Tesis: "Aromatic chemistry"

1

Robertson, Charles Ray. "Chemistry towards curved polycyclic aromatic hydrocarbons". abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1438911.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Sestiaa, Lionel G. "New pathways in aromatic polymer chemistry". Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402914.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Dainty, Richard Frank. "Aromatic annulations". Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242247.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Laws, Andrew Peter. "The quantitative electrophilic aromatic reactivity of some novel aromatic compounds". Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328304.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Myers, Eddie Leonard. "Heterocyclic aromatic nucleic acids". Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79056.

Texto completo

Resumen

In order to investigate the role played by the aromatic moiety of Aromatic Peptide Nucleic Acids (APNAs) in their ability to hybridize with RNA and DNA, as well as improve the solubility of APNA oligomers in aqueous solutions, a new generation of heterocyclic monomers were designed. APNA monomers, where the nucleobase can be thymine, cytosine adenine or guanine, with backbones contain thiophene and pyridine moieties were synthesized. Suitably protected APNA-APNA and PNA-APNA dimers were also synthesized as building blocks for the solid phase synthesis of APNA-PNA chimeras and APNA homopolymers. Due to the instability of the pyridine-containing APNA oligomers to the harsh acidic conditions required to cleave oligomers from the MBHA resin, a new protocol was developed for the synthesis of these molecules on the trityl chloride resin. Oligomers of PNA and APNA-PNA chimeras were successfully synthesized on this solid support, and cleaved from the resin using mild acidic conditions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Clough, Robert Steven. "The synthesis of aromatic polyethers by aromatic nucleophilic substitution". Case Western Reserve University School of Graduate Studies / OhioLINK, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=case1057072167.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Löbermann, Florian Wolfgang. "Contributions to the chemistry of polyhydroxylated aromatic compounds". Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-169770.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Ferguson, Jayne Louise. "Colossal Aromatic Molecules". Thesis, University of Canterbury. Chemistry, 2013. http://hdl.handle.net/10092/8108.

Texto completo

Resumen

This thesis describes the preparation of a series of compounds containing π-excessive, five-membered, heterocyclic rings with peripheral aryl substituents, designed to investigate their oxidative cyclodehydrogenation and/or photocyclisation to form curved, fused aromatic systems with a heterocyclic atom at the core of the compound. The ability of these compounds to undergo oxidative cyclodehydrogenation was investigated using a range of conditions, including the use of Lewis acidic transition metals, organic reagents and light as catalysts to carry out the desired carbon-carbon bond forming reactions. Two backbone linked 2,2’-biimidazole ligands were prepared to investigate their coordination chemistry with a range of different metal ions and counter ions. Two families of model compounds, including ten previously unreported compounds, were prepared and subjected to various conditions for oxidative cyclodehydrogenation and photocyclisation resulting in the isolation of compounds with one carbon-carbon bond formed between the peripheral aryl rings in the same position on the heterocyclic ring, nineteen previously unreported compounds were isolated. Additionally, in one case oxidative cyclodehydrogenation resulted in the formation of two carbon-carbon bonds, producing a highly strained aromatic compound containing a heterocyclic ring. Photocyclisation of one family of compounds resulted in the formation of a different heterocyclic core dependent upon the substituent on the nitrogen atom. Five pentaarylpyrrole compounds, three of which were previously unreported, were also prepared after the exploration of various synthetic routes towards the pentaarylpyrrole motif. Photocyclisation also resulted in the formation of one carbon-carbon bond. The compounds resulting from oxidative cyclodehydrogenation and photocyclisation were characterised by NMR spectroscopy, UV/vis spectroscopy and fluorometry, where possible X-ray crystallography was also used. The coordination chemistry of backbone linked 2,2’-biimidazole ligands to various metal ions could be controlled by the length of the backbone linker. The ethyl linked 2,2’-biimidazole ligand formed bridging and monodentate coordination compounds with various metal ions, the metallosupramolecular assemblies produced with silver ions could be controlled by the anion present. Discrete coordination complexes were usually formed, but in two cases metallopolymers were produced. The propyl linked 2,2’-biimidazole ligand formed exclusively discrete, chelating complexes with copper (II) metal ions. Eighteen coordination complexes were prepared during the course of this study characterized by X-ray crystallography, and NMR spectroscopy where appropriate.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Brown, James S. "The chemistry of nickel on the edge of polycyclic aromatic hydrocarbons /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1422914.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Walsh, Kelly Ann. "The alkylation of aromatic amines". Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7659.

Texto completo

Resumen

N-alkylated anilines can be obtained in moderate yields from aniline and methyl formate in the presence of Rh$\sb6$(CO)$\sb $ and KI after 72 hours at 180-200$\sp\circ$C. Ru$\sb3$(CO)$\sb $ gave similar results to the unpromoted rhodium carbonyl system. Formanilide and N-methylformanilide were also formed in the reaction. The (HCr(CO)$\sb5$) -anion in the form of its PPN$\sp+$ and Et$\sb4$N$\sp+$ salts also catalysed this reaction (under hydrogen) but was selective to the formanilide products. The presence of an electron donating group on the aromatic ring favoured the formation of alkylated products in the presence of bis(triphenylphosphine)iminium (PPN$\sp+$) hydridochromiumpenta-carbonyl. Several possible mechanisms were tested and the nature of the polynuclear catalysts investigated.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Poudel, Pramod Prasad. "NOVEL AROMATIC ION–PAIRS: SYNERGY BETWEEN ELECTROSTATICS AND Π-FACE AROMATIC INTERACTIONS". UKnowledge, 2012. http://uknowledge.uky.edu/chemistry_etds/4.

