Hydrocarbons computation

Computes thermodynamic properties of air, argon, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, water vapor, and products of combustion for hydrocarbons. Computes all properties from any two independent properties. 

Jerman-Blazic Dzonova, B. and Trinajstic, N. (1982). Computer-Aided Enumeration and Generation of the Kekule Structures in Conjugated Hydrocarbons. Computers Chem., 6,121-132. 

Castro, E.A., Tueros, M. and Toropov, A.A. (2000) Maximum topological distances based indices as molecular descriptors for QSPR 2 - application to aromatic hydrocarbons. Computers Chem., 24, 571-576. 

Klavzar, S., Zigert, P. and Gutman, I. (2000) An algorithm for the calculation of the hyper-Wiener index of henzenoid hydrocarbons. Computers Chem., 24, 229-233. 

Trohalaki S, Gifford E, Pachter R. Improved QSARs for predictive toxicology of halogenated hydrocarbons. Comput Chem 2000 24 421 427. 

Tasi, G., Izsak, R., Matisz, G., Csaszar, A.G., Kallay M., Ruscic, B., Stanton, J.F. The origin of systematic error in the standard enthalpies of formation of hydrocarbons computed via atomization schemes, ChemPhysChem 2006, 7,1664-7. 

Library Search Routines To aid in the identification of hydrocarbons, computer programs are being developed for comparing unknown spectra to libraries of known compounds. As an example, a sample of 2-hexadecanol was compared to a library of over 100 compounds. The library search identified 2-hexadecanol as the... 

In the last column, Mb is the number of chemical bonds (or nearest neighbors) in the hydrocarbon. [Computations based on data from Wen and Hung (1970) and McAuliffe (1966).]... 

Song, X.-H., Xiao, M., and Yu, R.-Q. (1994) Artificial neural networks applied to classification of mutagenic activity of nitro-substituted polycyclic aromatic hydrocarbons. Comput. Chem. 18,391-396. 

Table I lists solubility parameter values for oxygen and several hydrocarbons, computed at -297 F. The square of the differences between the parameters for hydrocarbons and oxygen, which qualitatively indicates the departure of that binary system from ideality, is listed in the right-hand column. The difference for the methane-oxygen system is small (0,33) and the system approximates ideality. The differences for the other materials are larger, showing greater departure from ideality.

In section III.B.6, it was mentioned that though Dewar and co-workers were able to reproduce energies of conjugated acyclic hydrocarbons computed by the Pariser—Parr—Pople method with an empirical scheme using only two bond types (single and double), we were unable to do this using Hiickel calcula-... 

This observation that the length of the hydrocarbon chain could be varied from 16 to 26 carbon atoms without affecting the limiting area could only mean that at this point the molecules were oriented vertically. From the molecular weight and density of palmitic acid, one computes a molecular volume of 495 A a molecule occupying only 21 A on the surface could then be about 4.5 A on the side but must be about 23 A long. In this way one begins to obtain information about the shape and orientation as well as the size of molecules. 

There has been considerable interest in the simulation of lipid bilayers due to their biological importance. Early calculations on amphiphilic assemblies were limited by the computing power available, and so relatively simple models were employed. One of the most important of these is the mean field approach of Marcelja [Marcelja 1973, 1974], in which the interaction of a single hydrocarbon chain with its neighbours is represented by two additional contributions to the energy function. The energy of a chain in the mean field is given by ... 

Du Pont called this new lubricant material Krytox (64,65) and initially it had such extraordinary properties that it sold for 200/kg ( 187kg ca 1993). Krytox was and is used ia most of the vacuum pumps and diffusion oil pumps for the microelectronics iadustry ia this country and ia Japan because it produces no hydrocarbon (or fluorocarbon) vapor contamination. It has also found important appHcations ia the lubrication of computer tapes and ia other data processiag appHcations as weU as military and space appHcations. 

The dipole moment (A) of a molecule is the first moment of the elec tric charge density of a molecule. Paraffins have dipole moments of zero, while dipole moments of almost all hydrocarbons are small. McClellan lists many dipole moments. The computer method of Dixon and Jurs" is the most useful method for predicting dipole moments. Lyman et al. give other methods of calculation. 

However, the total number of equilibrium stages N, N/N,n, or the external-reflux ratio can be substituted for one of these three specifications. It should be noted that the feed location is automatically specified as the optimum one this is assumed in the Underwood equations. The assumption of saturated reflux is also inherent in the Fenske and Underwood equations. An important limitation on the Underwood equations is the assumption of constant molar overflow. As discussed by Henley and Seader (op. cit.), this assumption can lead to a prediction of the minimum reflux that is considerably lower than the actual value. No such assumption is inherent in the Fenske equation. An exact calculational technique for minimum reflux is given by Tavana and Hansen [Jnd. E/ig. Chem. Process Des. Dev., 18, 154 (1979)]. A computer program for the FUG method is given by Chang [Hydrocarbon Process., 60(8), 79 (1980)]. The method is best applied to mixtures that form ideal or nearly ideal solutions. 

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