Database of physical properties

Databases of physical properties and their calculations are an integral part of any chemical/biological design problem. 

The typical approach to developing analytic potential energy functions is to assume a mathematical expression containing a set of parameters that are subsequently fit to a database of physical properties. An effective potential function requires a mathematical expression that both accurately reproduces this database and is transferable to structures and dynamics beyond those to which it is fit. The latter property is especially critical if an atomistic simulation is to have useful predictive capabilities. Whereas an extensive and well-chosen database from which parameters are determined is important, transferability ultimately depends on the chosen mathematical expression. The definitive expression, however, has yet to be developed. Indeed, many different forms are used, ranging from those derived from quantum mechanical bonding ideas to others based on ad hoc assumptions. 

Lipidat (a database of physical properties of lipids) www.lipidat.chemistry.ohio-state.edu. 

Equilibrium combustion product compositions and properties may be readily calculated using thermochemical computer codes which minimize the Gibbs free energy and use thermodynamic databases containing polynomial curve-fits of physical properties. Two widely used versions are those developed at NASA Lewis (Gordon and McBride, NASA SP-273, 1971) and at Stanford University (Reynolds, STANJAN Chemical Equilibrium Solver, Stanford University, 1987). 

As computers become more pervasive and increasingly powerful, specialized programs and databases are being developed to assist in a wide variety of research efforts. This is true in the search for solvent alternatives, and in this section we review the application of computers to solvent substitution studies and cover computer-aided molecular design of new solvents, methods developed for the prediction of physical properties, methods for predicting less precise chemical characteristics such as toxicity and carcinogenicity, and computer-aided design of alternative synthetic pathways. 

Although ASPEN-Plus is widely used to simulate petrochemical processes, its uses for modeling biomass processes are limited owing to the limited availability of physical properties that best describe biomass components such as cellulose, xylan, and lignin. For example, Lynd et al. (1) used conventional methods to calculate the economic viability of a biom-ass-to-ethanol process. However, with the development by the National Renewable Energy Laboratory (NREL) of an ASPEN-Plus physical property database for biofuels components, modified versions of ASPEN-Plus software can now be used to model biomass processes (2). Wooley et al. (3) used ASPEN-Plus simulation software to calculate equipment and energy costs for an entire biomass-to-ethanol process that made use of dilute-H2S04 acid pretreatment. 

Design Institute of Physical Properties and Data (DIPPR), American Institute of Chemical Engineers, New York, 1985-9 databases. 

A rectangular range of data in an Excel worksheet can be used as a list or database. A database consists of a number of records, each of which can contain a number of fields. For example, a compilation of physical properties of organic compounds, such as the one in the CRC Handbook of Chemistry and Physics, is a database the row of data for a particular compound is a record and the values for the melting point, boiling point, solubility, etc. are the data fields within the record. In Excel, a list or database must be arranged in tabular form, with row or column labels that s the only requirement. 

Willett, P. (1988). Ranking and Clustering of Chemical Structure Databases. In Physical Property Prediction in Organic Chemistry (Jochum, C., Hicks, M.G. and Sunkel, J., eds.), Springer-Ver-lag, Berlin (Germany), pp. 191-207. 

Syracuse ResearchCorporation(SRC)(http //www.syrres. com/esc/physdemo.htm) offers commercial online searches of a number of physical property databases, including online logP measurements (octanol-water partition coefficient), environmental fate for over 25,000 chemicals. 

NCMS has a rather interesting free and fairly extensive database of solvents that allows rather extensive input of physical property ranges and various user-specified limits such as not a carcinogen or not listed on the Montreal protocol (ozone) (http //solvdb.ncms.org/solvdb.htm). 

Further analyses of large proprietary databases have focused on matched pair analysis of phenyl substituent effects on metabolic stability and on cytochrome P450, hERG inhibition, solubility and artificial membrane permeability." These studies also show that substituent lipophilicity is the dominant driver of ADMET properties. However, because of the opposing effects of physical properties (for example on solubility and permeability) there are no perfect substituents, where all ADMET properties are improved at... 

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