Texto completo

Resumen

This dissertation focuses on the design and study of charged aromatic molecules where weak π-π interactions synergize with electrostatic interactions to enhance the overall interaction between aromatic moieties. Each chapter investigates some aspect of this hypothetical synergy between electrostatics and π-face aromatic cohesion. The first chapter unveiled the importance of electrostatics in the intramolecular stacking of flexible aromatic molecular templates 1-2Br and 2a. While our previous studies found dicationic molecular template 1-2Br to have intramolecular π-stacking between electron poor pyridinium and electron rich xylylene moieties, no such stacking interaction was observed in the neutral analog 2a. Chapter two systematically explored the stacking pattern of electron poor aromatics in the form of oxygen- and / or nitrogen- substituted triangulenium cations, [1(NR)3]+ and [1(O)3(OH)3]+. As indicated in the chemical literature, triazatriangulenium cations [1(NR)3]+ with N- ethyl (and longer alkyl chains) chains were found to pack as face-to-face dimers. This study found the formation of columnar, face-to-face, n-meric association between aromatic cations in the structures with decreased steric interactions of the side chains in the stacking planes ([1(NMe)3]+ and [1(O)3(OH)3]+). Similar iso-structural triangulene based aromatic anions, (2)- and (3)2- didn’t indicate any facial interactions in the solid states. The possible synergy between unit charge electrostatics and π-face aromatic interactions was explored in aromatic ion pairs 1•2 of triangulene based aromatic cations and aromatic anions. This charge-assisted π-π stacking seems to be the novel way of getting strong π-system interactions where the strongest non-covalent force and the weakest non-covalent force: ionic bonding and π-stacking respectively synergize together. The π-π interaction between ionic aromatics in the solid state was investigated by means of single crystal x-ray diffraction and powder x-ray diffraction (PXRD). The interaction in the solution state was examined by UV-Vis spectroscopy, electrospray ionization mass spectroscopy (ESI-MS) and electrochemical studies. Studies found that optimal synergy was possible only in the ion pairs with no steric interactions of alkyl (or aryl) side chains in the stacking planes (1(O)3•2 & 1(NMe)3•2) and the interaction was found to be comparable with the strongest radical-assisted π-stacking described in the chemical literature.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Connor, Alan Lee. "Determining Conformational Preferences of Shape-Persistent Aromatic Oligoamides and Folding of Aromatic Oligoureas with Ion-Pair Associations". Thesis, State University of New York at Buffalo, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13426856.

Texto completo

Resumen

The synthesis and characterization of folding aromatic oligoamides with reduced constraint, ion-pair associations and solvent-mediated folding of aromatic oligoureas, and oligoamides with unique conformational variations involving simple structural inversion are presented in this thesis.

Chapter 1 is a review of the foldamer field defining structural features of peptides that are desired for replication by artificial building blocks. Foldamers are characterized as either peptidomimetic or abiotic based on intrinsic properties of the building blocks utilized. Each section of peptidomimetic and abiotic foldamers demonstrates the systematic design and characterization utilized for each system, including highlights of progressive developments within the field. This leads into the early development of helical aromatic oligoamides, developed by Gong and coworkers, incorporating rotation restricting three-center hydrogen bonds imbedded in the backbone. Overall, providing the relationship between our helical aromatic oligoamides and their place in the foldamer field.

Chapter 2 presents modifications in the design of robust aromatic oligoamides to incorporate reduced hydrogen bonding constraint within the backbone. This increased flexibility was to improve protein-like folding behavior for these previously robust oligoamides. Flexibility was designed by removing aromatic side chains adjacent to the benzene residues allowing only 5-membered ring (two-center) hydrogen bonding to remain. Two variations of oligoamides were synthesized involving alternating constraint consisting of interchanging three- and two-center hydrogen bonding along the aromatic backbone, and reduced constraint with only 2-center hydrogen bonding. Folding potentials are presented utilizing a combination of circular dichroism, 1D/ 2D NMR experiments, thermal denaturation and titration experiments in varying solvent conditions.

Chapter 3 begins with an overview of past aromatic oligourea design and cationic recognition of uncyclized and cyclized aromatic tetraureas. Anionic recognition of halides with ureas observed in literature was confirmed by concentration-dependent ¹H-NMR experiments for aromatic urea dimers, similar in structure to elongated oligourea sequences. Anions were also observed to associate with oligourea trimers with similar affinities compared to their iv tetraethylammonium salt counterions, not previously observed for the dimers. Cation binding within the cavity of these trimers was confirmed by 2D NMR experiments. Correlations between 2D NMR spectra and results from concentration-dependent ¹H-NMR experiments led to the conclusion of positive cooperative association between anion and cation pairs with oligourea trimer hosts. The conformational preference of longer aromatic oligoureas, incorporating fivemembered hydrogen bonding constraining the urea-linkage, was determined to favor a trans-trans conformation based on urea-linkage bond rotations that were computationally derived in collaboration with Professor Eva Zurek and Daniel Miller. Longer oligoureas were confirmed to also to bind tetraethyl- and tetrabutylammonium cations by 2D NMR experiments. Folding and chain-length dependence of these longer oligoureas were characterized by circular dichroism and ¹H-NMR, confirming solvent-dependent folding and aggregation. Finally an aromatic oligourea 9mer was confirmed to favor a helical structure stabilized by dimethylformamide.

