Dissertations / Theses: 'Alkane And Alkene'

1

Peter, Sebastian. "Oxyfunctionalization of alkanes, alkenes and alkynes by unspecific peroxygenase (EC 1.11.2.1)." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-113321.

Full text

Abstract:

Unspecific peroxygenase (EC 1.11.2.1) represents a group of secreted hemethiolate proteins that are capable of catalyzing the selective mono-oxygenation of diverse organic compounds using only H2O2 as a cosubstrate. In this study, the peroxygenase from Agrocybe aegerita (AaeUPO) was found to catalyze the hydroxylation of various linear (e.g n-hexane), branched (e.g. 2,3-dimethylbutane) and cyclic alkanes (e.g. cyclohexane). The size of n-alkane substrates converted by AaeUPO ranged from gaseous propane (C3) to n-hexadecane (C16). They were mono-hydroxylated mainly at the C2 and C3 position, rather than at the terminal carbon, and the corresponding ketones were formed as a result of overoxidation. In addition, a number of alkenes were epoxidized by AaeUPO, including linear terminal (e.g. 1-heptene), branched (2-methyl-2-butene) and cyclic alkenes (e.g. cyclopentene), as well as linear and cyclic dienes (buta-1,3-diene, cyclohexa-1,4-diene). Furthermore, the conversion of terminal alkynes (e.g. 1- octyne) gave the corresponding 1-alkyn-3-ol in low yield. Some of the reactions proceeded with complete regioselectivity and - in the case of linear alkanes, terminal linear alkenes and alkynes - with moderate to high stereoselectivity. The conversion of n-octane gave (R)-3-octanol with 99% enantiomeric excess (ee) and the preponderance of the (S)-enantiomer reached up to 72% ee of the epoxide product for the conversion of 1-heptene. Catalytic efficiencies (kcat/ Km) determined for the hydroxylation and respectively epoxidation of the model compounds cyclohexane and 2-methyl-2-butene were 2.0 × 103 M-1 s-1 and 2.5 × 105 M−1 s−1. The results obtained in the deuterium isotope effect experiment with semideuterated n-hexane and the radical clock experiment with norcarane clearly demonstrated that the hydroxylation of alkanes proceeds via hydrogen abstraction, the formation of a substrate radical and a subsequent oxygen rebound mechanism. Moreover, stopped-flow experiments and substrate kinetics proved the involvement of a porphyrin radical cation species (compound I; AaeUPO-I) as reactive intermediate in the catalytic cycle of AaeUPO, similar to other hemethiolate enzymes (e.g. cytochrome P450 monooxygenases, P450s)
Die Gruppe der Unspezifischen Peroxygenasen (EC 1.11.2.1) umfasst extrazelluläre Häm-Thiolat-Enzyme, die mittels H2O2 als Cosubstrat die selektive Monooxygenierung unterschiedlicher organischer Verbindungen katalysieren. In der vorliegenden Arbeit konnte gezeigt werden, dass die von Agrocybe aegerita sekretierte Peroxygenase (AaeUPO) verschiedene lineare (z. B. n-Hexan), verzweigte (z. B. 2,3-Dimethylbutan) und zyklische Alkane (z. B. Cyclohexan) hydroxyliert. Die Größe der von der AaeUPO umgesetzten Substrate reichte vom gasförmigen Propan (C3) bis hin zu n-Hexadekan (C16). Die Alkane wurden bevorzugt am zweiten und dritten Kohlenstoffatom (C2 und C3) hydroxyliert; eine Hydroxylierung am terminalen Kohlenstoff konnte nur vereinzelt und in geringem Umfang beobachtet werden. Die Überoxidationen der primär gebildeten, sekundären Alkohole führte außerdem zur Entstehung der entsprechenden Ketonderivate. Darüber hinaus wurde eine Vielzahl linearer terminaler (z. B. 1-Hepten), verzweigter (z. B. 2-Methyl-2-Buten) und zyklischer Alkene (z. B. Cyclopenten) sowie linearer und zyklischer Diene (1,3-Butadien, 1,4-Cyclohexadien) durch die AaeUPO epoxidiert. Die Umsetzung terminaler Alkine (z. B. 1-Octin) führte zur Entstehung der jeweiligen 1-Alkin-3-ole. Manche dieser Reaktionen verliefen ausgeprägt regioselektiv und, im Falle der linearen Alkane sowie der linearen terminalen Alkene und Alkine, mit mittlerer bis hoher Stereoselektivität. So ergab beispielsweise die Umsetzung von n-Octan einen Enantiomerenüberschuss größer 99% für (R)-3-Octanol; die Epoxidierung von 1-Hepten lieferte einen Enatiomeerenüberschuss (ee) von bis zu 72% für das (S)-Enantiomer. Die katalytischen Effizienzen, die für die Hydroxylierung bzw. Epoxidierung der Modellverbindungen Cyclohexan und 2-Methyl-2-Buten ermittelt wurden, betragen 2.0 × 103 M-1 s-1 und 2.5 × 105 M−1 s−1. Der ausgeprägte Deuterium-Isotopen-Effekt, der im Zuge der Umsetzung von semideuteriertem n-Hexan beobachtet wurde sowie die Ergebnisse des Radical-Clock-Experiments mit Norcarane als Substrat bestätigten, dass die Hydroxylierung von Alkanen über Wasserstoffabstraktion, die Bildung eines Substratradikals und anschließende direkte Sauerstoffrückbindung verläuft. Die Stopped-Flow-Experimente belegen zudem das Auftreten eines Porphyrin-Kationradikal-Intermediates (Compound I; AaeUPO-I) im katalytischen Zyklus der AaeUPO (vergleichbar mit dem reaktiven Intermediat der P450-Monooxygenasen)

APA, Harvard, Vancouver, ISO, and other styles

2

Ly, Mai Anh. "Evaluation of components for the heterologous expression of Mycobacterium chubuense NBB4 monooxygenases." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11638.

