl Malonate, DEM),俗称胡萝卜酸乙酯,是一种重要的精细化工有机原料,被广泛应用于聚酯、医药、染料及香料等工业。本研究课题简要介绍了丙二酸二乙酯和乙酰乙酸乙酯(Ethyl acetoacetate, ACE)的性质、应用和合成工艺,详细阐述了克莱森酯缩合反应的机理。针对传统氰化钠法合成丙二酸二乙酯的环保等问题,提出以碳酸二乙酯(Diethyl carbonate, DEC)和乙酸乙酯(Ethyl acetate, EA)为原料,采用克莱森酯缩合法制备丙二酸二乙酯并联产乙酰乙酸乙酯的工艺路线,在分析反应机理后,考察了催化剂、溶剂、反应时间、物料配比、全回流时间、反应温度和回流比等工艺条件对反应结果的影响,进而开创了合成丙二酸二乙酯的绿色工艺。
实验结果表明：当催化剂使用HLG-1,溶剂使用HLS-1, HLS-1与碳酸二乙酯的体积比为2：1,反应时间为5小时,EA与DEC的物质的量之比为5：1,回流比为10：5,全回流时间为30min,反应温度为125℃时反应效果较好。在此工艺条件下,DEM的收率为49.32%,ACE的收率为37.77%。
关键词: 绿色合成 ；丙二酸二乙酯 ；碳酸二乙酯 ；克莱森酯缩合
被引量
4
摘要： 丙二酸二乙酯(DEM)是一种重要的精细有机化工原料，被广泛应用于医药、聚酯、染料及香料等工业。本文对丙二酸二乙酯的结构、性质及其应用进行了简单介绍，重点探讨了其合成工艺。目前国内大都采用传统氰化钠法生产丙二酸二乙酯，此工艺工序多，收率低且原料剧毒，危害环境。本课题采用Claisen酯缩合法合成丙二酸二乙酯，以碳酸二乙酯(DEC)和乙酸乙酯(EA)为原料，副产物乙酰乙酸乙酯(ACE)可作为重要的精细化工中间体，避免了剧毒化合物的使用，工艺流程简化，实现DEM的绿色化生产。主要研究了常压反应精馏工艺中催化剂复配、溶剂、活化时间等对反应结果的影响;并采用间歇式高压釜对加压精馏工艺的可行性进行探索。结果表明:在常压反应精馏中，催化剂为HSA，溶剂为LDB，反应时间为4h，n(DEC)∶n(EA)为1∶5，回流比为10∶5，反应温度为120℃时，DEM的收率为45.18％;在间歇式高压釜中，当催化剂为HSA，n(DEC)∶n(EA)为3∶1，反应时间为2h，反应温度110℃，加压至1.50MPa时，DEM收率为23.46％，ACE的收率为21.12％，证实了加压精馏工艺的可行性。
关键词: 丙二酸二乙酯 ；绿色合成 ；加压精馏工艺
摘要： 氨作为一种多用途化合物,在人类社会生活中发挥着重要作用。目前,氨的大规模生产依赖于能源密集型的Haber-Bosch工艺,这一工艺需要在高温高压的条件下进行,导致了巨大的能源消耗和环境负担。电合成技术是能在常温常压下生产氨的绿色合成工艺,电催化硝酸盐/亚硝酸盐还原合成氨(eNOxRR, x = 3和2)不仅可以解决环境污染问题,还能变废为宝,将污染物转化为高附加值产品。近几年来,eNOxRR催化剂的研究取得了一系列进展,其中铁基催化剂具有最大的电催化硝酸盐/亚硝酸盐还原合成氨潜力。然而,eNOxRR是一个复杂的多电子和多质子转移反应,反应过程中可能生成大量的副产物。同时,竞争性析氢反应会导致电子消耗和相对较低的选择性。因此eNOxRR系统的氨产率和法拉第效率仍有较大的提升空间。As a versatile compound, ammonia plays an important role in human social life. At present, the large-scale production of ammonia relies on the energy-intensive Haber–Bosch process, which requires reaction conditions of high temperature and pressure, resulting in huge energy consumption and environmental burden. Electrosynthesis technology is a green synthesis process that can produce ammonia at room temperature and pressure. Electrocatalytic nitrate/nitrite reduction to ammonia (eNOxRR, x = 3 and 2) can not only solve environmental pollution problems, but also turn waste into treasure and convert pollutants into high-value-added products. In recent years, research on eNOxRR catalysts has made a series of progress, among which iron-based catalysts have the greatest potential for electrocatalytic nitrate/nitrite reduction to ammonia. However, eNOxRR is a complex multi-electron and multi-proton transfer reaction, and a large number of byproducts can be generated. Meanwhile, competitive hydrogen evolution reaction results in electron consumption and relatively low selectivity. Therefore, there is still significant room for improvement of the ammonia yield rate and Faradaic efficiency of eNOxRR systems.
