Reaction Product Prediction System

The thermodynamic phase stability diagrams appear to be preferred by corrosion scientists and technologists for the evaluation of gas-metal systems where the chemical composition of the gaseous phase consisting of a single gas or mixture of gases has a critical influence on the formation of surface reaction products which, in turn, may either stifle or accelerate the rate of corrosion. Also, they are used to analyse or predict the reason for the sequence of formation of the phases in a multi-layered surface reaction product on a metal or alloy. 

In developing the thermodynamic framework for ECES, we attempted to synthesize computer software that would correctly predict the vapor-liquid-solid equilibria over a wide range of conditions for multicomponent systems. To do this we needed a good basis which would make evident to the user the chemical and ionic equilibria present in aqueous systems. We chose as our cornerstone the law of mass action which simply stated says "The product of the activities of the reaction products, each raised to the power indicated by its numerical coefficient, divided by the product of the activities of the reactants, each raised to a corresponding power, is a constant at a given temperature. ... 

In the case of heterogeneous catalysis, a DCKM or microkinetic model must incorporate the added dimension of adsorbed chemical species as well as active versus non-active sites. To obtain the full predictive capability from reactant influent to product effluent, all possible reactions in the system, both heterogeneous and homogeneous, must be accounted for. To properly understand the catalytic reaction sequence, it is possible that seemingly unimportant intermediates on the surface may be what initiate gas phase reactions. To begin this elucidation, the surface chemical species and their properties must be known. 

New Heterocyclic Ring Systems Predicted by Computer-AssIsted Organic Synthesis (CAOS). A computer program written for this purpose (55,56) can be used to predict the formation of additional heterocyclic systems from the reactants mentioned in the above sections. These are the systems which, of course, have not been experimentally detected as reaction products so far. 

A stereoselective 6-exo selenoamination to form a tetrahydroisoquinoline ring system is probably a result of the specific substitution pattern.252 Selenocyclizations which generate piperidine systems by 6-endo cyclization give products predicted by reaction through the more stable chair conformation (equation 116).41 158c 216e,232a... 

Any compd or mixt whose heat of formation is smaller by 500 J/g (or more) than the sum of the heats of formation of its reaction products must be regarded with suspicion and handled with more than usual care. The hazards involved in working with a potentially expl system are directly proportional to the amount and to the rate of energy release. Because the reaction kinetics cannot be predicted, the propensity of a new system for expl reaction must be determined. The sensitivity of the system can be evaluated by means of impact, friction, shock and electrostatic discharge. Appropriate methods are reviewed in the Experimental and Hazard Assessment section of this article. Sensitivity to heat or elevated temp may be evaluated by use of differential thermal analysis (DTA)... 

Substrate Reaction type Catalytic system Reaction product (%) Prevailing chirality Enantiomeric excess (%) Quadrant preferred by the substituentb Predicted Found ... 

Microwave food products are rarely as simple as the water and oil systems discussed above and caution must be exercised in predicting the reaction of individual flavor components in complex food systems containing salt, proteins, sugars, starches, and other food ingredients. Liquid products quickly dissipate the microwave energy and result in a more uniform product. Solid food products, multiphase systems, or frozen products develop hot spots during heating which further complicate flavor delivery in these systems. Performance of the flavor in the microwave is dependent not only on the physical/chemical properties of individual flavor components, but more importantly, on the Interaction of these components with complex food systems. 

These examples clearly indicate that the composition of the SSE need not always reflect itself in product distribution, as one would predict from prevailing theory of organic reactions in homogeneous systems. There is always a possibility that some species of the SSE is available in much higher or lower concentration at the electrode-solution interface. This seems to be especially important in the case of water which can strongly influence product composition even if it is present in trace amounts only in the SSE 51. Other hydrogen-bonding solvents show similar properties in this respect 81. ... 

Extending the theory to interpret or predict the rovibrational state distribution of the products of the unimolecular dissociation, requires some postulate about the nature of the motion after the unimolecularly dissociating system leaves the TS on its way to form products. For systems with no potential energy maximum in the exit channel, the higher frequency vibrations will tend to remain in the same vibrational quantum state after leaving the TS. That is, the reaction is expected to be vibrationally adiabatic for those coordinates in the exit channel (we return to vibrational adiabaticity in Section 1.2.9). The hindered rotations and the translation along the reaction coordinate were assumed to be in statistical equilibrium in the exit channel after leaving the TS until an outer TS, the PST TS , is reached. With these assumptions, the products quantum state distribution was calculated. (After the system leaves the PST TS, there can be no further dynamical interactions, by definition.)... 

Predict and explain the stereochemistry of E2 eliminations to form alkenes. Predict the products of E2 reactions on cyclohexane systems. 

In spite of its limitations (as outlined in the previous section) the solubility product relation is of great value in qualitative analysis, since with its aid it is possible not only to explain but also to predict precipitation reactions. The solubility product is in reality an ultimate value which is attained by the ionic product when equilibrium has been established between the solid phase of the slightly soluble salt and the solution. If conditions are such that the ionic product is different from the solubility product, the system will seek to adjust itself in such a manner that the ionic product attains the value of the solubility product. Thus, if the ionic product is arbitrarily made greater than the solubility product, for example by the addition of another salt with a common ion, the adjustment of the system results in the precipitation of the solid salt. Conversely, if the ionic product is made smaller than the solubility product, as, for instance, by diminishing the concentration of one of the ions, equilibrium in the system is attained by some of the solid salt passing into solution. 

Anthra[2,3-r ]furan, which was predicted to be a highly reactive polyene lacking any significant aromatic character despite being a 14 rt-electron system, was prepared by aromatic ring homologation of naphtho[2,3-< ]furan with hydroxybutenolide (Equation 129). The reaction product was trapped as a Diels-Alder adduct <1996S77>. 

The term di-ir-methane rearrangement is meant to describe the photoisomerization of 1,4-dienes (i.e. two TT-systems separated by a methane unit) leading to vinylcyclopropanes. The reaction can be generalized in schematic form as in equation (1). As will be discussed more specifically in the section dealing with mechanism, such a simplistic presentation is not intended as the actual reaction path, but it gready helps in predicting the reaction products. 

Pourbaix diagrams, or pH-potential diagrams, have been constructed to facilitate the prediction of the various phases (reactions and reaction products) that are stable in an aqueous electrochemical system at equilibrium. " Boundary lines in such diagrams divide the areas of stability for different phases and are derived from the use of Nemst equation... 

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