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Статті в журналах з теми "Organic reaction methodology"
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Chinchilla, Rafael, and Carmen Nájera. "The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†." Chemical Reviews 107, no. 3 (March 2007): 874–922. http://dx.doi.org/10.1021/cr050992x.
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Sharma, Sulekha. "Electro-organic Reactions: Direct and Indirect Electrolysis." Oriental Journal Of Chemistry 40, no. 2 (April 30, 2024): 321–32. http://dx.doi.org/10.13005/ojc/400202.
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Electro-organic synthesis is a new methodology for synthesizing organic molecules, which helped overcome the use of toxic oxidants and expensive catalysts and make the reaction greener. The fundamental concepts of electrochemistry involve simple oxidation and reduction reactions, where electrons act as the greener oxidant and reductant. This review discusses electrochemical principles and basic terminologies that find their roots in physical organic chemistry to influence a spectrum of organic and inorganic reactions. This review also discusses the different modes of electrolysis, i.e., direct and indirect. Finally, the review highlights the importance of direct and indirect electrolysis for various reactions.
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Noor, Rida, Ameer Fawad Zahoor, Muhammad Irfan, Syed Makhdoom Hussain, Sajjad Ahmad, Ali Irfan, Katarzyna Kotwica-Mojzych, and Mariusz Mojzych. "Transition Metal Catalyzed Hiyama Cross-Coupling: Recent Methodology Developments and Synthetic Applications." Molecules 27, no. 17 (September 2, 2022): 5654. http://dx.doi.org/10.3390/molecules27175654.
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Hiyama cross-coupling is a versatile reaction in synthetic organic chemistry for the construction of carbon–carbon bonds. It involves the coupling of organosilicons with organic halides using transition metal catalysts in good yields and high enantioselectivities. In recent years, hectic progress has been made by researchers toward the synthesis of diversified natural products and pharmaceutical drugs using the Hiyama coupling reaction. This review emphasizes the recent synthetic developments and applications of Hiyama cross-coupling.
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Lei, Ming, Qingtong Zhang, Douyong Min, and Shuangfei Wang. "The Treatment of Absorbable Organic Halogens and Organic Compounds in Simulated Bleaching Effluents Through the Response Surface Methodology Optimized Fenton System." Journal of Biobased Materials and Bioenergy 14, no. 2 (April 1, 2020): 280–86. http://dx.doi.org/10.1166/jbmb.2020.1949.
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In this study, the effects of four main factors on the removal of absorbable organic halogens were evaluated by response surface methodology, and the changes of absorbable organic halogens components were characterized by gas chromatography-mass spectrometer during the Fenton reaction. The high regression coefficient (R2 = 0.9028) and the low coefficient of variation (7.45%) indicated that the model was accurate in predicting the experimental results. The optimized pH, Fe2+ concentration, molar ratio of H2O2/Fe2+ and reaction time were respectively 3.4, 16.3 mM, 22.5 and 1.2 h. Consequently, 93.8% of absorbable organic halogens were removed under the optimized condition. The initial pH is the most important factor impacting the absorbable organic halogens removal. Furthermore, gas chromatography-mass spectrometer revealed that 25 out of 28 organic compounds including 7 absorbable organic halogens were thoroughly removed. Conclusively, Fenton reaction can effectively remove absorbable organic halogens from the simulated bleaching effluent.
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Jimenez, David Esteban Quintero, Lucas Lima Zanin, Luan Farinelli Diniz, Javier Ellena, and André Luiz Meleiro Porto. "Green Synthetic Methodology of (E)-2-cyano-3-aryl Selective Knoevenagel Adducts Under Microwave Irradiation." Current Microwave Chemistry 6, no. 1 (October 24, 2019): 54–60. http://dx.doi.org/10.2174/2213335606666190906123431.
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Background: The Knoevenagel condensation is an important reaction in organic chemistry because of its capacity to form new C-C bonds and its products are mainly used in organic synthesis as intermediates, due to the large number of reactions they can undergo. Based on the importance of the Knoevenagel adducts, a sustainable synthetic methodology was developed employing microwave irradiation. Objective: Develop a synthetic methodology employing microwave irradiation and green solvents to obtain Knoevenagel adducts with high yields. Methods: Knoevenagel condensation reactions were evaluated with different basic catalysts, as well as in the presence or absence of microwave irradiation. The scope of the reaction was expanded using different aldehydes, cyanoacetamide or methyl cyanoacetate. The geometry of the formed products was also evaluated. Results: After the optimization process, the reactions between aldehydes and cyanoacetamide were performed with triethylamine as catalyst, in the presence of microwave irradiation, in 35 minutes, using NaCl solution as solvent and resulted in high yields 90-99%. The reactions performed between aldehydes and methyl cyanoacetate were also performed under these conditions, but showed better yields with EtOH as solvent 70-90%. Finally, from X-ray analysis, the (E)-geometry of these compounds was confirmed. Conclusion: In this study we developed synthetic methodology of Knoevenagel condensation using triethylamine, green solvents and microwave irradiation. In 35 minutes, products with high yields (70- 99%) were obtained and the (E)-geometry of the adducts was confirmed.
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Lei, Jie, Jia Xu, Dian-Yong Tang, Jing-Wei Shao, Hong-yu Li, Zhong-Zhu Chen, and Zhi-Gang Xu. "A concise and unexpected one-pot methodology for the synthesis of pyrazinone-fused pyridones." Organic Chemistry Frontiers 7, no. 18 (2020): 2657–63. http://dx.doi.org/10.1039/d0qo00590h.
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A post-Ugi/Michael/Retro-Michael reaction, aromatization and 5-exo-dig cyclization cascade reaction was developed and utilized for the synthesis of pyrazinone-fused pyridone derivatives under mild reaction conditions in one-pot.
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Hakkou, H., D. Carrié, L. Paquin, and J. P. Bazureau. "Ionic liquid-phase organic synthesis (IoLiPOS) methodology applied to cross aldol reaction." Russian Journal of Organic Chemistry 47, no. 3 (March 2011): 371–73. http://dx.doi.org/10.1134/s1070428011030079.
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Reddy, K. Sateesh, Bandi Siva, S. Divya Reddy, N. Reddy Naresh, T. V. Pratap, B. Venkateswara Rao, Yi-An Hong, et al. "In Situ FTIR Spectroscopic Monitoring of the Formation of the Arene Diazonium Salts and Its Applications to the Heck–Matsuda Reaction." Molecules 25, no. 9 (May 8, 2020): 2199. http://dx.doi.org/10.3390/molecules25092199.
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This study depicts the use of a fiber-optic coupled Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) probe for the in-depth study of arene diazonium salt formation and their utilization in the Heck–Matsuda reaction. The combination of these chemical reactions and in situ IR spectroscopy enabled us to recognize the optimum parameters for arene diazonium salt formation and to track the concentrations of reactants, products and intermediates under actual reaction conditions without time consuming HPLC analysis and the necessity of collecting the sample amid the reaction. Overall advantages of the proposed methodology include precise reaction times as well as identification of keto enol tautomerization in allylic alcohols supporting the ‘path a’ elimination mechanism in the Heck–Matsuda reaction.