Full text

Abstract:

Bacterial monooxygenases have important roles in the biogeochemical cycling of carbon and nitrogen, as well as potential applications in biocatalysis of pharmaceutically important epoxides, and bioremediation of chlorinated pollutants. However, use of monooxygenases for biotechnology requires understanding of microbial physiology and the catalytic properties (e.g. substrate range and kinetic parameters) of monooxygenases themselves. Heterologous expression of monooxygenases is one way to advance our fundamental knowledge of MO functions, and also to enable future applications. This project focused on designing a new heterologous expression system for monooxygenases, using the soluble di-iron ethene monooxygenase (EtnMO) and the particulate copper hydrocarbon monooxygenase (HMO) from Mycobacterium strain NBB4 as models. The new Mycobacterium/E. coli shuttle vector (pMycoFos) allows stable cloning of the EtnMO and HMO enzymes in E. coli, and functional expression of these in Mycobacterium smegmatis mc2-155. This study evaluated the requirement for accessory proteins such as chaperonins and catalase peroxidase in the hydrocarbon metabolism of strain NBB4, and charactersied three such proteins (Cpn60.1, Cpn10, and KatG) by expression and purification in E. coli. Although co-expression of these proteins did not enhance MO activity in M. smegmatis, evidence for a role for KatG in alkane metabolism was obtained from the higher peroxidase activity seen in butane-grown cells relative to cells grown on acetate. Codon-optimisation was tested as a means of enabling expression of the EtnMO genes in E. coli, but this approach was not successful. However, possible evidence for the importance of codon usage was obtained from experiments on heterologous expression of the EtnMO in Pseudomonas putida strain KT2440. This high-GC bacterium was capable of expression of the unmodified EtnMO genes. This is the first example of functional expression of an alkene monooxygenase (group 4 SDIMO) in a gram-negative organism.

APA, Harvard, Vancouver, ISO, and other styles

3

Yip, Wing-ping, and 葉永平. "Alkane C-H bond oxidations and alkene dihydroxylations by oxorutheniumcomplexes of chelating tertiary amine ligands." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31246254.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Wagener, Alex [Verfasser], and Stefan [Akademischer Betreuer] Ernst. "Adsorptive Trennung von Gemischen kurzkettiger Alkane und Alkene an nanostrukturierten porösen Adsorbentien / Alex Wagener. Betreuer: Stefan Ernst." Kaiserslautern : Universitätsbibliothek Kaiserslautern, 2012. http://d-nb.info/1021529036/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Prat, Casellas Irene. "Bioinspired non-heme iron catalysts for challenging oxidative transformations: mechanistic studies and catalytic applications on selective alkane hydroxylation and alkene cis-dihydroxilation." Doctoral thesis, Universitat de Girona, 2013. http://hdl.handle.net/10803/117778.

Full text

Abstract:

The functionalization of hydrocarbons in a sustainable manner is one of the main challenges for chemists. Their abundance in nature as natural gas or crude oil makes them the most convenient chemical feedstock. The oxidation of hydrocarbons is one of the most interesting reactions, because the introduction of an oxygen atom introduces functionality in these molecules, increasing their value as reagents for further chemical transformation. However, these reactions are fundamentally difficult due to the low reactivity of alkyl C-H bonds. Current available methodologies involve highly reactive-oxidizing reagents, high temperatures and long-time reactions in order to overcome this lack of reactivity. These harsh conditions introduce drawbacks in terms of chemo- and regioselectivity, essential to produce synthetic valuable products. An important step forward is the development of one-step oxidation methodologies, allowing the oxidation of C-H and C=C with high regio- and stereoselectivity. Natural systems, such as iron enzymes, are capable of perform this chemistry with high selectivity and efficiency. Iron is the most abundant metallic element in the earth and is essential for live. In addition, this lack of toxicity makes it and attractive material to substitute more toxic and expensive metals currently used. One of the main objective of this thesis is design of iron complexes that mimics the structure and function of these natural enzymes with the aim of find new methodologies for the selective C-H and C=C bond oxidation using green conditions. Furthermore, the study of these compounds could give useful information about the oxidation mechanisms operating in oxygenase enzymes. The results obtained in this thesis clarify the mechanism by which the oxidation of the C-H bond with retention of stereochemistry takes place at a mononuclear non-heme iron site, and evidence the formation of a high valent iron (V) capable of perform the cis-dihydroxylation of alkenes. Furthermore, a new complex is described as an efficient and selective catalyst capable of performing this chemistry in a scale amenable for synthetic applications
La funcionalització d'hidrocarburs de manera sostenible i eficaç és un dels principals reptes per la química moderna, degut a que la seva abundància natural els fa una important matèria primera. L'oxidació d'hidrocarburs és una de les reaccions més interessants, ja que la introducció d’un àtom d’oxigen en l’estructura d’un hidrocarburs li confereix funcionalitat química, fa augmentar el seu valor i els converteix en reactius adients per subseqüents transformacions químiques. No obstant això, aquestes reaccions són difícils a causa de la inherent baixa reactivitat dels hidrocarburs. Les metodologies actualment disponibles impliquen la utilització d’espècies altament oxidants i tòxiques, altes temperatures i llargs temps de reacció per tal de superar aquesta manca de reactivitat. Aquestes condicions extremes eviten que la química es pugui dur a terme de manera selectiva, fet essencial per produir productes d’alt valor sintètic. Un avanç important és el desenvolupament de metodologies de reacció suaus que permetin l'oxidació d'enllaços C-H i C=C amb alta regio- i estereoselectivitat. Els sistemes naturals, com ara enzims de ferro, són capaços de realitzar aquesta química. El ferro és l’element metàl•lic més abundant a la terra i és clau per nombrosos processos vitals, a més la seva baixa toxicitat el fa un atractiu material per substituir els elements de segona i tercera seria de transició més cars i tòxics emprats actualment. Un dels principals objectius d’aquesta tesi és dissenyar catalitzadors de ferro que imiten l’estructura i la funció dels enzims naturals per tal de trobar una nova metodologia que permeti l'oxidació selectiva d'enllaços C-H i C=C utilitzant condicions suaus i mediambientalment més benignes que les metodologies tradicionals. A més, l’estudi d’aquests sistemes pot donar informació útil sobre el mecanisme d’oxidació del propi enzim. Els resultats obtinguts en aquesta tesi aclareixen el mecanisme pel qual es duu a terme la hidroxilació de l’enllaç C-H amb retenció de la estereoselectivitat en centres mononuclears de ferro, i evidencien la formació d’una espècie de ferro (V) d’alt estat d’oxidació capaç de catalitzar la cis-dihidroxilació d’alquens. A més a més, es descobreix un catalitzador eficient i selectiu capaç de dur a terme aquesta química en condicions d’escala preparativa

APA, Harvard, Vancouver, ISO, and other styles

6

Haak, Edgar. "Titankatalysatoren für die intermolekulare Hydroaminierung von Alkinen und Alkenen." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964517639.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Groaz, Elisabetta. "Alkene and alkyne metathesis reactions using ruthenium initiators." Thesis, King's College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440449.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Mehta, Brinda Mayank. "Green Resins based on Alkene- and Alkyne-containing Triglycerides." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1468795161.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Pongtavornpinyo, Ruti. "Indium Carbenes Alkenes and Alkanes." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508494.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Edwards, Andrew R. "Polyfluorinated alkenes and alkynes." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4772/.

