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Reactions pathway

Reaction pathways help. see the connection of all interacting species for multiple reactions. We have already seen two relatively. simple reaction paihw ays. one to explain the first-order rate law, (M + A -J A + M) and one [Pg.391]

Smog Formation. In Chapter 1. Problem PI-14. in the CD-ROM Sr, Web Module, we discussed a very simple model for smog removal in Ihe 1 basin by a Santa Ana wind. We will now look a little deeper into the chemi of smog formation. Nitrogen and oxygen react to form nitric oxide in the inder of automobile engine.s. The NO from automobile exhaust is oxidizei NOi in the presence of peroxide radicals. [Pg.392]

Nitrogen dioxide is then decomposed photochemically to give nascent oxy [Pg.392]

The ozone then becomes involved in a whole series of reactions with hy carbons in the atmosphere to form aldehydes, various free radicals, and o intermediates, which react further to produce undesirable products in pollution  [Pg.392]

One specific example is the reaction of ozone with 1,3-butadiene to f acrolein and formaldehyde, which are severe eye irritants. [Pg.392]

The following reaction types were modeled in SARCRACK  [Pg.269]

AHYC also models olefin saturation and (in an empirical way) paraffin isomerization. [Pg.270]

Recent publications confirm that a hydrotreater removes sulfur from organic sulfides, disulfides, and mercaptans with relative ease. Thiophenes, benzothiophenes, unhindered dibenzothiophenes and hindered dibenzo-thiophenes are successively harder to desulfurize. [Pg.270]

Structural differences between sulfur-containing compounds translate into significantly different HDS reaction rates. Table 8 shows pilot plant data for the HDS of small amounts of pure thiophenes in a clean-diesel solvent. The catalyst and temperature were the same for each compound. Note that HDS rates for the first three compounds, which are unhindered, are 30 to 100 times faster than rates for the last three compounds, which are hindered. [Pg.270]

Sulfur Compound ReL HDS Rate Boilii Point (°F) Boiling Point (°C) [Pg.271]

Several reaction pathways are built into the FREZCHEM model including (1) temperature change, (2) evaporation, (3) pressure change, (4) equilibrium or fractional crystallization and, for gas hydrates, (5) open or closed carbon systems, and (6) pure or mixed gas hydrates. Under the temperature change option, the user can specify the upper and lower temperature range and a decremental temperature interval (AT) at which equilibrium at a fixed pressure is calculated (e.g., 298.15 to 253.15K with AT = 5 would result in [Pg.22]

Under the pressure change option, the user can specify a lower and upper pressure range and an incremental pressure interval (AP) at which equilibrium is calculated at a fixed temperature (e.g., 1 to 1001 bars with AP = 100 bars would result in equilibrium calculations at 1, 101,. ..and 1001 bars). Under equilibrium crystallization , solid phases that have precipitated are allowed to dissolve and repreciptate as different solids when environmental drivers such as temperature, pressure, or evaporation change. Under fractional crystallization , a precipitated solid phase is not allowed to subsequently dissolve and reprecipitate when environmental drivers change this option allows for hypothetical removal (layering) of precipitates in basins when environmental drivers change. [Pg.23]

Having located the local minima and the Transition State connecting reactants to products, the question of the connecting pathway arises. While there are well-defined procedures for computing the actual reaction profile [11], the heavy computational demand makes this impractical for TM systems. In many cases, therefore, the relative energies of reactants, products and TSs are considered sufficient and a detailed reaction path is often not computed. [Pg.9]


Halgren T A and Lipscomb W N 1977 The synchronous transit method for determining reaction pathways and locating molecular transition states Chem. Phys. Lett. 49 225... [Pg.2358]

The EROS (Elaboration of Reactions for Organic Synthesis) system [26] is a knowledge-based system which was created for the simulation of organic reactions. Given a certain set of starting materials, EROS investigates the potential reaction pathways. It produces sequences of simultaneous and consecutive reactions and attempts to predict the products that will be obtained in those reactions. [Pg.481]

This is a question of reaction prediction. In fact, this is a deterministic system. If we knew the rules of chemistry completely, and understood chemical reactivity fully, we should be able to answer this question and to predict the outcome of a reaction. Thus, we might use quantum mechanical calculations for exploring the structure and energetics of various transition states in order to find out which reaction pathway is followed. This requires calculations of quite a high degree of sophistication. In addition, modeling the influence of solvents on... [Pg.542]

At the outset of the development of each module for one of the above mechanistic classes of reactions, a thorough analysis of the literature was performed. On that basis, the developer came up with an evaluation framework that was used to make decisions between various reaction pathways and mechanistic possibilities. [Pg.549]

Kinetic en aluation Clearly, the most in-depth evaluation would be based on the kinetic modeling of a reaction pathway. Unfortunately, in many cases insufficient experimental data arc available to develop a full kinetic model of a reaction pathway. Nevertheless, it has been shown with various examples that the development of a kinetic model is possible. This has been performed for the acid-... [Pg.552]

The question is now Which reaction pathways arc Followed, and to what extent This asks for a detailed modeling of the kinetics of the individual reaction steps of this network. This can be achieved on the basis of the half-lives of four s-triazinc herbicides in soil [17]. Figure 10.3-13 shows the four compounds For which data were Found in the literature. [Pg.553]

The challenges for computational chernislry are to characteri/e and predict the structure and stability of chemical systems, to estimate energy differences between different states, and to explain reaction pathways and mechanisms at the atomic level. Meeting these challenges could eliminate tinie-consiini mg experiments. [Pg.7]

Example Researchers have used MX DO and. AMI setn i-etn pirical methods It) calculate possible reaction pathways for the interae-... [Pg.9]

The success of simple theoretical models m determining the properties of stable molecules may not carry over into reaction pathways. Therefore, ah initio calcii lation s with larger basis sets ni ay be more successful in locatin g transition structures th an semi-empir-ical methods, or even methods using minimal or small basis sets. [Pg.307]

The traditional way to provide the nuclear coordinates to a quantum mechanical program is via a Z-matrix, in which the positions of the nuclei are defined in terms of a set of intei ii.il coordinates (see Section 1.2). Some programs also accept coordinates in Cartesian formal, which can be more convenient for large systems. It can sometimes be important to choow an appropriate set of internal coordinates, especially when locating rninima or transitinn points or when following reaction pathways. This is discussed in more detail in Section 5.7. [Pg.94]

The bond orders obtained from Mayer s formula often seem intuitively reasonable, as illustrated in Table 2.6 for some simple molecules. The method has also been used to compute the bond orders for intermediate structures in reactions of the form H -1- XH HX -1- H and X I- XH -H H (X = F, Cl, Br). The results suggested that bond orders were a useful way to describe the similarity of the transition structure to the reactants or to the products. Moreover, the bond orders were approximately conserved along the reaction pathway. [Pg.103]

A steepest descents minimisation algorithm produces a path that oscillates about the true reaction pathway Ihe transition structure to a minimum. [Pg.304]

Transition Structures and Reaction Pathways for Large Systems... [Pg.305]

Cee M L and M Page 1993. Computing Reaction Pathways on Molecular Potential Energy Surfaces. In Lipkowitz K B and D B Boyd (Editors). Reviews in Computational Chemistry Volume 4. New York, VCH Publishers, pp. 35-65. [Pg.314]

A transition structure is, of course, a maximum on the reaction pathway. One well-defined reaction path is the least energy or intrinsic reaction path (IRC). Quasi-Newton methods oscillate around the IRC path from one iteration to the next. Several researchers have proposed methods for obtaining the IRC path from the quasi-Newton optimization based on this observation. [Pg.154]

This genera] scheme could be used to explain hydrogen exchange in the 5-position, providing a new alternative for the reaction (466). This leads us also to ask whether some reactions described as typically electrophilic cannot also be rationalized by a preliminary hydration of the C2=N bond. The nitration reaction of 2-dialkylaminothiazoles could occur, for example, on the enamine-like intermediate (229) (Scheme 141). This scheme would explain why alkyl groups on the exocyclic nitrogen may drastically change the reaction pathway (see Section rV.l.A). Kinetic studies and careful analysis of by-products would enable a check of this hypothesis. [Pg.85]

The mechanism and the stereochemistry of the reaction was studied using borodeuteride andfor deuterium oxide (480) and a reaction pathway was suggested (Scheme 93). [Pg.133]

Like tert butyloxonium ion tert butyl cation is an intermediate along the reaction pathway It is however a relatively unstable species and its formation by dissociation of the alkyloxonium ion is endothermic Step 2 is the slowest step m the mechanism and has the highest activation energy Figure 4 8 shows a potential energy diagram for this step... [Pg.156]

Dehydrohalogenation of alkyl halides (Sections 5 14-5 16) Strong bases cause a proton and a halide to be lost from adjacent carbons of an alkyl halide to yield an alkene Regioselectivity is in accord with the Zaitsev rule The order of halide reactivity is I > Br > Cl > F A concerted E2 reaction pathway is followed carbocations are not involved and rearrangements do not occur An anti coplanar arrangement of the proton being removed and the halide being lost characterizes the transition state... [Pg.222]

Rearrangements when they do occur are taken as evidence for carbocation inter mediates and point to the S l mechanism as the reaction pathway Rearrangements are never observed m 8 2 reactions... [Pg.345]

The tertiary carbocation formed m this step can react according to any of the various reaction pathways available to carbocations One of these is loss of a proton to give a double bond... [Pg.1088]


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4-chlorophenol reaction pathway

A classification of photochemical reaction pathways

Active intermediates reaction pathways

Additional reaction pathway

Al reaction pathways

Aldol reaction pathway

Anionic pathways Heck reaction

Antioxidative reaction pathways

Aqueous reaction pathways

Arene-alkene photocycloaddition reactions exciplex pathway

Aryl-assisted pathway, nucleophilic reactions

Asymmetric hydrogenation enamide 94, reaction pathways

Asymmetric hydrogenation reaction pathway

Atom-water reaction pathways

Beckmann reaction pathway

Benzene reaction pathway

Bifunctional reaction pathway

Biochemical reactions organization into pathways

Biotransformation pathways, reaction

Butyl alcohols reaction pathways

Calculations , reaction pathways

Carbocations reaction pathways

Catabolic pathway, biological reactions

Cationic pathways, Heck reaction

Chemical reactions pathways

Chemical vapor deposition reaction pathways

Chemisorbed reaction pathway

Chiral and Achiral Pathways of Degenerate Reactions

Competing reaction pathways

Competition from other reaction pathways

Concerted pathway, aldol reaction

Concerted reaction pathways

Conrotatory Reaction pathway

Cyclic phosphorus compounds, reaction pathway

Cyclohexanol, reaction pathway

Cyclohexanone, reaction pathway

Cytosol pentose phosphate pathway reactions

Dehydroquinate pathway reactions

Determination of Reaction Pathways

Determination of Transition Structures and Reaction Pathways

Diagenesis reaction pathways

Dimerization reaction pathway

Dimethylphenol reaction pathways

Disrotatory Reaction pathway

Dominant reaction pathway

EPSP synthase, enzyme intermediates reaction pathway

Electrochemical reactions inner-sphere pathways

Electrode reactions irreversible reaction pathway

Electron ejection reaction pathways

Electrophilic reaction pathway

Enantiomeric products, reaction pathway

Energetics and Reaction Pathways Metallic Edge States as Active Sites

Energetics and reaction pathways

Energy transformation in biochemical reactions and pathways

Environment reaction pathways

Enzymatic reaction pathways, mapping

Ester hydrolysis reaction pathway

Ethanol decomposition, reaction pathway

Ethylene reaction pathways

Exothermic reactions pathway

Formation mechanisms Maillard reaction pathway

Formation mechanisms reaction pathway

Free energy reaction pathways

Gas-phase reaction pathways

Humification Maillard reaction pathway

Humification reaction pathway

Hydride Transfer Reaction Pathway

Hydrolysis reaction pathway

Hypersurfaces reaction pathways

Ion Radicals. Competition Between Reaction Pathways

Irreversible reaction pathway

Irreversible reaction pathway examples

Isocitrate dehydrogenase reaction pathway

Ketene-imine reaction pathway

Keys to Success Competitive Reaction Pathways and the Intramolecular Aldol Condensation

Kinetic consequences of reaction pathways

Maillard reaction oxidative pathways

Mannich/Michael reaction pathway

Metabolic pathways rate-limiting reactions

Metalloporphyrin reaction pathways

Methanol carbonylation reaction pathways

Methionine synthase reaction pathways

Mixed-function oxidation reaction pathway

Model compound reaction pathways and

Model compound reaction pathways and kinetics

Monophosphine pathway reaction

Mukaiyama aldol reaction pathway

Multiple reaction paths transition-state pathways

Neutral pathways, Heck reaction

Nitric oxide ozone reaction pathway

Nitric oxide reaction pathway

Nitrogen adsorption reaction pathway

Organic synthesis reaction pathways

Organometallic compounds reaction pathways

Oxidative addition reaction pathway

Oxygen reaction pathway

Oxygen reduction reaction 2-electron transfer pathway

Oxygen reduction reaction catalysts pathways

Oxygen reduction reaction pathway

Ozone propene reaction pathway

Pathway matrix, biochemical reactions

Pathway minimal energy reaction path

Pathway of Catalytic Reactions

Pathway of a chemical reaction

Pathways for Flavor Formation via the Maillard Reaction

Pathways to the Reaction Centre

Pentose phosphate pathway group-transfer reactions

Pentose phosphate pathway reaction details

Pentose phosphate pathway reactions

Perchloro-organic chemistry: structure, spectroscopy and reaction pathways

Phenol hydroxylation reaction pathway

Photochemical processes, reaction pathways

Photochemical reaction pathways

Photochemical reactions general pathways

Poisoning reaction pathways

Pollution prevention reaction pathway synthesis

Poly reaction pathways

Polyphenol pathway reaction

Possible reaction pathways

Potential energy surfaces reaction pathways

Principal reaction pathways

Principles Governing the Reaction Pathway

Prooxidative reaction pathways

Propylene oxide reaction pathways

Proton-transfer reaction pathways

Protonation reaction pathway

Pyrolytic reaction pathway

Quinone methides reaction pathway

REACTION MECHANISMS, PATHWAYS, BIOREACTIONS, AND BIOREACTORS

Radical reaction pathways

Radical reactions disproportionation pathways primary

Rates and Reaction Pathways The How Fast Question

Reaction Pathway or Catalytic Cycle

Reaction Pathways and Kinetics of Redox Reactions

Reaction Pathways and Mechanisms

Reaction Pathways for the Reduction of Molecular Oxygen

Reaction Pathways of

Reaction Pathways, Catalyst Selection and Performance Example Analysis

Reaction Rates and Transition Pathways

Reaction Signalling pathway

Reaction free radical pathway

Reaction pathway analysis

Reaction pathway and localization of the phenomena

Reaction pathway bifurcated

Reaction pathway control

Reaction pathway ground-state

Reaction pathway modification

Reaction pathway rectangular

Reaction pathway studies

Reaction pathway tetrahedral

Reaction pathway, and

Reaction pathway, energy profile

Reaction pathways RRKM calculations

Reaction pathways RRKM dynamics

Reaction pathways anodic dissolution

Reaction pathways bacteriorhodopsin

Reaction pathways etching

Reaction pathways hierarchical structure

Reaction pathways kinetic cycle

Reaction pathways molecular labeling

Reaction pathways numerical experiments

Reaction pathways of mineral-water interaction

Reaction pathways parameteres

Reaction pathways quantitative reasoning

Reaction pathways reactive systems

Reaction pathways redox couples

Reaction pathways research applications

Reaction pathways synthesis

Reaction pathways trajectory model

Reaction pathways transition state theory

Reaction pathways, complex

Reaction pathways, halogenated

Reaction pathways, halogenated salts

Reaction pathways, oxidative

Reaction rates and pathways

Reaction rates pathways

Reaction times left of the first peak in patients with prolonged linear pathway

Reaction, identity pathway

Reactions Are Organized into Sequences or Pathways

Reactions and reaction pathways

Reactions interaction pathways

Reactions reverse, pathway

Reactivity and Reaction Pathways of Organometallic Compounds

Reconstruction of reaction pathways

Redox mechanism reaction pathways

Reductive dehalogenation reaction pathways

Retro-Michael reaction pathway

Rhodium-catalyzed hydrogenation, reaction pathway

Ruthenium-catalyzed hydrogenation reaction pathway

Scheme of the Mixed-Function Oxidation Reaction Pathway

Schmidt reactions pathways

Serial reaction pathway

Steam reaction pathways

Structure reaction pathway

Subject reaction pathways

Sulfide catalysts reaction pathway

Tafel Slopes for Reactions Proceeding in Multistep Pathways

The Pathway of Photochemical Reactions

Theoretically Based Alkylation Reaction Pathways

Theoretically Based Carbocupration Reaction Pathway

Theoretically Based Conjugate Addition Reaction Pathway

Thermal reaction pathways

Thermodynamic pathways Intermediate reactions

Transition metal reaction pathways, calculation

Transition state theory , development reaction pathways

Transsulfuration pathway reactions

Unimolecular reactions reaction pathway

Weathering reaction pathways

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