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Radhika, Sankaran, Mohan Neetha, Thaipparambil Aneeja, and Gopinathan Anilkumar. "Microwave-assisted Amination Reactions: An Overview." Current Organic Chemistry 24, no. 19 (December 1, 2020): 2235–55. http://dx.doi.org/10.2174/1385272824999200914111246.
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C-N coupling reactions were found to be attractive among researchers owing to the importance of C-N bond formation in heterocyclic synthesis. Hence C-N bond formation via amination reaction with the assistance of microwave radiations gained significant attraction recently. Microwave-assisted reactions are greener, faster and generally efficient compared to the conventional thermal reactions offering better purity of the product with enhancement in the yield. It was surprisingly revealed that several new advancements in amination reactions were highly influenced by this greener technology. This first review on microwave-assisted amination reaction focuses on the novel amination strategies that emerged with the help of microwave methodology, and covers literature up to 2019.
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Roy, Snigdha. "Prins-Friedel-Crafts Cyclization: Synthesis of Diversely Functionalized Six- Membered Oxacycles." Current Organic Chemistry 25, no. 5 (March 15, 2021): 635–51. http://dx.doi.org/10.2174/1385272825666210114105020.
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Prins cyclization is a well-established synthetic protocol to generate a wide range of important oxygen heterocycles. It is a cyclization reaction performed by an oxocarbenium ion that undergoes an intramolecular pi-bond attack to construct a new carbon-carbon bond. When this cyclization process is conjugated with Friedel-Crafts reaction, it further expands the synthetic potential by fabricating two different carbon-carbon bonds in one single reaction. Different acid catalysts mediated the coupled Prins-Friedel-Crafts reaction which is conducted both in stepwise as well as in tandem fashion. In the stepwise route, three different reacting components were utilized whereas, the tandem methodology required proper modification of the initial substrate molecule. An array of allylic, propargylic, other related alkenols, and carbonyl reactants were employed to carry out the cyclization process. Several oxygenated heterocycles equipped with diverse functionalities were constructed in a stereoselective manner which again reinforced the significance of this cyclization protocol undoubtedly. The present mini-review highlights the utilization of different one-pot stepwise Prins-Friedel-Crafts reactions and the subsequent development of cascade Prins- Friedel-Crafts cyclization process to furnish intricate molecular architectures of vital six-membered oxacycles.
Дисертації з теми "Organic reaction methodology"
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Bhuiyan, Mosharef Hossain. "Synthetic organic reaction new methodology and applications." Thesis, University of North Bengal, 2003. http://hdl.handle.net/123456789/772.
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Biswas, Kinkar. "Development of organic reaction methodology using polymar-supported reagents, focused microwaves and on-water chemistry." Thesis, University of North Bengal, 2016. http://ir.nbu.ac.in/handle/123456789/2745.
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Larson, Shawn E. "Enantioselective Brønsted and Lewis Acid-Catalyzed Reaction Methodology: Aziridines as Building Blocks for Catalytic Asymmetric Induction." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4357.
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Chiral molecules as with biological activity are plentiful in nature and the chemical literature; however they represent a smaller portion of the pharmaceutical drug market. As asymmetric methodologies grow more powerful, the tools are becoming available to synthesize chiral molecules in an enantioselective and efficient manner.
Recent breakthroughs in our understanding of phosphoric acid now allow for Lewis acid catalysis via pairing with alkaline earth metals. Using alkaline earth metals with chiral phosphates is an emerging approach to asymmetric methodology, but already has an influential record.
The development of new conditions for the phosphoric acid-catalyzed highly enantioselective ring-opening of meso-aziridines with a series of functionalized aromatic thiol nucleophiles is described in this thesis. This methodology utilizes commercially available aromatic thiols, a series of meso-aziridines, and a catalytic amount of VAPOL calcium phosphate to explore the substrate scope of this highly enantioselective reaction.
Additionally, the development of new conditions for a catalytic asymmetric aza-Darzens aziridine synthesis mediated by a vaulted biphenanthrol (VAPOL) magnesium phosphate salt is described in this thesis. Using simple substrates, this methodology explores the scope and reactivity of a new magnesium catalyst for an aziridination reaction capable of building chirality and complexity simultaneously.
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Cavitt, Marchello Alfonzo. "Stress relief: Exercising Lewis acid catalysis for donor-acceptor cyclopropane ring-opening annulations, a basis for new reaction methodologies." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54448.
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Nature’s biodiversity is complex and filled with beauty and wonder which are all observable on the macroscopic scale. This exquisiteness of nature’s intricacies are mirrored on the molecular level such that substances, large or small, are assembled to serve as signaling molecules, protective agents, and fundamental composites of higher-order frameworks for the operation and survival of life. Over the years, chemists have isolated and synthesized these molecules, known as natural products, to understand and evaluate their functions in biology and potential for medicinal applications.
Although bioactive natural products demonstrate medicinal promise, poor pharmacological effects require further derivatization because semisynthesis is not sufficient to refine adverse pharmacokinetics. For some active molecules, isolation results in poor yields. In addition to small quantity isolation, many natural products, reflecting the immense complexity of biology itself, pose difficult synthetic challenges to organic chemists because of skeletal heterogeneity, stereochemical complexity, and substitution divergence. As a result of these synthetic obstacles to natural product utilization, improvements are needed in current chemical approaches, and new innovative methodologies for synthesis and chemical space exploration are necessary.
Pharmaceutically relevant frameworks, natural products, and synthetic biologically active molecules are comprised of polycarbocyclic and heterocyclic scaffolds. Traditionally, cycloadditions, transannular transformations, and annulation reactions serve as powerful methods for polycyclic formation. In order to assemble diverse polycycles, donor-acceptor cyclopropanes are useful, versatile synthetic equivalents for C-C bond formations. By taking advantage of the strain within these unique, polarized systems, differing molecular architectures can be accessed directly to perform contemporary organic synthesis. Moreover, the donor-acceptor cyclopropanes initially utilized in these studies provided a fundamental basis for new methods to synthesize other relevant scaffolds. Unique, efficient, Lewis acid-catalyzed intramolecular cyclization strategies for the construction of functionalized polycycles using Friedel-Crafts-type alkylation sequences are presented to expand the reaction repertoire of the molecular architect. Generally, products were formed from commercially-available starting materials in high yields with broad scope. The methodologies were demonstrated to be modular, operationally simple, and amenable to different substitution patterns and functional groups to afford tetrahydroindolizines, heteroaromatic cyclohexenones, hydropyrido[1,2-a]indoles, pyrrolo[1,2-a]indoles, pyrrolo[3,2,1-ij]quinolines, pyrrolizines, and tetrahydrobenzo[ij]quinolizines. To demonstrate the utility of the methodologies devised, progress toward, (±)-rhazinicine, a natural product, is discussed.
This dissertation is organized into six chapters: (1) an introduction, paradoxical stress and molecular strain’s utility in synthesis; (2) annulation reactions for the formation of heteroaromatic cyclohexenones; (3) hydropyrido[1,2-a]indole formation via an In(III)-catalyzed cyclopropane ring-opening/Friedel-Crafts alkylation sequence; (4) tetrahydroindolizine formation and progress toward the total synthesis of (±)-rhazinicine (5) pyrrolo[1,2-a]indole synthesis using a Michael-type Friedel-Crafts cyclization approach; and (6) a versatile protocol for the intramolecular formation of functionalized pyrrolo[3,2,1-ij]quinolines.
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Pelletier, Sophie Marie-Clémentine. "One-pot nitro-Mannich cascade reactions : new methodologies and synthetic applications." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:283641bf-bb4e-48a8-8a28-2e048b8c4ea6.
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Pyrrolidine and pyrrolidinone rings are common motifs found in many biologically active natural products and drugs. Accordingly, our work focuses on the development of new methodologies for their one-pot synthesis. An efficient diastereoselective nitro-Mannich / lactamisation reaction cascade of methyl 3-nitropropanoate with cyclic and acyclic imines for the direct preparation of trans-monocyclic and fused tricyclic pyrrolidinone derivatives was developed. The reaction is easy to perform, broad in scope and tolerates a wide variety of functional groups. For the monocyclic methodology, 28 examples with a very good average yield of 72% and excellent diastereocontrol (typical dr >98:2) were obtained using optimized conditions and varying the amine and the aldehyde reagents. The methodology has been extended to the synthesis of 1,3,5-trisubstituted 4-nitropyrrolidinone derivatives using α-substituted 3-nitropropanoate. Using a one-pot protocol, 22 derivatives were synthesised in good yields (65% average) and diastereomeric ratios ranging from 3:1 to 30:1 in favor of the trans/trans diastereoisomer. In addition, the nitro-Mannich / lactamisation cascade of methyl 3-nitropropanoate was developed further to allow the rapid synthesis of 5-isopropyl-4-nitropyrrolidin-2-one from reaction with ammonium acetate and 1-butyl-4-nitropyrrolidin-2-one from reaction with formaldehyde. Also, the synthetic utility of the nitro-pyrrolidinones formed was exemplified through various functional group modifications: the selective reduction of the lactam carbonyl, the reduction of the nitro group in the presence or absence of a carbonyl group and the reductive removal of the nitro group. The development of an enantioselective version of the cascade under chiral Brönsted acid catalysis provided promising results (up to 90% ee). Moreover, various studies were undertaken to understand the mechanism of the reaction and the nitro-Mannich / latamisation cascade is now well understood. Furthermore, a formal synthesis of rac-Slaframine in 8 steps and 15% overall yield was achieved and it inspired additional work towards a nitro-Mannich / epoxide ring opening cascade.
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Martinez, Ariza Guillermo, and Ariza Guillermo Martinez. "Exploiting Molecular Diversity to Access Biologically Relevant Chemotypes." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621718.
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Small-molecule libraries with enhanced structural diversity are of value in drug discovery campaigns where novel biologically active hits are desired. As such, multicomponent reactions (MCRs) have proven fruitful to enhance the molecular diversity of chemical collections and expedite forward progression of the drug discovery chain. Bicalutamide (Casodex), an anticancer drug, and Telaprevir (Incivek), an antiviral, are two examples of marketed drugs that can be synthesized using an MCR. The research topic of this dissertation involves the design, discovery, and development of novel MCRs and new combinations of MCRs with post-condensation modifications to generate over twenty-five new drug-like scaffolds in an operationally friendly, atom-economical, time- and cost-effective fashion. The developed chemical methodologies possess inherent 'iterative efficiency','high exploratory power', and 'bond forming efficiency' that allow them to quickly explore chemical space and navigate the 'hypothesis-synthesis-screening' loop that is key for a medicinal chemistry project. The prepared molecules were submitted to the Community for Open Antimicrobial Drug Discovery (CO-ADD) for antimicrobial screening against pathogens that are known to cause drug-resistance infections.
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Jha, Satadru. "Organic reactions methodology : studies on carbon-nitrogen hetero bond forming reactions." Thesis, University of North Bengal, 2004. http://hdl.handle.net/123456789/745.
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Baldwin, I. Craig. "New methodology involving allylic substitution and conjugate addition reactions." Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/27583.
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Chapter one reviews routes to the generation of α-aminophosphonates and α-aminophosphonic acids. These biologically important compounds are synthesised in both racemic and enantiomerically enriched forms. The second chapter describes the results of conjugate addition reactions of lower order cuprates to diethylvinylphosphonate followed by an electrophilic quench to give a range of alkylphosphonates. The third and fourth chapters are concerned with the generation of enantiomencally enriched α-aminophosphonates and α-aminoesters via palladium catalysed allylic substitution reactions With allyl acetate the resulting products were isolated with an enantiomeric excess of up to 19%. With 1,3-diphenyl-2-propenyl acetate products with both high diastereomeric and enantiomeric excesses were isolated with the best being 75 % de and 97 % ee.
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Das, Pralay. "New reactions and methodology : studies on transition metal catalyzed organic transformations." Thesis, University of North Bengal, 2005. http://hdl.handle.net/123456789/775.
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Bentley, Scott Alexander. "Asymmetric conjugate addition reactions." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:9e619a66-6277-48c2-8a2e-24f8206e52b3.
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This thesis is concerned with the asymmetric conjugate addition reactions of a range of chiral nucloeophiles. Chapter 1 introduces the conjugate addition reaction as a valuable carbon-carbon and carbon-heteroatom bond forming reaction in organic chemistry, and explores the asymmet- ric conjugate addition of a range of chiral and achiral carbon and nitrogen nucleophiles to a range of acceptors. Chapter 2 explores the use of the N-benzyl-N-(α-methylbenzyl)amino group as a chi- ral auxiliary, by employing the attempted conjugate additions of both N-benzyl-N-(α- methylbenzyl)hydrazine and N -benzyl-N -(α-methylbenzyl)hydroxylamine as chiral ammo- nia and water equivalents respectively. Chapter 3 describes the asymmetric and stereoselective preparation of a range of 4,4- disubstituted isoxazolidin-5-ones from the conjugate addition of lithium (S)-N-tert-butyl- dimethylsilyloxy-N -(α-methylbenzyl)amide. The isoxazolidin-5-ones are then globally de- protected via hydrogenolysis, giving rise to the corresponding β2,2,3-amino acids. Chapter 4 focuses on the development of a protocol to effect the conjugate addition of a chiral aniline equivalent. The scope of the reaction is delineated by varying both the nu- cleophile and the α,β-unsaturated ester. Finally, cyclisation of the β-N-arylamino esters to the corresponding tetrahydroquinolines is explored, and an application to the synthesis of the natural product (−)-angustureine is presented. Chapter 5 contains full experimental procedures and characterisation data for all com- pounds synthesised in Chapters 2, 3 and 4.
Книги з теми "Organic reaction methodology"
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Sun, Xiaoping. Organic mechanisms: Reactions, methodology, and biological applications. Hoboken, New Jersey: Wiley, 2013.
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Boger, Dale L. Hetero Diels-Alder methodology in organic synthesis. San Diego: Academic Press, 1987.
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Boger, Dale L. Hetero Diels-Alder methodology inorganic synthesis. San Diego: Academic Press, 1987.
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International Symposium on Organic Reactions (1991 Kyoto, Japan). Modern methodology in organic synthesis: Proceedings of the 1991 International Symposium on Organic Reactions, Kyoto. Tokyo: Kodansha, 1992.
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Sun, Xiaoping. Organic Mechanisms: Reactions, Methodology, and Biological Applications. Wiley & Sons, Incorporated, John, 2013.
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Sun, Xiaoping. Organic Mechanisms: Reactions, Methodology, and Biological Applications. Wiley & Sons, Limited, John, 2021.
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Sun, Xiaoping. Organic Mechanisms: Reactions, Methodology, and Biological Applications. Wiley & Sons, Incorporated, John, 2020.
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Sun, Xiaoping. Organic Mechanisms: Reactions, Methodology, and Biological Applications. Wiley & Sons, Incorporated, John, 2013.
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Sun, Xiaoping. Organic Mechanisms: Reactions, Methodology, and Biological Applications. Wiley & Sons, Incorporated, John, 2020.
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Sun, Xiaoping. Organic Mechanisms: Reactions, Methodology, and Biological Applications. Wiley & Sons, Incorporated, John, 2013.
Знайти повний текст джерелаЧастини книг з теми "Organic reaction methodology"
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Hirano, Takashi, and Chihiro Matsuhashi. "Soft Crystal Chemiluminescence Systems Using Organic Peroxides." In The Materials Research Society Series, 155–77. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-0260-6_9.
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AbstractChemiluminescence (CL) is a phenomenon in which a chemical reaction produces an excited-state product that emits light. Taking advantage of this property, several analytical methods to study the CL reactions by photon detection have been developed in the literature. By applying this methodology to molecular crystals, soft crystal CL systems have been constructed to analyze the intracrystalline reactions of chemiluminescent compounds. In this chapter, the fundamental concept and applications of CL are presented. Using the example of the CL reactions involving organic peroxides, important characteristics of CL such as chemiexcitation, quantum yield and emission wavelengths are discussed. Furthermore, CL in solid state and in molecular crystals are described. Finally, the application of organic peroxides as a soft crystal CL system and the characteristics of their intracrystalline reactions such as crystal structure-dependencies, reaction kinetics and inductions of phase transitions are elucidated. This chapter concludes with a brief outlook towards the future of soft crystal CL systems.
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Ghosh, Mithun Kumar, and Tanmay Kumar Ghorai. "Advantages of Nanocatalysts on Knoevenagel Condensation." In Diverse Strategies for Catalytic Reactions, 119–39. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815079036123020007.
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Nanocatalysts revolutionize organic chemistry for the conversion of various organic reactions to obtain a high yield, low hazard and stability. It plays an important role in the transformation of organic reactions due to its high surface area, small size, and low reaction time. Therefore, green methodology, both in the synthesis of nanocatalysts and organic transformation reactions, is an advanced technology, and findings promise results. Many scientists all over the world synthesised nanoparticles and used them as catalysts in Knoevenagel condensation. In this book chapter, we documented the synthesis and characterisation techniques of the homo/hetero metallic nanocatalyst and applied it in the Knoevenagel condensation reaction for its reusability and easy separation after a chemical reaction because, in organic chemistry, separation is a tedious job for finding pure compounds.
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Nakamura, Eiichi. "Me3SiCl-accelerated conjugate addition reactions of organocopper reagents." In Organocopper Reagents: A Practical Approach, 129–42. Oxford University PressOxford, 1995. http://dx.doi.org/10.1093/oso/9780198557579.003.0006.
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Abstract Conjugate addition to α,β-unsaturated carbonyl compounds represents an archetypical reaction of organocopper reagents (eqn 1). Various reagents including the classical Grignard-based catalytic copper reagent, the Gilman reagent (R2CuLi), and the ‘RCu•BF3’ reagent have been developed to improve the efficiency of the process by enhancing the reactivities of the reagents and by suppressing side-reactions such as 1,2-addition. Because of the paramount importance of the conjugate addition in organic synthesis, research efforts continue to make the reaction more versatile and more reliable. This chapter describes the Me3SiCl-accelerated reactions of organocopper reagents—a methodology which has proven its great synthetic utility in the past several years.
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Su, Z., and L. A. Paquette,. "Synthesis of an Enantiopure C-4 Functionalised 2-Iodocyclohexanone Acetal." In Exercises in Synthetic Organic Chemistry, 29. Oxford University PressOxford, 1997. http://dx.doi.org/10.1093/oso/9780198559443.003.0022.
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Abstract Discussion Points Explain the selectivity in the formation of the lactone ring in step a. What is the purpose of lithium chloride in step j? Further Reading For a modification of the Barton deoxygenation reaction using polystyrene-supported organotin hydride, see: W. P. Neumann and M. Peterseim, Synlett,1992, 10,801. For a review on the Barton—McCombie methodology, see: C. Chatgilialoglu and C. Ferreri, Res. Chem. Intermed.,1993, 19,755. For a review on the use of vinyl triflates in synthesis, see: K. Ritter, Synthesis,1993, 8,735.
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Govind, Rakesh, Shiva Charan, and Jack Baltzersen. "Systematic Generation of Reactions Pathways for Manufacturing Bulk Industrial Chemicals from Biomass." In Biomass [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103123.
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The objective of this work was to develop a systematic strategy for generating efficient, alternate reaction paths that could be used to manufacture the top 100 industrial chemicals, currently produced from crude oil, using renewable feedstocks. Manufacturing these chemicals from oil, coal, or natural gas results in increasing carbon dioxide levels in the atmosphere, responsible for global climate change. The methodology employed here uses the existing knowledge on the conversion of carbon-neutral feedstocks, such as biomass, wood, etc., to suitable precursor raw materials. Known industrial reaction paths, currently used for manufacturing the top 100 industrial organic chemicals, are then combined with the known conversion of carbon-neutral feedstocks to systematically develop and evaluate alternate carbon-efficient reaction paths. The fractional carbon economy was determined from a comprehensive listing of industrial reactions paths, which also gives the yields and efficiencies of these industrial reaction paths, currently being practiced in the chemical industry. Reaction pathways with maximum carbon economy for manufacturing the top 100 industrial chemicals from carbon-neutral feedstocks have been presented in this chapter.
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Li, Jie Jack, Chris Limberakis, and Derek A. Pflum. "Carbon−Carbon Bond Formation." In Modern Organic Synthesis in the Laboratory. Oxford University Press, 2008. http://dx.doi.org/10.1093/oso/9780195187984.003.0011.
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Reviews: (a) Vicarion, J. L.; Badia, D.; Carillo, L.; Reyes, E.; Etxebarria, J. Curr. Org. Chem. 2005, 9, 219-235. (b) Mahrwald, R. Ed. In Modern Aldol Reactions; Wiley-VCH: Weinheim, 2004; Vol. 1., pp. 1-335 (c) Mahrwald, R. Ed. In Modern Aldol Reactions; Wiley-VCH: Weinheim, 2004; Vol. 2., pp. 1-345.(d) Machajewski, T. D.; Wong, C.-H. Angew. Chem. Int. Ed. 2000, 39, 1352-1375. (e) Carriera, E. M. In Modern Carbonyl Chemistry; Otera, J.; Wiley-VCH: Weinheim, 2000; Chapter 8: Aldol Reaction: Methodology and Stereochemistry, 227-248. (f) Paterson, I.; Cowden, C. J.; Wallace, D. J. In Modern Carbonyl Chemistry; Otera, J.; Wiley-VCH: Weinheim, 2000; Chapter 9: Stereoselective Aldol Reactions in the Synthesis of Polyketide Natural Products, pp. 249-298. (g) Franklin, A. S.; Paterson, I. Contemp. Org. Synth. 1994, 1 317-338. (h) Heathcock, C. H. In Asymmetric Synthesis; Morrison, J. D., Ed.; Academic Press: Orlando, Fl.; 1984; Vol. 3., Chapter 2: The Aldol Addition Reaction, pp. 111-212. (i) Mukaiyama, T. Org. React. 1982, 28, 203-331. Since the early 1980s, aldol condensations involving boron enolates have gain great importance in asymmetric synthesis, particularly the synthesis of natural products with adjacent stereogenic centers bearing hydroxyl and methyl groups. (Z)-Boron enolates tend to give a high diastereoslectivity preference for the syn-stereochemistry while (E)-boron enolates favor the anti-stereochemistry. Because the B-O and B-C bonds are shorter than other metals with oxygen and carbon, the six membered Zimmerman–Traxler transition state in the aldol condensation tends to be more compact which accentuates steric interactions, thus leading to higher diastereoselectivity. When this feature is coupled with a boron enolate bearing a chiral auxillary, high enantioselectivity is achieved. Boron enolates are generated from a ketone and boron triflate in the presence of an organic base such as triethylamine. Reviews: (a) Abiko, A. Acc. Chem. Res. 2004, 37, 387-395. (b) Cowden, C. J. Org. React. 1997, 51, 1-200.
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Bhatia, B., T. Punniyamurthy, and J. Iqbal. "Oxidation of the C—H bond." In Asymmetric Oxidation Reactions, 5–18. Oxford University PressOxford, 2001. http://dx.doi.org/10.1093/oso/9780198502012.003.0002.
Повний текст джерелаАнотація:
Abstract The development of methodology for asymmetric functionalization of the C—H bond offers a challenge in the strive for acquiring optically active building-blocks from simple starting materials. Asymmetric synthesis has emerged as an exciting area of chemistry by judiciously employing the principles of organic synthesis, molecular recognition, metal coordination chemistry, and catalysis. Among the various strategies available for exploiting the pools of chiral compounds, catalytic asymmetric induction offers a distinct advantage in achieving a high level of enantioselectivity during bond formation mainly due to the influence of asymmetry possessed by the ligands in the catalyst. The titanium-catalysed epoxidation1−3 of allylic alcohols, the osmium-catalysed dihydroxylation4−7 of alkenes, the copper-catalysed cyclopropanation8−10 of alkenes, and the ruthenium-catalysed asymmetric hydrogenation11,12 of alkenes are outstanding achievements in the catalytic asymmetric induction approach. Another approach is inspired by the analogy derived from nature, where the monooxygenase enzymes are, for example, known to effect stereospecific oxidation of organic compounds. This biomimetic approach has led to widespread research activity in this area and as a result an impressive start has been made in achieving good levels of selectivity in the oxidation of organic substrates by employing well-crafted small molecular catalysts. The possibility of mimicking the enantio-selective reaction of monooxygenases is a highly viable proposition from the point of view of synthetic organic chemists. Indeed, the design and development of synthetic monooxygenase mimics that catalyse enantioselective epoxidation of unfunctionalized alkenes have already made an impressive impact on stereoselective synthesis mainly due to the pioneering efforts of the research groups of Groves, Jacobsen,15,17 and Katsuki,18−22 respectively. On the other hand, the enantioselective oxidation of the saturated C—H bond has proven more difficult to accomplish with synthetic catalysts. Consequently, there has been continual effort to achieve a high level of enantioselectivity in the oxidation of the saturated C—H bond over the past few years. The following sections deal with the results achieved so far on the enantioselective oxidation of the C—H bond by employing chiral catalysts derived from ligands easily prepared from simple and easily accessible starting materials. The emphasis is on the experimental procedures of those reactions which are operationally simple and easy to perform on a synthetically useful scale.
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Daly, Francis P., William M. Jensen, and Daniel J. Ostgard. "Influence of Catalyst Preparation Methodology on the Selectivity of Supported Transition Metal Catalysts." In Catalysis of Organic Reactions, 13–21. Routledge, 2017. http://dx.doi.org/10.1201/9781315138855-2.
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Chemla, F., and A. Pérez-Luna. "2.5 Radical–Polar Crossover Reactions." In Free Radicals: Fundamentals and Applications in Organic Synthesis 2. Stuttgart: Georg Thieme Verlag KG, 2021. http://dx.doi.org/10.1055/sos-sd-233-00075.
Повний текст джерелаАнотація:
AbstractRadical–polar crossover reactions, that is, single-electron redox events allowing for the interconversion between radical and ionic intermediates, make it possible to connect radical and polar processes in the same synthetic transformation. Such a combination is the basis of much original synthetic methodology, which is particularly useful in the context of domino, tandem, or multicomponent reactions. This chapter comprehensively covers the field of radical–polar crossover reactions, with a primary emphasis on transformations wherein both the radical and polar processes provide synthetic elaboration.
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Reiss-Husson, F., and D. Picot. "Crystallization of Membrane Proteins." In Crystallization of Nucleic Acids and Proteins. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780199636792.003.0013.
Повний текст джерелаАнотація:
Crystallization of membrane proteins is one of the most recent developments in protein crystal growth; in 1980, for the first time, two membrane proteins were successfully crystallized, bacteriorhodopsin (1) and porin (2). Since then, a number of membrane proteins (about 30) yielded three-dimensional crystals. In several cases, the quality of the crystals was sufficient for X-ray diffraction studies. The first atomic structure of a membrane protein, a photosynthetic bacterial reaction centre, was described in 1985 (3), followed by the structure of about ten other membrane protein families. Crystallization of membrane proteins is now an actively growing field, and has been discussed in several recent reviews (4-8). The major difficulty in the study of membrane proteins, which for years hampered their crystallization, comes from their peculiar solubility properties. These originate from their tight association with other membrane components, particularly lipids. Indeed integral membrane proteins contain hydrophobic surface regions buried in the lipid bilayer core, as well as hydrophilic regions with charged or polar residues more or less exposed at the external faces of the membrane. Disruption of the bilayer for isolating a membrane protein can be done in various ways: extraction with organic solvents, use of chaotropic agents, or solubilization by a detergent. The last method is the most frequently used, since it maintains the biological activity of the protein if a suitable detergent is found. This chapter will be restricted to specific aspects of three-dimensional crystallizations done in micellar solutions of detergent. In some cases, it is possible to separate soluble domains from the membrane protein either by limited proteolysis or by genetic engineering. Such protein fragments can then be treated as soluble proteins and so will not be discussed further in this chapter. We refer to Chapter 12 and the review by Kühlbrandt (9) for the methodology of two-dimensional crystallization used for electron diffraction. The general principles discussed in this book for the crystallization of soluble biological macromolecules apply for membrane proteins; the protein solution must be brought to supersaturation by modifying its physical parameters (concentrations of constituents, ionic strength, and so on), so that nucleation may occur.
Тези доповідей конференцій з теми "Organic reaction methodology"
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Mereu, Federico, Jayangi D. Wagaarachchige, Zulkifli Idris, Klaus-Joachim Jens, and Maths Halstensen. "Response Surface Modelling to Reduce CO2 Capture Solvent Cost by Conversion of OZD to MEA." In 64th International Conference of Scandinavian Simulation Society, SIMS 2023 Västerås, Sweden, September 25-28, 2023. Linköping University Electronic Press, 2023. http://dx.doi.org/10.3384/ecp200003.
Повний текст джерелаАнотація:
The increasing CO2 concentration in the atmosphere is the most urgent global challenge. The most mature CO2 abatement option is post-combustion CO2 capture employing Monoethanolamine (MEA) solvent. One challenge of using MEA is its in-service degradation to 2-oxazolidinone (OZD), a heterocyclic five-membered organic ring compound. Furthermore, OZD degrades more MEA leading to CO2 capture solvent loss and hence increased operational cost. It is therefore of interest to investigate methods to convert OZD back to MEA. This work reports the conversion of 2-oxazolidinone to MEA by heat treatment at an alkaline condition. Raman spectroscopy and Ion-Exchange chromatography were applied to qualify and quantify the reaction. The optimal reaction parameters were identified by an experimental design model using the Response Surface Methodology (RSM). A second-order model with three variables and five levels of focus was employed, with the OZD conversion percentage as the response. This methodology was chosen because such a model could estimate the main effects, interactions and quadratic terms by relying on a relatively small number of experiments. 17 experimental runs were designed by the software using this method. At a reaction time of 35 minutes, reaction temperature of 100°C, and 2.5 mole of hydroxide per mole of OZD resulted in a complete conversion of OZD to MEA.
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Burge, Scott R. "Automated Analysis of Trichloroethene and Chloroform." In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4648.
Повний текст джерелаАнотація:
Chloroform and trichloroethene (TCE) are two organic contaminants commonly encountered in ground water. TCE, formerly a common cleaning solvent, is usually associated with contaminated aquifers. Chloroform is usually associated with the chlorination of municipal water. The remediation level for TCE in aquifers is typically 5 ppb, therefore, the analytical method employed for monitoring these analytes must be capable of detecting and quantifying the analytes in the low ppb concentration range. The most common analytical methodology for the determination of TCE or chloroform in water is a purge and trap technique for sample introduction into a gas chromatographic system equipped with electroconductivity or mass spectroscopy detector. The instrumentation has a method limit of detection (LOD) of less than 0.5 ppb for TCE and chloroform, however, the expense, size and complexity of the gas chromatographic techniques limit its use outside the laboratory environment. An alternative to the gas chromatographic method for the analysis of select volatile chlorinated compounds in the low concentration range is an analytical instrument based on a halocarbon-specific optrode. The principle of detection is a quantitative, irreversible chemical reaction (modified Fujiwara reaction) that forms visible light-absorbing products. The operational basis of the optrode is the measure of the time history of the development of the colored (red) product formed by the reaction of the target analytes. The optrode has the selectivity and sensitivity for monitoring TCE and chloroform at the low ppb concentration range in the presence of other volatile chlorinated contaminants. The low-power requirements and simplicity of design make it a good choice for remote operations. This paper presents the analytical results (January 2002, to December 2002) of a panel-mounted instrument used to monitor the influent and effluent water of a TCE treatment facility located in Scottsdale, Arizona, and the analytical results of a well-mounted instrument used to monitor ground water (May 2002, to August 2002) at Edwards Air Force Base, California.
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Tioni, Estevan, and Pascal Rousseaux. "BRINGING TOGETHER MICROWAVE ASSISTED SYNTHESIS AND CHEMICAL ENGINEERING PRINCIPLES." In Ampere 2019. Valencia: Universitat Politècnica de València, 2019. http://dx.doi.org/10.4995/ampere2019.2019.9901.
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It is nowadays admitted that microwaves are frequently used in organic chemistry labs [1] (even if not as much as it was predicted 20 years ago, one must say [2]). On the other side it is also certain that this technology has not yet found its place in chemical industry: application at a production scale are very scarce [3][4] and this despite the potential advantages of the technology (selective heating, high heating rate, low thermal inertia…). The point is that mastering all the aspects of microwaves assisted synthesis at industrial scale demands a lot of different skills to work together: chemistry, process engineering, microwave engineering, materials science. This is so challenging that tools and methodologies for quantification of industrial microwave interest and scaling-up of lab results are missing. In this work we present our contributions to the deployment of microwaves for synthesis in the chemical industry which are mainly The development of small pilot reactors (1 L) in stainless steel, capable to withstand temperature and pressureThe application of a chemical engineering methodology to microwave assisted synthesisAn example of intensification (see table) of an industrially interesting reaction using microwave to access NPW (high temperature and pressure)A tentative of rationalization of process criteria to identify a priori the interest of microwave heating for a specific application [1]. Diaz-Ortiz et al., Chem. Rec. 2019, 19, 85–97 [2]. Kappe, Chem. Rec. 2019, 19, 15–39 [3]. Aldivia, brevet WO2004/066683A1 [4]. https://cen.acs.org/articles/94/i36/Microwaving-ton.html
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Zheng, Zhenguo, Oscar Julian Jaramillo, Jhon Patiño, John Fredy Reina, and Carlos Francisco Pacheco. "Successful Acid Stimulation in Limestone - Tobo-Monserrate Formation in Gigante Field - Colombia." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206037-ms.
Повний текст джерелаАнотація:
Abstract This paper presents the successful stimulation workflow case for a carbonate acidizing pilot project performed in Gigante field in the Matambo block of the Upper Magdalena Valley basin in Colombia. An adecuate diagnostic, laboratory testing, treatment fluid selection, on-site QAQC and placement technique selection was fundamental to obtain a successful design and an optimized application. Gigante field production is mainly coming from Tetuan and Caballos units producing 32-degree API crude oil during several years. Specifically, in Gigante-2 ST well, oil production has declined until its commercial limit. During a candidate wells review, it was identified a previous acid stimulation treatment performed in Tobo-Monserrate formation in Gigante-1 with very poor results in oil production –short production time in natural flow– giving to this zone a low potential as oil producer and it was not considered as a primary target zone. The well was completed in its main target at Tetuan formation leaving Tobo-Monserrate behind an intermediate 7 in casing with no future expectatives to produce. After a reservoir evaluation of Tobo-Monserrate formation done in Gigante-2 ST well, it was selected as a candidate for an intermedia matrix stimulation job to evaluate the real potential of this formation in Matambo block. During this phase, reservoir samples were tested against different acid treatments in the laboratory. A gelled HCL based acid was selected based on their laboratory testing performance to delay acid reaction –improving acid penetration– and having fluid loss control to enhance reservoir coverage. The complete chemical formula was customized to match the oil-treatment compatibility. An organic solvents treatment was added to dissolve organic scale prior to the acidizing. Acid was deployed directly through a TCP string to optimatize the operational time and managing treatment rate according to the pressure behavior. During the acid pumping, a pressure drop is observed and treatment rate was increased to generate rate diversion. Gigante-2 ST well came in production at natural flow reaching 502 BOPD and 105 MSCFD evaluated after 35 days of the stimulation job proving and adding important hydrocarbon reserves from Tobo-Monserrate formation. A post job evaluation using a specialized chemical stimulation simulator shows a significant skin removal. Measured treatment pressure and rate were matched with the simulated parameters resulting in −3.24 of skin value post acid stimulation having a productivity improvement factor of 4.35 and an average wormhole penetration estimated from 60 to 75 in into the reservoir. A correct diagnostic, reservoir understanding, design, laboratory testing, execution and post job evaluation was the right route to obtain a successful stimulation job in operational terms and production results. This paper is intended as a guideline for stimulation jobs in future interventions where the exact reservoir mineralogy is unknown. It shows a step-by-step methodology, a customized acid formula and finally, stimulation results as well as recommendations and learned lessons.
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Ferreira, Jorge A., João E. de Oliveira, and Vitor A. Costa. "Modeling of Hydraulic Systems for Hardware-in-the-Loop Simulation: A Methodology Proposal." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0766.
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Abstract The present paper proposes a methodology to organize model libraries of electro-hydraulic components. This methodology holds in the association of an object oriented modeling, equation based, language for model structure description, with a graphical formalism suitable for the dynamic behavior description of reactive hybrid systems. That is, a recent general purpose language for physical modeling, called Modelica, is used to develop object-oriented libraries of models for different physical domains; the hierarchical description of the dynamic behavior of each model is obtained by means of the Statecharts formalism. With the method proposed, complex models are built by model interconnection schemes; it is possible to organize the models for different complexity levels adapting them for distinct simulations (real-time or off-line), by refining their behavior using the Statecharts graphical formalism. The developed hydraulic models, once compiled into C-code, are assembled as a whole application, and executed by a digital signal processing card (DSP). The simulation task is based on hardware-in-the-loop techniques in such a way that the “virtual” hydraulic application is controlled by real hardware.
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Tsai, Lung-Wen, Dar-Zen Chen, and Ta-Wei Lin. "Dynamic Analysis of Geared Robotic Mechanisms Using Graph Theory." In ASME 1996 Design Engineering Technical Conferences and Computers in Engineering Conference. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-detc/mech-1554.
Повний текст джерелаАнотація:
Abstract A systematic methodology is developed for the dynamic analysis of a class of geared robotic mechanisms. The concepts of canonical graph representation, the equivalent open-loop chain, and the mechanical transmission lines of a mechanism are used to organize the analysis. The approach modifies the Newton-Euler recursive inverse dynamics algorithm for open-loop chains and tree structures to include gear joints. A recursive method for the evaluation of reaction forces is developed. It is shown that reaction forces can be efficiently computed from the highest level primary links followed by the secondary links, one or two levels at a time, working toward the base. This procedure is especially useful when the evaluation of dynamic loads of bearings and teeth teeth is desired for the design of such mechanisms. A two degree-of-freedom robot manipulator is used as an illustrative example.
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Jiang, Li, Suzanne Stewart, and Jonathan Abbott. "Downhole Mineral Scale Dissolution Booster." In Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/32069-ms.
Повний текст джерелаАнотація:
Abstract Mineral scale formation in the wellbore represents a widespread and serious threat to flow assurance and ultimately to well productivity. Scale formation is generally attributable to the incompatibility between reservoir and injection waters and the main mineral scale types include carbonate, sulfate and sulfide salts of divalent cations. Currently available scale dissolvers for the latter two types are often based on chelating ligand chemistry, restricted by a kinetically sluggish process of displacing the cations plus near static scale-fluid interface at the scale surface area in downhole scenarios. We wish to report two newly generated material developments aimed at accelerating downhole scale dissolution treatment performance by using either or both: Discrete surfactants able to encapsulate entrained gases in the form of micro- and nano-bubbles that migrate in the fluid body along the pressure differential.Gas generating reactions catalyzed by freshly produced divalent cations at the scale-fluid interface. It has been demonstrated through systematic, lab-based proof of concept tests that these minor additives can promote interfacial mass transfer of both reactant and products as such that some of the current physical and engineering challenges of downhole mineral scale treatment can be circumvented, resulting in remarkably enhanced scale dissolution rates. Further increase of scale dissolution rates can also be achieved by the inclusion of a genuinely sustainable biosurfactant which, at certain concentration range, can effectively remove any hydrocarbon coatings that might have saturated the mineral scale surface, hence eliminate the often-hazardous organic solvent based preflush. In addition to the aforementioned example, it is believed that the methodology reported in this manuscript can also be applicable to enhance other chemistry oriented downhole treatments where mechanic agitation is not viable.
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Jiang, Li, Suzanne Stewart, and Jonathan Abbott. "Downhole Mineral Scale Dissolution Booster." In Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/32069-ms.
Повний текст джерелаАнотація:
Abstract Mineral scale formation in the wellbore represents a widespread and serious threat to flow assurance and ultimately to well productivity. Scale formation is generally attributable to the incompatibility between reservoir and injection waters and the main mineral scale types include carbonate, sulfate and sulfide salts of divalent cations. Currently available scale dissolvers for the latter two types are often based on chelating ligand chemistry, restricted by a kinetically sluggish process of displacing the cations plus near static scale-fluid interface at the scale surface area in downhole scenarios. We wish to report two newly generated material developments aimed at accelerating downhole scale dissolution treatment performance by using either or both: Discrete surfactants able to encapsulate entrained gases in the form of micro- and nano-bubbles that migrate in the fluid body along the pressure differential.Gas generating reactions catalyzed by freshly produced divalent cations at the scale-fluid interface. It has been demonstrated through systematic, lab-based proof of concept tests that these minor additives can promote interfacial mass transfer of both reactant and products as such that some of the current physical and engineering challenges of downhole mineral scale treatment can be circumvented, resulting in remarkably enhanced scale dissolution rates. Further increase of scale dissolution rates can also be achieved by the inclusion of a genuinely sustainable biosurfactant which, at certain concentration range, can effectively remove any hydrocarbon coatings that might have saturated the mineral scale surface, hence eliminate the often-hazardous organic solvent based preflush. In addition to the aforementioned example, it is believed that the methodology reported in this manuscript can also be applicable to enhance other chemistry oriented downhole treatments where mechanic agitation is not viable.
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Moreira da Silva, Fernando. "Color processing and human perception." In Intelligent Human Systems Integration (IHSI 2023) Integrating People and Intelligent Systems. AHFE International, 2023. http://dx.doi.org/10.54941/ahfe1002840.
Повний текст джерелаАнотація:
Color processing is a complex phenomenon, which involves distinct variables, not being a relatively simple human capacity, as was long thought. Neurosciences have been helping to achieve new discoveries, recontextualizing existing knowledge and raising new questions.The brain is the organ responsible for decoding electrical signals into experiences that make sense for humans to perceive the world. Color vision is closely associated with visual processing and human perception. Cones, visual receptors in the human eye specialized for color vision, transform electromagnetic waves into electrical stimuli, which in turn are conducted to the human cortex through the geniculostriate pathway. The visual cortex is divided into at least five areas, present in the occipital lobe and designated according to their structure and function (V1, V2, V3, V4, and V5), each of these areas playing a specific role when it comes to visual processing. In previous studies, we have shown that areas V1 and V2 are mainly responsible for initial visual processing. However, more recent investigations have led to the conclusion that color processing is largely associated with the V4 area, since this area becomes significantly more active when performing tasks in which color processing is necessary, in addition to lesions in this region causing achromatopsia, dysfunction linked to chromatic identification and perception. We have been developing a quasi-experience with humans, in order to help the understanding of brain reactions to different color dimensions, especially color processing and human perception and cognition, comparing the results obtained with those of other projects previously developed. The study has also focused on color constancy, that is, the human tendency to perceive a given object as having the same color regardless of changes in lighting, angle or distance. This paper presents the work developed so far with the participation of various groups of individuals, with different ages and genders, as well as the results obtained by the application of the chosen methodology. Although at first glance it seems like a relatively simple human ability, color processing is a very complex phenomenon, involving distinct variables, many of which are still a mystery to researchers. It is hoped that this investigation may add knowledge, especially at the level of color processing and human perception, with a view to its future use and application in projects focused on the use of color.
Звіти організацій з теми "Organic reaction methodology"
1
Hochman, Ayala, Thomas Nash III, and Pamela Padgett. Physiological and Biochemical Characterization of the Effects of Oxidant Air Pollutants, Ozone and Gas-phase Nitric Acid, on Plants and Lichens for their Use as Early Warning Biomonitors of these Air Pollutants. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7697115.bard.
Повний текст джерелаАнотація:
Introduction. Ozone and related oxidants are regarded as the most important phytotoxic air pollutant in many parts of the western world. A previously unrecognized component of smog, nitric acid, may have even greater deleterious effects on plants either by itself or by augmenting ozone injury. The effects of ozone on plants are well characterized with respect to structural and physiological changes, but very little is known about the biochemical changes in plants and lichens exposed to ozone and/or HNO3. Objectives.To compare and contrast the responses of crop plants and lichens to dry deposition of HNO3 and O3., separately, and combined in order to assess our working hypothesis that lichens respond to air pollution faster than plants. Lichens are most suitable for use as biomonitors because they offer a live-organism-based system that does not require maintenance and can be attached to any site, without the need for man-made technical support systems. Original Immediate aims To expose the tobacco (Nicotiana tabacum L.) cultivar Bel-W3 that is ozone supersensitive and the ozone sensitive red kidney bean (Phaseolusvulgaris) and the lichen Ramalinamenziesii to controlled HNO3 and O3 fumigations and combined and to follow the resulting structural, physiological and biochemical changes, with special reference to reactive oxygen species related parameters. Revised. Due to technical problems and time limitations we studied the lichen Ramalinamenziesii and two cultivar of tobacco: Bel-W3 that is ozone supersensitive and a resistant cultivar, which were exposed to HNO3 and O3 alone (not combined). Methodology. Plants and lichens were exposed in fumigation experiments to HNO3 and O3, in constantly stirred tank reactors and the resulting structural, physiological and biochemical changes were analyzed. Results. Lichens. Exposure of Ramalinamenziesiito HNO3 resulted in cell membrane damage that was evident by 14 days and continues to worsen by 28 days. Chlorophyll, photosynthesis and respiration all declined significantly in HNO3 treatments, with the toxic effects increasing with dosage. In contrast, O3 fumigations of R. menziesii showed no significant negative effects with no differences in the above response variables between high, moderate and low levels of fumigations. There was a gradual decrease in catalase activity with increased levels of HNO3. The activity of glutathione reductase dropped to 20% in thalli exposed to low HNO3 but increased with its increase. Glucose 6-phosphate dehydrogenase activity increase by 20% with low levels of the pollutants but decreased with its increase. Tobacco. After 3 weeks of exposure of the sensitive tobacco cultivar to ozone there were visible symptoms of toxicity, but no danmage was evident in the tolerant cultivar. Neither cultivar showed any visible symptoms after exposure to HNO3.In tobacco fumigated with O3, there was a significant decrease in maximum photosynthetic CO2 assimilation and stomatal conductance at high levels of the pollutant, while changes in mesophyll conductance were not significant. However, under HNO3 fumigation there was a significant increase in mesophyll conductance at low and high HNO3 levels while changes in maximum photosynthetic CO2 assimilation and stomatal conductance were not significant. We could not detect any activity of the antioxidant enzymes in the fumigated tobacco leaves. This is in spite of the fact that we were able to assay the enzymes in tobacco leaves grown in Israel. Conclusions. This project generated novel data, and potentially applicable to agriculture, on the differential response of lichens and tobacco to HNO3 and O3 pollutants. However, due to experimental problems and time limitation discussed in the body of the report, our data do not justify yet application for a full, 4-year grant. We hope that in the future we shall conduct more experiments related to our objectives, which will serve as a basis for a larger scale project to explore the possibility of using lichens and/or plants for biomonitoring of ozone and nitric acid air pollution.