Full text

Abstract:

The research described within this thesis may be divided into four main subject areas: 1) The use of (Z)-2H-heptafluorobut-2-ene (10) as a synthon for hexafluorobut- 2-yne (4) in Diels-Alder reactions was investigated. Novel 'one-pot' routes to a variety of bis(trifluoromethyl) substituted furan and arene derivatives were discovered, along with the synthesis of the novel diene, bis(trifluoromethyl)cyclopentadiene (46), from cyclopentadiene.2) A variety of nucleophiles were successfully reacted with (10), the products of which were identical to those that have been, or would be expected to be, formed from the reaction of the same nucleophile with (4). A novel route to a fluorinated quinoline derivative was also discovered.3) Perfluoroperhydrophenanthrene (74) was used as a 'bulking agent' to replace the hydrocarbon solvent used in halogen exchange reactions for the preparation of octafluorocyclopentene (3), chlorofluoro -pyridine, -pyrimidine, and -benzene derivatives. New 'one-pot' syntheses of hexafluorobut-2-yne (4), octafluorobut-2-ene (6) and hexafluorocyclobutene (2) were also discovered.4) Various routes were explored in an attempt to improve the present literature preparations of tetrafluoropropyne (79), including pyrolysis and elimination methods. Tetrafluoroallene (81), and trace amounts of (79), were found to be formed on the elimination of hydrogen fluoride from 2H-pentafluoropropene (5).

APA, Harvard, Vancouver, ISO, and other styles

11

Pimm, Austen David. "The application of #alpha#-metallated heterosubstituted alkenes to trisubstituted alkene synthesis." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332548.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Mahelová, Zora. "Charakterizace chemického složení dehtu po zplyňování biomasy." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2016. http://www.nusl.cz/ntk/nusl-240964.

Full text

Abstract:

Biomass is a renewable source of energy and represents an acceptable alternative to fosil fuels. Usable methods of energetic use of biomass are combustion and gasification. Main interest is focused on gasification in last years. Gasification is based on conversion of organic material to usable gaseous product called syngas, which can be used as a fuel for energy production. Large amount of tar is formed as a by-product of incineration and gasification of biomass. Tar is composed by various mixture of organic substances, has a negative effect on operating conditions and is a potential threat to environment. Experimental part of this study was focused on analysis of tar obtained by gasification of various kind of biomass. Selected groups of hydrocarbons and oxygen compounds were identified in analysed samples. Individual biomass samples were compared regarding to determined relative content of selected substances. Analysis was done by complete twodimensional gas chromatography with mass spectrometric detection (GCxGC/TOF-MS).

APA, Harvard, Vancouver, ISO, and other styles

13

Greenhalgh, Mark David. "Iron-catalysed hydrofunctionalisation of alkenes and alkynes." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/17624.

Full text

Abstract:

The iron-catalysed hydrofunctionalisation of alkenes and alkynes has been developed to give a range of functionalised products with control of regio-, chemo- and stereochemistry. Using a bench-stable iron(II) pre-catalyst, the hydrosilylation, hydroboration, hydrogermylation and hydromagnesiation of alkenes and alkynes has been achieved. Iron-catalysed hydrosilylation, hydroboration and hydrogermylation of terminal, 1,1- and 1,2-disubstituted alkyl and aryl alkenes and alkynes was developed, in which the active iron catalyst was generated in situ (Scheme A1). Alkyl and vinyl silanes and pinacol boronic esters were synthesised in good to excellent yield in the presence of a range of functional groups. Catalyst loadings as low as 0.07 mol% were demonstrated, along with catalyst turn-over frequencies of up to 60 000 mol h−1. The iron-catalysed formal hydrocarboxylation of a range of styrene derivatives has been developed for the synthesis of α-aryl carboxylic acids using carbon dioxide and ethylmagnesium bromide as the stoichiometric hydride source (Scheme A2). Detailed mechanistic studies have shown this reaction proceeds by iron-catalysed hydromagnesiation to give an intermediate benzylic organomagnesium reagent. The nature of the active catalyst and reaction mechanism have been proposed.

APA, Harvard, Vancouver, ISO, and other styles

14

Shoai, Shiva. "Regioselective rhodium-catalyzed alkyne hydrothiolation with alkane thiols : substrate scope and mechanistic investigations." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/27028.

Full text

Abstract:

The optimization and substrate scope of ClRh(PPh₃)₃-catalyzed alkyne hydrothiolation with alkane thiols producing E-linear vinyl sulfides is presented. The reactions generally proceed in good yields with good selectivities for a variety of alkane thiols and alkynes. Bulky aliphatic alkynes result in the best selectivity, while aryl alkynes with para-substituted electron donating groups give the best yields. The presence of coordinating functional groups in either the substrate or solvent negatively affects the reaction both in yield and selectivity. Deuterium-labeling studies indicate that the reaction proceeds via thiol oxidative addition, migratory alkyne insertion into the Rh-H bond, followed by reductive elimination. Investigations into the mechanism of Tp*Rh(PPh₃)₂-catalyzed alkyne hydrothiolation are discussed. Five mechanisms are identified as being the most likely for this process; experiments were designed to support or refute each of these possibilities. Two mechanisms are definitively dismissed and another is dismissed as highly unlikely. The results cannot distinguish between the remaining two. The product distribution of hydrothiolation is analyzed and compared to other precatalysts. Stoichiometric reactivity of Tp*Rh(PPh₃)₂ with benzyl thiol is presented. Two new complexes, proposed to be Tp*Rh(PPh₃)₂(HSBn) and Tp*Rh(H)(SBn)(PPh₃), are generated. Presumed Tp*Rh(H)(SBn)(PPh₃), prepared in situ, does not catalyze alkyne hydrothiolation. Kinetic analysis was complicated by reaction inhibition at high thiol concentrations and competing side-reactions at high alkyne concentrations. Kinetic isotope effect experiments indicate that the alkyne is not involved in the rate-determining step; however, differences in the reactivity of several para-substituted phenyl acetylenes suggest that the rate-determining step is influenced by alkyne electronics. Overall, the reaction appears to obey the following rate law under normal catalytic reaction conditions rate = k[Tp*Rh(PPh₃)₂]¹[thiol]¹[alkyne]⁰. The reaction is hypothesized to proceed by thiol oxidative addition, migratory alkyne insertion into the Rh-S bond, followed by reductive elimination.

