Pseudo-pure compound

The first was presented by Kumar and Kunzru (1985) for modelling of naphtha pyrolysis. In this study, it is assumed that naphtha could be represented as a pseudo-pure compound and the primary decomposition represented by a single reaction with the initial selectivities determined experimentally. Based on the experimental results, the primary reaction is represented by a first order reaction for the whole range of conversions and the initial selectivities are assumed to be constant. The secondary reactions are also represented by molecular reactions and only important secondary reactions that can occur between the various primary products have been accounted for. A sixth-order Runge-Kutta-Verner method was used by these authors to solve a set of reactions which include 22 reactions and 14 components. The predicted and experimental product yields were compared and the rate constants adjusted, by trial-and-error, to minimize the deviation between the predicted and experimental values. The major limitation of this approach is that the initial selectivities are to be determined experimentally. 

Calculate the volume using Kay s method. In this method, V is found from the equation V = ZRT/P, where Z, the compressibility factor, is calculated on the basis of pseudocritical constants that are computed as mole-fraction-weighted averages of the critical constants of the pure compounds. Thus, T = Z K, 71, and similarly for Pc and Z, where the subscript c denotes critical, the prime denotes pseudo, the subscript i pertains to the ith component, and Y is mole fraction. Pure-component critical properties can be obtained from handbooks. The calculations can then be set out as a matrix ... 

All the above three provide extensive data sources and simulators for estimating various thermodynamic properties of pure compounds, well-defined mixtures and petroleum fluids. The respective manuals describe in detail various methods used for estimating the properties and their limitations while at the same time providing the user with choices. The Aspen Physical Property System and SUPBRTRAPP can also be used to estimate thermodynamic profrerties using the pseudo-component characterization of petroleum fluids. The reader is referred to the respective manuals/sim-ulators for details. 

Use of pseudo-chiral auxiliaries also allows the diastereoselective formation of substituted cyclobutane. Very high diastereo-selectivities can be achieved using the concept of chirality transfer from a suitably protected (T -glyceraldehyde derivative. After removal of the auxiliary, enantiomerically pure compounds are obtained (eq 129). However, use of chiral CuOTf coirjtlexes does not afford significant enantioselectivity (< 5%). ... 

On the other hand, when the pure anhydride (XXXIV) was heated on a steam bath, without hydrochloric acid, analyses with periodic acid at room temperature showed that the reaction is reversible and that an equilibrium is reached when the solution contains approximately 92 % of compound XXXIV. The investigators deduce from their experimental data that the dehydration reaction is reversible and pseudo-monomolecular. The data fit the following equation. 

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