关键词: 电催化硝酸盐还原 ；电催化亚硝酸盐还原 ；合成氨 ；合金化 ；异质结
摘要： 本文研究了以煤矸石和铝灰为主要原料合成沸石分子筛,并探讨了该分子筛对水中孔雀石绿(MG)的吸附性能。煤矸石和铝灰中含有丰富的二氧化硅和氧化铝,是合成分子筛的理想材料。通过水热法合成的NaP型分子筛表现出良好的结晶度和均匀的球状颗粒形貌。实验表明,分子筛对MG的吸附受分子筛用量、搅拌时间的影响。在吸附动力学研究中,拟二级动力学模型比拟一级模型更适合描述MG的吸附过程,表明该过程主要为化学吸附。此外,颗粒内扩散也对吸附起到了一定作用。这一研究为固体废弃物的资源化利用提供了新的思路,同时也为水体污染治理提供了潜在的解决方案。In this paper, zeolite molecular sieve was synthesized from coal gangue and aluminum ash, and the adsorption performance of the zeolite to malachite green (MG) in water was investigated. Coal gangue and aluminum ash contain rich silica and alumina and are ideal materials for synthesis of molecular sieves. NaP molecular sieves synthesized by hydrothermal method showed good crystallinity and uniform spherical particle morphology. The results showed that the adsorption of MG by molecular sieve was significantly affected by the amount of molecular sieve and the stirring time. In the study of adsorption kinetics, the pseudo-second-order kinetic model is more suitable to describe the adsorption process of MG than the first-order model, indicating that the process is mainly chemisorption. In addition, intra-particle diffusion also plays a role in adsorption. This research provides a new idea for the resource utilization of solid waste, and also provides a potential solution for water pollution control.
关键词: 煤矸石 ；水热法 ；NaP型分子筛 ；MG吸附
被引量
1
【会议论文】 •
+2位作者
会议时间： 2020-10-30
摘要： A green and efficient synthesis of azaheterocycle acetamide has been developed. Compared with previous reports, this method significantly reduced the dosage of nitrigen-containing reagent from more than 20 eq. to 1.5 eq.. Thus there were less pollution and less costing, especially when the nitrigen-containing reagent is expensive and difficult to recycle. So this statege is environmental frendly and sustainable. This process applied inorganic peroxysulfate which is econamic as oxidant into difunctionalization of alkenes with aminoformyl radial and aryl C（sp2）-H bonds, therefore providing an efficient and sustainable access to a broad substrate scope and promising functional-group tolerance. Also, it is noteworthy that a series of nonreported dioxisoquinolines and oxindoles derivatives have been synthesized by applying this green method which is very promising to have a widely application in medicinal related clinical research.
关键词: 氨甲酰化 ；自由基 ；串联反应
摘要： 目的对组胺H3受体拮抗剂/反向激动剂pitolisant进行合成工艺研究。方法以对氯氯苄、丙二酸二乙酯为起始原料,经过缩合、水解、脱羧、还原、酯化、取代反应制得pitolisant。结果与结论经过6步反应合成目标化合物pitolisant,其结构经1H-NMR及MS确证。对其中多步反应条件进行了工艺考察及优化,总收率为31.4%(以对氯氯苄计)。
关键词: pitolisant ；组胺H3受体 ；嗜眠病 ；合成
被引量
3
摘要： 报道了杀菌剂氟嘧菌酯的合成工艺研究。以4-羟基香豆素为原料,依次经过硝化、碱水解、甲胺化、环合、醚化和碱重排环合反应得到(E)-(5,6-二氢-[1,4,2]-二嗪-3-基)-(2-羟基苯基)-甲酮-O-甲基肟(中间体F);以2-氟丙二酸二乙酯为原料,经与醋酸甲脒成环后进行氯化反应合成中间体4,6-二氯-5-氟嘧啶;中间体F先后与4,6-二氯-5-氟嘧啶和2-氯苯酚进行醚化反应得到目标产物氟嘧菌酯。以4-羟基香豆素计,合成总收率达17%,产品质量分数为96%(HPLC)。
关键词: 氟嘧菌酯 ；合成 ；4-羟基香豆素 ；4,6-二氯-5-氟嘧啶
被引量
6
摘要： Adenine is an important chemical material widely used in the fields of medicine,organic synthesis and so on.Presently,adenine is produced from the condensation of diethyl malonate with formamide,which has serious pollution problems.To achieve the green production of adenine,non-catalyzed hydrolysis of adenosine in high temperature liquid water was carried out.The effects of initial concentration,agitating speed and temperature on adenosine hydrolysis were studied and the kinetics of adenosine hydrolysis was investigated at temperatures from 150℃ to 190℃.Rate constants were evaluated with the zeroth-order reaction assumption and the activation energy was 134.1 kJ·mol-1.The experimental results demonstrated that high selective preparation of adenine by non-catalyzed hydrolysis of adenosine in high temperature liquid water was possible.