APA, Harvard, Vancouver, ISO, and other styles

15

Sorigue, Damien. "Biosynthèse d'hydrocarbures dérivés des acides gras chez les microalgues." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4084.

Full text

Abstract:

Les alcanes et les alcènes sont des hydrocarbures non cycliques important dans l’industrie. Ils sont synthétisés à partir d'acides gras par une grande variété d’organismes mais les connaissances à ce sujet sont très limitées chez les microalgues. Le but de ces travaux était donc de rechercher la présence d’alcanes ou d’alcènes dans diverses microalgues modèles, et d’essayer d’identifier la ou les enzymes responsables de la synthèse de ces composés. Nous avons mis en évidence la présence d’hydrocarbures linéaires en C15-C17 chez les microalgues Chlorella et Chlamydomonas. Ces composés étaient synthétisés uniquement en présence de lumière. L’absence dans le génome de ces microalgues d’homologues de gènes codant pour des enzymes connues de synthèse d’alcanes/alcènes a permis de conclure à la présence d’un nouveau système de synthèse d’hydrocarbures. Des purifications enzymatique et des analyses protéomique ont permis d’identifier une enzyme candidate qui exprimée chezE. coli est suffisante à la synthèse d’hydrocarbures. L'étude de cette enzyme révella qu'il s'agissait d'une photoenzyme utilisant l'énergie des photons bleue pour décarboxyler les acides grass en alca(e)ne. La structure de cette photoenzyme montre la présence un tunnel hydrophobe contenant l’acide gras et le cofacteur FAD. Cette nouvelle enzyme nommée « alcane photosynthase » amène de nombreuses question: qu'elle est la fonction des hydrocarbures chez ces microorganismes? Quel est le mécanisme catalytique de l’alcane photosynthase? Enfin, elle offre de nouvelles possibilités pour la production de biocarburants utilisant directement l’énergie solaire
Alkanes and alkenes are important in industry. Alkanes and alkenes are synthesized from fatty acids by a variety of organisms, such as plants and insects. However, the presence in microalgae of enzymes converting fatty acids into hydrocarbons has been poorly studied. The aim of this work was to investigate the presence of alkanes and alkenes in various microalgae models, and try to identify the enzymes responsible for the synthesis of these compounds.We have first demonstrated the presence of linear hydrocarbons C15-C17 in microalgae Chlorella and Chlamydomonas. Then we have shown that the main hydrocarbon formed in Chlorella and Chlamydomonas was derived from cis-vaccenic acid and was synthesized only in the presence of light. Absence of homologues of genes coding for known alkane/alkene biosynthetic enzymes in the genome of Chlorella and Chlamydomonas indicate the presence of an unknown pathway. Enzymatic purification and proteomic analysis allowed to identify a candidate enzyme which, expressed in E. coli lead to the formation of hydrocarbons with variable chain lengths, thus demonstrating that it was really an synthase alkane. Characterization showed that the enzyme was a photoenzyme, which used blue light to catalyse the decarboxylation of fatty acid to an alka(e)ne. The three-dimensional structure of this enzyme revealed a hydrophobic tunnel containing the fatty acid and the FAD cofactor

APA, Harvard, Vancouver, ISO, and other styles

16

Naohisa, Nakagawa. "Selective Synthesis of Alkynes and Alkenes Using Iron-Catalyzed Cross-Coupling and Organometallic Addition Reactions." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/200444.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Hobbs, Paul Michael. "Computational sorption studies of alkanes and alkenes in zeolites." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320085.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Guo, Zijian. "Developing unstrained alkenes and alkynes for bioorthogonal chemistry." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289423.

Full text

Abstract:

Bioorthogonal reactions, due to its excellent selectivity and time-efficiency, have emerged as a popular tool for protein and cell probing. Among all the bioorthogonal reactions, the inverse electron-demand Diels-Alder reaction (IEDDA) reaction has its advantage of bearing the fastest kinetics. Although the IEDDA reaction drew considerable attention in chemical biology in the last decade, challenges lie in finding the suitable dienophiles. Strained dienophiles, for example, trans-cyclooctene derivatives, can undergo ultrafast IEDDA reactions and therefore have been extensively developed. Unstrained alkenes and alkynes, however, have not been well investigated as IEDDA handles. In general, unstrained dienophiles are more straightforward to synthesise compared with strained dienophiles, therefore they are more accessible to researchers. In addition, the absence of a highly reactive bond makes unstrained dienophiles inert to biological nucleophiles, which allows effectively cellular labelling. In this dissertation, I described three different unstrained dienophiles for different biological purposes. Allyl handle is thiol-stable and non-toxic, which was utilised to label apoptotic cells in a pre-targeting manner. Enol ethers can react with tetrazines to decage protected amino acids and prodrugs. Potassium arylethynyltrifluoroborate, as a novel dienophile, was shown to react fast with pyridyl tetrazines controllably and this new IEDDA was applied to label proteins site-selectively and to fluorescently label two proteins orthogonally. In addition to IEDDA reactions, other bioorthogonal reactions were also developed using these versatile unstrained handles. Allyl-bearing amino acids and proteins can undergo an acetophenone-mediated hetero-[2+2] photocycloaddition with maleimide derivatives, expanding the toolbox of photo-triggered chemistry for protein modification. The potassium arylethynyltrifluoroborate handle was also found reactive in copper(I)-catalyzed alkyne-azide cycloaddition reaction (CuAAC) and showcased the huge potential for protein labelling and multicolour cellular labelling.

APA, Harvard, Vancouver, ISO, and other styles

19

STADERINI, Samuele. "Photoinduced hydrothiolation and hydrophosphonylation of alkenes and alkynes." Doctoral thesis, Università degli studi di Ferrara, 2014. http://hdl.handle.net/11392/2389036.

Full text

Abstract:

Hydrofunctionalization of terminal double or triple bonds have become classical ligation tools for facile assembly of building blocks into larger molecules especially because comply Sharpless’ prerequisite to be considered “click-chemistry” reactions. In particular the free-metal photoinduced radical thiol-ene (TEC) and thiol-yne (TYC) couplings are well-known to be atom economy, high-efficient, catalyzed only by light and completely regioselective. If both TEC and TYC have already been studied on simple substrates as linear terminal alkenes or alkynes, only few researches have been carried out about particular molecules as protein, peptides and endo-glycals. Hydrothiolation of protein, peptides and aminoacids has been studied to obtain a double different substitution of the peptidic scaffold with one carbohydrate and one marker (fluoresceine or biotine) using TYC. A new technique to synthesize S-disaccharides has been developed starting from different glycals and thio-glucose, demonstrating the efficiency of TEC on internal internal double bonds. The successful work about hydrothiolation of different substrates has pushed us to study both hydrophosphonylation of alkenes and alkynes starting from the same conditions of TEC and TYC reactions. The different reactivity of the functionalization agent (thiol or H-phosphonate) has resulted in different conditions for the addition to double bonds, but not in a loss of efficiency o regioselectivity. On the other hand the addition on a triple bond has resulted to be ineffective and to stop at the internal double bond intermediate. A thiol-ene coupling on this intermediate, formally a vinyl phosphonate, gives equilibration to E form of the alkene without traces of hydrothiolation adducts. It is well known that multivalent effect is a key factor in supramolecular chemistry and it governs many biological interactions, in particular in the relationship between pathogenic microorganisms and their host that involves protein–glycan recognition. The affinity of a multivalent cluster is highly dependent on the combination of the carbohydrate head with the cluster core and the spacer between them; several families of multivalent bioactive molecules have been developed by a large numbers of groups all around the world using disparate synthetic techniques. Thiol-Ene (TEC) and Thiol-Yne (TYC) couplings have been chosen as ligation tool for the synthesis of a variety of multivalent biomolecules containing carbohydrates or peptidic termini supported on different bio-inactive clusters as dendrimers and the rigid silica cube known as POSS (polyhedral oligomeric silsesquioxane). Both TEC and TYC are highly efficient, regioselective and atom economy reactions that, moreover, permit us to avoid purification problems due to metal catalysis or to use large excess of reagents to have a complete substitution on the central core. In fact all the reactions have been carried out with success, high yield and without by-products of any kind. Affinity toward specific target of this large library of compounds has been tested by Enzyme-Linked Lectin Assay (ELLA) and results from good to excellent have been found in all classes of compounds.

APA, Harvard, Vancouver, ISO, and other styles

20

Hoenigman, Rebecca Lee. "Theoretical and experimental investigations of diradicals, pyramidalized alkenes, and bent alkynes /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/8580.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Hunt, Ashley D. "Intramolecular Cope-type Hydroamination of Alkenes and Alkynes Using Hydrazides." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19881.

Full text

Abstract:

Nitrogen-containing molecules are ubiquitous in both natural products and pharmaceutical drugs, thus an efficient method for the formation of these motifs is of great importance. Hydroamination, that is the addition of an N-H bond across an unsaturated carbon-carbon bond of an alkene or alkyne, stands out as a potential approach to obtain such molecules. To date, most research in this area relies on transition-metal catalysis to enable such reactivity. In efforts directed towards metal-free alternatives, we have developed a simple, metal-free hydroamination of alkenes using hydrazides. Further investigation into the corresponding reactivity of alkynes with hydrazides has provided access to novel azomethine imine products. In Chapter 2, expansion of the substrate scope with respect to the intramolecular hydroamination of alkenes using hydrazides, as well as studies directed towards elucidation of the mechanism of this reaction will be presented. The intramolecular hydroamination of alkynes using hydrazides and methods to access and isolate the azomethine imine products formed will be discussed in Chapter 3.

APA, Harvard, Vancouver, ISO, and other styles

22

Zhang, Yaming. "Electron spin resonance studies of organic radical cations : theoretical and experimental approach." Thesis, Liverpool John Moores University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313090.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Peter, Sebastian [Verfasser], Martin [Akademischer Betreuer] Hofrichter, John T. [Akademischer Betreuer] Groves, and Katrin [Akademischer Betreuer] Scheibner. "Oxyfunctionalization of alkanes, alkenes and alkynes by unspecific peroxygenase (EC 1.11.2.1) / Sebastian Peter. Gutachter: Martin Hofrichter ; John T. Groves ; Katrin Scheibner. Betreuer: Martin Hofrichter." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://d-nb.info/1068152370/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Kleinschmidt, Olaf. "Photokatalytische Oxidation von Alkenen und Alkanen mit Sauerstoff an belichtetem Titandioxid." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962781142.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Ingle, R. "Selective oxidation of alkanes and alkenes by polyoxometalates using green oxidants." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2008. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2631.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

ZHENG, TAO. "MOLECULAR SIMULATION OF DIFFUSION AND SORPTION OF ALKANES AND ALKANE MIXTURES IN POLY[1-(TRIMETHYLSILYL)-1-PROPYNE]." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin973701057.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Régent, Damien [Verfasser], and Bernhard [Akademischer Betreuer] Breit. "Rhodium-catalyzed intra- and intermolecular alkene hydroacylation = Rhodium-katalisierte Intra- und Intermolecular Alken Hydroacylation." Freiburg : Universität, 2014. http://d-nb.info/1115813811/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Fröhling, Bettina. "Reaktionen elektrophiler und nucleophiler Schwefeldonoren mit cyclischen Alkenen und Alkinen." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964453169.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Janson, Pär. "Oxidative Trifluoromethylation and other Functionalization Reactions of Alkenes and Alkynes." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-103064.

Full text

Abstract:

This thesis concerns the use of various potent oxidants in organic synthesis. The main focus is directed at selectively introducing trifluoromethyl groups into compounds containing double or triple bonds. All reactions proceed under mild conditions and can in most cases be performed on the bench-top. We have developed three different procedures for transformations of activated alkenes and alkynes as well as quinones. In paper I the selective introduction of a trifluoromethyl group together with an oxygen functionality to double and triple bonds is demonstrated. Paper II is focused on the related chemoselective cyanotrifluoromethylation in which a cyano group is added instead of the oxygen functionality. Paper III describes a new procedure for C–H trifluoromethylation of quinones. Our studies on the mechanistic aspects of the above reactions are described in Paper IV. In these studies we investigated the ligand and substituent effects in Cu-catalyzed reactions. Paper V is focused on a conceptually new palladium-catalyzed allylic C–H acyloxylation of olefins under oxidative conditions. The procedure uses an inexpensive, safe and environmentally benign oxidant, sodium perborate, which is activated with acetic anhydride.

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.

APA, Harvard, Vancouver, ISO, and other styles

30

Okada, Takumi. "Studies on Ruthenium Complex-Catalyzed Functionalization of Alkenes and Alkynes." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149811.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Garba, Mustapha Danlami. "Valorisation of alkanes and alkynes by transhydrogenation in petrochemical processes." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8719/.

Full text

Abstract:

The production of high premium fuel is an issue of priority to every refinery. The trans-hydrogenation process was devised to convert two low value refinery cracked products to premium products; the conversion processes involve the combination of dehydrogenation and hydrogenation reactions as a single step process. The low value refinery products (i.e. alkanes and alkynes or alkadienes) have been converted to alkenes (olefins) by trans-hydrogenation using catalysts system based on VOx, CrOx and Pt all supported on alumina. Although trans-hydrogenation has been disclosed in many patents over decades, only little academic literature is available. The success of the process over various catalysts has been claimed in many of these patents. However, further studies are still required to ascertain the actual reaction mechanism, mitigating carbon deposition and catalyst deactivation, and the role of different catalysts to optimize the reaction desired products. The current research work evaluates the potential of CrOx/Al2O3, K-CrOx/Al2O3, Pt/Al2O3 and K-Pt/Al2O3 to investigate the trans-hydrogenation of the pentane (P)/1-hexyne (1HY) system, the pentane (P)/1,5-hexadiene (1,5-HD) system and the pentane (P)/2,4-Hexadiene (2,4-HD) system over a range temperatures (523-773 K). The fresh catalysts were first characterised by N2 adsorption using the BET method, X-ray diffraction, Raman spectroscopy, Thermogravimetric analysis, Temperature programme oxidation (TPO), Temperature programmed reduction (TPR), Electron paramagnetic resonance (EPR), Atomic absorption spectroscopy (AAS) and colorimetric analysis. The Free energy (ΔG) for the reaction of pentane with 1-hexyne, 1,5-hexadiene and 2,4-hexadiene shows that trans-hydrogenation is thermodynamically favoured at most temperatures for the reaction of pentane with 1-hexyne, however this is not always the case when hexadienes are the hydrogen acceptors. When 2,4-HD is the acceptor, ΔG is +ve at all the reaction temperatures tested. When pentane or hexyne/hexadiene or a 5:1 mixture was passed over the catalyst, in the temperature range of 523K -773 K, it was found that trans-hydrogenation process had taken place but many of the products are alkylated olefinic and alkylated hydrocarbons. Regarding all systems previously mentioned above, the ratio of olefin to alkylated olefin products was ~50:50 at 773K, however, this ratio was found to vary at other temperatures. The lowest ratio of ~10:90 was obtained at 523K. Dissociation of the hydrocarbon reactant was also observed leading to production of cracked products such as CH4, C2H4 and subsequent formation of a carbonaceous overlayer on the catalyst surface. This was not the case with the 2,4-hexadiene reactant, the trans-hydrogenation is poor, as expected from the free energies. The trans-hydrogenation process was shown to improve the conversion of pentane when co-fed with the hexyne to ~26% and to ~90% when co-fed with 1,5HD using the chromia catalyst at 773K, both values are much higher than the equilibrium conversion of the pentane dehydrogenation. Higher conversions of the pentane were subsequently obtained with other catalysts, but the chromia/alumina and K-CrOx/Al2O3 catalyst exhibits greater trans-hydrogenation activity. With the 2,4HD acceptor, very low conversions of pentane were obtained with all the catalysts: in general conversions lower than when the pentane was run alone were obtained. The products observed were unique for each catalyst. However, it was observed that for each catalyst, only the distribution of the products changed with temperature. This also accounted for changes in both the cracking products and the carbon laydown on the catalyst. The deactivation regeneration cycles shows very similar conversion of both reactants. There is a small deactivation observed for the longer time run; however these were not very significant. It was observed that some of the major products were consumed with time, but are used for the formation of other major products. However, this is more prominent with pentane/hexyne run using the CrOx/Al2O3 catalyst.

APA, Harvard, Vancouver, ISO, and other styles

32

Szuromi, Endre. "Alkene-oxo and alkene-alkene coupling on Pt(II)." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4156.

Full text

Abstract:

Thesis (Ph. D.)--University of Missouri-Columbia, 2005.
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 on (November 14, 2006) Vita. Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

33

Chan, Wing-kei. "Oxidation of alkenes and alkynes catalyzed by a cyclodextrin-modified ketoester and metalloporphyrins." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B36709591.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Kluwer, Alexander Marco. "Palladium-catalyzed stereoselective hydrogenation of alkynes to (Z)-alkenes in common solvents and supercritical CO2." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/75435.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Fosu, Stacy C. "Functionalization of Arenes, Amines, Alkenes, and Alkynes Mediated by Radical Pathways." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555514456659022.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Rode, Katharina. "Studies Toward Selenium-pi-Acid Catalyzed Oxidative Functionalizations of Olefinic and Acetylenic Multiple Bonds." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-1491-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Elser, Iris [Verfasser], and Michael R. [Akademischer Betreuer] Buchmeiser. "(Pre-)ionic and/or chiral alkene and alkyne metathesis catalysts of group 6 / Iris Elser ; Betreuer: Michael R. Buchmeiser." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2018. http://d-nb.info/1183678274/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Tóth, Krisztián [Verfasser], and Klaus T. [Akademischer Betreuer] Wanner. "Synthesis and biological evaluation of novel N-substituted nipecotic acid derivatives with an alkyne, trans-alkene or cis-alkene spacer as GABA uptake inhibitors / Krisztián Tóth ; Betreuer: Klaus T. Wanner." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2018. http://d-nb.info/1177682087/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Daini, Masaki. "Catalytic Carboboration of Alkynes and Alkenes via Activation of Boron-Chlorine Bond." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/159405.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Yada, Akira. "Nickel/Lewis Acid Dual Catalysis for Carbocyanation Reactions of Alkynes and Alkenes." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/120818.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Yeo, Benjamin Roy. "Alkanes, alkenes and aromatics : the oxidative dehydrogenation of n-octane using iron molybdate catalysts." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/76035/.

Full text

Abstract:

The oxidative dehydrogenation (ODH) of n-octane to produce octene at atmospheric pressure has been studied using an industrially supplied iron molybdate catalyst from Johnson Matthey (JM). In situ X-ray diffraction studies revealed at temperatures ≥450 °C the catalyst undergoes a reductive phase transition when reacted with noctane at 450 °C where the phase changes from Fe2(MoO4)3-MoO3 to FeMoO4-MoO2-Mo4O11. As a result, if the temperature is taken back below this point the catalyst does not revert to the original phase and therefore the same activity and selectivity cannot be achieved.

APA, Harvard, Vancouver, ISO, and other styles

42

Chan, Wing-kei, and 陳永基. "Oxidation of alkenes and alkynes catalyzed by a cyclodextrin-modified ketoester and metalloporphyrins." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B36709591.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Gómez, Martín Laura. "Bioinspired iron and manganese catalysts for the effective and selective oxidation of alkanes and alkenes." Doctoral thesis, Universitat de Girona, 2010. http://hdl.handle.net/10803/8056.

Full text

Abstract:

La gran eficiència, selectivitat i les condicions suaus exhibides per les reaccions que tenen lloc al centre actiu de les metal·looxigenases són la font d'inspiració per la present dissertació. Amb l'objectiu de dissenyar catalitzadors d'oxidació eficients hem fet ús de dues estratègies: la primera consisteix en el disseny de complexos amb baix pes molecular inspirats en aspectes estructurals de la primera esfera de coordinació del centre metàl·lic d'enzims de ferro i de manganès. Aquests complexos s'han estudiat com a catalitzadors en l'oxidació selectiva d'alcans i d'alquens fent servir oxidants "verds" com ara l'H2O2. La segona estratègia està basada en l'ús de la química supramolecular per tal de desenvolupar estructures moleculars auto-acoblades amb la forma i les propietats químiques desitjades. Concretament, la construcció de nanocontenidors amb un catalitzador d'oxidació incrustat a la seva estructura ens permetria dur a terme reaccions més selectives, tal com passa en les reaccions catalitzades per enzims.
The high efficiency, selectivity and mild conditions exhibited by the reactions that take place in the active site of metallooxygenases are the source of inspiration of the present dissertation. With the aim of designing efficient oxidation catalysts, we make use of two different strategies: the first one is the design of low molecular weight complexes inspired by structural aspects of the first coordination sphere of the metal active site of non-heme iron and manganese enzymes. These complexes are studied as catalysts for the selective oxidation of alkanes and alkenes using green oxidants such as H2O2. The second strategy is based on the use of supramolecular chemistry to develop self-assembled molecular structures with desired shape and chemical properties. Particularly, the construction of cavity-containing 3D nanovessels with an oxidation catalyst embedded in their structures would allow us to perform more selective reactions, analogously to the reactions catalyzed by enzymes.

APA, Harvard, Vancouver, ISO, and other styles

44

Wilkinson, Jon N. "Regioselective reactions at a diruthenium centre." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266954.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Correia, Leslie Daniel Camara. "Oxygen transfer in hydrocarbon-aqueous dispersions and its applicability to alkane-based bioprocesses." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/999.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Criswell, Leah. "Neutron diffraction and quasielastic neutron scattering studies of films of N-alkanes and a branched alkane absorbed on graphite." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/6010.

Full text

Abstract:

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 on March 11, 2008) Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

47

Wassermann, Tobias N. "Umgebungseinflüsse auf die C-C- und C-O-Torsionsdynamik in Molekülen und Molekülaggregaten Schwingungsspektroskopie bei tiefen Temperaturen." Berlin Logos, 2009. http://d-nb.info/1000809706/04.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

de, Orbe Izquierdo María Elena. "Gold-Catalyzed Intermolecular Reactions of Alkynes with Alkenes: Novel Reactivities and Global Mechanistic Picture." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/663302.

Full text

Abstract:

La catàlisi amb or es una ferramenta poderosa per la construcció d’enllaços C-C i la creació de complexitat molecular mitjançant l’activació selectiva d’alquins. Malgrat els avanços en reaccions intramoleculars d’alquins amb alquens, la versió intermolecular es encara desafiant, ja que els productes finals son també alquens que competeixen amb els substrats donant oligomeritzacions. En aquesta Tesi Doctoral, explorem reaccions intermoleculars d’un ampli rang d’alquins amb alquens i investiguem els mecanismes experimentalment i mitjançant càlculs DFT. El nostre grup va desenvolupar la cicloadició [2+2] d’arilalquins amb alquens catalitzada per or(I) donant regioselectivament ciclobutens. Ara hem trobat que els arilalquins orto-substituits reaccionen amb alquens donant 1,3-diens mitjançant un procés tipus metàtesis, mentre que 1,3-butadiins menys estèricament impedits reaccionen amb alquens proporcionant 1-alqinilciclobutens. Un complet estudi teòric va mostrar que els intermedis clau en estes transformacions son els ciclopropilcarbens d’or(I), les propietats electròniques i estèriques dels quals determinen la seua evolució per divergents camins amb energies properes. Així, sofreixen un reordenament per passos generant 1,3-diens, o una expansió d’anell donant ciclobutens. La implicació d’aquests intermedis va ser suportada per generació d’aquests independentment, examinant la seua reactivitat. Com els ciclobutens son esquelets importants en productes naturals i farmacèutics, vam decidir expandir la cicloadició [2+2] catalitzada per or, sintetitzant ciclobutens mes funcionalitzats. 1,3-Enins i poliens van ser substrats apropiats per a la construcció d’1-vinil-, 3-vinil o 3-alquinilciclobutens. Esta metodologia es complementaria a les cicloadicions [2+2] catalitzades per altres metalls. També es van desenvolupar transformacions directes de ciclobutens a diverses arquitectures mitjançant cicloadicions, apertura d’anell, expansió o contracció. Finalment, hem descobert reaccions de bromoalquins amb al·lilsilans catalitzades per or que proporcionen resultats totalment diferents: 1,4-enins mitjançant un procés tipus d’acoblament creuat, o 1,4-diens per al·lilació/ciclació en cascada. Basant-nos en experiments i càlculs, el mecanisme pareix procedir a través d’un reordenament sense precedents.
La catálisis de oro es una poderosa herramienta para construir enlaces C–C y crear complejidad molecular mediante la activación selectiva de alquinos. Pese a los avances en reacciones intramoleculares de alquinos con alquenos, la versión intermolecular supone aún un reto, ya que los productos finales son también alquenos que compiten con los sustratos dando oligomerizaciones. En esta Tesis Doctoral, exploramos reacciones intermoleculares de un amplio rango de alquinos con alquenos e investigamos los mecanismos por experimentos y cálculos DFT. Nuestro grupo desarrolló la cicloadición [2+2] de arilalquinos con alquenos catalizada por oro para construir regioselectivamente ciclobutenos. Ahora hemos encontrado que los arilalquinos orto-sustituidos reaccionan con alquenos para formar también 1,3-dienos en un proceso tipo metátesis, pero los 1,3-butadiinos menos estéricamente impedidos generan 1-alquinilciclobutenos. Un estudio mecanístico detallado mostró que los intermedios clave en estas transformaciones son ciclopropil carbenos de oro, cuyos efectos estéricos y electrónicos determinan su evolución por caminos divergentes próximos en energía. Así, sufren una transposición por pasos dando butadienos o expansión de anillo forjando ciclobutenos. La participación de estos intermedios se demostró generándolos independientemente y examinando su reactividad. Como los ciclobutenos son importantes esqueletos en productos naturales y farmacéuticos, decidimos expandir la cicloadición [2+2] catalizada por oro para sintetizar ciclobutenos más funcionalizados. Encontramos que 1,3-eninos y polienos son sustratos apropiados para lograr 1-vinil-, 3-vinil, o 3-alquinilciclobutenos. Esta metodología resulta complementaria a cicloadiciones [2+2] catalizadas por otros metales. Además, desarrollamos transformaciones directas de los versátiles ciclobutenos en diversas arquitecturas mediante cicloadiciones, aperturas, expansiones y contracciones de anillo. Finalmente, descubrimos reacciones intermoleculares de bromoalquinos con alilsilanos catalizadas por oro que proporcionan un resultado completamente distinto: 1,4-eninos mediante un proceso de tipo acoplamiento cruzado o 1,4-dienos mediante alilación/ciclación. Basado en experimentos y computaciones, el mecanismo parece ocurrir mediante una transposición sin precedentes.
Gold catalysis is a powerful tool to build C–C bonds and create molecular complexity via selective activation of alkynes. Despite the advances in intramolecular reactions of alkynes with alkenes, the intermolecular version remains challenging and sparse, since the final products are also alkenes which compete with the initial substrates leading to oligomerizations. In this Doctoral Thesis, we explored intermolecular reactions of a wide range of alkynes with alkenes and investigated the mechanisms by experiments and DFT calculations. Our group developed the gold(I)-catalyzed [2+2] cycloaddition of arylalkynes with alkenes to furnish regioselectively cyclobutenes. Now we found that ortho-substituted arylalkynes react with alkenes to give 1,3-dienes by a metathesis-type process, whereas less sterically demanding 1,3-butadiynes react with alkenes leading to 1-alkynylcyclobutenes. A comprehensive theoretical study showed that key intermediates in these transformations are cyclopropyl gold(I) carbenes, whose electronic and steric effects determine their evolution through divergent pathways close in energy. Thus, they undergo a stepwise rearrangement to form butadienes or a ring expansion to forge cyclobutenes. To support the involvement of these intermediates, they were independently generated and their reactivity was examined. As cyclobutenes are important features in natural and pharmaceutical products, we focused on expanding the scope of the gold-catalyzed [2+2] cycloaddition to synthesize more functionalized cyclobutenes. 1,3-Enynes and polyenes were found to be suitable substrates to construct 1-vinyl-, 3-vinyl- or 3-alkynylcyclobutenes. This methodology is complementary to the previously reported metal-catalyzed [2+2] cycloadditions. Furthermore, we developed one-pot transformations of the versatile cyclobutenes into diverse architectures via cycloaddition, ring opening, expansion or contraction. Finally, we discovered novel intermolecular reactions of bromoalkynes with allylsilanes catalyzed by gold which render a totally different outcome: skipped enynes via a cross-coupling type process or skipped dienes via allylation/cyclization cascade. Based on experiments and computations, the reaction mechanism was proposed to proceed via an unprecedented rearrangement.

APA, Harvard, Vancouver, ISO, and other styles

49

Lippincott, Daniel John. "Allenes, Alkenes & Alkynes| My Piece of the pi ...in Water at Room Temperature." Thesis, University of California, Santa Barbara, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10982306.

Full text

Abstract:

I. An environmentally responsible, mild method for the synthesis of functionalized 1,3-butadienes is presented. It utilizes allenic esters of varying substitution patterns, as well as a wide range of boron-based nucleophiles under palladium catalysis, generating sp–sp², sp²–sp², and sp²–sp³ bonds. Functional group tolerance measured via robustness screening, along with room temperature and aqueous reaction conditions highlight the methodology’s breadth and potential utility in synthesis.

II. A mild method for the synthesis of highly functionalized [3]–[6]dendralenes is reported, representing a general strategy to diversely substituted higher homologues of the dendralenes. The methodology utilizes allenoates bearing various substitution patterns, along with a wide range of boron and alkenyl nucleophiles that couple under palladium catalysis leading to sp-, sp²-, and sp³-substituted arrays. Regioselective transformations of the newly formed unsymmetrical dendralene derivatives are demonstrated. The use of micellar catalysis, where water is the global reaction medium, and room temperature reaction conditions, highlights the green nature of this technology.

III. A copper-catalyzed oxidative cleavage of electron-rich olefins into their corresponding carbonyl derivatives is described as an alternative to ozonolysis. The scope includes various precursors to aryl ketone derivatives, as well as oxidations of enol ethers bearing atypical alkyl and dialkyl substitution, the first of their kind among such metal catalyzed alkene cleavage reactions. The use of an inexpensive copper salt, room temperature conditions, an aerobic atmosphere, and water as the global reaction medium highlight the green features of this new method. Associated mechanistic investigations are also presented.

APA, Harvard, Vancouver, ISO, and other styles

50

Banerjee, S. "Conversion of alkanes and alkenes over Ga-modified ZSM-5 type zeolites and metal oxide catalyst." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2001. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2314.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Alkane And Alkene'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles