Gotowa bibliografia na temat „Difunctionnalization of internal olefins”

A highly regio- and stereoselective cobalt catalyzed allylic selective dehydrogenative Heck reaction with internal aliphatic olefins was developed. Both internal and terminal aliphatic olefins can be employed, thereby significantly expanding the scope of alkenylation chemistry.

Efficient and H₂O-controlled selective thiocyanation and alkenylation of internal olefins, to afford tetrasubstituted olefins under electrochemical oxidation, has been successfully developed.

L’atome de fluor joue un rôle crucial dans la modulation des propriétés physico-chimiques des molécules organiques. Son incorporation au sein de la structure des médicaments a connu une expansion rapide et importante. En raison de sa forte électronégativité et de sa lipophilie, le motif trifluorométhyle est couramment employé par l’industrie pharmaceutique. De plus, parmi les composés fluorés, les alcènes substitués par du fluor sont également d’une grande importance en chimie médicinale. Dans ce contexte, nous nous sommes intéressés au développement de voies de synthèses pour incorporer des motifs trifluorométhyles et alcènes monofluorés au sein de molécules. Dans un premier temps, nous avons développé une méthode de chlorotrifluorométhylation d’alcènes internes, médiée par la lumière visible et catalysée par un catalyseur photoredox à base de cuivre. La réaction s’est déroulée avec une régiosélectivité totale dans des conditions de réaction douces en utilisant le CF3SO2Cl disponible dans le commerce comme source de trifluorométhyle et de chlore, conduisant à une synthèse de produits chimiques à haute valeur ajoutée avec une économie d'atomes. Les molécules obtenues ont été testés in vitro pour évaluer leurs cytotoxicités contre les lignées cellulaires cancéreuses ainsi que pour leurs activités antifongiques et antibactériennes. Dans un second temps, une synthèse sans solvant a été développée par mécanochimie afin d’accéder à des monofluoroalcènes. La réaction en une étape est très rapide, sans solvant et se déroule dans des conditions douces permettant de limiter l’impact environnemental de synthèse. Le protocole a montré une efficacité et une tolérance générales à un large panel de substrats carbonylés, y compris les aldéhydes et les cétones, et des dérivés de fluorophosphonoacétate.La douleur chronique touche 20 à 30% de la population mondiale et représente des milliards de dollars en coût annuel. Elle représente un véritable enjeu de santé publique rendant essentiel la poursuite des recherches scientifiques dans ce domaine afin de mieux comprendre la douleur chronique et de développer des solutions innovantes pour améliorer la qualité de vie des patients. Les peptides sont des cibles de choix dans la synthèse de nouveaux médicaments. Le peptide neurotensine (8-13) a démontré son efficacité dans le traitement de la douleur, par modulation des signaux nociceptifs, en se liant aux récepteurs neurotensinergiques, principalement NTS1 et NTS2. Néanmoins, la liaison au récepteur NTS1 provoque des effets secondaires néfastes, ce qui n’est pas le cas lors de la liaison à NTS2. Ainsi, une grande sélectivité envers le récepteur NTS2 est essentielle. Cependant, la forte sélectivité du peptide NT(8-13) envers le récepteur NTS1 ne fait pas de ce peptide un composé de choix dans le cas du traitement de la douleur. Ainsi, synthétiser des analogues peptidiques capables d'interagir de manière sélective avec NTS2, dans l'objectif d'améliorer leur efficacité et leur profil pharmacologique tout en minimisant les effets secondaires, représente un défi de choix. Dans ce contexte, ce dernier chapitre décrit la synthèse de composés capables de se lier aux récepteurs neurotensinergiques tout en maximisant la sélectivité envers NTS2. Pour cela, la synthèse peptidique de JMV 7323, JMV 7324, JMV 7325 et JMV 7326 sur support solide a été effectuée. De plus, les peptides obtenus doivent être capable de passer la barrière hémato-encéphalique. Pour cela, le peptide angiopep-2 a été couplé sur le peptide JMV 7324 pour être utilisé comme navette afin d’atteindre la barrière hémato-encéphalique. Les composés ont été testés in vivo dans des modèles de douleur induite par la formaline montrant des résultats prometteurs et les effets secondaires ont été étudiés
The fluorine atom plays a crucial role in modulating the physicochemical properties of organic molecules. Its incorporation into the structure of drugs has expanded rapidly and significantly. Due to its strong electronegativity and lipophilicity, the trifluoromethyl moiety is commonly used by the pharmaceutical industry. In addition, among fluorinated compounds, monofluoroalkenes are also of great importance in medicinal chemistry. In this context, we were interested in the development of synthetic pathways to incorporate trifluoromethyl and monofluoroalkene moieties into molecules. In a first project, we developed a method of chlorotrifluoromethylation of internal alkenes, mediated by visible light and catalyzed by a copper-based photoredox catalyst. The reaction took place with full regioselectivity under mild reaction conditions using commercially available CF3SO2Cl as the source of trifluoromethyl and chlorine, leading to a synthesis of value-added chemicals with atom economy. The molecules obtained were tested in vitro to evaluate their cytotoxicity against cancer cell lines as well as for their antifungal and antibacterial activities. In a second project, a solvent-free synthesis was developed by mechanochemistry to access monofluoroalkenes. The very fast, solvent-free one-step reaction under mild conditions has limited the environmental impact of synthesis. The protocol showed general efficacy and tolerance to a wide range of carbonyl substrates, including aldehydes and ketones, and fluorophosphonoacetate derivatives.Chronic pain affects 20 to 30% of the world's population and represents billions of dollars in annual costs. It represents a real public health issue that makes it essential to continue scientific research in this field to better understand chronic pain and develop innovative solutions to improve the quality of life of patients. Peptides are prime targets in the synthesis of new drugs. The neurotensin peptide (8-13) has demonstrated its efficacy in the treatment of pain, by modulating nociceptive signals, by binding to neurotensinergic receptors, mainly NTS1 and NTS2. Nevertheless, binding to the NTS1 receptor causes harmful side effects, which is not the case when binding to NTS2. Thus, a high selectivity towards the NTS2 receiver is essential. However, the high selectivity of the NT(8-13) peptide towards the NTS1 receptor does not make this peptide a compound of choice for pain treatment. Thus, synthesizing peptide analogues capable of selectively interacting with NTS2, with the aim of improving their efficacy and pharmacological profile while minimizing side effects, represents a challenge of choice. In this context, this chapter describes the synthesis of compounds capable of binding to neurotensinergic receptors while maximizing selectivity towards NTS2. For this, peptide synthesis of JMV 7323, JMV 7324, JMV 7325 and JMV 7326 on solid support was performed. In addition, the resulting peptides must be able to cross the blood-brain barrier. For this, the angiopep-2 peptide was coupled to the JMV 7324 peptide to be used as a shuttle to reach the blood-brain barrier. The compounds were tested in vivo in models of formalin-induced pain showing promising results and side effects were studied

This study investigates the synthesis of several new Gemini surfactants with various hydrophobic carbon chain length amide groups (C12, C14, C16, and C18) using triethylenetetramine, maleic anhydride, and internal olefins with different carbon chain lengths as raw materials. The research examined the adsorption mechanism and hydrophilic modification capacity of four different kinds of Gemini surfactants on the polymethyl methacrylate (PMMA) surface. Surface tension and contact angle data for each Gemini surfactant were used to compute the adhesion work and adhesion tension. According to the surface activity parameters, the critical micelle concentration and maximum adsorption amount decrease with the increase in the length of the hydrophobic carbon chain. However, the equilibrium surface tension first decreases and then increases with the increase in the length of the hydrophobic carbon chain. The four surfactants exhibit complex self-aggregation behavior in the solution due to their long hydrophobic chain structure and flexible spacer. The four surfactants are heavily adsorbed on the PMMA surface, forming semicolloidal aggregates, according to the combination of contact angle measurements, adhesion tension, and interfacial tension data. Moreover, compared with literature, the four surfactants synthesized in this study show better hydrophilic modification ability on the PMMA surface.

This largest class of natural products, with >75 000 known structures, arises from a pair of five-carbon isopentenyl diphosphate isomers, one acting as a π-electron double bond carbon nucleophile, the other as an allylic cation electrophile in C–C bond alkylations. Isoprene/terpene chain growth thus occurs five carbons at a time in head-to-tail couplings by prenyl transferase enzymes. At both the C15 or C20 chain length stages, enzymes can carry out related head-to-head chain couplings to generate the C30 hexaene squalene or the C40 nonaene phytoene. Squalene is the precursor to cyclase-mediated conversion to tetracyclic sterol frameworks and pentacyclic plant systems, such as amyrin and cycloartenol. The C10 (geranyl-PP = monoterpene), C15 (farnesyl-PP = sesquiterpene), and C20 (geranylgeranyl = diterpene) head-to-tail coupled metabolites can undergo many variations of internal carbocation-mediated cyclizations to generate a large array of mono- to tetracyclic olefins and alcohols. The predominant animal sterol is the C27 membrane lipid cholesterol, available from the initial C30 biosynthetic tetracyclic lanosterol by oxygenative removal of three C–CH3 groups. This phase of sterol metabolism marks a shift from carbocation-based reactions, to radical chemistry by oxygenases, as nine O2 molecules are consumed. In further conversion of cholesterol to the female sex hormone estradiol, another eight O2 molecules are consumed, for a total of 17 O2 being reductively split in the metabolic traverse from lanosterol to cholesterol. Meroterpenoid assembly involves the intersection of isoprene biosynthetic machinery with polyketide- or indole-processing enzymes.

Linear even-carbon-number alpha-olefins (LAO) with four or more carbon atoms are important compounds of high demand in chemical industry as precursors of a wide range of value-added chemicals [1]. LAO are used as co-monomers for polyethylene production, for the production of alcohols (mainly in detergents and plasticizers) and for synthesis of polyalphaolefins (used in synthetic lubricants). Alpha-olefins (C4, C6, C8 and C10) are mainly used to produce poly(vinyl chloride) plasticizers, high-density and linear low-density polyethylene to impart the stress-crack resistance. C10–C14 alpha-olefins can be used to synthesize linear alkylbenzene sulfonates (synthetic detergents). A conventional route to produce alpha-olefins is oligomerization of ethylene. The process provides production of high quality alpha-olefins but is very costly. If not oligomerization, LAO can be produced by thermal cracking of waxy paraffins but the product is not pure and contains numerous internal olefins, dienes and paraffin impurities. The process is conducted in the vapor phase at relatively low cracking temperatures and needs rapid quenching to prevent side reactions such as isomerization or cyclization. In our previous work [2], we showed that the selectivity to alpha-olefins can be increased considerably via catalytic cracking of n-alkanes under selective MW heating of catalysts. In the present work, the general regularities of MW cracking of n-alkanes are presented. Porous ceramic matrix Al2O3/Al composites (ceramometals) and various carbon materials (CM) having high dielectric losses were studied as supports of the catalysts. MW cracking was conducted with n-C16H34 and n-C28H58. The influence particle size and surface morphology of ceramometals and CM on the structural and group composition of the products was studied. It was established that LAO (C2-C23) and n-alkanes (C2-C26) were the main cracking products under selective MW heating of the used supports. The quantitative analysis of the products demonstrated that the liquid-phase process is more selective to alpha-olefins at the MW catalytic cracking than at the convectional thermal cracking. Silica modification of the surface of CM was shown to suppress spark discharge (usually observed at MW heating of CM); hence, the thermal cleavage of C-C bonds on the CM surface but not in the plasma discharge contributes the most to the formation of radicals. It was shown that the selectivity to liquid alpha-olefin could be more than 85 % under MW heating of cermets in region of the E - field node and decrease considerably in the region of H - field node.

Abstract During oil and gas drilling operations, formation gas (mostly methane) may enter the wellbore annulus or the drilling riser. This gas influx may get absorbed into the surrounding mud causing complexity for kick detection. Absorption mass transfer experiments of methane into four different fluid systems were performed. The continuous phase for all these fluids was Internal olefins (IO) which is widely used within the drilling industry as a base fluid. Two of the fluids were emulsions (Water as the second phase) and the other fluid comprised of Internal Olefins with Suspentone. Ultrahigh purity methane was used as the absorbing gas phase. The system pressure was kept at 100psi (0.689MPa) with a superficial velocity of 0.009 m/s. Volumetric mass transfer coefficients (kLa) from these experiments were individually determined using a bubble column with an internal diameter of 0.0381m. The volume of the liquid was kept constant during each of the tests. It was observed that methane in pure IO has the highest kLa value while its value is the lowest when it was flown through the IO/Water/suspentone fluid system. The reduction of kLa values was attributed to the increase of viscosity of the fluid and reduction of interfacial area of the IO due to the addition of water.

The HCCI combustion process is highly reliant upon a favorable in-cylinder thermal environment in an engine, for a given fuel. Commercial fuels can differ considerably in composition and auto-ignition chemistry, hence strategies intended to bring HCCI to market must account for this fuel variability. To this end, a test matrix consisting of eight gasoline fuels comprised of blends made solely from refinery streams were run in an experimental, single cylinder HCCI engine. All fuels contained 10% ethanol by volume and were representative of a cross-section of fuels one would expect to find at gasoline pumps across the United States. The properties of the fuels were varied according to research octane number (RON), sensitivity (S=RON-MON) and volumetric content of aromatics and olefins. For each fuel, a sweep of load (mass of fuel injected per cycle) was conducted and the intake air temperature was adjusted in order to keep the crank angle of the 50% mass fraction burned point (CA50) constant. By analyzing the amount of temperature compensation required to maintain constant combustion phasing, it was possible to determine the sensitivity of HCCI to changes in load for various fuels. In addition, the deviation of fuel properties brought about variations in important engine performance metrics like specific fuel consumption. Though the injected energy content per cycle was matched at the baseline point across the test fuel matrix, thermodynamic differences resulted in a spread of specific fuel consumption for the fuels tested.

HCCI combustion is highly dependent on in-cylinder thermal conditions favorable to auto-ignition, for a given fuel. Fuels available at the pump can differ considerably in composition and auto-ignition chemistry, hence strategies intended to bring HCCI to market must account for the fuel variability. To this end, a test matrix consisting of eight gasoline fuels composed of blends made solely from refinery streams was investigated in an experimental, single cylinder HCCI engine. The base compositions were largely representative of gasoline one would expect to find across the United States, although some of the fuels had slightly lower average octane values than the ASTM minimum specification of 87. All fuels had 10% ethanol by volume included in the blend. The properties of the fuels were varied according to research octane number (RON), sensitivity (S=RON−MON) and the volumetric fractions of aromatics and olefins. For each fuel, a sweep of the fuelling was carried out at each speed from the level of instability to excessive ringing to determine the limits of HCCI operation. This was repeated for a range of speeds to determine the overall operability zone. The fuels were kept at a constant intake air temperature during these tests. The variation of fuel properties brought about changes in the overall operating range of each fuel, as some fuels had more favorable low load limits, whereas others enabled more benefit at the high load limit. The extent to which the combustion event changed from the low load limit to the high load limit was examined as well, to provide a relative criterion indicating the sensitivity of HCCI range to particular fuel properties.

Risk Based Inspection (RBI) results in calculating a risk value for each piece of plant fixed-equipment. Usually RBI implementation results in fixed-equipment inspection program modification. Inspection is specified for equipment items that exceed Owner acceptable risk criteria while it is waived for equipment that is below acceptable risk levels. In RBI analysis, equipment risk value consists of a Likelihood-of-Failure (LOF) and a Consequence-of-Failure (COF) element. Furthermore LOF value is the sum of different equipment damage mechanisms (internal corrosion, external corrosion and cracking mechanisms). This paper describes on Olefins plant gains from applying RBI as a reliability-engineering tool instead of an inspection optimization tool. Based on RBI calculated risk values, fixed-equipment relative risk ranking is established to: • set priorities and focus our attention on the critical areas; • justify capital investment for Lifetime Extension projects; • proactively address Loss of Primary Containment and Process safety issues.

With advanced engines pushing the limits of fuel efficiency, rapid development and improvement of engines increasingly rely on insights from simulations. Reliable simulations require fuel models that consist of a fuel surrogate and its kinetic mechanism. As complexity and sources of fuels vary, a good surrogate needs to be tailored for the specific test fuel. A simple surrogate, typically consisting of 1 to 3 components, can match a single property of the real fuel, such as ignition quality or average molecular weight. More complex surrogates with 4 to 7 components can capture many properties simultaneously. While simple surrogates are good for estimating ignition in engines they require some compensation for the mismatch of the fuels’s physical properties. Complex surrogates can be used to directly represent real fuels in both laboratory experiments and simulations. We have developed a surrogate blending methodology to identify surrogates with a desired degree of complexity. This involves methods that estimate properties for fuel blends, including ignition quality, sooting propensity, distillation curve, as well as other physical and chemical properties that are important to combustion behavior in simulations. We have assembled and developed a rich library of over 60 fuel components from which we can formulate surrogates to represent most gasoline, diesel, gaseous fuels, renewable fuels, and several additives. The components cover a carbon number range from 1 to 20, and chemical classes including linear and branched alkanes, olefins, aromatics with one and two rings, alcohols, esters, and ethers. As part of the library, we have assembled self-consistent and detailed reaction mechanisms for all the components. The mechanisms also include comprehensive NOx creation and destruction pathways, molecular weight growth kinetics leading to the formation of polycyclic aromatic hydrocarbons (PAH), and a detailed soot-surface mechanism. The mechanisms have been validated extensively using over 500 published sets of experimental kinetics data from a wide range of facilities and diagnostic methods. Over the past decade, the validation suite has been used to improve the kinetics database such that good predictions and agreement to data are achieved for the fuel components and fuel-component blends, within experimental uncertainties. This effectively eliminates the need to tune specific rate parameters when employing the kinetics mechanisms in combustion simulations. For engine simulations, the master mechanisms have been reduced using a combination of available reduction methods while strictly controlling the error tolerances for targeted predictions. These include several directed relation graph (DRG) based methods and sensitivity analysis. Iteratively using these reduction methods has resulted in small mechanisms for efficiently incorporating the validated kinetics into computational fluid dynamics (CFD) applications. The surrogate formulation methodology, the comprehensive fuel library, and mechanism reduction strategies suggested in this work allow the use of CFD to explore design concepts and fuel effects in engines with reliable predictions.