关键词: 腺苷 ；无催化水解 ；腺嘌呤 ；高温液态水
摘要： A new green technology of producing chromic anhydride with an electrochemical synthesis method was studied to solve the pollution problems in the traditional production process of chromic anhydride.The anolyte used was sodium dichromate solution, and the anode used was a self-made combination electrode of titanium matrix with a multiple-unit metal oxides active coating.The electrochemical behavior of sodium dichromate solution on a combination electrode of titanium matrix was studied with cyclic voltammetry as a part of the fundamental researches of this technique.The electrooxidation reaction of 160 cycles indicated that the electrode possessed a very stable electrochemical behavior.The peak currents ip and peak potentials Ep of the oxidation peaks for sodium dichromate solution of different concentrations, i.e., water under the existence of sodium dichromate, were experimentally measured at different temperatures and sweep rates v on the electrode.The equations of peak current ip versus v1/2 and peak potential Ep versus lnv were established, indicating that the electrode reaction was an irreversible diffusion-controlled reaction.The kinetic parameters and activation energy of electrode reaction was calculated, and the effects of temperature on the kinetic parameters and activation energy were preliminarily discussed.
关键词: 重铬酸钠 ；电化学合成 ；循环伏安法 ；不可逆反应 ；动力学参数
被引量
12
摘要： The annual world carbon conference,Carbon’09,was held in Biarritz,France on 14-19,June,2009,which gathered 602 attendants from 46 countries contributing 4 plenary lectures,36 keynote lecturess,208 oral presentations,2 award lectures and 624 posters under 11 topics including natural carbons,carbons grown or deposited from gas phase and plasmas,carbons from soft precursors,energy storage and conversion,carbon-based composites and their mechanical properties,chemical and physical modifications,liquid and gas storage,adsorption,electronic/optical/opto-electronic properties and applications,nuclear and solar applications,thermal management,biocarbons related to biology/toxicity/health,and advances in processing/characterization/mode～ling.Carbon in the universe,the carbon cycle,carbon and health,and the direction observation of carbon at the atomic level were the subjects of the plenary lectures.Current active research on carbons can be summarized in the following five aspects:(1) significant efforts have been made on experimental research combined with simulation/modeling on the structure,formation mechanism,properties and applications of porous carbon,carbon nanotubes(CNTs),graphene,composites,aerogels and intercalation compounds.The synthesis of bio-carbon or carbon nanomaterials in a green,economic,and effective manner to alleviate the greenhouse gas effect is drawing more and more attention;(2) research on porous carbons in environmental protection and energy sto～rage has been on the top of the agenda of carbon scientists;(3) the electromagnetic,optoelectronic and field emission application of CNTs and graphenes,and the nuclear,solar energy and thermal application of graphite and carbon constitute a main research field of carbon science;(4) research of medical applications,biomaterials and biocompatability of carbon materials is receiving more and more attention;(5) the measurement and observation of carbon materials by means of high resolution transmission electron microscopy,Raman spectrometry and electron energy loss spectrometry have been strengthened by other characterization means and simulations to assure more accurate structural information on carbon materials.
关键词: Carbon ；发展趋势 ；国际 ；科学 ；炭 ；中国大陆 ；碳 ；西南部
被引量
4
摘要： 采用相转移催化法,以丙二酸二乙酯和2-氯乙基苯硫醚为原料,四丁基溴化铵为催化剂,碱性条件下合成了(2-苯硫基乙基)丙二酸二乙酯。研究了四种碱对收率的影响,发现以叔丁醇钠作为碱时收率最高。同时,研究了各种反应条件对收率的影响,得到最佳条件为n(丙二酸二乙酯)∶n(叔丁醇钠)∶n(2-氯乙基苯硫醚)=1.3∶1∶1,100℃反应3 h。产物用1H NMR和MS进行了表征。
关键词: 相转移催化法 ；四丁基溴化铵 ；(2-苯硫基乙基)丙二酸二乙酯
【专利/发明】 • CN201811183661.7 •
+2位作者
•
申请日：2018-10-11,
公开日：2019-05-07
申请人： 云南民族大学
公开（公告）号： CN109721532A
摘要： 本发明公开了一种2‑吡啶酮类化合物的绿色高效合成方法。方法如下：本发明所述的高效绿色合成2‑吡啶酮类化合物的方法是在微波条件下以简单易得的二羰基化合物、丙二酸二乙酯、N,N‑二甲基甲酰胺二甲基缩醛和胺类化合物四组分化合物一锅投料，100℃保温反应2.0 h，停止反应经过柱层析得到2‑吡啶酮母环化合物，产物的纯度高达98.8%以上。本发明所述的2‑吡啶酮的合成工艺简单、操作方便、收率较高、绿色环保，反应过程无任何溶剂和催化剂的使用，从根本上解决了原路线污染较大、操作难度高等问题。