Chapter 4 presents two aromatic oligoamides with a simple inversion between their αβ and βα-amino acid spacers which caused the individual conformational identity to differ dramatically, preventing these complementary strands to associate. A qualitative examination compared differences in structural properties by ¹H-NMR concentration-dependent, titrationdependent and temperature-dependent experiments. It was concluded that the oligoamide involving the αβ spacer preferred to fold upon itself, generating a stable β-turn which was confirmed by 2D NMR. The oligoamide incorporating a βα spacer self-dimerized with significant conformational interconversion, requiring the oligoamide to be examined at cryogenic temperatures to derive a specific conformation. In collaboration with Professor Eva Zurek and Daniel Miller, conformations derived from NOEs observed by 2D NMR experiments were examined computationally. A favored model paired with atomic distances calculated from optimized NOEs concluded the refinement of a specific conformation regarding this oligoamide.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Kennedy, R. J. "Copper-promoted nucleophilic aromatic substitution". Thesis, University of Kent, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355148.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Stephens, R. J. "Aromatic nitrations using dinitrogen pentoxide". Thesis, University of Exeter, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370935.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Crowley, Colin. "Fullerenes from polycyclic aromatic hydrocarbons". Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360582.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Nguyen, Quang. "Reinventing Aromatic Substitution: A Novel Look". TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1292.

Texto completo

Resumen

Electrophilic aromatic substitution (EAS) and directed ortho-metalation (DoM) involve the direct substitution of an arene hydrogen. A major drawback involving EAS is the necessity for harsh forcing conditions for the reaction to proceed. Catalysts such as Lewis acids FeBr3 and AICI3 for the introduction of halogens and acyl groups, respectively, are each highly toxic and corrosive. Textbook preparations of aryl iodides classicaly involved the use of iodine and nitric acid. This approach affords only modest yields and does not provide regiospecific substitution of most substituted aromatics because most contain ortho/para directors which afford mixtures of isomers. The novelty of our procedure for the synthesis of the iodinated aromatics is twofold in that regiospecific para-iodination is observed and hydrocarbon media are utilized. Hydrocarbon media are less hazardous and greener than media used for halogenations reported in literature. This procedure always yields derivatives regiospecifically substituted para to an electron donating substituent. Moreover, this method eliminates the need to use hazardous oxidative catalysts. DoM is a reaction regiospecifically substitute an arene hydrogen at the ortho position. The media used in DoM reactions are less hazardous than those required for a variety of EAS reactions. The only problem for this reaction is use of extremely strong bases, alkyllithium reagents, which are known to be air and water sensitive. However, the DoM reaction does eliminate the need to separate ortho/para isomer mixtures so that only a single product is generated. The metalation yields predominantly products regiospecifically substituted ortho-to the direcing metalating group (DMG). With our deficiency catalysis concept and subsequent purificaion methods, relatively pure ortho-lithiated intermediates have been prepared. The study of catalysts/promoters on the derivatization of these intermediates is anticipated to be extremely insightful. For this study, we have shown that highly selective, efficient ortho-lithiation can be achieved by deficiency catalysis utilizing n-BuLi as the only strong metalating base.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Mannion, Michael R. "Synthesis and chemistry of highly distorted polycyclic aromatic hydrocarbons". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0017/NQ52693.pdf.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Jones, Jason Robert. "Mechanism, catalysis and control in aromatic diazonium ion chemistry". Thesis, University of York, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306605.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Caron, Laurence. "Direct arylation of aromatic rings using palladium catalysis". Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28232.

Texto completo

Resumen

The first section illustrates the novel route to access the biphenyl motif. Starting from simple materials, nitroarenes and aryl halides, we are able to obtain different cross-coupled products in good to moderate yields using palladium as a catalyst. The optimization of the reaction conditions as well as the various biaryl motifs obtained are described.* The second section summarizes our efforts towards the development of universal reaction conditions that can be used for the arylation of a wide range of heterocycles. Although direct arylation products are available in the literature, no broadly accessible method is available yet. The heterocycles described are limited to azoles and the various motifs obtained are illustrated.* *Please refer to dissertation for diagrams.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Buckingham, Grant Thornton. "Pyrolysis and spectroscopy of cyclic aromatic combustion intermediates". Thesis, University of Colorado at Boulder, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10108707.

Texto completo

Resumen

We have studied the pyrolysis of aromatic combustion intermediates using an array of detection techniques. The molecules investigated include cyclic aromatic molecules with hydrocarbon substituents (ethylbenzene, n-propylbenzene, isopropylbenzene, and styrene), oxygen-containing substituents (anisole and phenol), resonance stabilized radicals (benzyl radical and tropyl radical) and phenyl radical. At the exit of a resistively heated micro-reactor (1 mm inner diameter, 3 cm long), the pyrolysis fragments are detected using photoionization mass spectrometry (PIMS), matrix isolation vibrational spectroscopy, microwave spectroscopy, tunable VUV synchrotron-based PIMS, and tabletop VUV PIMS with photoelectron photoion coincidence spectroscopy (PEPICO). This array of detection methods allows for the identification of all possible fragments including metastables, radicals, and atoms. The findings allow for detailed mechanistic information regarding which pathways are active at different pyrolysis temperatures and can also be used to help identify products and individual isomers that are formed during the gas-phase thermal decomposition of aromatic systems. By providing direct experimental pyrolysis data, models for fuel decomposition and soot formation can be improved to help understand current combustion systems and eventually aid in the design of superior fuel sources in the near future.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Murphy, Nicholas Patrick. "Radical aromatic cyclisation and substitution reactions". Thesis, University of Warwick, 2008. http://wrap.warwick.ac.uk/2286/.

Texto completo

Resumen

This dissertation is divided into five chapters. Chapter One consists of an introduction to radical cyclisation and rearrangement reactions. Chapter Two investigates the reactions of substituted arylsulfonamides 278a-l with copper bromide and an amine ligand-TPA. This reaction involves an alkyl radical generated from the copper (I) bromide/TPA complex, which can then undergo a 1,5- ipso attack onto the sulfonamide leading to a cyclohexadienyl radical intermediate. Re-aromatisation and extrusion of sulfur dioxide leads to an amidyl radical intermediate. This can undergo either cyclisation back onto the aromatic ring to give the 6-substituted oxindole 336, or reduction from H-atom abstraction by the solvent leading to rearranged amides. A minor product identified as a 5-substituted oxindole 333 may be formed from direct radical cyclisation onto the sulfonamide followed by extrusion of sulfur dioxide. An unambiguous synthesis of 333 was obtained through the Stollé method in order to rigorously identify this product. For completion, the rearranged amide 280e was also unambiguously synthesised from known literature sources. It has been shown that the selectivity towards either rearrangement or cyclisation is dependent upon the solvent used and temperature. For example, toluene induces excellent selectivity towards cyclisation (to furnish oxindoles), while using dichloromethane (DCM) induces a greater selectivity towards rearranged amides. Chapter Three explores the effects of varying the alkyl chain length on the nitrogen atom on selectivity, while keeping both the aryl group and initiator the same. It has been shown that selectivity towards the rearrangement (or decrease in cyclisation) occurred when the alkyl chain was increased from N-butyl to N-dodecyl. In addition a similar solvent effect on selectivity was observed as discussed in Chapter 3, notably relatively more rearranged amide was produced with DCM and oxindoles with toluene. Chapter four involves investigating the copper-mediated radical cyclisation of haloamides to give oxindoles directly. The final chapter consists of the experimental.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

McMurdo, J. "Electrophilic aromatic substitution using methoxyacetyl chloride". Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302997.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Wilson, Mark James. "Activity relationships for aromatic crown ethers". Thesis, University of Strathclyde, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249872.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Abbott, Andrew. "Transition metal electrochemistry in aromatic solvents". Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330164.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Nowicka, Ewa. "Selective oxidation of polynuclear aromatic hydrocarbons". Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/40092/.

Texto completo

Resumen

This thesis targets the selective oxidation of polynuclear aromatic compounds, which is considered as a preliminary step of upgrading of heavy oils, resids and bitumens to higher value materials in the liquid phase using different catalytic systems. Oxidation studies concentrated on simple model polyaromatic compounds and their alkylated derivatives. Ruthenium ion catalyzed oxidation chemistry has the potential to selectively oxidize PAHs and this system was studied in great detail with particular attention made to the reaction solvent system. Through careful studies it was found that the use of a monophasic solvent system led to the selective oxidative opening of an aromatic ring to produce the dialdehyde derivative. It was demonstrated that under standard conditions the rate of oxidation increased with the size of the fused ring system. 1H NMR methodology was developed to quantify the percentage of alkyl chain hydrogens preserved after reaction. It was found that the ruthenium based system demonstrated a high affinity for the oxidation of aromatic carbon with a low tendency to oxidise aliphatic carbon. These studies formed the basis of a detailed investigation into the mechanism of ruthenium ion catalyzed oxidation of PAHs. Investigation into another catalytic system which uses a homogeneous tungsten catalyst with hydrogen peroxide as the oxidant was also performed. Early studies showed that the H2WO4/H2O2 catalytic system exhibits high solvent dependant selectivity towards preferential oxidation of aromatic carbon. What is more, studies using alkylated aromatics with a alkyl chain greater than C8 showed that even in a non polar solvent the selectivity of oxidation is directed towards the aromatic carbon. A range of catalytic systems containing tungsten, ruthenium, heteropolyacids and their heterogenised equivalents were also applied to the oxidation of PAHs. Au-Pd supported catalysts in combination with molecular oxygen and H2WO4 were also used for the oxidation of PAHs and the results obtained opened a new path in the research of PAHs. Studies on the oxidative desulfurization, denitrogenation of heteroaromatics and the demetallation of nickel and vanadium porphyrines was also performed and are reported in this thesis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Chen, Yali. "New benzyne precursors : the chemistry of benzobisoxadisilole and benzotrisoxadisilole". HKBU Institutional Repository, 2006. http://repository.hkbu.edu.hk/etd_ra/723.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Noble, Darren Robert. "Regiospecific aromatic nitration via nitrosation". Thesis, University of Exeter, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263236.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Berryman, Orion Boyd 1981. "Anions and electron-deficient aromatic rings". Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/8159.

Texto completo

Resumen

xx, 281 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
More than two-thirds of all enzyme substrates and cofactors are anionic, emphasizing the essential role that anions play in biological processes. Moreover, anions can have detrimental effects on the environment by causing ground water contamination when anions such as perchlorate, phosphate and nitrate develop in intolerable levels. Owing to the prevalent nature of anions, traditional strategies employed to target anions--including hydrogen bonding, metal ion coordination and electrostatic interactions--have been extensively studied. An alternative approach to anion binding would complement the powerful array of existing techniques. Recently, in the supramolecular chemistry community, new insight has been cast on how anions attractively interact with electron-deficient arenes, suggesting that aromatic rings are a viable anion binding strategy to balance existing methods. Chapter I provides a historical perspective of anions interacting with electron- deficient arenes. This outlook has its origins in the late 1800s with the discovery of colored charge-transfer complexes between donor and acceptor molecules and continues with the progression of the field leading up to the recent supramolecular fascination. Chapter II represents our initial efforts at measuring anion/arene interactions in solution. In particular, sulfonamide based hydrogen bonding receptors were developed with pendant aromatic rings to test the strength of anion/arene interactions in solution. Complementary computational chemistry and crystallography were utilized to supplement the solution studies. Chapter III describes our quantum calculations and crystallographic efforts at using only electron-deficient arenes to bind halides. A Cambridge Structure Database survey supports our emphasis of understanding multiple anion/arene interactions. Chapter IV illustrates how tripodal anion receptors can be developed to bind anions using only electron-deficient aromatic rings. Furthermore, subtle changes in anion binding geometries are observed with isomeric receptors and corroborated with Density Functional Theory calculations. Chapter V is dedicated to the preparation of electron-deficient anion receptors that are conformationally stabilized by hydrogen bonds. Chapter VI is committed to using our knowledge of anion binding to study a series of ethynyl-pyridine sulfonamides capable of hydrogen bonding to small molecules and anions. In conclusion, Chapter VII is a summary and future prospective for the field of anion/arene interactions. This dissertation includes previously published and co-authored material.
Adviser: Darren W. Johnson

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Ellis, Colin. "The oxidation chemistry of the xylenes and related aromatic hydrocarbons". Thesis, University of Hull, 1999. http://hydra.hull.ac.uk/resources/hull:8040.

Texto completo

Resumen

The research was concerned with obtaining kinetic data and product information for the oxidation chemistry of the isomeric xylenes and benzyl radicals at 753K. A trace amount (0.01 % for kinetic study, 0.5% for product study) of each xylene was separately added to slowly reacting mixtures of H₂ + O₂ in aged boric-acid-coated Pyrex reaction vessels at 753K and 500 Torr total pressure. From measurements of the relative loss of H₂ and hydrocarbon rate constants for the reactions of the radicals H and H0₂ with each xylene were obtained. H + Xylene → Products k=1.3* 10⁹ 1 mol¯¹ S¯¹ (p-xylene), 1.4*10⁹ I mol¯¹ S¯¹ (m-xylene), 1.8* 10⁹ 1 mol¯¹ S¯¹ (a-xylene). HO₂ + Xylene → Products k=9.4*10⁴ I mol¯¹ S¯¹ (p-xylene), 1.03*10⁵ 1 mol¯¹ S¯¹ (m-xylene), 1.2*10⁵ 1 mol¯¹ S¯¹ (o-xylene). A detailed examination of the reaction products was carried out over a wide range of mixture composition. The major aromatic products from the oxidation of the xylenes were the isomeric tolualdehydes, toluene and a-xylylcne oxide (from a-xylene). These were found to be similar to the products formed from the oxidation of toluene at 753K. From examination of the products available it was also possible to obtain more detailed rate constants for the attack of H radicals at each xylene giving specific products. H + Xylene → Methylbenzyl k=7.3*10⁸ 1 mol¯¹ s¯¹ (p-xylene), 8.3*10⁸ 1 mol¯¹ s¯¹ (m-xylene), 1.2*10⁹ 1 mol¯¹ s¯¹ (o-xylene). H + Xylene → Toluene k=5.6*10⁸ 1 mol¯¹ s¯¹ (for all three xylenes). H + Xylene → CH₃-C₆H₃-CH₃ k=9.1 * 10⁶ I mol¯¹ s¯¹ (p-xylene), 8.4 * 10⁶ I mol¯¹ s¯¹ (m-xylene), 9* 10⁵ I mol¯¹ s¯¹ (a-xylene). In the case of H0₂ + RH, thermochemical considerations lead to the conclusion that both abstraction from and addition to the ring will be considerably less energetically favourable than the equivalent reaction of H atoms. Consequently k(HO₂₊xylene) should be taken to be the rate constant for HO₂ + Xylene → Methylbenzyl. The decomposition of neopentylbenzene in the presence of oxygen and propene at 753K and a total pressure of 60Torr in an aged boric-acid-coated Pyrex reaction vessel was used to determine rate constant" for the reactions between H0₂ and benzyl radicals. The decomposition of neopentylbenzene at 753K produced t-butyl and benzyl radicals. The t-butyl radicals react with O₂ to produce HO₂ radicals. The presence of propene was used to determine the concentration of HO₂ radicals by monitoring the rate of production of propylene oxide. From measurement of the yields of benzaldehyde and toluene yields, and the rate of production of propylene oxide, rate constants for the reactions of HO₂ with benzyl radicals producing benzaldehyde and toluene were determined as 4.36* 10⁹ I mol¯¹ s¯¹ and 8.44* 10⁸ I mol¯¹ s¯¹ respectively at 753K. A detailed examination of the products produced from the decomposition of neopentylbenzene in the presence of oxygen showed that the primary products were benzaldehyde, toluene, i-butene and 2-methyl-l-phenylprop-l-ene. The key features highlighted in this research are the similarity in the oxidation chemistry between the xylenes and toluene and the importance of the reactions of the benzyl radical in the oxidation of methyl-substituted benzenes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Close, Adam James. "Regioselective routes to tetrasubstituted aromatic compounds". Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/64912/.

Texto completo

Resumen

Polysubstituted aromatics are highly desirable in medicinal chemistry for library generation and the tetrasubstituted aryl motif appears in many pharmaceuticals. Current methods to access 1,2,4,5- and 1,2,3,4- tetrasubstituted aromatics are problematic. Therefore new routes giving defined regiochemical outcomes with four different orthogonal functionalities were sought. This work took two directions; 1) the bromination and nitration of trisubstituted aryl MIDA boronates, and 2) the nitration of trisubstituted aryl bromides, both leading to the desired tetrasubstituted aromatics. MIDA boronates are boronic acids masked with N-methyliminodiacetic acid (MIDA). This allows for iterative palladium cross-coupling reactions. The first step in the work was developing a new rapid microwave-mediated method (5-15 min) towards MIDA boronates using ether poly-ethylene glycol 300, acetonitrile or dimethylformamide as a solvent. This methodology gave a library of over 20, mainly aryl or heteroaryl MIDAboronates.1,2 Trisubstituted aryl-MIDAboronates were then brominated or nitrated giving 6 novel tetrasubstituted aromatic compounds. The 3 new tetrasubstituted aryl-MIDAboronates bromides were then used in a selection of iterative Suzuki–Miyaura cross coupling reactions (SM) to show the potential uses of the compound in library generation. Three different bromo-fluorobenzaldehyde regioisomers were nitrated giving 3 different tetrasubstituted aromatics. These 3 compounds were then subjected to several different conditions to modify them i.e. nitro reduction, Sonogashira couplings, reductive aminations, Clauson-Kaas pyrrole synthesis. A number of tetrasubstituted anilines were reacted with 4-chloro-6,7-dimethoxyquinazoline to afford novel, potential kinase inhibitors.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Straw, T. A. "Aspects of the chemistry of some highly crowded aromatic ligands". Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6215/.

Texto completo

Resumen

A series of ortho-substituted arylchlorophosphoranes has been prepared. The structures of these compounds have been studied by the use of (^31)Cl n.q.r. and solid-state (^31)P n.m.r. . It has been shown that ortho substitution by groups such as CH(_3) or CF(_3) in phosphoranes of the type P(Ar)Cl4 prevents complexation with Lewis bases, and this is also found to be the case for the derived phosphoniumions [P(Ar)Cl(_3)](^+). The bis(aryl)chlorophosphoranes with these bulky aryl groups (where it is possible for them to be formed) are found to have ionic phosphonium salt structures, regardless of the electronic properties of the aryl group. In some cases, where the aryl groups are too bulky and too electronegative, P-C bond cleavage takes place on chlorination of the bis(aryl)chlorophosphine, and the most bulky group is lost. The phosphoranes PRCl(_4) (where R = CH(_2)Cl or CHCl(_2)) were also prepared. For R = CH(_2)Cl, the solid phosphorane was found to have the ionic, [PRCl(_3)] [PRCl(_5)], structure. This is the first example of an organo-substituted chlorophosphorane to be shown to have the "phosphorus pentachloride structure” in the solid state. By contrast, P(CHCl(_2))Cl(_4) was shown by solid-state (^31)P n.m.r. to be a molecular, 5-coordinate species. The generation of phosphoranides of the type [P(Ar)(CN)(_2)X](^-), with ortho- substituted aryl substituents, has also been investigated. From (^31)P n.m.r. it has been shown that the 2-(methyl)phenyl group can be incorporated into such systems. Various aryl- and aryloxy-1,3,2-dioxaphospholanes were prepared, with the aim of generating metaphosphate species via ethylene elimination. Data from mass spectrometry and from flow pyrolysis suggest that transient metaphosphates of the type ArPO(_2) can be formed in this manner. Results would also indicate that where Ar = 2,6-(CF(_3))(_2)C(_6)H(_3) the respective metaphosphate undergoes a rearrangement via insertion into the ortho-CF(_3) group. It has been shown that the symmetrical diphosphene ArP=PAr (where Ar - 2,4,6-(CF(_3))(_3)C(_6)H(_2)) can be formed by magnesium couphng of the aryldichloro- phosphine. However, attempts to form asymmetrical diphosphines and other low- coordinate phosphorus species by DBU coupling of P(2,6-(CF(_3))(_2)C(_6)H(_3))H(_2) with the respective chloro species were unsuccessful, due to preferred formation of Ar(H)P- P(H)Ar or ArP=PAr. The 2,4,6-(CF(_3))(_3)C(_6)H(_2) group was successfully incorporated into various dia- zophosphine systems. Of particular note was the characterization of the first ever P(III)-P(III) stabilized nit rile imine. By varying the aryl groups on phosphorus in such systems (C(_6)H(_5), C(_6)F(_5) or 2,4,6-(CF(_3))(_3)C(_6)H(_2)) it was possible to obtain further insights into the requirements for the stabilization of nitrile imines, and various trapping reaction were also performed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Musgrave, Oliver Charles. "Studies in the chemistry of synthetic and natural aromatic compounds". Thesis, University of Aberdeen, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408791.

Texto completo

Resumen

Describes investigations in three areas of aromatic chemistry, namely, the preparation and properties of aromatic organoboron compounds, the reactions of carbonyl compounds with aromatics, and the structure and synthesis of naturally occurring carbonyl compounds. The papers cover an extended period, from 1955 to 2003, during which time spectroscopic techniques developed greatly. The early work did not have the advantage of modern NMR and MS techniques let alone X-ray crystal structure determination and had to rely on the limited structural information provided by UV and IR measurements.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Lee, Han Baek. "Organo nickel and platinum chemistry at the edge of corannulene". Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5928.

Texto completo

Resumen

Thesis (Ph. D.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Dec. 27, 2007). Includes bibliographical references.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Pilgrim, Ben Samuel. "Novel palladium-catalysed routes to aromatic heterocycles". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:d143b5bf-1738-48ce-be75-4a25249acb9d.