摘要： 高血压,是心血管疾病最常见的危险因素,也是导致心血管疾病死亡率居高不下的主要原因。培哚普利作为治疗高血压的一线药物,近3年来,每年的全球销售额均高达5至6亿美元。(S)-吲哚啉-2-甲酸是大规模合成培哚普利的重要中间体,因此,研究开发高效绿色的(S)-吲哚啉-2-甲酸的合成工艺具有重要的意义。本文中,我们设计了一条全新的工艺路线合成(S)-吲哚啉-2-甲酸。首先,以廉价易得的2-氯苄氯和乙酰氨基丙二酸二乙酯为起始物料,在碱性条件下发生亲核取代反应,生成2-乙酰氨基-2-(2-氯苄基)丙二酸二乙酯(化合物3);然后,化合物3在DMAP催化下与丙酸酐反应生成2-氨基-3-(2-氯苯基)丙酸盐酸盐(化合物4);接着,化合物4与丙酰氯发生酯化,得到2-氨基-3-(2-氯苯基)丙酸乙酯盐酸盐(化合物5b);化合物5b在生物酶HEC-8催化下,水解得到单一构型的(S)-2-氨基-3-(2-氯苯基)丙酸(化合物6);最后,化合物6在氯化亚铜催化下发生分子内的亲核取代反应,得到目标产物(S)-吲哚啉-2-甲酸(化合物7)。其中,化合物6和化合物7的合成是整个合成工艺中的关键步骤。因此,本文对这两个步骤的工艺进行优化。(1)我们采用酶促动态动力学拆分法合成关键中间体(S)-2-氨基-3-(2-氯苯基)丙酸(化合物6),通过对工艺条件的筛选,得到了最优化的合成工艺条件如下:底物浓度为100 g/L、生物酶为HEC-8、HEC-8浓度为2 wt%、缓冲液浓度为0.2 mol/L、p H调节剂为10%氢氧化钠溶液、反应体系p H为7.5、反应温度为45℃±5℃、消旋试剂为5-硝基水杨醛、5-硝基水杨醛的用量0.03 eq。该关键步骤的收率高达89%,反应产物的ee值高达99.74%。(2)我们对(S)-吲哚啉-2-甲酸(化合物7)合成工艺条件进行优化,得到最优化的工艺条件如下:碳酸钾用量为1.60 eq、水的质量比为5 g/g～6 g/g、氯化亚铜的用量为0.005eq、反应温度为65℃～85℃。该关键步骤的收率高达85%,最终产物化合物7的纯度为98.46%,ee值为96.52%。本文的合成路线具有反应条件温和,成本低廉,收率高,目标产物的化学和光学纯度高,环境友好等优点,能很好的推进(S)-吲哚啉-2-甲酸的产业化生产。
关键词: 生物酶催化 ；动态动力学拆分 ；L-2-卤代苯丙氨酸 ；(S)-吲哚啉-2-甲酸
摘要： Biodegradable polyesters are a relevant candidate in the field of biomedical applications suchas drug delivery, wound dressings, tissue engineering owing to their suitable properties to supportcellular growth and proliferation.However, the applications of biodegradable polyesters in thebiomedical are limited due to their low degradation rate, uncontrollable degradation for manyclinical applications, poor mechanical and thermal properties.Therefore by understanding thecombined effects of inorganic ZnO nanoparticles and biomass cellulose nanocrystals (CNCs) frommost abundant natural cellulose resources as UV absorber and antibacterial agents into biopolyesterespecially (poly (3-hydroxybutyrate-co-3-hydroxy valerate, PHBV) matrix with or without theaddition of polyethylene glycol (PEG) as organic phase change materials could provide newprospects to the sustainable use of nanotechnology and nanocomposites with improvement in thethermal and mechanical properties for potential applications in antibacterial wound dressings, UVshielding materials, drug delivery, and thermal energy storages fields.In this dissertation, a seriesof ultra-high performance biopolyester nanocomposites were successfully fabricated by welldispersed of CNC-ZnO nanohybrids with modulated contents as nanofillers into bio-polyester(poly (3-hydroxybutyrate-co-3-hydroxy valerate, PHBV) matrix.The impact of nanofillerscontent and fabrication techniques on their structures designs and properties were discussed indetails.This research can provide a theoretical basis and technical guidance for the preparation andfabrication of these novel biopolyester nanocomposites with multi-functional properties forpotential uses as biomedical biomaterials.The main results are summarized as follows: 1) Green synthesis of sheet-like cellulose nanoerystal-zinc oxide nanohybrids withmultifunctional performance through one-step hydrothermal method.In this study, wereport novel sheet-like cellulose nanocrystal-zinc oxide nanohybrids (CNC-ZnO) by using aone-step hydrothermal method.Various concentrations of Zn2+ ions were functionalized inCNC surface and a possible mechanism for the formation of CNC-ZnO nanohybrids withhexagonal sheet-like structure converted to the flower-like structure was also presented. Additionally, the sheet-like CNC-ZnO5.0 showed good antimicrobial activity, excellentthermal stability and high photocatalytic activity of 95.21％ of MB dye was decomposed after200 min under UV light irradiation.More significantly, the CNC-ZnO5.0 nanohybrid can berecycled three times with good Turnover frequency values (TOF).Compared to pure CNC, themaximum degradation temperature (Tmax) of sheet-like nanocrystal-Zinc oxide nanohybridwith the addition of 5 mmol Zn2+ ions (CNC-ZnO50) nanohybrid was improved by 23.1 ℃,and its limiting oxygen index increased up to 49.6％.This work provides a simple preparationprocedure of sheet-like CNC-ZnO nanohybrids with good antimicrobial, photocatalytic andthermal properties for attractive applications as biomedical materials and flame-retardants. 2) Sheet-like cellulose nanocrystal-ZnO nanohybrids as multifunctional reinforcing agentsin biopolyestercomposite nanofibers with ultrahigh UV-Shielding and antibacterialperformanees.The uses of inorganic metal oxide and ZnO nanohybrids as UV absorbershave potential to increase the production of UV-protective textile, which will also overcomethe drawbacks of organic molecules and prevent negative impacts on human health andenvironment.In this work, sheet-like cellulose nanocrystal-Zinc oxide (CNC-ZnO)nanohybrid was successfully developed by a one-step hydrothermal method.The obtainedCNC-ZnO nanohybrids as UV absorber and antibacterial agents were introduced intobiopolyester (poly (3-hydroxybutyrate-co-3-hydroxyvalerate, PHBV) by usingelectrospinning process.The addition of sheet-like CNC-ZnO can greatly enhance PHBVthermal stability and crystallization ability.In addition, excellent antimicrobial ratios ofEscherichia coli and Staphylococcus aureus, and high absorbency of solution A (9.82 g/g)were obtained for the composite nanofibers with 5 wt ％ CNC-ZnO.Moreover, most of theUV irradiations were blocked out for both UVA (99.72％) and UVB (99.95％) with high UPFvalue of 1674.9 in the resulting composite nanofibers with 9 wt ％ CNC-ZnO.This studyprovides a novel method to produce sheet-like CNC-ZnO with multifunctional properties andits nanocomposite for potential uses as wound dressings and other functional biomaterials. 3) In vitro degradation and possible hydrolytic mechanism of PHBV nanocomposites byincorporating cellulose nanocrystal-ZnO nanohybrids.Fabrication and characterization ofbiodegradable nanocomposites based on poly (3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) matrix reinforced with cellulose nanocrystal (CNC-ZnO) nanohybrids via simplesolution casting process for possible use as antibacterial biomedical materials is reported.Theobtained nanocomposites exhibited good antibacterial ratio of 95.
关键词: 纤维素纳米晶 ；氧化锌 ；杂化材料 ；结构设计 ；生物聚酯膜 ；改性机理
摘要： Following harvest,the fresh tea leaves will naturally undergo a withering treatment,in which they are moved to a proper environment and spread evenly on a flat surface before being subjected to the enzyme-deactivating pan-firing process.In traditional tea manufacturing process,the fresh tea leaves were supposed to be pan-fired as soon as possible after harvest,while withering was treated as a “unnecessary” process,and its significance was neglected.During withering,the water content of fresh tea leaves will drop,and their texture will become pliable.This will make the following fixation and shaping processes easier to conduct.In the meanwhile,since the enzyme is still active,dynamic metabolic changes will occur during this process.There are several researches that investigate the metabolic changes of tea leaves during withering process.However,despite these changes being well documented and a general notion that a proper withering treatment before pan firing was beneficial to green tea's quality,the underlying mechanisms of these metabolic changes still remains unknown.To understand the quality formation of withering tea leaves and its underlying mechanism more comprehensively and systematically,UHPLC-Orbitrap-MS metabolomics,as well as tandem mass tag(TMT)-based proteomics analysis were applied to samples of tea leaves that were collected at different times of withering(up to 15 h).Global metabolic changes in tea leaves undergoing withering treatment and the underlying proteinic mechanisms were explored,and an integrated multi-omics analysis were conducted using both the metabolomic and proteomic results.The results are as follows:(1)A total of 69 metabolites were identified in metabolomic analysis.During withering(up to 15 h),The differentiated metabolites in fresh tea leaves were showing a monotonic shift.Among them,the levels of 12 amino acids significantly increased.The levels of catechins and several glycosidically bound volatiles decreased.The level of caffeine remained relatively unchanged.And the levels of flavonoids and their glycosides did not demonstrate specific patterns of change.(2)Up to 136 differentially expressed proteins(13h / 0h comparison)were obtained through pair-wise comparisons in proteomic analysis.The number of differentially expressed proteins increased with the time of withering,and most differentially expressed proteins showed monotonic changes of expression.The differentially expressed proteins mainly participated in dehydration response,starch synthesis and catalysis,plant hormone and signal regulation,flavonoid biosynthesis,the synthesis and catalysis of glycosidically bound volatiles,and so on.In general,the proteome of withering tea leaves was changed ascribing to the tea leaves' response to multiple stresses in the withering process.These changes will in turn lead to the metabolic shift of tea leaves.(3)During the withering process,the levels of metabolites in fresh leaves changed synchronically with the expression levels of related proteins.Among them,the increase of amino acids' level could be ascribed to the overall up-regulation of proteases and peptidases;the biosynthesis of catechins and flavonoids were inhibited,thus cause the drop of catechins' level;the decrease of glycosidically bound volatiles' level could be attributed to the downregulation of UDP-glycosyltransferase and up-regulation of glycosyl hydrolase.Overall,the withering process could help lower the phenol/amino ratio of fresh tea leaves,but would also cause the loss of aroma substances by turning them from glycosidically-binding state to free state.This suggests that the withering process is beneficial to the quality of fresh tea leaves in some respects.A prolonged withering process,however,may cause negative effect to the aroma of made tea.
关键词: fresh tea leaves ；withering ；metabolomics ；proteomics ；multi-omics
被引量
1
摘要： 作为一种功能性材料，聚天冬氨酸(PASP)已广泛应用于水处理领域。但是，由于其缓蚀性能并不突出且阻垢性能也有待于提高，目前PASP研究的重点集中在开发兼具阻垢缓蚀性能、高效、绿色化的改性产品方面。本研究分别以三种β-二羰基化合物乙酰乙酸乙酯(EAA)、丙二酸二乙酯(DEM)以及苯甲酰乙酸乙酯(EBA)为改性试剂，对PASP的中间体聚琥珀酰亚胺(PSI)进行开环改性，获得系列β-二羰基化合物改性PASP。然后，在遵循绿色化学的宗旨下，以化学改性产品为主剂，选择合理的复配药剂，得到系列多元物理改性PASP功能材料。并对改性产品的阻垢和缓蚀性能进行了研究。主要研究内容如下: (1)以马来酸酐和碳酸铵为原料，通过热缩聚合成了中间PSI，并用红外表征技术对其分子结构进行了表征。以阻垢性能为评价指标，探索了中间体PSI的合成条件，最终确定出其最佳合成条件为:马来酸酐∶碳酸铵（摩尔比）=1∶1.2、脱水温度90℃、聚合温度180℃。 (2)分别以乙酰乙酸乙酯(EAA)、丙二酸二乙酯(DEM)、苯甲酰乙酸乙酯(EBA)为开环介质，对PSI进行开环改性，得到了EAA-PASP、DEM-PASP及EBA-PASP三种改性PASP。用红外光谱表征了产品的结构。研究并确定出三种改性产品的最佳合成工艺条件。其中，EAA-PASP的最佳合成条件为PSI∶EAA∶NaOH(摩尔比)=1∶0.6∶6，质量分数为15％，反应温度为35℃，反应时间为18h;DEM-PASP为PSI∶DEM∶NaOH(摩尔比)=1∶0.6∶6，质量分数为15％，反应温度为35℃，反应时间为24h;EBA-PASP为PSI∶EBA∶NaOH=1∶0.6∶5，质量分数为15％，反应温度为35℃，反应时间为20h。 (3)采用静态阻垢法研究了EAA-PASP、DEM-PASP以及EBA-PASP的阻垢性能（主要为CaCO3垢）;运用动态旋转挂片法研究了改性产品的缓蚀性能（主要为A3碳钢）。结果表明:在药剂浓度为8mg/L时，EAA-PASP和EBA-PASP的阻垢率都达到了100％，而DEM-PASP在加药量为10mg/L阻垢率也达到了100％;在药剂浓度为5mg/L时，EAA-PASP和EBA-PASP的缓蚀效果最好，缓蚀率分别为53.44％和51.61％，DEM-PASP在加药量为10mg/L时，缓蚀效果最好，缓蚀率为56.96％。 (4)分别以三种改性聚天冬氨酸为主剂，与Na2MoO4、HEDP与ZnSO4等进行复配研究，得到三种改性PASP配方。研究结果显示，对于EAA-PASP，在加药量为39mg/L情况下，HEDP∶EAA-PASP∶ZnSO4∶Na2MoO4=5∶6∶15∶13（摩尔比）时，缓蚀率为99.11％，阻垢率为100％;对于DEM-PASP，HEDP∶DEM-PASP∶ZnSO4∶Na2MoO4=5∶4∶15∶11（摩尔比），在加药量为35mg/L情况下，缓蚀率为99.73％,阻垢率为100％;对于EBA-PASP而言，HEDP∶EBA-PASP∶ZnSO4∶Na2MoO4=5∶4∶17∶11（摩尔比），在加药量为37mg/L时，缓蚀率为97.41％，阻垢率为100％。 (5)用XRD、SEM、IR等技术分析了改性产品的阻垢机理，结果表明三种改性聚天冬氨酸都具有良好的螯合分散性，可以使CaCO3垢由稳定的方解石转变为不稳定的球霰石。用SEM分析了改性产品的缓蚀机理，结果表明改性聚天冬氨酸分子结构中的活性基团很好地吸附在了碳钢的表面，形成了一层化学吸附膜，进而阻止了A3碳钢的腐蚀。对于复配后的改性产品，由于改性PASP与钼酸钠、HEDP、硫酸锌之间具有协同效应，推测其在金属表面形成了一种复合膜，所以更好地阻止了A3碳钢的腐蚀。此外，对比可以看出，复配药剂产生的复合膜缓蚀效果好于化学吸附膜。
关键词: β-二羰基化合物 ；聚天冬胺酸 ；缓蚀阻垢性能 ；改性机理
被引量
2
摘要： 当今世界,流感病毒仍严重威胁着人类的身体健康。法匹拉韦是一款新型抗流感病毒药物,已证实对多种流感病毒株有效,其广谱抗RNA病毒活性表明,在治疗致命性流感的抗流感药物中,它有望发挥核心作用。目前国内仅有浙江海正药业具有生产资质,市场前景广阔。近年来,微反应器以其高效的传质传热、安全绿色的优点逐渐进入于化工领域,具有广泛的应用前景。本论文总结和分析了已报道的法匹拉韦的合成路线,发现其中间体6-硝基-3-羟基吡嗪-2-甲酰胺合成法匹拉韦的路线最为简短,于是结合微反应器提出了合成该中间体的新工艺路线,经过肟化,加氢,氨解,环化,硝化五步反应,高产率得到目标产物。其中加氢,氨解,硝化基于循环回路反应器与微通道反应器采用流动化学手段进行连续制备。主要工作及结果如下:(1)优化了丙二酸二乙酯制备肟基丙二酸二乙酯的反应条件,当丙二酸二乙酯与醋酸、亚硝酸钠、水、甲苯的摩尔比为1:1.6:1.6:0.3:2,反应时间4 h,反应温度40℃时,转化率达99%,收率96%。然后以肟基丙二酸二乙酯为原料,利用循环回路反应器连续催化加氢制备了2-氨基丙二酸二乙酯,得出了连续加氢最佳工艺条件。当物料流速为15 mL/min,反应压力2.5 MPa,反应温度75℃,4%负载的Pd/C催化剂添加量为40 g(约占系统持液量8%)时,反应转化率达到99.6%,连续运行8小时转化率仍旧稳定。(2)以上一步得到的反应液为原料,基于微通道反应器连续化制备了2-氨基丙二酰胺,采用单因素实验法,研究了各反应因素对产物收率的影响,得出了最佳工艺条件。实验表明,当2-氨基丙二酸二乙酯与氨水摩尔比1:15,反应时间7 min,反应压力1.5～2.0MPa,反应温度50℃时,收率达到92.5%,相对于常规反应器,缩短了反应时间且时空转化率高出两个数量级,收率和生产能力大大提高。(3)比较了2-氨基丙二酰胺制备3-羟基吡嗪-2-甲酰胺的几种方法,推测了其可能的反应机理,选定了具体的制备方案,收率为90%;给出了3-羟基吡嗪-2-甲酰胺制备6-硝基-3-羟基吡嗪-2-甲酰胺的硝化机理,并得出了微通道反应器内该硝化反应的最佳工艺条件,当硝硫混酸摩尔比1:1,3-羟基吡嗪-2-甲酰胺与硫酸的摩尔比为1:8,与硝酸的摩尔比为1:1.7,反应温度40℃,停留时间4 min,系统压力1 MPa时,产物收率达到89.0%,纯度99.5%。较于常规反应器,收率提高了20%且提高了反应安全性,降低了环境污染和健康危害。五步反应总收率达71.1%,打通了由肟基丙二酸二乙酯到2-氨基丙二酰胺的连续化生产工艺以及由3-羟基吡嗪-2-甲酰胺到6-硝基-3-羟基吡嗪-2-甲酰胺的连续硝化工艺,使法匹拉韦中间体合成工艺路线更加简捷,安全,环保,具有工业化生产前景,为法匹拉韦的全连续流合成奠定了坚实基础。
关键词: 法匹拉韦 ；微通道反应器 ；连续加氢 ；2-氨基丙二酰胺 ；6-硝基-3-羟基吡嗪-2-甲酰胺
摘要： 光催化反应作为绿色合成的新型代表,已在有机合成领域中引起了广泛关注。光催化产生的自由基物种具有多样性转化的潜力,然而其选择性控制却是合成科学面临的挑战。相比之下,酶催化由于蛋白骨架丰富的手性结构,可以实现高选择性催化转化。但是目前仅发现到三个天然光酶,这限制了酶催化在光促合成中的应用;同时酶高度进化导致的专一性使得天然酶难以对非天然底物的分子骨架进行高效催化,这进一步限制了其在功能分子合成中的应用。如何设计与改造光酶催化元件,拓展天然光酶催化的化学反应边界,是光促酶合成领域亟待解决的问题。本论文通过对天然光促脱羧酶CvFAP进行改造,拓展了其催化的底物类型;从烯还原酶催化的化学原理出发,设计了光促酶催化的自由基转化反应。本文的研究工作将化学合成与生物催化相结合,拓展了光催化反应的工具类型,丰富了生物催化的光酶元件。
本文前半部分主要围绕脂肪酸光脱羧酶（CvFAP）进行改造研究。脂肪酸光脱羧酶（CvFAP）是一类从小球藻（Chlorella variabilis）中发现的能够在蓝光照射下对长链脂肪酸进行脱羧变成烷烃或者烯烃类化合物的光促脱羧酶。然而天然的CvFAP仅能识别和催化链状的一级羧酸进行脱羧,对大体积的二级羧酸和三级羧酸几乎不能催化,这限制了此酶的应用,因此迫切需要对CvFAP进行定向改造使其能够对大体积的二级和三级羧酸进行脱羧。本文主要采用了聚焦理性迭代突变（FRISM）结合半理性设计的策略,对野生型的CvFAP进行改造,以具有刚性的大体积三级羧酸-金刚烷酸1a作为模板底物,经过大量筛选,发现了突变体G2（Y466F-F469V-T131V）能够对其进行高效脱羧。通过对反应条件的优化,采用10 mg/m L的冻干全细胞作为催化剂,在室温下以tris-HCl（p H 8.5）作为缓冲液进行催化脱羧。选择大体积的环己烷类、苯环类、萘环类和杂环类的二级和三级羧酸来考察该突变体的底物兼容性,结果表明,突变体G2比野生型能更好地兼容这些底物进行高效脱羧,最高收率达到96%。与此同时,将底物放大到1 mmol的规模,也能得到70%的分离收率,说明此方案具有广阔的应用前景。
由于目前CvFAP只能针对α-羟基和α-氨基的链状羧酸进行动力学拆分,而不能对其它类型的羧酸进行拆分,因此有必要利用其它取代基的大体积羧酸来研究。选取野生型不能兼容的α-甲基环状二级羧酸1r为底物,采用突变体G2对其进行动力学拆分,能够达到60%的对映选择性。为了考察突变体G2比野生型更兼容的原因,本文对野生型和每一代突变体进行了动力学实验,从Km和kcat的角度来解释了每一代酶的差异性。此外也对野生型和突变体G2与底物进行了分子动力学模拟,从羧酸基团与FAD中N5之间的距离、酶与底物的结合能、反应中心的水分子数量等方面来证实了突变体
比野生型更适合兼容大体积羧酸。表明本文的改造研究拓宽了FAP的底物适用范围,增加了其应用价值。
由于CvFAP只能针对羧酸底物进行脱羧的去官能团化反应,如何拓展光酶的催化类型,实现光促新型化学键的构建与官能团的引入成为了我们面临的新问题。烯还原酶是一类对烯烃进行还原氢化的酶,这类酶中所包含的辅因子FMN具有光敏性,可以利用光照对此酶进行激发使其改变天然的底物类型和反应类型,达到开发新的生物催化化学反应的目的。
本文的后半部分主要围绕对烯还原酶进行光赋能来开发新类型的非天然反应展开研究。采用在反应体系中不引入NADPH及其再生系统时,利用氧化状态的FMNox来启动反应,通过筛选不同的烯还原酶发现到OYE3、PQR1907、Cs ER、Nem A能够催化3-甲氧基噻吩与溴代丙二酸二乙酯进行芳香偶联反应。通过对噻吩环类、苯环类、吡咯环类、吡啶环类、呋喃环类的底物进行考察,发现此体系对噻吩环类化合物具有非常好的兼容性,最高能达到95%的催化收率。与此同时,将底物放大到1 mmol的规模,也能得到83%的分离收率,表明氧化状态的FMNox在光激发下对噻吩环类化合物进行了单电子氧化,生成的自由基阳离子对溴代丙二酸酯进行自由基取代形成新的取代产物,实现了自由基取代反应目的。
本文通过将光与酶进行结合来开发光促酶的自由基反应,不仅解决了天然光酶类型有限问题,也开辟了酶催化非天然反应的新途径。作为一个新兴的交叉学科,光促酶催化的非天然反应是一个具有很大潜力的方向,将为化学与生物的深度交叉注入新的力量。
关键词: 光脱羧酶CvFAP ；定向进化 ；二级三级羧酸脱羧 ；动力学拆分 ；烯还原酶 ；光促酶催化 ；自由基反应
摘要： 喹啉类衍生物是一种具有药理活性和生物活性的杂环化合物，本文选择两类具有重要价值的喹啉类化合物作为目标产物，创新性的提出了以Conrad-Limpach反应喹啉合成法为基础的一步法合成3-位无取代的2,4-二羟基喹啉衍生物工艺，另外也进行了skraup喹啉合成工艺改进。 首先，对于3位无取代2,4-二羟基喹啉的一步合成，文献报道仅限于微波辅助合成，其不具备实际应用价值，除此之外，没有其他3位无取代2,4-二羟基喹啉的一步合成法。本文研究了一种全新高效以Conrad-Limpach喹啉合成法为基础的一步法合成2,4-二羟基喹啉及其衍生物的工艺，具体为在氮气环境下，利用苯胺类衍生物，丙二酸二乙酯作为原料，强酸伊顿试剂作为溶剂，无水氯化铝作为催化剂关环合成2,4-二羟基喹啉及其衍生物。专门合成或分离提纯了七个在合成2,4-二羟基喹啉及其衍生物时可能出现的中间体，以用来论证其反应机理。本方法的创新性在于首次采用非微波法一步合成2,4-二羟基喹啉及其3位无取代基团的衍生物，并具有收率较高，操作简便，原料易得经济等特点。 其次，本文还研究了不同取代基丙二酸酯在二苯醚高温下合成3位取代2,4-二羟基喹啉路线，并且获得了五个反应过程中有可能出现的中间体并以此来进一步详细说明高温热环化机理。 Skraup反应是合成喹啉芳香环衍生物的重要方法，本文对其工艺的改进主要是寻找此反应中更经济、绿色、环保的氧化剂，即用催化量的碘化钠作为氧化剂替代传统的间硝基苯磺酸钠。最终结果是所需浓硫酸用量只需传统工艺的六分之一，从而大大减少后处理调节pH所需氨水用量以及所产生的硫酸铵废水量，并且杜绝了后处理油状物质的出现的现象。达到了预期绿色环保的效果。
关键词: 喹啉类衍生物 ；Conrad-Limpach喹啉合成法 ；Skraup反应 ；药理活性
已选:0 清除
批量下载
批量引用
- 1
- 2
- 3