Texto completo

Resumen

A brief summary of the use of palladium as a catalyst, the characteristic reactivity of palladium complexes and the commonly used palladium-catalysed cross coupling reactions is given, with a special focus on the palladium-catalysed α-arylation of enolates and its application to the synthesis of aromatic heterocycles. The synthesis of aromatic heterocycles via both traditional methods and more recent metal-catalysed approaches is discussed in the context of isoquinolines. The palladium-catalysed oxidation of dihydrofurans bearing an ortho-bromophenyl group at the 2-position to the corresponding 2-phenyl furans is disclosed along with some preliminary mechanistic investigations. A novel synthetic route to isoquinolines is detailed involving the palladium-catalysed α-arylation of ketone enolates with an appropriate ortho-substituted aryl halide to furnish a protected 1,5-dicarbonyl intermediate. The versatility of these intermediates is demonstrated with their conversion into isoquinolines, isoquinoline N-oxides and naphthols. The scope of the synthetic procedure is fully exemplified across more than 30 different scaffolds covering the full spectrum of electron-rich to electron-deficient moieties. The intermediates were shown to be amenable to functionalisation with electrophiles, leading to isoquinolines bearing additional substitution at the C4 position. Sequential one-pot procedures were developed allowing three and four component couplings to directly deliver highly-substituted isoquinolines from commercially available starting materials. This methodology was utilised in the total synthesis of the natural product berberine in 26% overall yield and a longest linear sequence of six steps.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

James, Ian M. "Behaviour of aromatic hydrocarbons in urban atmospheres". Thesis, Northumbria University, 2001. http://nrl.northumbria.ac.uk/2681/.

Texto completo

Resumen

Quasi-continuous measurement of benzene, toluene, ethylbenzene and isomers of xylene in northern England has been performed using an automated thermal desorption - gas chromatography - flame ionisation detector (TD-GC-FID) system. The TD-GC-FID system was mounted in a mobile laboratory, together with a TEOM (Tapered Element Oscillating Microbalance) system for particulate monitoring, and a weather station. Both systems have been applied to urban and suburban sites in order to examine the behaviour of BTEX aromatics at these localities, under a range of boundary layer environments. Measurement of BTEX aromatics and particulate matter has also been performed within a bus depot, a site which was effectively isolated from the free boundary layer overnight, to contrast the behaviour of BTEX in sunlit and non-sunlit atmospheres. Time series analysis of the concentration ratios of individual BTEX aromatics has been performed and diurnal seasonality has been demonstrated at a number of sites. Significant differential removal of individual BTEX aromatics has been found to occur overnight. Relative removal rates have been measured for this period, and values indicate that accepted tropospheric transformation mechanisms of the BTEX aromatics are not responsible. The available experimental and theoretical evidence collected in this research serves to support the supposition that a physical process, which is related to atmospheric temperature, volatility of individual BTEX aromatics, and pressures of individual BTEX aromatics, governs nocturnal differentiation of the concentration of BTEX aromatics. A postulated effect, which may contribute to nocturnal differential, is preferential absorption of particular BTEX aromatics to a liquid organic carbon phase, which has been shown to be associated with diesel carbonaceous combustion aerosol. The latter supposition has been partially corroborated by the findings of a separate study exploring the composition of carbonaceous combustion aerosol by GCMS, XRF, DTA, DSC, and FTIR.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Jones, Kerina Helen. "The metabolism of aromatic compounds by fungi". Thesis, Aberystwyth University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309993.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Williams, Alvin Scott. "Charge transfer induced osmylation of aromatic compounds". Thesis, University College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309472.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Norman, Lana Laurette. "Solution properties of self-assembling azo aromatic polymers". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19563.

Texto completo

Resumen

Amphiphilic copolymers of hydrophobic Disperse Red 1 acrylate (DR1A) and hydrophilic acrylic acid (AA) were dissolved in THF and a H2O/THF co-solvent series. The thermal cis-trans isomerization behavior of the azo groups was measured by means of flash photolysis to investigate self-assembled structure in solution. The rate constants observed for the azo-containing polymers permit an estimation of how the thermal isomerization is influenced by both polymer and solution properties. In pure THF the relaxation can be analyzed by a monoexponential decay. In aqueous-organic solutions all poly(DRlA-co-AA) samples show a slow isomerization process due to inhibited mobility of the azo groups, preceded by a faster isomerization process for unaggregated azo groups. In such cases, the relaxation of the cz's-isomer was fit to a biexponential function which clearly demonstrates two distinct local chromophore environments. The spectroscopic results of this study suggest that weakly aggregated states of the amphiphilic polymers in an aqueous-organic solution can be readily studied through isomerization spectroscopy to estimate the fractions of aggregated groups involved and their local environment.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Whitham, Michael Edward. "The Cure Reaction of an Aromatic Thermosetting Polyimide". W&M ScholarWorks, 1986. https://scholarworks.wm.edu/etd/1539625349.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Peat, Andrew J. E. 1970. "Novel approaches to functionalized indoles and polysubstituted aromatic compounds". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10221.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Ouellette, Mélanie. "Gas-phase Ion Chemistry of Hydroxy and Amino-substituted Interstellar Polycyclic Aromatic Hydrocarbons and Protonated Polycyclic Aromatic Hydrocarbons". Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31349.

Texto completo

Resumen

The gas-phase ion chemistry of hydroxyl- and amino-substituted polycyclic aromatic hydrocarbons (PAHs) and their protonated counterparts were studied using mass spectrometry. Ions were generated using an electron ionization (EI) source and the unimolecular chemistry of metastable ions was studied by performing mass-analysed ion kinetic energy spectrometry (MIKES) experiments with a magnetic sector tandem mass spectrometer. Collision-induced dissociation (CID) experiments were used in conjunction with MIKES experiments to determine ion structure. The ten molecules studied were: 1-naphthol, 2-naphthol, 1-naphthylamine, 2-naphthylamine, 1-aminoanthracene, 2-aminoanthracene, 1-phenanthrol, 9-phenanthrol, 1-hydroxypyrene and 1-aminopyrene. Since it is believed that larger PAHs, on the order of more than 50 carbon atoms, populate the interstellar medium, the goal of this study was to attempt to extrapolate the results from smaller systems to larger ones. The trends found include: hydroxy-substituted PAH radical cations lose carbon monoxide spontaneously and amino-substituted PAH radical cations lose HCN. Mechanisms for both processes are proposed, and it appears from the present results that this process should extrapolate to larger PAHs. Another trend found was that all the remaining fragment ions were always a closed ring. Protonated amino-substituted PAHs were generated by electrospray ionization using a quadruple time-of-flight mass spectrometer. By protonating 1-naphthol and 2-naphthol using methane in the high-pressure EI source, it was found that they lost exclusively H2O. As for 2-naphthylamine, 1-aminoanthracene and 2-aminoanthracene, it was found that 2-naphthylamine lost NH3 and a hydrogen atom, NH3being the dominant channel. However, as the ion size 3 increases, the hydrogen-loss channel became the dominant channel. This means that larger PAHs will likely lose exclusively a hydrogen atom to reform the parent radical cation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Tian, Zhenjiao. "Oxidation and Reduction Process for Polycyclic Aromatic Hydrocarbons and Nitrated Polycyclic Aromatic Hydrocarbons". The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1228333650.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Vogt, Robert Aaron. "ULTRAFAST DYNAMICS IN NITRO- AND (ORGANOPHOSPHINE)GOLD(I)-POLYCYCLIC AROMATIC HYDROCARBONS". Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1363168243.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Liljenberg, Magnus. "Quantum Chemical Studies of Aromatic Substitution Reactions". Doctoral thesis, KTH, Tillämpad fysikalisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-206964.

Texto completo

Resumen

In this thesis, density functional theory (DFT) is used to investigate the mechanisms and reactivities of electrophilic and nucleophilic aromatic substitution reactions (SEAr and SNAr respectively). For SEAr, the σ-complex intermediate is preceded by one (halogenation) or two (nitration) π-complex intermediates. Whereas the rate-determining transition state (TS) for nitration resembles the second π-complex, the corresponding chlorination TS is much closer to the σ-complex. The last step, the expulsion of the proton, is modeled with an explicit solvent molecule in combination with PCM and confirmed to be a nearly barrierless process for nitration/chlorination and involves a substantial energy barrier for iodination. It is also shown for nitration that the gas phase structures and energetics are very different from those in polar solvent. The potential energy surface for SNAr reactions differs greatly depending on leaving group; the σ-complex intermediate exist for F-/HF, but for Cl-/HCl or Br-/HBr the calculations indicate a concerted mechanism. These mechanistic results form a basis for the investigations of predictive reactivity models for aromatic substitution reactions. For SEAr reactions, the free energy of the rate-determining TS reproduces both local (regioselectivity) and global reactivity (substrate selectivity) with good to excellent accuracy. For SNAr reactions good accuracies are obtained for Cl-/HCl or Br-/HBr as leaving group, using TS structures representing a one-step concerted mechanism. The σ-complex intermediate can be used as a reactivity indicator for the TS energy, and for SEAr the accuracy of this method varies in a way that can be rationalized with the Hammond postulate. It is more accurate the later the rate-determining TS, that is the more deactivated the reaction. For SNAr reactions with F-/HF as leaving group, the same method gives excellent accuracy for both local and global reactivity irrespective of the degree of activation.

QC 20170510

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Hammonds, Mark. "On the chemistry and spectroscopy of PAHs in circumstellar and interstellar environments". Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602526.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Kettley, J. C. "Van der Waals complexes of large aromatic molecules". Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371128.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Davies, Ilona Lynn. "Analysis of polycyclic aromatic compounds by multidimensional chromatography". Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328575.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Black, Michael. "Gas phase cyclisation reactions of aromatic free radicals". Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/10822.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Murray, Tracey Arnold. "Mechanism of flavin cofactor binding to flavodoxins: the role of aromatic residues and the aromatic gate". The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1060639958.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Jalali, Elnaz. "Regiospecific P-Bromination of Activated Aromatic Systems – Greener Approach". TopSCHOLAR®, 2017. http://digitalcommons.wku.edu/theses/1950.

Texto completo

Resumen

The halogenated derivatives of heterocyclic compounds (haloarenes) are highly utilized in many fields of chemistry, including drug discovery, medicinal, and material chemistry. There are a variety of ways to functionalize an aromatic system and introduce halogen substituent into the ring. However, electrophilic aromatic substitution (EAS) has been the focus of growing attention, particularly for electronrich substrates. Electrophilic aromatic bromination protocols are one of the most important electrophilic aromatic substitution reactions. However, preparation of bromoarenes classically recommends the use of highly oxidative agents along with utilizing various metal catalysts in a halogenated solvent. The corrosive and toxic nature of these reagents and need of harsh conditions for these protocols make their utility less desirable in current practice. Furthermore, lack of regioselectivity for most substituted aromatics is the other distinguished drawback, since most products contain ortho/para directors which afford a mixture of isomers. The innovation of our procedure for the bromination of various substituted aromatic compounds is twofold in that highly regiospecific para-bromination of activated aryls by treatment with NBS has been accomplished. Although various reaction mediums, such as cyclohexane, acetone, and acetonitrile has been used in this procedure, the significant high yields of the product formation along with the very short reaction times using acetonitrile make this approach more attractive. That this regiospecific p-substitution takes place under such mild conditions leads us to question whether it is EAS.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tesis sobre el tema "Aromatic chemistry"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros